Perioperative Risk Factors for Persistent Postsurgical Pain After Inguinal Hernia Repair: Systematic Review and Meta-Analysis

Persistent postsurgical pain (PPSP) is one of the most bothersome and disabling long-term complications after inguinal hernia repair surgery. Understanding perioperative risk factors that contribute to PPSP can help identify high-risk patients and develop risk-mitigation approaches. The objective of this study was to systematically review and meta-analyze risk factors that contribute to PPSP after inguinal hernia repair. The literature search resulted in 303 papers included in this review, 140 of which were used for meta-analyses. Our results suggest that younger age, female sex, preoperative pain, recurrent hernia, postoperative complications, and postoperative pain are associated with a higher risk of PPSP. Laparoscopic techniques reduce the PPSP occurrence compared to anterior techniques such as Lichtenstein repair, and tissue-suture techniques such as Shouldice repair. The use of fibrin glue for mesh fixation was consistently associated with lower PPSP rates compared to tacks, staples, and sutures. Considerable variability was observed with PPSP assessment and reporting methodology in terms of study design, follow-up timing, clarity of pain definition, as well as pain intensity or interference threshold. High or moderate risk of bias in at least one domain was noted in >75% of studies. These may limit the generalizability of our results. Future studies should assess and report comprehensive preoperative and perioperative risk factors for PPSP adjusted for confounding factors, and develop risk-prediction models to drive stratified PPSP-mitigation trials and personalized clinical decision-making. PERSPECTIVE: This systematic review and meta-analysis summarizes the current evidence on risk factors for persistent pain after inguinal hernia repair. The findings can help identify patients at risk and test personalized risk-mitigation approaches to prevent pain. PROSPERO REGISTRATION: htttps://www.crd.york.ac.uk/prospero/display_record.php?RecordID=154663.

Radiofrequency Ablation of the Infrapatellar Branch of the Saphenous Nerve for the Treatment of Chronic Anterior Inferomedial Knee Pain

INTRO

Genicular nerve radiofrequency ablation (GNRFA) is an effective treatment for chronic knee pain related to osteoarthritis. It is often utilized when conservative management has failed and patients wish to avoid arthroplasty, are poor surgical candidates due to comorbid medical conditions, or in those suffering from persistent pain after arthroplasty. The classic targets for GNRFA include the superior lateral genicular nerve, superior medial genicular nerve, and inferior medial genicular nerve but multiple anatomic studies have demonstrated additional sensory innervation to the knee.

OBJECTIVE

In this research article, we propose an image-guided technique that can safely target the infrapatellar branch of the saphenous nerve which also provides sensory innervation to the anterior capsule.

PROPOSAL

The proposed technique includes variations for conventional bipolar radiofrequency ablation, cooled radiofrequency ablation, dual-tined bipolar radiofrequency ablation, and monopolar radiofrequency ablation using a long axis approach. The described technique is based on updated anatomic studies and takes into account safety concerns such as thermal risk to the skin and/or pes anserine tendons and breaching of the synovial cavity.

CONCLUSION

Future clinical research should be performed to confirm the safety and effectiveness of this specific approach.

Abstract 1140: A novel MTA non-competitive PRMT5 inhibitor

The chromosome 9p21 (chr9p21) locus is deleted in almost 10% of all cancer types. This locus includes the CDKN2A gene that encodes the critical tumor suppressors p19-ARF and p16-INK4a. Methylthioadenosine phosphorylase (MTAP), a gene proximal to CDKN2A, is co-deleted in 80%-90% of tumors with CDKN2A deletion. MTAP plays a critical role in the methionine salvage pathway, and the deletion of MTAP results in the accumulation of its substrate methythioadenosine (MTA). Accumulation of MTA partially inhibits the activity of the arginine methyltransferase PRMT5, causing MTAP deficient cancer cells to be more sensitive to the genetic knockdown of PRMT5. In contrast to genetic knockdown, sensitivity to pharmacological inhibition of PRMT5 does not appear to stratify with MTAP status. However, currently known PRMT5 inhibitors all possess SAM competitive or uncompetitive MOIs, which generally require displacement of MTA from the active site for binding. We hypothesize that leveraging the high MTA state induced by MTAP deficiency will require an inhibitor that can bind PRMT5 without disrupting bound MTA. Here we report the discovery of a PRMT5 inhibitor with a novel binding mode that is compatible with MTA binding. While this compound possesses the desired MOI, it shows only modestly increased potency toward MTAP-null cells. Mathematical simulations of different inhibitor mechanisms indicate that the degree of selectivity that can be achieved depends on the difference in MTA levels between MTAP-null and WT cells. Our in vitro data suggest that the elevation in intracellular MTA concentrations that occurs with MTAP deletion is not sufficient to confer significantly increased sensitivity to PRMT5 inhibition. We anticipate that the therapeutic index that can be achieved between MTAP-null tumor cells and PRMT5-sensitive normal tissues will be similarly limited in vivo.

