Patient values in breast cancer surgical decision-making - The WhySurg study.

BACKGROUND: The objective of this study was to describe patient values and personality traits associated with breast surgery choice for patients with breast cancer. METHODS: A survey based on qualitative patient interviews and the Big-Five personality trait profile was distributed to Love Research Army volunteers aged 18-70 years old who underwent breast cancer surgery from 2009 to 2020. Multivariable logistic regression analysis was used to determine independent patient values and personality traits for the choice of breast-conserving surgery (BCS), unilateral mastectomy (UM) and bilateral mastectomy (BM). RESULTS: 1497 participants completed the survey. Open-mindedness was associated with UM and sociability was associated with BM. A majority of patients prioritized cancer outcomes. Compared to BM patients, BCS and UM patients were significantly more likely to choose values associated with maintaining their self-image, optimizing surgical recovery, and following their doctor's recommendation. CONCLUSIONS: Other values besides cancer outcomes differentiate patient surgical choice for BCS or mastectomy.

Rates of newly diagnosed breast cancer at commission on cancer facilities during the early phase of the COVID-19 pandemic.

INTRODUCTION: The objective of this study was to examine the impact of the early part of the COVID-19 pandemic on the number of newly diagnosed breast cancer cases at Commission on Cancer (CoC)-accredited facilities relative to the United States (U.S.) population. METHODS: We examined the incidence of breast cancer cases at CoC sites using the U.S. Census population as the denominator. Breast cancer incidence was stratified by patient age, race and ethnicity, and geographic location. RESULTS: A total of 1,499,806 patients with breast cancer were included. For females, breast cancer cases per 100,000 individuals went from 188 in 2015 to 203 in 2019 and then dropped to 176 in 2020 with a 15.7% decrease from 2019 to 2020. Breast cancer cases per 100,000 males went from 1.7 in 2015 to 1.8 in 2019 and then declined to 1.5 in 2020 with a 21.8% decrease from 2019 to 2020. For both females and males, cases per 100,000 individuals decreased from 2019 to 2020 for almost all age groups. For females, rates dropped from 2019 to 2020 for all races and ethnicities and geographic locations. The largest percent change was seen among Hispanic patients (-18.4%) and patients in the Middle Atlantic division (-18.6%). The stage distribution (0-IV) for female and male patients remained stable from 2018 to 2020. CONCLUSION: The first year of the COVID-19 pandemic was associated with a decreased number of newly diagnosed breast cancer cases at Commission on Cancer sites.

Diffusely invasive supratentorial rosette-forming glioneuronal tumor: illustrative case.

BACKGROUND: Rosette-forming glioneuronal tumors (RGNTs) are rare tumors composed of mixed glial and neurocytic components. Most lesions are confined to the posterior fossa, especially in the region of the fourth ventricle, in young adults. In few instances, diffuse involvement of the supratentorial region is identified, thereby creating significant challenges in diagnosis, surgical intervention, and prognostication. OBSERVATIONS: The authors present a 23-year-old female with chronic headaches, papilledema, and hydrocephalus who underwent radiographic evaluation revealing obstructive hydrocephalus and diffuse supratentorial enhancing and nonenhancing cystic and nodular lesions. The patient underwent a right frontal craniotomy and septostomy. An exophytic nonenhancing right frontal horn lesion was resected, and an enhancing third-ventricular lesion was biopsied. Final pathology of both of the lesions sampled was consistent with RGNT. Next-generation sequencing demonstrated tumor alterations in the FGFR-1 and PIK3CA genes. Targeted therapy with the FGFR inhibitor erdafitinib demonstrated a partial remission. LESSONS: Diffuse supratentorial spread of RGNT is an extremely rare presentation of an already uncommon pathology. In some cases, gross-total resection may not be feasible. Goals of surgery include acquiring tissue for diagnosis, maximizing safe resection, and treating any associated hydrocephalus. FGFR inhibitors may be of benefit in cases of disease progression.

Exploring Breast Surgeons' Attitudes on Universal Genetic Testing: A Qualitative Study.

