Climate-smart forestry through innovative wood products and commercial afforestation and reforestation on marginal land.

Afforestation and reforestation (AR) on marginal land are nature-based solutions to climate change. There is a gap in understanding the climate mitigation potential of protection and commercial AR with different combinations of forest plantation management and wood utilization pathways. Here, we fill the gap using a dynamic, multiscale life cycle assessment to estimate one-century greenhouse gas (GHG) mitigation delivered by (both traditional and innovative) commercial and protection AR with different planting density and thinning regimes on marginal land in the southeastern United States. We found that innovative commercial AR generally mitigates more GHGs across 100 y (3.73 to 4.15 Giga tonnes of CO2 equivalent (Gt CO2e)) through cross-laminated timber (CLT) and biochar than protection AR (3.35 to 3.69 Gt CO2e) and commercial AR with traditional lumber production (3.17 to 3.51 Gt CO2e), especially in moderately cooler and dryer regions in this study with higher forest carbon yield, soil clay content, and CLT substitution. In a shorter timeframe (≤50 y), protection AR is likely to deliver higher GHG mitigation. On average, for the same wood product, low-density plantations without thinning and high-density plantations with thinning mitigate more life cycle GHGs and result in higher carbon stock than that of low-density with thinning plantations. Commercial AR increases the carbon stock of standing plantations, wood products, and biochar, but the increases have uneven spatial distributions. Georgia (0.38 Gt C), Alabama (0.28 Gt C), and North Carolina (0.13 Gt C) have the largest carbon stock increases that can be prioritized for innovative commercial AR projects on marginal land.

Prokaryotic ammonium transporters: what has three decades of research revealed?

The exchange of ammonium across cellular membranes is a fundamental process in all domains of life. In plants, bacteria and fungi, ammonium represents a vital source of nitrogen, which is scavenged from the external environment. In contrast, in animal cells ammonium is a cytotoxic metabolic waste product and must be excreted to prevent cell death. Transport of ammonium is facilitated by the ubiquitous Amt/Mep/Rh transporter superfamily. In addition to their function as transporters, Amt/Mep/Rh proteins play roles in a diverse array of biological processes and human physiopathology. Despite this clear physiological importance and medical relevance, the molecular mechanism of Amt/Mep/Rh proteins has remained elusive. Crystal structures of bacterial Amt/Rh proteins suggest electroneutral transport, whilst functional evidence supports an electrogenic mechanism. Here, focusing on bacterial members of the family, we summarize the structure of Amt/Rh proteins and what three decades of research tells us concerning the general mechanisms of ammonium translocation, in particular the possibility that the transport mechanism might differ in various members of the Amt/Mep/Rh superfamily.

Synthesis, characterization and absolute configurations of methyl ladderanoates.

Methyl esters of [5]-ladderanoic acid and [3]-ladderanoic acid were prepared by esterification of the acids isolated from biomass at a wastewater treatment plant. Optical rotations at six different wavelengths (633, 589, 546, 436, 405 and 365 nm) and vibrational circular dichroism (VCD) spectra in the 1800-900 cm-1 region were measured in CDCl3 solvent and compared with quantum chemical (QC) predictions using B3LYP functional and 6-311++G(2d,2p) basis set with polarizing continuum model representing the solvent. QC predictions gave negative optical rotations at all six wavelengths for (R)-methyl [5]-ladderanoate and positive optical rotations for (R)-methyl [3]-ladderanoate, the same signs as previously reported for the corresponding acids. The crystal structure of (-)-methyl [5]-ladderanoate independently confirmed (R) configuration. The QC-predicted VCD spectra using Boltzmann population weighted spectra of individual conformers did not provide satisfactory quantitative agreement with the experimental VCD spectra. An improved quantitative agreement for VCD spectra could be obtained when conformer populations were optimized to maximize the similarity between experimental and predicted VCD spectra, but more improvements in VCD predictions are needed.

Surgical approach to penile reconstruction for shaft skin excision from circumcision.