Citation Format: Rohit Malik, Peter K. Park, Christopher M. Barbieri, Yuval Blat, Steven Sheriff, Carolyn A. Weigelt, Lisa M. Kopcho, Muge Celiktas, Max Ruzanov, Joseph G. Naglich, Jennifer L. Price, Mary Harner, Kevin M. Omalley, JIngjing Deng, William Schmitz, Guo Li, Zheming Ruan, Lan-ying Qin, Gerald J. Duke, Iyoncy Rodrigo, Mark R. Witmer, David G. Harden, Shilpa Demes, Brian J. Arey, Matt Soars, Brian E. Fink, Ashvinikumar V. Gavai, Gregory D. Vite, Charles F. Voliva. A novel MTA non-competitive PRMT5 inhibitor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1140.

Substituted diaryl ether compounds as retinoic acid-related orphan Receptor-γt (RORγt) agonists

The discovery of a series of substituted diarylether compounds as retinoic acid related orphan receptor γt (RORγt) agonists is described. Compound 1 was identified from deck mining as a RORγt agonist. Hit-to-lead optimization led to the identification of lead compound 5, which possesses improved potency (10x). Extensive SAR exploration led to the identification of a potent and selective compound 22, that demonstrated an improved pharmacokinetic profile and a dose-dependent pharmacodynamic response. However, when dosed in a MC38 syngeneic tumor model, no evidence of efficacy was observed. ©2020 Elsevier Science Ltd. All rights reserved.

LncRNAs-directed PTEN enzymatic switch governs epithelial-mesenchymal transition

Despite the structural conservation of PTEN with dual-specificity phosphatases, there have been no reports regarding the regulatory mechanisms that underlie this potential dual-phosphatase activity. Here, we report that K27-linked polyubiquitination of PTEN at lysines 66 and 80 switches its phosphoinositide/protein tyrosine phosphatase activity to protein serine/threonine phosphatase activity. Mechanistically, high glucose, TGF-β, CTGF, SHH, and IL-6 induce the expression of a long non-coding RNA, GAEA (Glucose Aroused for EMT Activation), which associates with an RNA-binding E3 ligase, MEX3C, and enhances its enzymatic activity, leading to the K27-linked polyubiquitination of PTEN. The MEX3C-catalyzed PTENK27-polyUb activates its protein serine/threonine phosphatase activity and inhibits its phosphatidylinositol/protein tyrosine phosphatase activity. With this altered enzymatic activity, PTENK27-polyUb dephosphorylates the phosphoserine/threonine residues of TWIST1, SNAI1, and YAP1, leading to accumulation of these master regulators of EMT. Animals with genetic inhibition of PTENK27-polyUb, by a single nucleotide mutation generated using CRISPR/Cas9 (PtenK80R/K80R), exhibit inhibition of EMT markers during mammary gland morphogenesis in pregnancy/lactation and during cutaneous wound healing processes. Our findings illustrate an unexpected paradigm in which the lncRNA-dependent switch in PTEN protein serine/threonine phosphatase activity is important for physiological homeostasis and disease development.

PTEN-induced partial epithelial-mesenchymal transition drives diabetic kidney disease

Epithelial-mesenchymal transition (EMT) contributes significantly to interstitial matrix deposition in diabetic kidney disease (DKD). However, detection of EMT in kidney tissue is impracticable, and anti-EMT therapies have long been hindered. We reported that phosphatase and tensin homolog (PTEN) promoted transforming growth factor beta 1 (TGF-β), sonic hedgehog (SHH), connective tissue growth factor (CTGF), interleukin 6 (IL-6), and hyperglycemia-induced EMT when PTEN was modified by a MEX3C-catalyzed K27-linked polyubiquitination at lysine 80 (referred to as PTENK27-polyUb). Genetic inhibition of PTENK27-polyUb alleviated Col4a3 knockout-, folic acid-, and streptozotocin-induced (STZ-induced) kidney injury. Serum and urine PTENK27-polyUb concentrations were negatively correlated with glomerular filtration rate (GFR) for diabetic patients. Mechanistically, PTENK27-polyUb facilitated dephosphorylation and protein stabilization of TWIST, SNAI1, and YAP in renal epithelial cells, leading to enhanced EMT. We identified that a small molecule, triptolide, inhibited MEX3C-catalyzed PTENK27-polyUb and EMT of renal epithelial cells. Treatment with triptolide reduced TWIST, SNAI1, and YAP concurrently and improved kidney health in Col4a3 knockout-, folic acid-injured disease models and STZ-induced, BTBR ob/ob diabetic nephropathy models. Hence, we demonstrated the important role of PTENK27-polyUb in DKD and a promising therapeutic strategy that inhibited the progression of DKD.