BACKGROUND: The American Society of Breast Surgeons released a consensus statement that genetic testing should be made available to all patients with a personal history of breast cancer. However, it is not clear whether physicians feel comfortable with universal genetic testing (UGT) or if they have sufficient knowledge to interpret results and manage them appropriately. OBJECTIVE: The purpose of this study was to explore breast surgeons' attitudes toward UGT. METHODS: Breast surgeons were consented and scheduled for a semi-structured virtual interview. Transcripts were uploaded into qualitative analysis software where they were exhaustively and iteratively coded. Codes were then organized into higher-order categories and themes and data saturation were assessed. RESULTS: Thirty-one surgeons completed the qualitative interview. Most surgeons practiced in the academic or community setting and most practiced in the Midwest (71.0%). The majority (90.3%) reported having a structured genetics program. The majority (96.8%) referred their patients to genetics for counseling and most preferred ordering testing through a genetic services provider. Some surgeons had concerns about access to genetic services. A minority of surgeons order UGT for all newly diagnosed breast cancer patients. The majority of respondents thought that more training in genetics was needed for surgeons. Many surgeons expressed concern about the psychosocial effects of UGT on patients. CONCLUSIONS: Many surgeons expressed concerns about UGT, mainly related to discomfort with their training, access to genetic services, and the psychosocial impact on their patients. Future work is needed to determine how to improve surgeon's comfort level in implementing UGT.

Transcatheter Left Atrial Appendage Exclusion: Preclinical and Early Clinical Results With the Laminar Device.

BACKGROUND: The Laminar device rotates and closes the left atrial appendage (LAA) using an integrated ball and lock that excludes and eliminates the LAA pouch. There is a low device surface area, minimizing the risk of peridevice leak (PDL) and device-related thrombus (DRT) formation. OBJECTIVES: This study evaluates the safety and efficacy of the Laminar LAA exclusion device in healthy animals and human subjects with nonvalvular atrial fibrillation at risk of ischemic stroke and systemic thromboembolism. METHODS: The preclinical study implanted the Laminar device into canine subjects that underwent transesophageal echocardiography (TEE) and fluoroscopic evaluation, followed by necropsy and histological assessment at 45 and 150-days post-implant. The early clinical study implanted the device in human subjects, followed to 12 months postimplantation. Procedural success was defined as device implantation in the intended location without residual LAA leak >5 mm as seen by TEE. Safety endpoints included freedom from stroke, systemic embolism, pericardial effusion, or tamponade, life-threatening/major bleeding, or death. RESULTS: The Laminar device was successfully implanted in 10 canines. In all animals at 45 days and 150 days, no PDL or DRT was found, and histological examination showed fully closed LAAs covered with neo-endocardium. The device was successfully implanted in 15 human subjects with no safety events out to 12 months postimplantation. All subjects had successful protocol-defined LAA closure without DRT at 45 days by TEE and computed tomography, which remained stable through 12 months' follow-up. CONCLUSIONS: The preclinical and early clinical results demonstrate a promising safety and efficacy profile for the Laminar LAA exclusion device.

Ischemic myelomalacia and closed spinal dysraphism in multiple finishing swine.

Ischemic myelomalacia secondary to fibrocartilaginous emboli (FCE) is an idiopathic disease in humans and animals. On the other hand, congenital spinal cord malformations result from neural tube defects in fetal development (ie, spinal dysraphism), with structural anomalies referred to collectively as myelodysplasia. Spinal dysraphisms are frequently accompanied by skin and vertebral abnormalities because of the embryogenic relationship. In this observational case study, we report the pathologic findings of 13, 18- to 24-weeks-old pigs from a large conventional operation that presented with acute paraparesis. Ischemic myelomalacia secondary to FCE was observed in 5 of 13 examined pigs. Congenital spinal cord malformations located between the caudal thoracic and sacral spinal cord were identified in 7 pigs, with structural abnormalities that ranged from diplomyelia/split cord malformation to segmental spinal dysgenesis (myelodysplasia) to caudal agenesis. Concurrent myelomalacia and congenital spinal cord malformations in the same or different sites were noted in 2 pigs. No spinal lesion was observed in 3 pigs. Although gross vertebral abnormalities were not observed herein, intervertebral instability due to minor defects in the articular facets, as well as other unidentified factors, is suspected to contribute high incidence of FCE. It is likely that these congenital malformations were previously underdiagnosed or are possibly new conditions associated with continuous inbreeding and genetic improvement in the modern swine industry.

Life-long deficits in social adaptation and the frontal lobes: New evidence, seventy-five years after Ackerly and Benton's landmark case report of JP.