PURPOSE: Circumcision is one of the most frequently performed surgical procedures. Complications are infrequent, including bleeding, though can be significant such as shaft skin excision. The aim of this study was to identify mechanism of injury and reconstructive techniques for skin excision using a full thickness skin graft (FTSG) or with the novel application of tissue expanders (TE). METHODS: Patients who underwent penile reconstruction following shaft skin excision from an overzealous circumcision were retrospectively reviewed. The penis was covered using a FTSG, harvested from the groin/hip, or using TE, with expanders placed in residual shaft skin. RESULTS: Twelve patients experienced significant skin loss (range 65-95%) including 2 with partial glans loss. Ten were reconstructed using a FTSG and 2 with TE. Injury was most frequently from a Mogen clamp (n = 9), or from a Gomco clamp, Plastibell device, and electrocautery burns. Six FTSG patients experienced complications with lymphedema (n = 3) most common. CONCLUSION: Shaft skin excision is a devastating complication with risk greatest from Mogen clamp use. TE is preferred as this avoids donor site morbidity which reassures parents but requires sufficient residual skin that can be expanded. Both techniques effectively provide soft tissue coverage with acceptable appearance and long-term function.

Scalable purification of recombinant structural proteins, hagfish intermediate filament α and É£, from inclusion bodies for fiber formation.

The purpose of this study was to determine a method to purify recombinant hagfish intermediate filament proteins, alpha and gamma, in a scalable manner. The study succeeded by having an increase in protein recovery of up to 35% when comparing centrifuge purification and the developed tangential flow purification. The proteins were approximately the same purity of 70% pure but further purification increased the purity of the proteins by 16%, based on ImageJ analysis. The developed tangential flow filtration purification and final purification methods could be easily scaled up to meet industry scale purification needs. The scaled-up processes described in this study did not interfere with fiber production or formation, indicating the methods can produce usable proteins for material development.

A Single Institutional Review of Periauricular Vestiges and Renal Anomalies: The Role of Screening Renal Ultrasonography.

ABSTRACT: Children with minor ear malformations including periauricular vestiges often undergo renal ultrasonography (RUS) to exclude renal anomalies associated with genetic conditions. The aim of this study is to assess the association between isolated periauricular vestiges and renal anomalies and delineate the indication for RUS in screening for renal anomalies. This is a retrospective review of infants who underwent surgical consultation for periauricular vestige excision to probe a possible relationship with renal anomalies. Patients with an isolated vestige were compared to patients presenting with additional clinical findings suggestive of a possible genetic disorder. A total of 150 infants underwent periauricular vestige excision; 47 were referred for RUS, 23 with no additional clinical findings, and 24 with periauricular vestiges in addition to other suspicious clinical and/or developmental findings. Of these 47 patients, 10 had renal anomalies: 4 (17.4%) with an isolated periauricular vestige had minor anomalies and 6 (25.0%) with a vestige plus suspicious clinical signs had 5 minor anomalies and one major anomaly. The odds of a patient with an isolated periauricular vestige having positive RUS findings were not significantly different than a patient with additional clinical findings having positive RUS findings (P = 0.72).The incidence of renal anomalies in infants with an isolated periauricular vestige was similar to that in patients with associated clinical signs suggestive of a possible genetic disorder. This was higher than the background population rate. Although most anomalies in patients with isolated ear findings were minor, our results suggest routine screening RUS should be considered.

Pedicled Anterolateral Thigh and Radial Forearm Free Flap Phalloplasty for Penile Reconstruction in Patients With Bladder Exstrophy.

PURPOSE: Male patients with exstrophy-epispadias complex have a congenitally short penis. Adolescent and adult patients often desire penile reconstruction to enable penetrative intercourse. When penile lengthening using local tissue and/or skin graft is unsuitable, phalloplasty is performed. We provide updated experiences using radial forearm free flap and pedicled anterolateral thigh flap phalloplasty techniques over a 6-year period in exstrophy-epispadias complex patients. MATERIALS AND METHODS: Consecutive patients who underwent radial forearm free flap or pedicled anterolateral thigh flap phalloplasty between 2013 and 2019 were reviewed. A total of 11 patients were identified, including 8 with classic bladder exstrophy and 3 with cloacal exstrophy. In each case, flap dimensions, donor and recipient vessels and nerves, complications, outcomes and subsequent surgical procedures are reported. RESULTS: A radial forearm free flap was performed in 6 patients and a pedicled anterolateral thigh flap in 5. Flap survival was observed in all cases and 5 patients subsequently received an inflatable penile prosthesis. Among patients undergoing a pedicled anterolateral thigh flap, there was 1 mortality from acute pulmonary embolism, and the other 4 required at least 1 debulking procedure. CONCLUSIONS: Phalloplasty is an important procedure in patients with exstrophy-epispadias complex with severe penile inadequacy. Both techniques have favorable long-term outcomes, although the pedicled anterolateral thigh flap frequently requires a later debulking procedure. The radial forearm free flap is preferred but if the radial forearm is overly thin and the risk of inflatable penile prosthesis extrusion is high, the pedicled anterolateral thigh flap is an acceptable alternative.