IMRT planning parameter optimization for spine stereotactic radiosurgery

Spine stereotactic radiosurgery (SSRS) is a noninvasive treatment for metastatic spine lesions. MD Anderson Cancer Center reports a quality assurance (QA) failure rate approaching 15% for SSRS cases, which we hypothesized is due to difficulties in accurately calculating dose resulting from a large number of small-area segments. Clinical plans typically use 9 beams with an average of 10 segments per beam and minimum segment area of 2 to 3 cm2. The purpose of this study was to identify a set of intensity-modulated radiation therapy (IMRT) planning parameters that attempts to optimize the balance among QA passing rate, plan quality, dose calculation accuracy, and delivery time for SSRS plans. Using Pinnacle version 9.10, we evaluated the effects of 2 IMRT parameters: maximum number of segments and minimum segment area. Initial evaluation of the data revealed that 5 segments per beam along with minimum segment area of 4 cm2 and 4 minimum Monitor Units (MU) per segment (544 plans) was the most promising. IMRT QA was performed using an OCTAVIUS 4D phantom with a 2D detector array. Our data showed no significant plan quality change with decreased number of segments and increased minimum segment area. The average coverage of GTV and CTV was 82.5 ± 13% (clinical) vs 82.5 ± 13% (544) and 92.3 ± 8% (clinical) vs 91.5 ± 8% (544). Maximum point dose to cord was 11.4 ± 3.5 Gy (clinical) vs 11.0 ± 4.0 Gy (544). Total plan delivery time was decreased by an average of 11.3% for the 544 plans. In addition, the QA passing rate for the original plan vs the 544 plan averaged 90.3% and 91.9%, respectively. In conclusion, IMRT parameters of 5 segments per beam and 4 cm2 minimum segment area provided a better balance of plan quality, delivery efficiency, and plan dose calculation accuracy for SSRS.

Expression of Long Noncoding RNA YIYA Promotes Glycolysis in Breast Cancer

Long noncoding RNA (lncRNA) is yet to be linked to cancer metabolism. Here, we report that upregulation of the lncRNA LINC00538 (YIYA) promotes glycolysis, cell proliferation, and tumor growth in breast cancer. YIYA is associated with the cytosolic cyclin-dependent kinase CDK6 and regulated CDK6-dependent phosphorylation of the fructose bisphosphatase PFK2 (PFKFB3) in a cell-cycle-independent manner. In breast cancer cells, these events promoted catalysis of glucose 6-phosphate to fructose-2,6-bisphosphate/fructose-1,6-bisphosphate. CRISPR/Cas9-mediated deletion of YIYA or CDK6 silencing impaired glycolysis and tumor growth in vivo In clinical specimens of breast cancer, YIYA was expressed in approximately 40% of cases where it correlated with CDK6 expression and unfavorable survival outcomes. Our results define a functional role for lncRNA in metabolic reprogramming in cancer, with potential clinical implications for its therapeutic targeting.Significance: These findings offer a first glimpse into how a long-coding RNA influences cancer metabolism to drive tumor growth. Cancer Res; 78(16); 4524-32. ©2018 AACR.

Mimicry of an HIV broadly neutralizing antibody epitope with a synthetic glycopeptide

A goal for an HIV-1 vaccine is to overcome virus variability by inducing broadly neutralizing antibodies (bnAbs). One key target of bnAbs is the glycan-polypeptide at the base of the envelope (Env) third variable loop (V3). We have designed and synthesized a homogeneous minimal immunogen with high-mannose glycans reflective of a native Env V3-glycan bnAb epitope (Man₉-V3). V3-glycan bnAbs bound to Man₉-V3 glycopeptide and native-like gp140 trimers with similar affinities. Fluorophore-labeled Man₉-V3 glycopeptides bound to bnAb memory B cells and were able to be used to isolate a V3-glycan bnAb from an HIV-1-infected individual. In rhesus macaques, immunization with Man₉-V3 induced V3-glycan-targeted antibodies. Thus, the Man₉-V3 glycopeptide closely mimics an HIV-1 V3-glycan bnAb epitope and can be used to isolate V3-glycan bnAbs.

