Isolation, molecular identification, and genomic analysis of Mangrovibacter phragmitis strain ASIOC01 from activated sludge harboring the bioremediation prowess of glycerol and organic pollutants in high-salinity.

The physiological and genotypic characteristics of Mangrovibacter (MGB) remain largely unexplored, including their distribution and abundance within ecosystems. M. phragmitis (MPH) ASIOC01 was successfully isolated from activated sludge (AS), which was pre-enriched by adding 1,3-dichloro-2-propanol and 3-chloro-1,2-propanediol as carbon sources. The new isolate, MPH ASIOC01, exhibited resilience in a medium containing sodium chloride concentration up to 11% (with optimal growth observed at 3%) and effectively utilizing glycerol as their sole carbon source. However, species delimitation of MGBs remains challenging due to high 16S rRNA sequence similarity (greater than 99% ANI) among different MGBs. In contrast, among the housekeeping gene discrepancies, the tryptophan synthase beta chain gene can serve as a robust marker for fast species delimitation among MGBs. Furthermore, the complete genome of MPH ASIOC01 was fully sequenced and circlized as a single contig using the PacBio HiFi sequencing method. Comparative genomics revealed genes potentially associated with various phenotypic features of MGBs, such as nitrogen-fixing, phosphate-solubilizing, cellulose-digesting, Cr-reducing, and salt tolerance. Computational analysis suggested that MPH ASIOC01 may have undergone horizontal gene transfer events, possibly contributing unique traits such as antibiotic resistance. Finally, our findings also disclosed that the introduction of MPH ASIOC01 into AS can assist in the remediation of wastewater chemical oxygen demand, which was evaluated using gas chromatograph-mass spectrometry. To the best of our knowledge, this study offers the most comprehensive understanding of the phenotypic and genotypic features of MGBs to date.

Intraoperative Laparoscopic Ultrasound Increases Fibroid Detection During Laparoscopic Myomectomy.

Objective: To assess the utility of intraoperative laparoscopic ultrasound in detecting additional fibroids during laparoscopic myomectomy (LM). Methods: Forty-two patients were enrolled in this prospective cohort study. All cases were performed by the same surgeon at a university affiliated hospital between April 1, 2019 and February 29, 2020. Following routine laparoscopic myomectomy, the laparoscopic ultrasound was then introduced, and ultrasonography was performed directly on the uterus. Any additional fibroids discovered were enucleated. Results: Using the laparoscopic ultrasound, an additional 54 fibroids among 27 (64%) of the 42 patients were found, with a median of 2 additional fibroids per patient (interquartile range [IQR] 1,3). Median fibroid size detected by laparoscopic ultrasound was 1.5 centimeters (IQR 1-3) and the most common types were FIGO grades 3 and 2 (43% and 33% respectively). The median surgical time was longer among patients in whom additional fibroids were found (170 minutes (IQR 137-219) vs 150 minutes (IQR 120-193), p = .044). When ≥ 2 fibroids were removed by usual methods, the laparoscopic ultrasound found additional fibroids 80% of the time, compared to 25% when < 2 fibroids were removed by usual methods (p < .001). Conclusion: Intraoperative laparoscopic ultrasonography is a useful tool in detecting additional fibroids that would have otherwise been missed. It is particularly helpful in identifying smaller intramural fibroids and in patients with multiple fibroids. By detecting additional fibroids, laparoscopic ultrasonography can help maximize the effectiveness of laparoscopic myomectomy and help decrease the rates of residual fibroids.

The Antileukemic and Anti-Prostatic Effect of Aeroplysinin-1 Is Mediated through ROS-Induced Apoptosis via NOX Activation and Inhibition of HIF-1a Activity.