Large scale production of synthetic spider silk proteins in Escherichia coli.

Spider silk, which has remarkable mechanical properties, is a natural protein fiber produced by spiders. Spiders cannot be farmed because of their cannibalistic and territorial nature. Hence, large amounts of spider silk cannot be produced from spiders. Genetic engineering is an alternative approach to produce large quantities of spider silk. Our group has produced synthetic spider silk proteins in E. coli to study structure/function and to produce biomaterials comparable to the silks produced by orb-weaving spiders. Here we give a detailed description of our cloning, expression, and purification methods of synthetic spider silk proteins ranging from ~30 to ~200 kDa. We have cloned the relevant genes of the spider Nephila clavipes and introduced them into bacteria to produce synthetic spider silk proteins using small and large-scale bioreactors. We have optimized the fermentation process, and we have developed protein purification methods as well. The purified proteins are spun into fibers and are used to make alternative materials like films and adhesives with various possible commercial applications.

Alkali Metal- and Acid-Catalyzed Interconversion of Goniodomin A with Congeners B and C.

Goniodomin A (GDA, 1) is a phycotoxin produced by at least four species of Alexandrium dinoflagellates that are found globally in brackish estuaries and lagoons. It is a linear polyketide with six oxygen heterocyclic rings that is cyclized into a macrocyclic structure via lactone formation. Two of the oxygen heterocycles in 1 comprise a spiro-bis-pyran, whereas goniodomin B (GDB) contains a 2,7-dioxabicyclo[3.3.1]nonane ring system fused to a pyran. When H2O is present, 1 undergoes facile conversion to isomer GDB and to an α,ß-unsaturated ketone, goniodomin C (GDC, 7). GDB and GDC can be formed from GDA by cleavage of the spiro-bis-pyran ring system. GDA, but not GDB or GDC, forms a crown ether-type complex with K+. Equilibration of GDA with GDB and GDC is observed in the presence of H+ and of Na+, but the equilibrated mixtures revert to GDA upon addition of K+. Structural differences have been found between the K+ and Na+ complexes. The association of GDA with K+ is strong, while that with Na+ is weak. The K+ complex has a compact, well-defined structure, whereas Na+ complexes are an ill-defined mixture of species. Analyses of in vitro A. monilatum and A. hiranoi cultures indicate that only GDA is present in the cells; GDB and GDC appear to be postharvest transformation products.

Challenges and Controversies in Foot and Ankle Trauma.

Management of foot and ankle trauma continues to evolve and change. It is important to be informed about the latest challenges and controversies in management of these injuries, which include ankle fractures, calcaneus fractures, Lisfranc injuries, and Jones fracture. Important concepts related to ankle fracture are the changing indications for surgery, utilization of stress radiographs, the role of arthroscopy, repair of the deltoid ligament, fixation of the posterior malleolus, and diagnosis and treatment of syndesmotic injuries. Regarding calcaneus fractures, discussion revolves around defining indications for fixation, factors that influence outcomes, less invasive approaches versus traditional extensile exposures, and the nature of the constant fragment. With Lisfranc injuries, the orthopaedic surgeon should be aware of fixation methods as well as the issue of fixation versus fusion. Discussion of Jones fracture should include evaluation of indications and different fixation techniques.

Brachytherapy with surgical resection as salvage treatment for recurrent high-grade meningiomas: a matched cohort study.

PURPOSE: To evaluate surgical resection with brachytherapy placement as a salvage treatment in patients with recurrent high-grade meningioma who exhausted prior external beam treatment options. METHODS: Single-center retrospective review of our institutional experience of brachytherapy implantation from 2012 to 2018. The primary outcome of the study was progression free survival (PFS). Secondary outcomes included overall survival (OS) and complications. A matched cohort of patients not treated with brachytherapy over the same time period was evaluated as a control group. All patients had received prior radiation treatment and underwent planned gross total resection (GTR) surgery. RESULTS: A total of 27 cases were evaluated. Compared with prior treatment, brachytherapy implantation demonstrated a statistically significant improvement in tumor control [HR 0.316 (0.101 - 0.991), p = 0.034]. PFS-6 and PFS-12 were 92.3% and 84.6%, respectively. Compared with the matched control cohort, brachytherapy treatment demonstrated improved PFS [HR 0.310 (0.103 - 0.933), p = 0.030]. Overall survival was not statistically significantly different between groups [HR 0.381 (0.073 - 1.982), p = 0.227]. Overall postoperative complications were comparable between groups, although there was a higher incidence of radiation necrosis in the brachytherapy cohort. CONCLUSION: Brachytherapy with planned GTR improved PFS in recurrent high-grade meningioma patients who exhausted prior external beam radiation treatment options. Future improvement of brachytherapy dose delivery methods and techniques may continue to prolong control rates and improve outcomes for this challenging group of patients.