The case of JP, reported by Ackerly and Benton in 1948 with a detailed follow-up by Ackerly in 1964, stands as the index case of developmental prefrontal damage and its impact on social adaptation. Although the 1948 case report included findings from a 1933 pneumoencephalogram and exploratory craniotomy, a definitive cause was never established for JP's prefrontal damage. Etiologies were never determined for the left-sided seizures that occurred when JP was age four, nor for the progressive anterograde amnesia that JP developed in middle age. Given Ackerly's thoroughness and long-term follow-up of his patient, it was hoped that a brain cutting would have been done, though no report of a post-mortem examination was published. The lead author of this paper (SB) set out to discover what had happened to JP after Ackerly's 1964 report and whether a brain cutting had in fact occurred. Using a variety of investigative approaches, it was discovered that a post-mortem brain examination had taken place. Those present at the brain cutting were identified, and the still-living witnesses to the brain cutting were interviewed. Previously unpublished, relevant materials were uncovered from archival sources. A film of the brain cutting, as well as photos, were located. A film of Ackerly interviewing JP prior to JP's death at age sixty-four also was found. The authors studied autopsy findings in the newly discovered video and still images. These findings were judged consistent with massive perinatal hemorrhagic damage to both frontal lobes. JP's left-sided seizures were likely due to activation of a focus from his congenital brain damage. The anterograde amnesia that was documented when JP was twenty-five and that was noted to worsen when he was forty-nine remains unexplained but may have been related to slowly progressive hydrocephalus. This paper expands what is known about the case of JP, making it the only report of a person with congenital frontal injury followed for their entire life including post-mortem brain examination.

Iatrogenic Atrial Septal Defect Closure Through the Steerable Guide Catheter: Description of Technique and Single-Center Experience.

OBJECTIVES: To introduce a novel method of direct iatrogenic atrial septal defect (iASD) closure through the MitraClip steerable guide catheter (SGC). BACKGROUND: MitraClip implantation requires transseptal puncture and the creation of an iASD. There are relatively rare instances, such as hemodynamically significant shunting or concerns for embolus, where iASD must be closed during index procedure. In these instances, it may be beneficial to not give up access to left atrium. METHODS: We retrospectively reviewed all iASD closures during MitraClip implantation at our institution from 2015 to 2020. Cases where an ASD occluder was deployed directly through SGC were included. RESULTS: Eleven patients had immediate iASD closure through the SGC. Indications for using this method included concern for paradoxical embolus, large defect size and/or significant shunting. Closure device sizes ranged from 8 to 22 mm. Mean time from removal of clip delivery system to occlusion of iASD was 14.6 minutes. There were no procedural complications related to iASD closure using this method. CONCLUSION: Closure of iASD intra-procedurally directly through transseptal guide sheath via the method described was safe and allowed for continuous left atrium access.

Anomalous Thermal Characteristics of Poly(ionic liquids) Derived from 1-Butyl-2,3-dimethyl-4-vinylimidazolium Salts.

The synthesis of 1-butyl-2,3-dimethyl-4-vinylimidazolium triflate, its polymerization, and ion exchange to yield a trio of 1-butyl-2,3-dimethyl-4-vinylimidazolium polymers is described. Irrespective of the nature of the anion, substitution at the 2-position of the imidazolium moiety substantially increases the distance between the anion and cation. The methyl substituent at the 2-position also served to expose the importance of H-bonding for the attractive potential between imidazolium moiety and anions in polymers without a methyl group at the 2-position. The thermal characteristics of poly(1-butyl-2,3-dimethyl-4-vinylimidazolium) salts and corresponding poly(1-ethyl-3-methyl-4-vinylimidazolium) salts were evaluated. While the mid-point glass transition temperatures, Tg-mid, for 1-ethyl-3-methyl-4-vinylimidazolium polymers with CF3SO3-, (CF3SO2)2N- and PF6- counterions, were 153 °C, 88 °C and 200 °C, respectively, the Tg-mid values for 1-butyl-2,3-dimethyl-4vinylimidazolium polymers with corresponding counter-ions were tightly clustered at 98 °C, 99 °C and 84 °C, respectively. This dramatically reduced influence of the anion type on the glass transition temperature was attributed to the increased distance between the center of the anions and cations in the 1-butyl-2,3-dimethyl-4-vinylimidazolium polymer set, and minimal H-bonding interactions between the respective anions and the 1-butyl-2,3-dimethyl-4-vinylimidazolium moiety. It is believed that this is the first observation of substantial independence of the glass transition of an ionic polymer on the nature of its counterion.