Aeroplysinin-1 is a brominated isoxazoline alkaloid that has exhibited a potent antitumor cell effect in previous reports. We evaluated the cytotoxicity of aeroplysinin-1 against leukemia and prostate cancer cells in vitro. This marine alkaloid inhibited the cell proliferation of leukemia Molt-4, K562 cells, and prostate cancer cells Du145 and PC-3 with IC50 values of 0.12 ± 0.002, 0.54 ± 0.085, 0.58 ± 0.109 and 0.33 ± 0.042 µM, respectively, as shown by the MTT assay. Furthermore, in the non-malignant cells, CCD966SK and NR8383, its IC50 values were 1.54 ± 0.138 and 6.77 ± 0.190 µM, respectively. In a cell-free system, the thermal shift assay and Western blot assay verified the binding affinity of aeroplysinin-1 to Hsp90 and Topo IIα, which inhibited their activity. Flow cytometry analysis showed that the cytotoxic effect of aeroplysinin-1 is mediated through mitochondria-dependent apoptosis induced by reactive oxygen species (ROS). ROS interrupted the cellular oxidative balance by activating NOX and inhibiting HIF-1α and HO-1 expression. Pretreatment with N-acetylcysteine (NAC) reduced Apl-1-induced mitochondria-dependent apoptosis and preserved the expression of NOX, HO-1, and HIF-1a. Our findings indicated that aeroplysinin-1 targeted leukemia and prostate cancer cells through multiple pathways, suggesting its potential application as an anti-leukemia and prostate cancer drug lead.

Voltage-Gated Electrocatalysis of Efficient and Selective Methane Oxidation by Tricopper Clusters under Ambient Conditions.

Selective methane oxidation is difficult chemistry. Here we describe a strategy for the electrocatalysis of selective methane oxidation by immobilizing tricopper catalysts on the cathodic surface. In the presence of dioxygen and methane, the activation of these catalysts above a threshold cathodic potential can initiate the dioxygen chemistry for O atom transfer to methane. The catalytic turnover is completed by facile electron injections into the tricopper catalysts from the electrode. This technology leads to dramatic enhancements in performance of the catalysts toward methane oxidation. Unprecedented turnover frequencies (>40 min-1) and high product throughputs (turnover numbers >30 000 in 12 h) are achieved for this challenging chemical transformation in water under ambient conditions. The technology is green and suitable for on-site direct conversion of methane into methanol.

Clinical and Patient Reported Outcomes of Pre- and Postsurgical Treatment of Symptomatic Uterine Leiomyomas: A 12-Month Follow-up Review of TRUST, a Surgical Randomized Clinical Trial Comparing Laparoscopic Radiofrequency Ablation and Myomectomy.

STUDY OBJECTIVE: The objective of this study was to determine the efficacy, safety, and healthcare resource use of laparoscopic radiofrequency ablation (LAP-RFA) compared with myomectomy in patients with symptomatic uterine leiomyomas (ULs). DESIGN: This was a secondary analysis of the original postmarket randomized, multicenter, longitudinal, comparative TRUST (Treatment Results of Uterine Sparing Technologies) United States trial in patients with symptomatic ULs. After the procedure, subjects were followed over a 12-month period. SETTING: Multicenter trial, including hospitals with or without an academic affiliation, surgery centers, and fertility centers performing outpatient procedures for uterine myomas. PARTICIPANTS: A total of 57 patients were randomized to either LAP-RFA (n = 30) or myomectomy (n = 27). INTERVENTIONS: LAP-RFA or myomectomy (laparoscopic or abdominal). MEASUREMENTS AND MAIN RESULTS: The main outcome measures of this study were part of the secondary outcomes of the original TRUST trial. The primary outcome of this study was the reduction of UL symptoms and the improvement in patient-reported outcomes scores over time. Secondary outcomes included postprocedure hospitalization, length of stay, complications, reinterventions, and recovery time. There was a significant improvement in UL symptoms at 3 and 12 months after the procedure within each treatment group, and these improvements were similar between treatment groups. There was a significant reduction in UL symptoms per month between baseline and 12-months after the procedure for both LAP-RFA and myomectomy of 72% and 85%, respectively. A significant improvement was seen in all patient-reported outcomes scores over time for both groups. At 3 and 12 months after the procedure, the percentages of patients who were hospitalized in the LAP-RFA group were 74% and 49% lower than those of patients in the laparoscopic myomectomy group, respectively, with the 3-month difference being statistically significant. The length of hospital stay was significantly shorter in the LAP-RFA group compared with the myomectomy group (8.0 ± 5.7 hours vs 18.8 ± 14.6 hours; p < .05). Doctors recommended taking significantly less time off before returning to work for the patients in the LAP-RFA group compared with those in the myomectomy group (10.3 ± 5.1 days vs 14.5 ± 5.4 days; p < .05). The total number of days until back to normal activity was significantly lower in the LAP-RFA group compared with the myomectomy group (16.3 ± 15.2 days vs 26.5 ± 15.9 days; p < .05). CONCLUSION: The results from this 12-month follow-up study suggest that LAP-RFA is a safe, effective, uterine-sparing alternative to laparoscopic myomectomy in the treatment of ULs. These data points build on previously published studies showing that LAP-RFA has lower healthcare resource use overall, including lower postprocedure hospitalization rate and shorter length of stay. In clinical practice, LAP-RFA is a promising treatment approach to ULs for women.