Vaccine Elicitation of High Mannose-Dependent Neutralizing Antibodies against the V3-Glycan Broadly Neutralizing Epitope in Nonhuman Primates

Induction of broadly neutralizing antibodies (bnAbs) that target HIV-1 envelope (Env) is a goal of HIV-1 vaccine development. A bnAb target is the Env third variable loop (V3)-glycan site. To determine whether immunization could induce antibodies to the V3-glycan bnAb binding site, we repetitively immunized macaques over a 4-year period with an Env expressing V3-high mannose glycans. Env immunizations elicited plasma antibodies that neutralized HIV-1 expressing only high-mannose glycans-a characteristic shared by early bnAb B cell lineage members. A rhesus recombinant monoclonal antibody from a vaccinated macaque bound to the V3-glycan site at the same amino acids as broadly neutralizing antibodies. A structure of the antibody bound to glycan revealed that the three variable heavy-chain complementarity-determining regions formed a cavity into which glycan could insert and neutralized multiple HIV-1 isolates with high-mannose glycans. Thus, HIV-1 Env vaccination induced mannose-dependent antibodies with characteristics of V3-glycan bnAb precursors.

JAK2-binding long noncoding RNA promotes breast cancer brain metastasis

Conventional therapies for breast cancer brain metastases (BCBMs) have been largely ineffective because of chemoresistance and impermeability of the blood-brain barrier. A comprehensive understanding of the underlying mechanism that allows breast cancer cells to infiltrate the brain is necessary to circumvent treatment resistance of BCBMs. Here, we determined that expression of a long noncoding RNA (lncRNA) that we have named lncRNA associated with BCBM (Lnc-BM) is prognostic of the progression of brain metastasis in breast cancer patients. In preclinical murine models, elevated Lnc-BM expression drove BCBM, while depletion of Lnc-BM with nanoparticle-encapsulated siRNAs effectively treated BCBM. Lnc-BM increased JAK2 kinase activity to mediate oncostatin M- and IL-6-triggered STAT3 phosphorylation. In breast cancer cells, Lnc-BM promoted STAT3-dependent expression of ICAM1 and CCL2, which mediated vascular co-option and recruitment of macrophages in the brain, respectively. Recruited macrophages in turn produced oncostatin M and IL-6, thereby further activating the Lnc-BM/JAK2/STAT3 pathway and enhancing BCBM. Collectively, our results show that Lnc-BM and JAK2 promote BCBMs by mediating communication between breast cancer cells and the brain microenvironment. Moreover, these results suggest targeting Lnc-BM as a potential strategy for fighting this difficult disease.

The LINK-A lncRNA interacts with PtdIns(3,4,5)P3 to hyperactivate AKT and confer resistance to AKT inhibitors

Phosphatidylinositol-3,4,5-trisphosphate (PIP₃) mediates signaling pathways as a second messenger in response to extracellular signals. Although primordial functions of phospholipids and RNAs have been hypothesized in the “RNA world”, physiological RNA-phospholipid interactions and their involvement in essential cellular processes has remained a mystery. We explicate the contribution of lipid-binding long non-coding RNAs (lncRNAs) in cancer cells. Among them, Long Intergenic Noncoding RNA for Kinase Activation (LINK-A) directly interacts with AKT pleckstrin homology domain and PIP₃ at the single nucleotide level, facilitating AKT-PIP₃ interaction and consequent enzymatic activation. LINK-A-dependent AKT hyperactivation leads to tumorigenesis and resistance to AKT inhibitors. Genomic deletions of the LINK-A PIP₃-binding motif dramatically sensitized breast cancer cells to AKT inhibitors. Furthermore, meta-analysis showed the correlation between LINK-A expression and incidence of a SNP (rs12095274: A>G), AKT phosphorylation status, and poor outcomes for breast and lung cancer patients. PIP₃-binding lncRNA modulates AKT activation with broad clinical implications.

LncRNA BCAR4 wires up signaling transduction in breast cancer

Long noncoding RNAs (lncRNAs) are dysregulated in many cancer types and are believed to play crucial roles in regulating several hallmarks of cancer biology. Currently, most studies support the concept that lncRNAs are involved in either transcriptional or post-transcriptional processes via binding/targeting epigenetic modifiers or hRNP complexes. The discovery of new biological functions of lncRNA and novel RNA binding proteins suggests that lncRNAs may be implicated in a broad spectrum of biological processes such as signal transduction, allosteric regulation of cytoplasmic enzymatic activities, among other potential processes. In a recent report that we have made, based on open-ended lncRNA pulldown technology and a series of systematic analyses, we suggest that lncRNAs also play critical roles in the regulation of noncanonical Hedgehog/GLI 2 signal transduction pathways in cancer cells, which further broadens the scope of known lncRNA functions and aids in the discovery and design of more effective and evidence-based therapeutic targets for the treatment of human cancers and other diseases.

