Osteonecrosis of the Humeral Head 3 Years Following Fracture Fixation of a 4-Part Proximal Humerus Fracture: A Case Report.

Introduction: Osteonecrosis (ON) of the humeral head is defined as "avascular" when the death of bone is due to a disrupted blood supply. It is a known complication following proximal humeral fractures and can lead to poor long-term outcomes and even additional revision surgeries. Case Report: Patient AP developed symptomatic ON, 3 years following repair of a 4-part valgus impacted proximal humerus fracture. The point of interest in this case is the length of time from injury at which she developed symptomatic ON. Following surgical repair, she was seen at standard intervals, 6 weeks, 3-, 6-, and 12- month follow-ups and demonstrated an excellent recovery. By the 1 year follow-up appointment, she had obtained a range of motion in her left shoulder of 170° forward elevation and 60° in external rotation. At this point, she was able to discontinue physical therapy and was radiographically and clinically healed. However, 2 years after, she began experiencing sudden onset of pain with shoulder ROM and progressive limitation. She was diagnosed with an ON of her proximal humerus. The patient was prescribed a 3-month course of corticosteroid, 3 months following her operation for a gynecological-related issue. However, with strong progress being made 9 months after this prescription, and problems occurring over 2 years after taking the medication, it is unclear whether the ON was related to her fracture pattern or developed as a result of the corticosteroid usage or a combination of the 2 due to a "double hit." Conclusion: This case review points out the potential need for continued monitoring even after radiographic and clinical healing is achieved in these injuries.

Case report: A novel somatic SDHB variant in a patient with bladder paraganglioma.

Background: Paragangliomas (PGL) are rare neuroendocrine tumors derived from the autonomic nervous system paraganglia. Urinary bladder paragangliomas (UBPGL) originate from the sympathetic neurons of the urinary bladder wall and represent 0.7% of all paragangliomas and <0.05% of all bladder tumors. PGL and UBPGL can be associated with SDHB, SDHD, NF1, and VHL gene variants, with the most common germline alterations found in SDHB and VHL. Case report: We report a case of a 42-year-old woman who presented with menorrhagia/hematuria, uterine leiomyomas, as well as cardiac and bladder masses. The cardiac mass was favored to be a myxoma based on clinical findings, while the bladder mass was diagnosed as UBPGL. A novel SDHB mutation (c.642G>A, p Q214Q), detected in the UBPGL, was proven to be somatic. Although this variant was seemingly synonymous, it was predicted to have a loss of function due to the splice site effect, which was further supported by the immunohistochemical loss of SDHB. Conclusion: This case highlights the challenges of diagnosing an extremely rare entity, bladder paraganglioma, with an emphasis on the multidisciplinary approach to navigate various clinical and imaging findings that may initially be misleading. In addition, a novel loss of function SDHB variant that could have been overlooked as a synonymous variant is herein reported, while also illustrating the importance of both germline and somatic mutation testing.

Soil microbial community response to corrinoids is shaped by a natural reservoir of vitamin B12.

Soil microbial communities perform critical ecosystem services through the collective metabolic activities of numerous individual organisms. Most microbes use corrinoids, a structurally diverse family of cofactors related to vitamin B12. Corrinoid structure influences the growth of individual microbes, yet how these growth responses scale to the community level remains unknown. Analysis of metagenome-assembled genomes suggests corrinoids are supplied to the community by members of the archaeal and bacterial phyla Thermoproteota, Actinobacteria, and Proteobacteria. Corrinoids were found largely adhered to the soil matrix in a grassland soil, at levels exceeding those required by cultured bacteria. Enrichment cultures and soil microcosms seeded with different corrinoids showed distinct shifts in bacterial community composition, supporting the hypothesis that corrinoid structure can shape communities. Environmental context influenced both community and taxon-specific responses to specific corrinoids. These results implicate corrinoids as key determinants of soil microbiome structure and suggest that environmental micronutrient reservoirs promote community stability.

Surgery for Spinal Stenosis in Achondroplasia: Causes of Reoperation and Reduction of Risks.