Scalarane-Type Sesterterpenoids from the Marine Sponge Lendenfeldia sp. Alleviate Inflammation in Human Neutrophils.

Sponge-derived scalaranes are remarkable sesterterpenoids previously found to exhibit profound inhibitory effects against neutrophilic inflammation. In our current work, we constructed the metabolomic profile of marine sponge Lendenfeldia sp. for the first time using a tandem mass spectrometry (MS/MS) molecular networking approach. The results highlighted the rich chemical diversity of these scalaranes, motivating us to conduct further research to discover novel scalaranes targeting neutrophilic inflammation. MS- and NMR-assisted isolation and elucidation led to the discovery of seven new homoscalaranes, lendenfeldaranes K-Q (1-7), characterized by methylation at C-24, together with five known derivatives, lendenfeldarane B (8), 25-nor-24-methyl-12,24-dioxoscalar-16-en-22-oic acid (9), 24-methyl-12,24,25-trioxoscalar-16-en-22-oic acid (10), felixin B (11), and 23-hydroxy-20-methyldeoxoscalarin (12). Scalaranes 1-4 and 6-12 were assayed against superoxide anion generation and elastase release, which represented the neutrophilic inflammatory responses of respiratory burst and degranulation, respectively. The results indicated that 1-3 and 6-12 exhibited potential anti-inflammatory activities (IC50 for superoxide anion scavenging: 0.87~6.57 µM; IC50 for elastase release: 1.12~6.97 µM).

Catalytic machinery of methane oxidation in particulate methane monooxygenase (pMMO).

In this focused review, we portray the recently reported 2.5 Å cyro-EM structure of the particulate methane monooxygenase (pMMO) from M. capsulatus (Bath). The structure of the functional holo-pMMO near atomic resolution has uncovered the sites of the copper cofactors including the location of the active site in the enzyme. The three coppers seen in the original X-ray crystal structures of the enzyme are now augmented by additional coppers in the transmembrane domain as well as in the water-exposed C-terminal subdomain of the PmoB subunit. The cryo-EM structure offers the first glimpse of the catalytic machinery capable of methane oxidation with high selectivity and efficiency. The findings are entirely consistent with the biochemical and biophysical findings previously reported in the literature, including the chemistry of hydrocarbon hydroxylation, regeneration of the catalyst for multiple turnovers, and the mechanism of aborting non-productive cycles to ensure kinetic competence.

Resolving Entangled JH-H-Coupling Patterns for Steroidal Structure Determinations by NMR Spectroscopy.

For decades, high-resolution 1H NMR spectroscopy has been routinely utilized to analyze both naturally occurring steroid hormones and synthetic steroids, which play important roles in regulating physiological functions in humans. Because the 1H signals are inevitably superimposed and entangled with various JH-H splitting patterns, such that the individual 1H chemical shift and associated JH-H coupling identities are hardly resolved. Given this, applications of thess information for elucidating steroidal molecular structures and steroid/ligand interactions at the atomic level were largely restricted. To overcome, we devoted to unraveling the entangled JH-H splitting patterns of two similar steroidal compounds having fully unsaturated protons, i.e., androstanolone and epiandrosterone (denoted as 1 and 2, respectively), in which only hydroxyl and ketone substituents attached to C3 and C17 were interchanged. Here we demonstrated that the JH-H values deduced from 1 and 2 are universal and applicable to other steroids, such as testosterone, 3ß, 21-dihydroxygregna-5-en-20-one, prednisolone, and estradiol. On the other hand, the 1H chemical shifts may deviate substantially from sample to sample. In this communication, we propose a simple but novel scheme for resolving the complicate JH-H splitting patterns and 1H chemical shifts, aiming for steroidal structure determinations.