Algal Toxin Goniodomin A Binds Potassium Ion Selectively to Yield a Conformationally Altered Complex with Potential Biological Consequences.

The marine toxin goniodomin A (GDA) is a polycyclic macrolide containing a spiroacetal and three cyclic ethers as part of the macrocycle backbone. GDA is produced by three species of the Alexandrium genus of dinoflagellates, blooms of which are associated with "red tides", which are widely dispersed and can cause significant harm to marine life. The toxicity of GDA has been attributed to stabilization of the filamentous form of the actin group of structural proteins, but the structural basis for its binding is not known. Japanese workers, capitalizing on the assumed rigidity of the heavily substituted macrolide ring, assigned the relative configuration and conformation by relying on NMR coupling constants and NOEs; the absolute configuration was assigned by degradation to a fragment that was compared with synthetic material. We have confirmed the absolute structure and broad features of the conformation by X-ray crystallography but have found GDA to complex with alkali metal ions in spite of two of the heterocyclic rings facing outward. Such an arrangement would have been expected to impair the ability of GDA to form a crown-ether-type multidentate complex. GDA shows preference for K+, Rb+, and Cs+ over Li+ and Na+ in determinations of relative affinities by TLC on metal-ion-impregnated silica gel plates and by electrospray mass spectrometry. NMR studies employing the K+ complex of GDA, formed from potassium tetrakis[pentafluorophenyl]borate (KBArF20), reveal a major alteration of the conformation of the macrolide ring. These observations argue against the prior assumption of rigidity of the ring. Alterations in chemical shifts, coupling constants, and NOEs indicate the involvement of most of the molecule other than ring F. Molecular mechanics simulations suggest K+ forms a heptacoordinate complex involving OA, OB, OC, OD, OE, and the C-26 and C-27 hydroxy groups. We speculate that complexation of K+ with GDA electrostatically stabilizes the complex of GDA with filamentous actin in marine animals due to the protein being negatively charged at physiological pH. GDA may also cause potassium leakage through cell membranes. This study provides insight into the structural features and chemistry of GDA that may be responsible for significant ecological damage associated with the GDA-producing algal blooms.

A systematic review of the effectiveness of sleep hygiene in children with ADHD.

Attention deficit/hyperactivity disorder (ADHD) is often accompanied by sleep problems in children. Sleep hygiene is defined as a set of behavioural, environmental, or cognitive modifications to improve sleep, and is routinely clinically utilised as first-line treatment for insomnia in ADHD. The objective of this systematic review of the literature is to evaluate the effectiveness of sleep hygiene interventions for sleep difficulties in children with ADHD. Sixteen relevant articles met the inclusion criteria, involving 1,469 participants, with a mean age of 9.6 years, across 6 countries. Fifteen studies found that sleep hygiene interventions were effective in improving sleep, while one did not show any significant improvement. Definite conclusions on the effectiveness of the interventions are difficult to draw due to the limited number of studies and a high risk of bias. There is growing evidence to support the use of sleep hygiene interventions to improve sleep quality in children with ADHD and sleep disturbance. However, well-conducted clinical trials are required to strengthen the evidence.

Stimulated grip strength measurement: Validation of a novel method for functional assessment.

BACKGROUND: Reliable measurement of functional recovery is critical in translational peripheral nerve regeneration research. Behavioral functional assessments such as volitional grip strength testing (vGST) are limited by inherent behavioral variability. Isometric tetanic force testing (ITFT) is highly reliable but precludes serial measurements. Combining elements of vGST and ITFT, stimulated grip strength testing (sGST) involves percutaneous median nerve stimulation to elicit maximal tetanic contraction of digital flexors, thereby allowing for consistent measurement of maximal grip strength. METHODS: We measured side-to-side equivalence of force using sGST, vGST, and ITFT to determine relative reliability and repeatability. We also performed weekly force measurements following median nerve repair. RESULTS: sGST demonstrated greater reliability and inter-trial repeatability than vGST and similar reliability to ITFT, with the added benefit of serial measurements. CONCLUSIONS: sGST is a valid method for assessing functional recovery that addresses the limitations of the currently available modalities used in translational peripheral nerve regeneration research.