BACKGROUND: Individuals with achondroplasia are prone to symptomatic spinal stenosis requiring surgery. Revision rates are thought to be high; however, the precise causes and rates of reoperation are unknown. The primary aim of this study is to investigate the causes of reoperation after initial surgical intervention in individuals with achondroplasia and spinal stenosis. In addition, we report on surgical techniques aimed at reducing the risks of these reoperations. METHODS: A retrospective review was conducted over an 8-year period of all patients with achondroplasia at a single institution that serves as a large referral center for patients with skeletal dysplasias. Patients with achondroplasia who underwent spinal surgery for stenosis were identified and the need for revision surgery was studied. Data collected included demographic, surgical, and revision details. Fisher exact test was used to determine if an association existed between construct type and the need for revisions. RESULTS: Thirty-three of the 130 (22%) patients with achondroplasia required spinal stenosis surgery. Twenty-four individuals who met the criteria were selected for analysis. The initial spine surgery was at an average age of 18.7 years (SD: 10.1 y). Nine patients (38%) required revision surgeries, and 3 required multiple revisions. Five of 9 (56%) of the revisions had primary surgery at an outside institution. Revision surgeries were due to caudal pseudarthrosis (the distal instrumented segment) (8), proximal junctional kyphosis (PJK) (7), and new neurological symptoms (7). There was a significant association found between construct type and the need for revision (P=0.0111). The pairwise comparison found that short fusions were significantly associated with the need for revision compared with the interbody group (P=0.0180). PJK was associated with short fusions when compared with the long fusion group (P=0.0294) and the interbody group (P=0.0300). Caudal pseudarthrosis was associated with short fusions when compared with the interbody group (P=0.0015). Multivariate logistic regression found long fusion with an interbody was predictive of and protective against the need for revision surgery (P=0.0246). To date, none of the initial cases that had long fusions with caudal interbody required a revision for distal pseudarthrosis. CONCLUSIONS: In patients with achondroplasia, the rate of surgery for spinal stenosis is 22% and the risk of revision is 38% and is primarily due to pseudarthrosis, PJK, and recurrent neurological symptoms. Surgeons should consider discussing spinal surgery as part of the patient's life plan and should consider wide decompression of the stenotic levels and long fusion with the use of an interbody cage at the caudal level in all patients to reduce risks of revision. LEVEL OF EVIDENCE: Level IV-Retrospective case series.

Peroneal Nerve Decompression in Patients with Multiple Hereditary Exostoses: Indications, Complications, and Recurrence.

BACKGROUND: To our knowledge, there have been no studies examining peroneal nerve decompression and proximal fibular osteochondroma excision exclusively in patients with multiple hereditary exostoses (MHE). The purpose of this study was to evaluate the indications, complications, and recurrence associated with nerve decompression and proximal fibular osteochondroma excision in patients with MHE. METHODS: The records on patients with MHE undergoing peroneal nerve decompression from 2009 to 2023 were retrospectively reviewed. Indications, clinical status, surgical technique, recurrence, and complications were recorded and were analyzed using the Fisher exact test, logistic regression, and the Kaplan-Meier method. RESULTS: There were 126 limbs identified in patients with MHE who underwent peroneal nerve decompression. The most common indications were pain over the proximal fibula, tibialis anterior and/or extensor hallucis longus weakness, and dysesthesias and/or neuropathic pain. Seven cases experienced postoperative foot drop as a complication of the decompression and osteochondroma excision. Logistic regression found significant relationships between complications and excision of anterior osteochondromas (odds ratio [OR], 5.21; p = 0.0062), proximal fibular excision (OR, 14.73; p = 0.0051), and previous decompression (OR, 5.77; p = 0.0124). The recurrence rate was 13.8%, and all recurrences occurred in patients who were skeletally immature at the index procedure. The probability of skeletally immature patients not experiencing recurrence was 88% at 3 years postoperatively and 73% at 6 years postoperatively. CONCLUSIONS: Indications for peroneal nerve decompression included neurologic symptoms and pain. The odds of a complication increased with excision of anterior osteochondromas and previous decompression. Recurrence of symptoms following decompression and osteochondroma excision was found exclusively in skeletally immature patients. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Phylogenetic distribution and experimental characterization of corrinoid production and dependence in soil bacterial isolates.