Mechanism of Pyrroloquinoline Quinone-Dependent Hydride Transfer Chemistry from Spectroscopic and High-Resolution X-ray Structural Studies of the Methanol Dehydrogenase from Methylococcus capsulatus (Bath).

The active site of methanol dehydrogenase (MDH) contains a rare disulfide bridge between adjacent cysteine residues. As a vicinal disulfide, the structure is highly strained, suggesting it might work together with the pyrroloquinoline quinone (PQQ) prosthetic group and the Ca2+ ion in the catalytic turnover during methanol (CH3OH) oxidation. We purify MDH from Methylococcus capsulatus (Bath) with the disulfide bridge broken into two thiols. Spectroscopic and high-resolution X-ray crystallographic studies of this form of MDH indicate that the disulfide bridge is redox active. We observe an internal redox process within the holo-MDH that produces a disulfide radical anion concomitant with a companion PQQ radical, as evidenced by an optical absorption at 408 nm and a magnetically dipolar-coupled biradical in the EPR spectrum. These observations are corroborated by electron-density changes between the two cysteine sulfurs of the disulfide bridge as well as between the bound Ca2+ ion and the O5-C5 bond of the PQQ in the high-resolution X-ray structure. On the basis of these findings, we propose a mechanism for the controlled redistribution of the two electrons during hydride transfer from the CH3OH in the alcohol oxidation without formation of the reduced PQQ ethenediol, a biradical mechanism that allows for possible recovery of the hydride for transfer to an external NAD+ oxidant in the regeneration of the PQQ cofactor for multiple catalytic turnovers. In support of this mechanism, a steady-state level of the disulfide radical anion is observed during turnover of the MDH in the presence of CH3OH and NAD+.

Selective Oxidation of Simple Aromatics Catalyzed by Nano-Biomimetic Metal Oxide Catalysts: A Mini Review.

The process of selective oxy-functionalization of hydrocarbons using peroxide, O3, H2O2, O2, and transition metals can be carried out by the reactive oxygen species such as hydroxyl/hydroperoxyl radical and/or metal oxygenated species generated in the catalytic reaction. Thus, a variety of mechanisms have been proposed for the selective catalytic oxidation of various hydrocarbons including light alkanes, olefins, and simple aromatics by the biological metalloproteins and their biomimetics either in their homogeneous or heterogeneous platforms. Most studies involving these metalloproteins are Fe or Cu monooxygenases. The pathways carried out by these metalloenzymes in the oxidation of C-H bonds invoke either radical reaction mechanisms including Fenton's chemistry and hydrogen atom transfer followed by radical rebound reaction mechanism or electrophilic oxygenation/O-atom transfer by metal-oxygen species. In this review, we discuss the metal oxide nano-catalysts obtained from metal salts/molecular precursors (M = Cu, Fe, and V) that can easily form in situ through the oxidation of substrates using H2O2(aq) in CH3CN, and be facilely separated from the reaction mixtures as well as recycled for several times with comparable catalytic efficiency for the highly selective conversion from hydrocarbons including aromatics to oxygenates. The mechanistic insights revealed from the oxy-functionalization of simple aromatics mediated by the novel biomimetic metal oxide materials can pave the way toward developing facile, cost-effective, and highly efficient nano-catalysts for the selective partial oxidation of simple aromatics.

Sponge-Derived 24-Homoscalaranes as Potent Anti-Inflammatory Agents.

Scalarane-type sesterterpenoids are known for their therapeutic potential in cancer treatments. However, the anti-inflammatory properties of this class of metabolites remain elusive. Our current work aimed to investigate the anti-inflammatory scalaranes from marine sponge Lendenfeldia sp., resulting in the isolation of six new 24-homoscalaranes, lendenfeldaranes E-J (1-6). The structures of the new metabolites were determined by extensive spectroscopic analyses, and the absolute configuration of 1 was established by electronic circular dichroism (ECD) calculations. Compounds 2 and 3 were discovered to individually reduce the generation of superoxide anions, and compound 1 displayed an inhibitor effect on the release of elastase. These three compounds were proven to be the first anti-neutrophilic scalaranes.