Advanced spectroscopic analysis and 15N-isotopic labelling study of nitrate and nitrite reduction to ammonia and nitrous oxide by E. coli.

Nitrate and nitrite reduction to ammonia and nitrous oxide by anaerobic E. coli batch cultures is investigated by advanced spectroscopic analytical techniques with 15N-isotopic labelling. Non-invasive, in situ analysis of the headspace is achieved using White cell FTIR and cavity-enhanced Raman (CERS) spectroscopies alongside liquid-phase Raman spectroscopy. For gas-phase analysis, White cell FTIR measures CO2, ethanol and N2O while CERS allows H2, N2 and O2 monitoring. The 6 m pathlength White cell affords trace gas detection of N2O with a noise equivalent detection limit of 60 nbar or 60 ppbv in 1 atm. Quantitative analysis is discussed for all four 14N/15N-isotopomers of N2O. Monobasic and dibasic phosphates, acetate, formate, glucose and NO3- concentrations are obtained by liquid-phase Raman spectroscopy, with a noise equivalent detection limit of 0.6 mM for NO3- at 300 s integration time. Concentrations of the phosphate anions are used to calculate the pH in situ using a modified Henderson-Hasselbalch equation. NO2- concentrations are determined by sampling for colorimetric analysis and NH4+ by basifying samples to release 14N/15N-isotopomers of NH3 for measurement in a second FTIR White cell. The reductions of 15NO3-, 15NO2-, and mixed 15NO3- and 14NO2- by anaerobic E. coli batch cultures are discussed. In a major pathway, NO3- is reduced to NH4+via NO2-, with the bulk of NO2- reduction occurring after NO3- depletion. Using isotopically labelled 15NO3-, 15NH4+ production is distinguished from background 14NH4+ in the growth medium. In a minor pathway, NO2- is reduced to N2O via the toxic radical NO. With excellent detection sensitivities, N2O serves as a monitor for trace NO2- reduction, even when cells are predominantly reducing NO3-. The analysis of N2O isotopomers reveals that for cultures supplemented with mixed 15NO3- and 14NO2- enzymatic activity to reduce 14NO2- occurs immediately, even before 15NO3- reduction begins. Optical density and pH measurements are discussed in the context of acetate, formate and CO2 production. H2 production is repressed by NO3-; but in experiments with NO2- supplementation only, CERS detects H2 produced by formate disproportionation after NO2- depletion.

Multiparametric cardiac18F-FDG PET in humans: pilot comparison of FDG delivery rate with82Rb myocardial blood flow.

Myocardial blood flow (MBF) and flow reserve are usually quantified in the clinic with positron emission tomography (PET) using a perfusion-specific radiotracer (e.g.82Rb-chloride). However, the clinical accessibility of existing perfusion tracers remains limited. Meanwhile,18F-fluorodeoxyglucose (FDG) is a commonly used radiotracer for PET metabolic imaging without similar limitations. In this paper, we explore the potential of18F-FDG for myocardial perfusion imaging by comparing the myocardial FDG delivery rateK1with MBF as determined by dynamic82Rb PET in fourteen human subjects with heart disease. Two sets of FDGK1were derived from one-hour dynamic FDG scans. One was the original FDGK1estimates and the other was the correspondingK1values that were linearly normalized for blood glucose levels. A generalized Renkin-Crone model was used to fit FDGK1with Rb MBF, which then allowed for a nonlinear extraction fraction correction for converting FDGK1to MBF. The linear correlation between FDG-derived MBF and Rb MBF was moderate (r= 0.79) before the glucose normalization and became much improved (r> 0.9) after glucose normalization. The extraction fraction of FDG was also similar to that of Rb-chloride in the myocardium. The results from this pilot study suggest that dynamic cardiac FDG-PET with tracer kinetic modeling has the potential to provide MBF in addition to its conventional use for metabolic imaging.

Mouse closed head traumatic brain injury replicates the histological tau pathology pattern of human disease: characterization of a novel model and systematic review of the literature.