Soil microbial communities impact carbon sequestration and release, biogeochemical cycling, and agricultural yields. These global effects rely on metabolic interactions that modulate community composition and function. However, the physicochemical and taxonomic complexity of soil and the scarcity of available isolates for phenotypic testing are significant barriers to studying soil microbial interactions. Corrinoids-the vitamin B12 family of cofactors-are critical for microbial metabolism, yet they are synthesized by only a subset of microbiome members. Here, we evaluated corrinoid production and dependence in soil bacteria as a model to investigate the ecological roles of microorganisms involved in metabolic interactions. We isolated and characterized a taxonomically diverse collection of 161 soil bacteria from a single study site. Most corrinoid-dependent bacteria in the collection prefer B12 over other corrinoids, while all tested producers synthesize B12, indicating metabolic compatibility between producers and dependents in the collection. Furthermore, a subset of producers release B12 at levels sufficient to support dependent isolates in laboratory culture at estimated ratios of up to 1000 dependents per producer. Within our isolate collection, we did not find strong phylogenetic patterns in corrinoid production or dependence. Upon investigating trends in the phylogenetic dispersion of corrinoid metabolism categories across sequenced bacteria from various environments, we found that these traits are conserved in 47 out of 85 genera. Together, these phenotypic and genomic results provide evidence for corrinoid-based metabolic interactions among bacteria and provide a framework for the study of nutrient-sharing ecological interactions in microbial communities.

Some patients with type 2 diabetes may benefit from intensive glycaemic and blood pressure control: A post-hoc machine learning analysis of ACCORD trial data.

AIM: The action to control cardiovascular risk in diabetes (ACCORD) trial showed a neutral average treatment effect of intensive blood glucose and blood pressure (BP) controls in preventing major adverse cardiovascular events (MACE) in individuals with type 2 diabetes. Yet, treatment effects across patient subgroups have not been well understood. We aimed to identify patient subgroups that might benefit from intensive glucose or BP controls for preventing MACE. MATERIALS AND METHODS: As a post-hoc analysis of the ACCORD trial, we included 10 251 individuals with type 2 diabetes. We applied causal forest and causal tree models to identify participant characteristics that modify the efficacy of intensive glucose or BP controls from 68 candidate variables (demographics, comorbidities, medications and biomarkers) at the baseline. The exposure was (a) intensive versus standard glucose control [glycated haemoglobin (HbA1c) <6.0% vs. 7.0%-7.9%], and (b) intensive versus standard BP control (systolic BP <120 vs. <140 mmHg). The primary outcome was MACE. RESULTS: Compared with standard glucose control, intensive one reduced MACE in those with baseline HbA1c <8.5% [relative risk (RR): 0.79, 95% confidence interval (CI): 0.67-0.93] and those with estimated glomerular filtration rate ≥106 ml/min/1.73 m2 (RR: 0.74, 95% CI: 0.55-0.99). Intensive BP control reduced MACE in those with normal high-density lipoprotein levels (women >55 mg/dl, men >45 mg/dl; RR: 0.51, 95% CI: 0.34-0.74). Risk reductions were not significant in other patient subgroups. CONCLUSIONS: Our findings suggest heterogeneous treatment effects of intensive glucose and BP control and could provide biomarkers for future clinical trials to identify more precise HbA1c and BP treatment goals for individualized medicine.

Soil microbial community response to corrinoids is shaped by a natural reservoir of vitamin B12.

Soil microbial communities perform critical ecosystem services through the collective metabolic activities of numerous individual organisms. Most microbes use corrinoids, a structurally diverse family of cofactors related to vitamin B12. Corrinoid structure influences the growth of individual microbes, yet how these growth responses scale to the community level remains unknown. Analysis of metagenome-assembled genomes suggests corrinoids are supplied to the community by members of the archaeal and bacterial phyla Thermoproteota, Actinobacteria, and Proteobacteria. Corrinoids were found largely adhered to the soil matrix in a grassland soil, at levels exceeding those required by cultured bacteria. Enrichment cultures and soil microcosms seeded with different corrinoids showed distinct shifts in bacterial community composition, supporting the hypothesis that corrinoid structure can shape communities. Environmental context influenced both community and taxon-specific responses to specific corrinoids. These results implicate corrinoids as key determinants of soil microbiome structure and suggest that environmental micronutrient reservoirs promote community stability.

Disordered-to-ordered transitions in assembly factors allow the complex II catalytic subunit to switch binding partners.