Probing Anti-Proliferative 24-Homoscalaranes from a Sponge Lendenfeldiasp.

In the current study, an NMR spectroscopic pattern-based procedure for probing scalarane derivatives was performed and four new 24-homoscalaranes, lendenfeldaranes A-D (1- 4), along with three known compounds, 12α-acetoxy-22-hydroxy-24-methyl-24-oxoscalar-16-en- 25-al (5), felixin F (6), and 24-methyl-12,24,25-trioxoscalar-16-en-22-oic acid (7) were isolated from the sponge Lendenfeldia sp. The structures of scalaranes 1-7 were elucidated on the basis of spectroscopic analysis. Scalaranes 1-7 were further evaluated for their cytotoxicity toward a series of human cancer cell lines and the results suggested that 5 and 7 dominated in the anti- proliferative activity of the extract. The 18-aldehyde functionality was found to play a key role in their activity.

Post-Market Safety of Laparoscopic Ultrasound-Guided Radiofrequency Ablation.

BACKGROUND AND OBJECTIVES: Postoperative safety outcomes with laparoscopic intra-abdominal ultrasound-guided radiofrequency ablation, as performed by gynecologic surgeons new to the procedure, were evaluated and compared to the premarket, pivotal study. Post-procedure feedback from surgeons was reported. METHODS: This was a post-market, prospective, single-arm analysis with 4 to 8 weeks follow-up among surgeons (n = 29) with varying levels of laparoscopic surgery experience participating in the ongoing, multinational Treatment Results of Uterine Sparing Technologies randomized clinical trial. Patients were premenopausal adult women (n = 110) desiring uterine-conserving treatment for symptomatic fibroids. During run-in, surgeons received proctored training. Following training, and after performing ≥ 2 procedures, surgeons provided self-assessment and feedback using a standardized form. RESULTS: Surgeons performed 105 procedures with 100 per-protocol patients. The average number of proctored cases per surgeon was 2.48. No acute (≤ 48 hours) serious adverse events occurred (0/101, 0.0%) compared with 2 acute serious adverse events in the premarket study (2/137, 1.46%). Both studies reported 1 near-term (∼30 days) serious adverse event (< 1% for both). In this study, the near-term complication was fever of unknown origin requiring hospitalization related to uterine entry/manipulation. This was categorized as probably device-related; the patient was treated with antibiotics and discharged. Twenty-six surgeons completed the evaluation form; none reported experiencing problems with the procedure. CONCLUSION: Minimally invasive gynecologic surgeons can learn laparoscopic intraabdominal ultrasound-guided radiofrequency ablation and perform it safely (in terms of acute and near-term serious adverse events) after ≥ 2 proctored cases. There were no significant differences in safety outcomes compared to the premarket, pivotal study.

The PmoB subunit of particulate methane monooxygenase (pMMO) in Methylococcus capsulatus (Bath): The CuI sponge and its function.

In this study, we describe efforts to clarify the role of the copper cofactors associated with subunit B (PmoB) of the particulate methane monooxygenase (pMMO) from Methylococcus capsulatus (Bath) (M. capsulatus). This subunit exhibits strong affinity toward CuI ions. To elucidate the high copper affinity of the subunit, the full-length PmoB, and the N-terminal truncated mutants PmoB33-414 and PmoB55-414, each fused to the maltose-binding protein (MBP), are cloned and over-expressed into Escherichia coli (E. coli) K12 TB1 cells. The Y374F, Y374S and M300L mutants of these protein constructs are also studied. When this E. coli is grown with the pmoB gene in 1.0 mM CuII, it behaves like M. capsulatus (Bath) cultured under high copper stress with abundant membrane accumulation and high CuI content. The recombinant PmoB proteins are verified by Western blotting of antibodies directed against the MBP sub-domain in each of the copper-enriched PmoB proteins. Cu K-edge X-ray absorption near edge spectroscopy (XANES) of the copper ions confirms that all the PmoB recombinants are CuI proteins. All the PmoB proteins show evidence of a "dicopper site" according to analysis of the Cu extended X-ray absorption edge fine structure (EXAFS) of the membranes. No specific activities toward methane and propene oxidation are observed with the recombinant membrane-bound PmoB proteins. However, significant production of hydrogen peroxide is observed in the case of the PmoB33-414 mutant. Reaction of the dicopper site with dioxygen produces hydrogen peroxide and leads to oxidation of the CuI ions residing in the C-terminal sub-domain of the PmoB subunit.