lncRNA directs cooperative epigenetic regulation downstream of chemokine signals

lncRNAs are known to regulate a number of different developmental and tumorigenic processes. Here, we report a role for lncRNA BCAR4 in breast cancer metastasis that is mediated by chemokine-induced binding of BCAR4 to two transcription factors with extended regulatory consequences. BCAR4 binding of SNIP1 and PNUTS in response to CCL21 releases the SNIP1's inhibition of p300-dependent histone acetylation, which in turn enables the BCAR4-recruited PNUTS to bind H3K18ac and relieve inhibition of RNA Pol II via activation of the PP1 phosphatase. This mechanism activates a noncanonical Hedgehog/GLI2 transcriptional program that promotes cell migration. BCAR4 expression correlates with advanced breast cancers, and therapeutic delivery of locked nucleic acids (LNAs) targeting BCAR4 strongly suppresses breast cancer metastasis in mouse models. The findings reveal a disease-relevant lncRNA mechanism consisting of both direct coordinated protein recruitment and indirect regulation of transcription factors.

Chemical synthesis of highly congested gp120 V1V2 N-glycopeptide antigens for potential HIV-1-directed vaccines

Critical to the search for an effective HIV-1 vaccine is the development of immunogens capable of inducing broadly neutralizing antibodies (BnAbs). A key first step in this process is to design immunogens that can be recognized by known BnAbs. The monoclonal antibody PG9 is a BnAb that neutralizes diverse strains of HIV-1 by targeting a conserved carbohydrate-protein epitope in the variable 1 and 2 (V1V2) region of the viral envelope. Important for recognition are two closely spaced N-glycans at Asn(160) and Asn(156). Glycopeptides containing this synthetically challenging bis-N-glycosylated motif were prepared by convergent assembly, and were shown to be antigenic for PG9. Synthetic glycopeptides such as these may be useful for the development of HIV-1 vaccines based on the envelope V1V2 BnAb epitope.

A fascinating journey into history: exploration of the world of isonitriles en route to complex amides

We describe herein our recent explorations in the field of isonitrile chemistry. An array of broadly useful coupling methodologies has been developed for the formation of peptidyl and glycopeptidyl amide bonds. We further describe the application of these methods to the syntheses of complex systems, including the cyclic peptide cyclosporine A, constrained peptide systems, and heterocycles.

Expanding the limits of isonitrile-mediated amidations: on the remarkable stereosubtleties of macrolactam formation from synthetic seco-cyclosporins

The scope of isonitrile-mediated amide bond-forming reactions is further explored in this second-generation synthetic approach to cyclosporine (cyclosporin A). Both type I and type II amidations are utilized in this effort, allowing access to epimeric cyclosporins A and H from a single precursor by variation of the coupling reagents. This work lends deeper insight into the relative acylating ability of the formimidate carboxylate mixed anhydride (FCMA) intermediate, while shedding light on the far-reaching impact of remote stereochemical changes on the effective preorganization of seco-cyclosporins.

Synthetic studies toward (+)-cortistatin A

We describe herein the synthesis of a late-stage intermediate en route to cortistatin A. Key transformations included a Snieckus-like cascade sequence culminating in a 6π-electrocyclization, an alkylative dearomatization, and the stereoselective functionalization of the cortistatin A-ring. While the total synthesis we sought was not accomplished, the work sets the stage for several approaches to the preparation of novel analogs via diverted total synthesis.

On the synthesis of conformationally modified peptides through isonitrile chemistry: implications for dealing with polypeptide aggregation

A method for introducing a dimethyleneoxy constraint joining the N atoms of two consecutive amino acids in the context of a polypeptide has been developed. This constraint can profoundly affect the tendency of a polypeptide to suffer aggregation and desolubilization, and it can be readily removed under mild conditions.

Total synthesis of dolabelide D

The first total synthesis of dolabelide D (or of any of the closely related dolabelides) has been achieved with a longest linear sequence of 17 steps. Key features of the synthesis include an application of the catalytic asymmetric silane alcoholysis, the tandem silylformylation-crotylsilylation, and a Brook-like 1,4-carbon to oxygen silyl migration.

Approach to the synthesis of dolabelides A and B: fragment synthesis by tandem silylformylation-crotylsilylation

[structure: see text] A synthesis of the C(15)-C(30) fragment of Dolabelides A and B has been achieved. The recently developed asymmetric silane alcoholysis and tandem silylformylation-crotylsilylation reactions were used as the key steps to establish the C(23)-C(27) 1,5-syn-diol. In addition, the flexibility of this methodology has been demonstrated with an efficient synthesis of the C(24)-C(25) trisubstituted olefin.