Traumatic brain injury (TBI) constitutes one of the strongest environmental risk factors for several progressive neurodegenerative disorders of cognitive impairment and dementia that are characterized by the pathological accumulation of hyperphosphorylated tau (p-Tau). It has been questioned whether mouse closed-head TBI models can replicate human TBI-associated tauopathy. We conducted longitudinal histopathological characterization of a mouse closed head TBI model, with a focus on pathological features reported in human TBI-associated tauopathy. Male C57BL/6 J mice were subjected to once daily TBI for 5 consecutive days using a weight drop paradigm. Histological analyses (AT8, TDP-43, pTDP-43, NeuN, GFAP, Iba-1, MBP, SMI-312, Prussian blue, IgG, ßAPP, alpha-synuclein) were conducted at 1 week, 4 weeks, and 24 weeks after rTBI and compared to sham operated controls. We conducted a systematic review of the literature for mouse models of closed-head injury focusing on studies referencing tau protein assessment. At 1-week post rTBI, p-Tau accumulation was restricted to the corpus callosum and perivascular spaces adjacent to the superior longitudinal fissure. Progressive p-Tau accumulation was observed in the superficial layers of the cerebral cortex, as well as in mammillary bodies and cortical perivascular, subpial, and periventricular locations at 4 to 24 weeks after rTBI. Associated cortical histopathologies included microvascular injury, neuroaxonal rarefaction, astroglial and microglial activation, and cytoplasmatic localization of TDP-43 and pTDP-43. In our systematic review, less than 1% of mouse studies (25/3756) reported p-Tau using immunostaining, of which only 3 (0.08%) reported perivascular p-Tau, which is considered a defining feature of chronic traumatic encephalopathy. Commonly reported associated pathologies included neuronal loss (23%), axonal loss (43%), microglial activation and astrogliosis (50%, each), and beta amyloid deposition (29%). Our novel model, supported by systematic review of the literature, indicates progressive tau pathology after closed head murine TBI, highlighting the suitability of mouse models to replicate pertinent human histopathology.

MitraClip Implantation Guided by Volumetric Intracardiac Echocardiography: Technique and Feasibility in Patients Intolerant to Transesophageal Echocardiography.

Transesophageal echo (TEE) guidance is essential for successful MitraClip implantation. In patients intolerant to TEE, options are limited. Three patients, with contraindications to TEE, underwent MitraClip implantation using volumetric intracardiac echo (vICE). All patients had severe symptomatic degenerative mitral regurgitation (MR) and had successful implantation of at least one clip with reduction of MR to ≤2+ maintained at 30d follow-up. All patients had improvement in functional status without any adverse clinical, clip, or vICE related events. We discuss in detail the technical considerations and limitations to performing the MitraClip procedure with vICE guidance.

Preserving the organ donor pool and suprahepatic vena cava: Case series of transverse hepatectomy for polycystic liver disease.

Management of symptomatic polycystic liver disease (PLD) has remained primarily unchanged since the early 20th century when multiple case reports described management of non-parasitic liver cysts. In 1968, Lin et al. described the fenestration procedure, "aspiration of the cysts, incision, partial excision with or without external drainage, or marsupilization and anastomosis to the gastrointestinal tract". Further surgical options have included cyst sclerotherapy, laparoscopic cyst aspiration, partial hepatectomy, and orthotopic liver transplant (OLT). Recently there has been discussion of medical management with somatostatin analogs to reduce hepatomegaly in PLD with varying success. There is no current consensus on treatment or standard of care for symptomatic PLD, it is largely up to surgeon preference and ability; however, there has been a movement toward early OLT with Model for End-Stage Liver Disease (MELD) score exception points. This case series reviews two female patients with normal renal and hepatic function with symptomatic PLD treated with transverse hepatectomy. We propose that patients suffering from symptomatic PLD, with retained renal and hepatic function, can be treated with transverse hepatectomy conserving limited donor livers for decompensated patients; moreover, transverse hepatectomy does not disrupt the major suprahepatic vena cava preserving potential surgical access for future OLT.

Fatty Acid-binding Protein 4 Expression in Tumor Cells as a Potential Marker for Anaplastic Meningiomas.