A Carbon Electrode Functionalized by a Tricopper Cluster Complex: Overcoming Overpotential and Production of Hydrogen Peroxide in the Oxygen Reduction Reaction.

A study of the oxygen reduction reaction (ORR) on a screen printed carbon electrode surface mediated by the tricopper cluster complex Cu3 (7-N-Etppz(CH2 OH)) dispersed on electrochemically reduced carbon black, where 7-N-Etppz(CH2 OH) is the ligand 3,3'-(6-(hydroxymethyl)-1,4-diazepane-1,4-diyl)bis(1-(4-ethyl piperazin-1-yl)propan-2-ol), is described. Onset oxygen reduction potentials of about 0.92 V and about 0.77 V are observed at pH 13 and pH 7 vs. the reversible hydrogen electrode, which are comparable to the best values reported for any synthetic copper complex. Based on half-wave potentials (E1/2 ), the corresponding overpotentials are about 0.42 V and about 0.68 V, respectively. Kinetic studies indicate that the trinuclear copper catalyst can accomplish the 4 e- reduction of O2 efficiently and the ORR is accompanied by the production of only small amounts of H2 O2 . The involvement of the copper triad in the O2 activation process is also verified.

Irrigation after Laparoscopic Power Morcellation and the Dispersal of Leiomyoma Cells: A Pilot Study.

STUDY OBJECTIVE: To evaluate if copious irrigation and suctioning after electromechanical power morcellation will reduce myoma cell dissemination and if there is a difference between sterile water and normal saline. DESIGN: Prospective single-center cohort pilot study (Canadian Task Force classification II-2). SETTING: Academic tertiary referral center. PATIENTS: Sixteen women undergoing laparoscopic myomectomy with 1 surgeon between January 1, 2017 and August 31, 2017. INTERVENTIONS: Peritoneal washings were collected 3 specific times during surgery: after dissection of myoma(s) and hysterotomy repair but before morcellation, after morcellation, and after irrigation with 3 L normal saline or sterile water. The primary outcome was the detection of benign spindle cells (BSCs) in peritoneal washings. MEASUREMENTS AND MAIN RESULTS: Sixteen patients were enrolled in the study. Eight were randomized to the normal saline group and 8 to the sterile water group. In the normal saline group BSCs were detected in 3 of 8 patients (37.5%) after closure of the hysterotomy but before morcellation, in 3 of 8 (37.5%) after morcellation, and in 0 of 8 (0%) after irrigation and suctioning of the peritoneal cavity with 3 L normal saline. In the sterile water group BSCs were detected in 3 of 8 patients (37.5%) after closure of the hysterotomy but before morcellation, 2 of 8 (25%) after morcellation, and in 0 of 8 (0%) after irrigation and suctioning with 3 L sterile water. Thus, no differences were found between the normal saline and sterile water groups. CONCLUSION: In this pilot study myoma cells were disseminated before electromechanical morcellation. Irrigation and suctioning with 3 L normal saline or sterile water after morcellation may reduce myoma cell dissemination.

Electrochemical Hydroxylation of C3-C12 n-Alkanes by Recombinant Alkane Hydroxylase (AlkB) and Rubredoxin-2 (AlkG) from Pseudomonas putida GPo1.

An unprecedented method for the efficient conversion of C3-C12 linear alkanes to their corresponding primary alcohols mediated by the membrane-bound alkane hydroxylase (AlkB) from Pseudomonas putida GPo1 is demonstrated. The X-ray absorption spectroscopy (XAS) studies support that electrons can be transferred from the reduced AlkG (rubredoxin-2, the redox partner of AlkB) to AlkB in a two-phase manner. Based on this observation, an approach for the electrocatalytic conversion from alkanes to alcohols mediated by AlkB using an AlkG immobilized screen-printed carbon electrode (SPCE) is developed. The framework distortion of AlkB-AlkG adduct on SPCE surface might create promiscuity toward gaseous substrates. Hence, small alkanes including propane and n-butane can be accommodated in the hydrophobic pocket of AlkB for C-H bond activation. The proof of concept herein advances the development of artificial C-H bond activation catalysts.