Complex II (CII) activity controls phenomena that require crosstalk between metabolism and signaling, including neurodegeneration, cancer metabolism, immune activation, and ischemia-reperfusion injury. CII activity can be regulated at the level of assembly, a process that leverages metastable assembly intermediates. The nature of these intermediates and how CII subunits transfer between metastable complexes remains unclear. In this work, we identify metastable species containing the SDHA subunit and its assembly factors, and we assign a preferred temporal sequence of appearance of these species during CII assembly. Structures of two species show that the assembly factors undergo disordered-to-ordered transitions without the appearance of significant secondary structure. The findings identify that intrinsically disordered regions are critical in regulating CII assembly, an observation that has implications for the control of assembly in other biomolecular complexes.

Multisize Electrode Field-of-View: Validation by High Resolution Gadolinium-Enhanced Cardiac Magnetic Resonance.

BACKGROUND: Voltage mapping to detect ventricular scar is important for guiding catheter ablation, but the field-of-view of unipolar, bipolar, conventional, and microelectrodes as it relates to the extent of viable myocardium (VM) is not well defined. OBJECTIVES: The purpose of this study was to evaluate electroanatomic voltage-mapping (EAVM) with different-size electrodes for identifying VM, validated against high-resolution ex-vivo cardiac magnetic resonance (HR-LGE-CMR). METHODS: A total of 9 swine with early-reperfusion myocardial infarction were mapped with the QDOT microcatheter. HR-LGE-CMR (0.3-mm slices) were merged with EAVM. At each EAVM point, the underlying VM in multisize transmural cylinders and spheres was quantified from ex vivo CMR and related to unipolar and bipolar voltages recorded from conventional and microelectrodes. RESULTS: In each swine, 220 mapping points (Q1, Q3: 216, 260 mapping points) were collected. Infarcts were heterogeneous and nontransmural. Unipolar and bipolar voltage increased with VM volumes from >175 mm3 up to >525 mm3 (equivalent to a 5-mm radius cylinder with height >6.69 mm). VM volumes in subendocardial cylinders with 1- or 3-mm depth correlated poorly with all voltages. Unipolar voltages recorded with conventional and microelectrodes were similar (difference 0.17 ± 2.66 mV) and correlated best to VM within a sphere of radius 10 and 8 mm, respectively. Distance-weighting did not improve the correlation. CONCLUSIONS: Voltage increases with transmural volume of VM but correlates poorly with small amounts of VM, which limits EAVM in defining heterogeneous scar. Microelectrodes cannot distinguish thin from thick areas of subendocardial VM. The field-of-view for unipolar recordings for microelectrodes and conventional electrodes appears to be 8 to 10 mm, respectively, and unexpectedly similar.

The Order of Operative Repair Does Not Influence Outcomes in Patients with Concomitant Popliteal Artery and Orthopedic Injuries.

BACKGROUND: The most challenging lower extremity traumatic injuries involve concomitant vascular and orthopedic injuries with amputation rates approaching 50%. Controversy exists as to how to prioritize the vascular and orthopedic repairs. We reviewed patients with popliteal artery and lower extremity orthopedic injuries to analyze the sequence of the vascular and orthopedic repairs on outcomes. METHODS: All adult patients with a diagnosis of concomitant popliteal artery and lower extremity fracture or dislocation were identified through a review of an institutional trauma registry performed at a level 1 trauma center from 2014 to 2019. Patient demographics, timing of presentation, injury severity score (ISS), surgical interventions, and limb outcome data were collected and examined. The sequence of operative repairs and factors influencing the operative order were analyzed. RESULTS: Twenty-nine patients were treated for popliteal artery injuries. Twelve of these 29 patients had concomitant popliteal artery and orthopedic fractures requiring surgical repair. Injury mechanisms included both blunt (50%, 6/12) and penetrating trauma (50%, 6/12); the majority involved femur fractures (58%, 7/12). Vascular repair included arterial bypass (75%, 9/12) or interposition grafts (25%, 3/12). Orthopedic repair included external fixation (83%, 10/12) and open reduction internal fixation (17%, 2/12). Vascular repair was performed first in 7/12 limbs (58%). Patients having vascular repair first had a trend toward lower blood pressure on arrival (P = 0.068). There was no significant difference in emergency department to operating room (OR) time, OR time, ISS, mangled extremity severity score, estimated blood loss, or blood transfusion for the sequence of operative repair. Fasciotomy was nearly ubiquitous, present in 11/12 patients (92%). There were no graft complications related to orthopedic manipulation, and there were no reported limb-length to graft-length discrepancies. Early limb salvage trended lower in the cohort with revascularization first (71% vs. 100%, P = 0.19). Of the remaining limbs available for follow-up, limb salvage at 4.25 years is 100%. CONCLUSIONS: In this small study of patients with concomitant lower extremity popliteal artery and orthopedic injuries, the order of operative repair does not appear to influence the success of revascularization.