ATR is not required for p53 activation but synergizes with p53 in the replication checkpoint

ATR (ataxia telangiectasia and Rad-3-related) is a protein kinase required for survival after DNA damage. A critical role for ATR has been hypothesized to be the regulation of p53 and other cell cycle checkpoints. ATR has been shown to phosphorylate p53 at Ser(15), and this damage-induced phosphorylation is diminished by expression of a catalytically inactive (ATR-kd) mutant. p53 function could not be examined directly in prior studies of ATR, however, because p53 was mutant or because cells expressed the SV40 large T antigen that blocks p53 function. To test the interactions of ATR and p53 directly we generated human U2OS cell lines inducible for either wild-type or kinase-dead ATR that also have an intact p53 pathway. Indeed, ATR-kd expression sensitized these cells to DNA damage and caused a transient decrease in damage-induced serine 15 phosphorylation of p53. However, we found that the effects of ATR-kd expression do not result in blocking the response of p53 to DNA damage. Specifically, prior ATR-kd expression had no effect on DNA damage-induced p53 protein up-regulation, p53-DNA binding, p21 mRNA up-regulation, or G(1) arrest. Instead of promoting survival via p53 regulation, we found that ATR protects cells by delaying the generation of mitotic phosphoproteins and inhibiting premature chromatin condensation after DNA damage or hydroxyurea. Although p53 inhibition (by E6 or MDM2 expression) had little effect on premature chromatin condensation, when combined with ATR-kd expression there was a marked loss of the replication checkpoint. We conclude that ATR and p53 can function independently but that loss of both leads to synergistic disruption of the replication checkpoint.

Depot-specific variation in protein-tyrosine phosphatase activities in human omental and subcutaneous adipose tissue: a potential contribution to differential insulin sensitivity

Compared with the sc depot, omental (om) adipose tissue is relatively resistant to the metabolic actions of insulin. Protein-tyrosine phosphatases (PTPases) modulate receptor kinase activation and signal transduction in insulin-sensitive tissues, and their activity is dependent on the reduced state of the cysteine thiol required for catalysis. Using a novel anaerobic technique to avoid air oxidation, we found that the mean endogenous PTPase activity was 2.1-fold higher in om compared with paired samples of sc adipose tissue (P < 0.003). The specific activity of PTP1B isolated under anaerobic conditions was also 41% higher in om adipose tissue (P < 0.001). Interestingly, the total PTPase activity from both adipose depots and the specific activity of PTP1B was increased by 42-71% after reduction in vitro with dithiothreitol, indicating that a major fraction of the cellular PTPase activity can be reactivated by sulfhydryl reduction. The mass of the insulin receptor beta-subunit and the PTPases PTP1B and leukocyte antigen related was not significantly different between the two adipose depots. These studies provide the first demonstration that endogenous PTPase activity, including PTP1B, is increased in om adipose tissue and may contribute to the relative insulin resistance of this fat depot. The finding that a substantial fraction of PTPase activity in human adipose tissue is present in a latent, oxidized form also suggests a potential means of in vivo regulation of these important cellular enzymes that modulate the insulin signaling cascade.

ATR inhibition selectively sensitizes G1 checkpoint-deficient cells to lethal premature chromatin condensation

Premature chromatin condensation (PCC) is a hallmark of mammalian cells that begin mitosis before completing DNA replication. This lethal event is prevented by a highly conserved checkpoint involving an unknown, caffeine-sensitive mediator. Here, we have examined the possible involvement of the caffeine-sensitive ATM and ATR protein kinases in this checkpoint. We show that caffeine's ability to inhibit ATR (but not ATM) causes PCC, that ATR (but not ATM) prevents PCC, and that ATR prevents PCC via Chk-1 regulation. Moreover, mimicking cancer cell phenotypes by disrupting normal G(1) checkpoints sensitizes cells to PCC by ATR inhibition plus low-dose DNA damage. Notably, loss of p53 function potently sensitizes cells to PCC caused by ATR inhibition by a small molecule. We present a molecular model for how ATR prevents PCC and suggest that ATR represents an attractive therapeutic target for selectively killing cancer cells by premature chromatin condensation.

Identification of yacE (coaE) as the structural gene for dephosphocoenzyme A kinase in Escherichia coli K-12

Dephosphocoenzyme A (dephospho-CoA) kinase catalyzes the final step in coenzyme A biosynthesis, the phosphorylation of the 3'-hydroxy group of the ribose sugar moiety. Wild-type dephospho-CoA kinase from Corynebacterium ammoniagenes was purified to homogeneity and subjected to N-terminal sequence analysis. A BLAST search identified a gene from Escherichia coli previously designated yacE encoding a highly homologous protein. Amplification of the gene and overexpression yielded recombinant dephospho-CoA kinase as a 22.6-kDa monomer. Enzyme assay and nuclear magnetic resonance analyses of the product demonstrated that the recombinant enzyme is indeed dephospho-CoA kinase. The activities with adenosine, AMP, and adenosine phosphosulfate were 4 to 8% of the activity with dephospho-CoA. Homologues of the E. coli dephospho-CoA kinase were identified in a diverse range of organisms.