CRISPR/Cas9 Initiated Transgenic Silkworms as a Natural Spinner of Spider Silk.

Using transgenic silkworms with their natural spinning apparatus has proven to be a promising way to spin spider silk-like fibers. The challenges are incorporating native-size spider silk proteins and achieving an inheritable transgenic silkworm strain. In this study, a CRISPR/Cas9 initiated fixed-point strategy was used to successfully incorporate spider silk protein genes into the Bombyx mori genome. Native-size spider silk genes (up to 10 kb) were inserted into an intron of the fibroin heavy or light chain (FibH or FibL) ensuring that any sequence changes induced by the CRISPR/Cas9 would not impact protein production. The resulting fibers are as strong as native spider silks (1.2 GPa tensile strength). The transgenic silkworms have been tracked for several generations with normal inheritance of the transgenes. This strategy demonstrates the feasibility of using silkworms as a natural spider silk spinner for industrial production of high-performance fibers.

Biomechanical comparison of fixation stability using a Lisfranc plate versus transarticular screws.

BACKGROUND: To obtain adequate fixation in treating Lisfranc soft tissue injuries, the joint is commonly stabilized using multiple transarticular screws; however iatrogenic injury is a concern. Alternatively, two parallel, longitudinally placed plates, can be used to stabilize the 1st and 2nd tarsometatarsal joints; however this may not provide adequate stability along the Lisfranc ligament. Several biomechanical studies have compared earlier methods of fixation using plates to the standard transarticular screw fixation method, highlighting the potential issue of transverse stability using plates. A novel dorsal plate is introduced, intended to provide transverse and longitudinal stability, without injury to the articular cartilage. METHODS: A biomechanical cadaver model was developed to compare the fixation stability of a novel Lisfranc plate to that of traditional fixation, using transarticular screws. Thirteen pairs of cadaveric specimens were tested intact, after a simulated Lisfranc injury, and then following implant fixation, using one method of fixation randomly assigned, on either side of each pair. Optical motion tracking was used to measure the motion between each of the following four bones: 1st metatarsal, 2nd metatarsal, 1st cuneiform, and 2nd cuneiform. Testing included both cyclic abduction loading and cyclic axial loading. RESULTS: Both the Lisfranc plate and screw fixation method provided stability such that the average 3D motions across the Lisfranc joint (between 2nd metatarsal and 1st cuneiform), were between 0.2 and 0.4mm under cyclic abduction loading, and between 0.4 and 0.5mm under cyclic axial loading. Comparing the stability of fixation between the Lisfranc plate and the screws, the differences in motion were all 0.3mm or lower, with no clinically significant differences (p>0.16). CONCLUSIONS: Diastasis at the Lisfranc joint following fixation with a novel plate or transarticular screw fixation were comparable. Therefore, the Lisfranc plate may provide adequate support without risk of iatrogenic injury to the articular cartilage.

miR-375 Regulates Invasion-Related Proteins Vimentin and L-Plastin.

Invasion is a hallmark of advanced head and neck squamous cell carcinoma (HNSCC). We previously determined that low relative miR-375 expression was associated with poor patient prognosis. HNSCC cells with increased miR-375 expression have lower invasive properties and impaired invadopodium activity. Using stable isotope labeling with amino acids in cell culture and reverse-phase liquid chromatography mass spectrometry, we assessed the impact of miR-375 expression on protein levels in UM-SCC-1 cells. Increased miR-375 expression was associated with down-regulation of proteins involved in cellular assembly and organization, death and survival, and movement. Two invasion-associated proteins, vimentin and L-plastin, were strongly down-regulated by miR-375. Luciferase reporter assays demonstrated that high miR-375 expression reduced vimentin promoter activity, suggesting that vimentin is an indirect target of miR-375. Runt-related transcription factor 1 (RUNX1) is a potential miR-375 direct target, and its knockdown reduced vimentin and L-plastin expression. Data in The Cancer Genome Atlas HNSCC database showed a significant inverse correlation between miR-375 expression and RUNX1, vimentin, and L-plastin RNA expression. These clinical correlations validate our in vitro model findings and support a mechanism in which miR-375 suppresses RUNX1 levels, resulting in reduced vimentin and L-plastin expression. Furthermore, knockdown of RUNX1, L-plastin, and vimentin resulted in significant reductions in cell invasion in vitro, indicating the functional significance of miR-375 regulation of specific proteins involved in HNSCC invasion.