Medical Management of Traumatic Vertebral Artery Injury Is Safe Regardless of the Severity of Injury.

BACKGROUND: Management of traumatic vertebral artery injury (VAI) remains under debate. Current consensus reserves surgical or endovascular management for high-grade injury in order to prevent stroke. We sought to evaluate the factors that influence posterior fossa stroke outcomes following traumatic VAI. METHODS: A search of the prospectively maintained PROOVIT trauma registry of patients older than 18 years of age with a diagnosis of VAI was performed at a level 1 trauma center from 2013 to 2019. Patient demographics, type of injury, the timing of presentation, Biffl Classification of Cerebrovascular Injury Grade score, medical management, procedural interventions, and stroke outcomes were analyzed. RESULTS: VAIs were identified in 66 trauma patients were identified out of 14,323 patients entered into the PROOVIT registry. The dominant mechanism was blunt injury (91.5% vs. 8.5%, blunt versus penetrating). Nine patients presented with symptomatic ipsilateral posterior circulation strokes visible on imaging. The average Biffl classification grade was similar between the stroke and nonstroke groups (2.0 vs. 1.5; P = 0.39). The average injury severity score (ISS) between stroke and nonstroke groups was also similar (9.0 vs. 14.0; P = 0.35). All 9 patients in the stroke group had magnetic resonance imaging verification of their infarct within an average of 21.2 hr from presentation. In the stroke group, 1 patient underwent diagnostic angiography but had no intervention. In the nonstroke group, all were treated with medical management alone and none underwent vertebral artery intervention. During a mean follow-up of 14.5 months, no patients experienced a new neurological deficit. CONCLUSIONS: The severity of VAI by Biffl grading and ISS are not associated with ischemic stroke at presentation following VAI. Medical management of VAI appears safe regardless of Biffl and ISS staging in this trauma population. Neurological changes related to embolic stroke were generally appreciated on presentation. Conservative medical management was sufficient to protect from secondary neurological deficit regardless of index vertebral injury.

Management of phaeochromocytoma and paraganglioma in patients with germline SDHB pathogenic variants: an international expert Consensus statement.

Adult and paediatric patients with pathogenic variants in the gene encoding succinate dehydrogenase (SDH) subunit B (SDHB) often have locally aggressive, recurrent or metastatic phaeochromocytomas and paragangliomas (PPGLs). Furthermore, SDHB PPGLs have the highest rates of disease-specific morbidity and mortality compared with other hereditary PPGLs. PPGLs with SDHB pathogenic variants are often less differentiated and do not produce substantial amounts of catecholamines (in some patients, they produce only dopamine) compared with other hereditary subtypes, which enables these tumours to grow subclinically for a long time. In addition, SDHB pathogenic variants support tumour growth through high levels of the oncometabolite succinate and other mechanisms related to cancer initiation and progression. As a result, pseudohypoxia and upregulation of genes related to the hypoxia signalling pathway occur, promoting the growth, migration, invasiveness and metastasis of cancer cells. These factors, along with a high rate of metastasis, support early surgical intervention and total resection of PPGLs, regardless of the tumour size. The treatment of metastases is challenging and relies on either local or systemic therapies, or sometimes both. This Consensus statement should help guide clinicians in the diagnosis and management of patients with SDHB PPGLs.

Analysis of Extracranial Cerebrovascular Injuries: Clinical Predictors of Management and Outcomes.