Potential and limitations of alum or zeolite addition to improve the performance of a submerged membrane bioreactor

In this study, alum and natural zeolite were added to a submerged membrane bioreactor (MBR) not only to reduce membrane fouling but also to increase the removal of nitrogen and phosphorus. Alum addition reduced significantly the rising rate of suction pressure and also resulted in stable and better COD removal. Although phosphorus removal was more than 90% by chemical precipitation, nitrification inhibition was observed. With the addition of natural zeolite, membrane permeability was greatly enhanced by the formation of rigid floc that had lower specific resistance than that of the control activated sludge floc. In particular, the nitrification efficiency was over 95% even at N-shock loading due to the ion-exchange capacity of zeolite. The mechanisms for improved membrane permeability through alum or zeolite addition were discussed in detail.

Use of guanylyl cyclase C for detecting micrometastases in lymph nodes of patients with colon cancer

INTRODUCTION

Guanylyl cyclase C appears to be expressed only in colorectal cancer cells in extraintestinal tissues. Thus, guanylyl cyclase C may be useful as a marker to detect colorectal cancer micrometastases not detectable by histopathology in lymph nodes of patients.

METHODS

Twelve patients with colon adenocarcinoma, Dukes Stages A through C2, and one patient with a tubulovillous adenoma were included in this study. Forty-two lymph nodes were collected from fresh surgical specimens, and each was examined by histopathology and reverse transcription followed by polymerase chain reaction using guanylyl cyclase C-specific primers. Histopathology identified colon cancer cells in 6 of 16 lymph nodes from five Dukes Stage C patients but not in lymph nodes from the patient with a tubulovillous adenoma, the Dukes Stage A patient, or six Dukes Stage B patients. Reverse transcription followed by polymerase chain reaction using guanylyl cyclase C-specific primers was performed on all 42 lymph nodes.

RESULTS

Guanylyl cyclase C messenger RNA was not detected by reverse transcription followed by polymerase chain reaction in lymph nodes from the patient with the tubulovillous adenoma or the patient with Dukes Stage A colon carcinoma. Seven lymph nodes from Dukes Stage C patients revealed guanylyl cyclase C messenger RNA including six lymph nodes containing histopathologically confirmed metastases. Of significance, guanylyl cyclase C messenger RNA was detected in 6 of 21 lymph nodes from Dukes Stage B patients. Indeed, clinical staging of two patients could be upgraded from B to C using reverse transcription followed by polymerase chain reaction and guanylyl cyclase C-specific primers.

CONCLUSION

Reverse transcription followed by polymerase chain reaction using guanylyl cyclase C-specific primers might be useful to more accurately assess micrometastases in lymph nodes of colorectal cancer patients undergoing disease staging.

Guanylyl cyclase C is a selective marker for metastatic colorectal tumors in human extraintestinal tissues

Guanylyl cyclase C (GCC) has been detected only in intestinal mucosa and colon carcinoma cells of placental mammals. However, this receptor has been identified in several tissues in marsupials, and its expression has been suggested in tissues other than intestine in placental mammals. Selective expression of GCC by colorectal tumor cells in extraintestinal tissues would permit this receptor to be employed as a selective marker for metastatic disease. Thus, expression of GCC was examined in human tissues and tumors, correlating receptor function with detection by PCR. GCC was detected by ligand binding and catalytic activation in normal intestine and primary and metastatic colorectal tumors, but not in extraintestinal tissues or tumors. Similarly, PCR yielded GCC-specific amplification products with specimens from normal intestine and primary and metastatic colorectal tumors, but not from extraintestinal tissues or tumors. Northern blot analysis employing GCC-specific probes revealed an approximately 4-kb transcript, corresponding to recombinant GCC, in normal intestine and primary and metastatic colorectal tumors, but not in extraintestinal tissues. Thus, GCC is selectively expressed in intestine and colorectal tumors in humans and appears to be a relatively specific marker for metastatic cancer cells in normal tissues. Indeed, PCR of GCC detected tumor cells in blood from some patients with Dukes B colorectal cancer and all patients examined with Dukes C and D colorectal cancer, but not in that from normal subjects or patients with Dukes A colon carcinoma or other nonmalignant intestinal pathologies.

Escherichia coli heat-stable enterotoxin receptors. A novel marker for colorectal tumors

PURPOSE

Receptors for Escherichia coli heat-stable toxin (ST) are selectively expressed in membranes of intestinal mucosa cells and colon carcinoma cells in vitro, suggesting their use as a marker for colorectal tumors in vivo. The present studies examined the expression and function of ST receptors in normal human tissues and primary and metastatic colorectal tumors obtained from patients at surgery.