Apolipoprotein E Promotes Invasion in Oral Squamous Cell Carcinoma.

Oral squamous cell carcinoma (OSCC) patients generally have a poor prognosis, because of the invasive nature of these tumors. In comparing transcription profiles between OSCC tumors with a more invasive (worst pattern of tumor invasion 5) versus a less invasive (worst pattern of tumor invasion 3) pattern of invasion, we identified a total of 97 genes that were overexpressed at least 1.5-fold in the more invasive tumor subtype. The most functionally relevant genes were assessed using in vitro invasion assays with an OSCC cell line (UM-SCC-1). Individual siRNA knockdown of 15 of these 45 genes resulted in significant reductions in tumor cell invasion compared to a nontargeting siRNA control. One gene whose knockdown had a strong effect on invasion corresponded to apolipoprotein E (APOE). Both matrix degradation and the number of mature invadopodia were significantly decreased with APOE knockdown. APOE knockdown also resulted in increased cellular cholesterol, consistent with APOE's role in regulating cholesterol efflux. APOE knockdown resulted in decreased levels of phospho-extracellular signal-regulated kinase 1/2, phospho-c-Jun N-terminal kinase, and phospho-cJun, as well as decreased activator protein 1 (AP-1) activity. Expression of matrix metalloproteinase 7 (MMP7), an AP-1 target, was also significantly decreased. Our findings suggest that APOE protein plays a significant role in OSCC tumor invasion because of its effects on cellular cholesterol and subsequent effects on cell signaling and AP-1 activity, leading to changes in the expression of invasion-related proteins, including MMP7.

Medical Student Experiences on Consultation-Liaison Psychiatry Rotations: A Nationwide Survey.

BACKGROUND: Consultation-liaison (C-L) psychiatry clerkship rotations may improve medical students' understanding of psychiatric principles relevant to the settings in which they will ultimately practice. This study aimed to characterize students' experiences on C-L rotations. METHODS: This cross-sectional survey study, sponsored by the Academy of Psychosomatic Medicine Subcommittee on Medical Student Education, was conducted at 5 US medical schools between 2012 and 2016. After the C-L rotation, students completed a voluntary 17-item survey. RESULTS: A total of 235 surveys were collected (mean response rate = 92%). The most frequently endorsed benefit of C-L was learning to manage psychiatric disorders in the context of medical illness (89%). The most frequently endorsed drawback was inconsistent/excessively variable workload (40%). Overall, 82% of respondents recommended C-L to other students; 80% reported that the ideal clerkship would include exposure to both C-L and inpatient psychiatry. Overall, 38% reported that their C-L experience increased their interest in psychiatry as a career. Effect of C-L on interest in psychiatry did not differ by study site, age, sex, clerkship length, or time spent on C-L. Respondents who noted more positive role-modeling on C-L compared to other clerkship rotations were more likely to report increased interest in a psychiatry career (odds ratio = 2.70). CONCLUSIONS: Most medical students perceive C-L rotations favorably. Positive role modeling may increase their consideration of psychiatry specialization. The findings that C-L rotation length did not correlate with attitudes and that most students preferred exposure to both inpatient and C-L psychiatry suggest that C-L exposure can beneficially be integrated into core clerkships containing other elements.

Absolute Configurations of Naturally Occurring [5]- and [3]-Ladderanoic Acids: Isolation, Chiroptical Spectroscopy, and Crystallography.

We have isolated mixtures of [5]- and [3]-ladderanoic acids 1a and 2a from the biomass of an anammox bioreactor and have separated the acids and their phenacyl esters for the first time by HPLC. The absolute configurations of the naturally occurring acids and their phenacyl esters are assigned as R at the site of side-chain attachment by comparison of experimental specific rotations with corresponding values predicted using quantum chemical (QC) methods. The absolute configurations for 1a and 2a were independently verified by comparison of experimental Raman optical activity spectra with corresponding spectra predicted using QC methods. The configurational assignments of 1a and 2a and of the phenacyl ester of 1a were also confirmed by X-ray crystallography.