BACKGROUND: Optimal management of traumatic extracranial cerebrovascular injuries (ECVIs) remains undefined. We sought to evaluate the factors that influence management and neurologic outcomes (stroke and brain death) following traumatic ECVI. METHODS: A retrospective review of a single level 1 trauma center's prospectively maintained data registry of patients older than 18 years of age with a diagnosis of ECVI was performed from 2013 to 2019. Injuries limited to the external carotid artery were excluded. Patient demographics, type of injury, timing of presentation, Biffl Classification of Cerebrovascular Injury Grade, Injury Severity Score (ISS), and Abbreviated Injury Scale were documented. Ultimate treatments (medical management and procedural interventions) and brain-related outcomes (stroke and brain death) were recorded. RESULTS: ECVIs were identified in 96 patients. The primary mechanism of injury was blunt trauma (89.5% vs. 10.5%, blunt versus penetrating), with 70 cases (66%) of vertebral artery injury and 37 cases of carotid artery injury. Treatments included vascular intervention (6.5%) and medical management (93.5%). Overall outcomes included ipsilateral ischemic stroke (29%) and brain death (6.5%). In the carotid group, vascular intervention was associated with higher Biffl grades (mean Biffl 3.17 vs. 2.23; P = 0.087) and decreased incidence of brain death (0% vs. 19%, P = 0.006), with no difference seen in ISS scores. Brain death was associated with higher ISS scores (40.29 vs. 24.17, P = 0.01), lower glascow coma score on arrival (3.57 vs. 10.63, P < 0.001), and increased rates of ischemic stroke (71% vs. 30%, P = 0.025). In the vertebral group, neither Biffl grade nor ISS were associated with treatment or outcomes. Regarding the timing of stroke in ECVI, there was no significant difference in the time from presentation to cerebral infarction between the carotid and vertebral artery groups (24.7 hr vs. 21.20 hr, P = 0.739). After this window, 98% of the ECVI cases demonstrated no further aneurysmal degeneration or new neurological deficits beyond the early time period (mean follow-up 9.7 months). CONCLUSIONS: Blunt cerebrovascular injuries should be viewed distinctly in the carotid and vertebral territories. In cases of injury to the carotid artery, Biffl grade and ISS score are associated with surgical intervention and neurologic events, respectively; vertebral artery injuries did not share this association. Neurologic deficits were detected in a similar time frame between the carotid artery and the vertebral artery injury groups and both groups had rare late neurologic events.

Internal Carotid Artery Aneurysm Disguised as Pituitary Macroadenoma.

Hypopituitarism due to an internal carotid artery (ICA) aneurysm is rare. We present a case of hypopituitarism and hyperprolactinemia due to a giant right ICA aneurysm. A 56-year-old woman with a history of primary hypothyroidism presented with fatigue, right-sided headache, and blurred vision. Magnetic resonance (MR) of the brain revealed a sellar mass measuring 3.5 × 2.2 cm involving the right cavernous sinus. Initial neurologic examination was unremarkable, and her biochemical evaluation revealed secondary adrenal insufficiency, central hypogonadism, low serum free thyroxine, and mildly elevated serum prolactin, consistent with stalk effect. Hydrocortisone therapy was started for secondary adrenal insufficiency and her levothyroxine dose was adjusted. The patient was referred to neurosurgery for surgical management of her sellar lesion. Preoperative computed tomography angiography (CTA) of the brain revealed a right ICA aneurysm that contacted the optic chiasm and displaced the pituitary gland. The aneurysm was embolized and diverting stents were placed. Repeat laboratory tests showed resolution of the patient's secondary adrenal insufficiency, normalization of serum prolactin, and an increase in serum gonadotropin concentrations to the postmenopausal range. This case highlights that not all sellar lesions are pituitary adenomas, and CTA should be performed in the evaluation of large cavernous sinus lesions to exclude ICA aneurysm.

A chemically-defined growth medium to support Lactobacillus-Acetobacter sp. community analysis.

Lactobacilli and Acetobacter sp. are commercially important bacteria that often form communities in natural fermentations, including food preparations, spoilage, and in the digestive tract of the fruit fly Drosophila melanogaster. Communities of these bacteria are widespread and prolific, despite numerous strain-specific auxotrophies, suggesting they have evolved nutrient interdependencies that regulate their growth. The use of a chemically-defined medium (CDM) supporting the growth of both groups of bacteria would facilitate the identification of the molecular mechanisms for the metabolic interactions between them. While numerous CDMs have been developed that support specific strains of lactobacilli or Acetobacter, there has not been a medium formulated to support both genera. We developed such a medium, based on a previous CDM designed for growth of lactobacilli, by modifying the nutrient abundances to improve growth yield. We further simplified the medium by substituting casamino acids in place of individual amino acids and the standard Wolfe's vitamins and mineral stocks in place of individual vitamins and minerals, resulting in a reduction from 40 to 8 stock solutions. These stock solutions can be used to prepare several CDM formulations that support robust growth of numerous lactobacilli and Acetobacters. Here, we provide the composition and several examples of its use, which is important for tractability in dissecting the genetic and metabolic basis of natural bacterial species interactions.