Meningiomas are highly vascularized tumors originating from arachnoid cap cells of the leptomeninges. The majority of meningiomas are classified as World Health Organization (WHO) grade I and display a benign clinical course with a low risk of recurrence. In contrast, WHO grade III meningiomas carry a high risk of recurrence and poor prognosis. However, it is commonly recognized that histopathologic grading does not always reliably predict recurrence or progression of meningiomas. Fatty acid-binding protein 4 (FABP4) is a small molecular weight lipid chaperone that plays a proangiogenic role in vascular endothelial cells. FABP4 is not expressed in normal brain vasculature but is detected in some glioblastoma and arteriovenous malformations. The expression pattern of FABP4 in meningiomas have not been reported to date. We analyzed FABP4 expression in a cohort of paraffin-embedded meningioma specimens by immunohistochemistry and double immunofluorescence analyses. FABP4 expression was detected in a subset of endothelial cells in 47 of 48 meningioma samples analyzed. Interestingly, tumor cell-FABP4 expression was also detected in only 1 of 22 grade I, none of grade II, but 10 of 12 grade III meningiomas (P<0.0001). These results demonstrate that FABP4 is commonly expressed in meningioma vascular endothelial cells while tumor cell expression of FABP4 is primarily observed in anaplastic meningiomas. A combination of FABP4 immunostaining with histopathologic grading might provide a more accurate prediction of the biological behavior of meningiomas than histopathologic grading alone.

Adjunctive use of fluoroscopy during MitraClip implantation reduces procedural complexity: The parallax technique.

BACKGROUND: During MitraClip implantation sub-valvular correction of trajectory and/or alignment may increase adverse clip or leaflet events. With systematic adjunctive use of fluoroscopy ("Parallax technique"), we aimed to assess parameters that minimize the need for corrective measures and help increase procedural efficiency. METHODS: We retrospectively analyzed 30 patients without (Fl-) and 39 patients utilizing adjunctive fluoroscopy (Fl+) during MitraClip implantation. After establishing trajectory and supra-valvular alignment, the Parallax technique was utilized. Trajectory and alignment are maintained during advancement. RESULTS: All patients had 3 or 4+ MR. There were no differences in baseline demographics. The average number of clips (Fl- vs Fl+) was 1.72 ± 0.8 vs 1.59 ± 0.5, p = .57. For the first clip, the need for sub-valvular alignment (80% vs. 36%, p = .0001), eversion with retraction back to left atrium (23% vs. 10%, p = .001) and the number of grasps (2.3 ± 1.2 vs 1.4 ± 0.9) was reduced. The time from transseptal puncture to first clip deployment (71 ± 21 vs 44 ± 16 min, p = .01) was reduced. Procedural success was achieved in all but one patient in the Fl- group (p = ns). There were no differences noted for in-hospital or 30-day outcomes. CONCLUSIONS: Systematic use of a simple and easy to implement "Parallax technique" was associated with reduced need for sub-valvular manipulation and was associated with improved procedural times. Further larger scale studies are needed to assess the applicability of the technique.

On-line analysis and in situ pH monitoring of mixed acid fermentation by Escherichia coli using combined FTIR and Raman techniques.

We introduce an experimental setup allowing continuous monitoring of bacterial fermentation processes by simultaneous optical density (OD) measurements, long-path FTIR headspace monitoring of CO2, acetaldehyde and ethanol, and liquid Raman spectroscopy of acetate, formate, and phosphate anions, without sampling. We discuss which spectral features are best suited for detection, and how to obtain partial pressures and concentrations by integrations and least squares fitting of spectral features. Noise equivalent detection limits are about 2.6 mM for acetate and 3.6 mM for formate at 5 min integration time, improving to 0.75 mM for acetate and 1.0 mM for formate at 1 h integration. The analytical range extends to at least 1 M with a standard deviation of percentage error of about 8%. The measurement of the anions of the phosphate buffer allows the spectroscopic, in situ determination of the pH of the bacterial suspension via a modified Henderson-Hasselbalch equation in the 6-8 pH range with an accuracy better than 0.1. The 4 m White cell FTIR measurements provide noise equivalent detection limits of 0.21 µbar for acetaldehyde and 0.26 µbar for ethanol in the gas phase, corresponding to 3.2 µM acetaldehyde and 22 µM ethanol in solution, using Henry's law. The analytical dynamic range exceeds 1 mbar ethanol corresponding to 85 mM in solution. As an application example, the mixed acid fermentation of Escherichia coli is studied. The production of CO2, ethanol, acetaldehyde, acids such as formate and acetate, and the changes in pH are discussed in the context of the mixed acid fermentation pathways. Formate decomposition into CO2 and H2 is found to be governed by a zeroth-order kinetic rate law, showing that adding exogenous formate to a bioreactor with E. coli is expected to have no beneficial effect on the rate of formate decomposition and biohydrogen production.