Alkane Oxidation: Methane Monooxygenases, Related Enzymes, and Their Biomimetics.

Methane monooxygenases (MMOs) mediate the facile conversion of methane into methanol in methanotrophic bacteria with high efficiency under ambient conditions. Because the selective oxidation of methane is extremely challenging, there is considerable interest in understanding how these enzymes carry out this difficult chemistry. The impetus of these efforts is to learn from the microbes to develop a biomimetic catalyst to accomplish the same chemical transformation. Here, we review the progress made over the past two to three decades toward delineating the structures and functions of the catalytic sites in two MMOs: soluble methane monooxygenase (sMMO) and particulate methane monooxygenase (pMMO). sMMO is a water-soluble three-component protein complex consisting of a hydroxylase with a nonheme diiron catalytic site; pMMO is a membrane-bound metalloenzyme with a unique tricopper cluster as the site of hydroxylation. The metal cluster in each of these MMOs harnesses O2 to functionalize the C-H bond using different chemistry. We highlight some of the common basic principles that they share. Finally, the development of functional models of the catalytic sites of MMOs is described. These efforts have culminated in the first successful biomimetic catalyst capable of efficient methane oxidation without overoxidation at room temperature.

Mechanistic Study of the Stereoselective Hydroxylation of [2-2 H1 ,3-2 H1 ]Butanes Catalyzed by Cytochrome P450 BM3 Variants.

Engineered bacterial cytochrome P450s are noted for their ability in the oxidation of inert small alkanes. Cytochrome P450 BM3 L188P A328F (BM3 PF) and A74E L188P A328F (BM3 EPF) variants are able to efficiently oxidize n-butane to 2-butanol. Esterification of the 2-butanol derived from this reaction mediated by the aforementioned two mutants gives diastereomeric excesses (de) of -56±1 and -52±1 %, respectively, with the preference for the oxidation occurring at the C-HS bond. When tailored (2R,3R)- and (2S,3S)-[2-2 H1 ,3-2 H1 ]butane probes are employed as substrates for both variants, the obtained de values from (2R,3R)-[2-2 H1 ,3-2 H1 ]butane are -93 and -92 % for BM3 PF and EPF, respectively; whereas the obtained de values from (2S,3S)-[2-2 H1 ,3-2 H1 ]butane are 52 and 56 % in the BM3 PF and EPF systems, respectively. The kinetic isotope effects (KIEs) for the oxidation of (2R,3R)-[2-2 H1 ,3-2 H1 ]butane are 7.3 and 7.8 in BM3 PF and EPF, respectively; whereas KIEs for (2S,3S)-[2-2 H1 ,3-2 H1 ]butanes are 18 and 25 in BM3 PF and EPF, respectively. The discrepancy in KIEs obtained from the two substrates supports the two-state reactivity (TSR) that is proposed for alkane oxidation in cytochrome P450 systems. Moreover, for the first time, experimental evidence for tunneling in the oxidation mediated by P450 is given through the oxidation of the C-HR bond in (2S,3S)-[2-2 H1 ,3-2 H1 ]butane.

Radiofrequency Ablation of Uterine Fibroids: a Review.

Laparoscopic, ultrasound-guided radiofrequency ablation (RFA) is a new, FDA-cleared uterine sparing, outpatient procedure for uterine fibroids. The procedure utilizes recent technological advancements in instrumentation and imaging, allowing surgeons to treat numerous fibroids of varying size and location in a minimally invasive fashion. Early and mid-term data from multi-center clinical trials have demonstrated safety and efficacy, with resolution or improvement of symptoms and significant volume reduction. Re-intervention rates for fibroid symptoms have been low. The procedure is well tolerated with a typically uneventful and rapid recovery requiring NSAIDs only for postoperative pain. While post RFA pregnancy data are limited, the results are promising.