Transphyseal Humeral Separations: An Often-Missed Fracture.

BACKGROUND: Transphyseal humeral separations (TPHS) are rare injuries often associated with non-accidental trauma, necessitating accurate diagnosis. This study aims to assess the accuracy of diagnosis of TPHS. METHODS: A retrospective review was conducted at five academic pediatric institutions to identify all surgically treated TPHS in patients up to 4 years of age over a 25-year period. Demographics, misdiagnosis rates, and reported misdiagnoses were noted. Comparative analyses were performed to analyze the effects of patient age and injury mechanism on misdiagnosis rates. RESULTS: Seventy-nine patients (average age: 17.4 months) were identified, with injury mechanisms including accidental trauma (n = 49), non-accidental trauma (n = 21), Cesarean-section (n = 6), and vaginal delivery (n = 3). Neither age nor injury mechanism were significantly associated with diagnostic accuracy in the emergency department (ED)/consulting physician group. ED/consulting physicians achieved an accurate diagnosis 46.7% of the time, while radiologists achieved an accurate diagnosis 26.7% of the time. Diagnostic accuracy did not correlate with Child Protective Services (CPS) involvement or with a delay in surgery of more than 24 h. However, a significant correlation (p = 0.03) was observed between injury mechanism and misdiagnosis rates. CONCLUSION: This multicenter analysis is the largest study assessing TPHS misdiagnosis rates, highlighting the need for raising awareness and considering advanced imaging or orthopedic consultation for accurate diagnosis. This also reminds orthopedic surgeons to always have vigilant assessment in treating pediatric elbow injuries. LEVEL OF EVIDENCE: Level III-Retrospective Cohort Study.

A mutant fitness compendium in Bifidobacteria reveals molecular determinants of colonization and host-microbe interactions.

Bifidobacteria commonly represent a dominant constituent of human gut microbiomes during infancy, influencing nutrition, immune development, and resistance to infection. Despite interest as a probiotic therapy, predicting the nutritional requirements and health-promoting effects of Bifidobacteria is challenging due to major knowledge gaps. To overcome these deficiencies, we used large-scale genetics to create a compendium of mutant fitness in Bifidobacterium breve (Bb). We generated a high density, randomly barcoded transposon insertion pool in Bb, and used this pool to determine Bb fitness requirements during colonization of germ-free mice and chickens with multiple diets and in response to hundreds of in vitro perturbations. To enable mechanistic investigation, we constructed an ordered collection of insertion strains covering 1462 genes. We leveraged these tools to improve models of metabolic pathways, reveal unexpected host- and diet-specific requirements for colonization, and connect the production of immunomodulatory molecules to growth benefits. These resources will greatly reduce the barrier to future investigations of this important beneficial microbe.

Geochemical constraints on bacteriophage infectivity in terrestrial environments.

Lytic phages can be potent and selective inhibitors of microbial growth and can have profound impacts on microbiome composition and function. However, there is uncertainty about the biogeochemical conditions under which phage predation modulates microbial ecosystem function, particularly in terrestrial systems. Ionic strength is critical for infection of bacteria by many phages, but quantitative data is limited on the ion thresholds for phage infection that can be compared with environmental ion concentrations. Similarly, while carbon composition varies in the environment, we do not know how this variability influences the impact of phage predation on microbiome function. Here, we measured the half-maximal effective concentrations (EC50) of 80 different inorganic ions for the infection of E. coli with two canonical dsDNA and ssRNA phages, T4 and MS2, respectively. Many alkaline earth metals and alkali metals enabled lytic infection but the ionic strength thresholds varied for different ions between phages. Additionally, using a freshwater nitrate-reducing microbiome, we found that the ability of lytic phages to influence nitrate reduction end-products depended upon the carbon source as well as ionic strength. For all phage:host pairs, the ion EC50s for phage infection exceeded the ion concentrations found in many terrestrial freshwater systems. Thus, our findings support a model where phages most influence terrestrial microbial functional ecology in hot spots and hot moments such as metazoan guts, drought influenced soils, or biofilms where ion concentration is locally or transiently elevated and nutrients are available to support the growth of specific phage hosts.