METHODS

Surgical specimens were obtained as follows: from normal colon; from primary adenocarcinomas from all anatomic divisions of the colon and rectum; from gallbladder, kidney, liver, lung, lymph node, ovary, peritoneum, stomach; and from colon carcinomas metastatic to liver, lung, lymph node, ovary, and peritoneum. Membranes prepared from these specimens were assessed for the presence and functional characteristics of ST receptors.

RESULTS

ST bound specifically to membranes from each division of normal colon and rectum and all primary and metastatic colorectal tumors examined. The affinity and density of ST receptors were similar in tumors of different grades and from various metastatic sites. ST-receptor interaction was coupled to activation of guanylyl cyclase in all normal samples of colon and rectum and all primary and metastatic colorectal tumors examined. In contrast, neither ST binding nor ST activation of guanylyl cyclase was detected in any extraintestinal tissues examined.

CONCLUSIONS

Functional ST receptors are expressed in normal colonic tissue and primary and metastatic colorectal tumors but not by extraintestinal tissues in humans. Expression of ST receptors does not vary as a function of the metastatic site or grade of these tumors. Receptors expressed by colorectal tumors retain their characteristic function, with binding of ST coupled to activation of guanylyl cyclase. These studies support the suggestion that ST receptors represent a specific marker for human colorectal tumors that may have use as a target for directing diagnostics and therapeutics to these tumors in vivo.

Role of thrombin in endothelial cell monolayer repair in vitro

PURPOSE

We examined the effect of thrombin on human iliac artery endothelial cell monolayer repair and proliferation after denuding vascular injury.

METHODS

Human iliac artery endothelial cell monolayer repair was determined by scrape wounding confluent monolayers and measuring the advancement of the cells into the wounded area for 3 days. Proliferation studies involved plating human iliac artery endothelial cells at one tenth confluence and counting the increase in cell number every 2 days for a 2-week period. Proliferation during monolayer repair was examined by determining bromodeoxyuridine uptake in cells located at the leading edge of a scrape-wounded monolayer.

RESULTS

Thrombin (1 to 8 U/ml) inhibited human iliac artery endothelial cell monolayer repair in a concentration-related, reversible manner. The effect was augmented by decreasing serum concentration and was independent of the presence of endothelial cell growth supplement. Inactivation of thrombin's proteolytic site with diisopropylfluorophosphate eliminated its effect on monolayer repair. Thrombin (0.5 to 8 U/ml) inhibited human iliac artery endothelial cell proliferation in a dose-related manner. This effect was augmented by decreasing serum concentration. Finally, thrombin (4 U/ml) inhibited the proliferative response of cells located at the leading edge of wounded monolayers compared with control groups.

CONCLUSION

Thrombin inhibits human arterial endothelial cell monolayer repair and proliferation after denuding vascular injury.

Formation of a multilayer cellular lining on a polyurethane vascular graft following endothelial cell sodding

Small-diameter (less than 6 mm) clinically available vascular grafts often fail due in part to the inherent thrombogenicity of artificial polymers. Transplantation of endothelial cells onto the lumen of these vascular grafts has been suggested as one method to overcome this thrombogenicity. We have developed a compliant polyurethaneurea (PEUU) 4-mm graft with a luminal surface modified by a glow discharge gas plasma. Autologous microvessel endothelial cells were isolated from canine falciform ligament fat, were transplanted onto the luminal surface of the grafts using an intraoperative isolation and sodding technique, and both endothelial-cell-treated and non-cell-treated grafts were placed as bilateral carotid interposition grafts in a canine model. After 5 weeks of implantation, explanted control (non-cell-treated) grafts exhibited a deposition of platelets, white cells and fibrin characteristic of a thrombogenic surface. MVEC sodded grafts exhibited a multicellular lining within but distinct from the lumen of the PEUU graft. The blood-contacting surface of this lining exhibited an antithrombogenic endothelial cell monolayer. We suggest that the PEUU graft supported the initial deposition of MVEC and development of and endothelial cell lining. During the 5 weeks of implantation this lining continued to proliferate and detached from the PEUU graft substratum. The final neocellular lining exhibited a luminal diameter and histological features similar to a native artery.

Thrombus-free, human endothelial surface in the midregion of a Dacron vascular graft in the splanchnic venous circuit--observations after nine months of implantation

The addition of an endothelial cell lining to a prosthetic vascular graft may reduce the thrombogenicity of the blood-contacting surface. An endothelialized mesoatrial graft was implanted in a patient with Budd-Chiari syndrome caused by a primary inferior vena caval leiomyosarcoma. During the initial surgery a Dacron vascular graft was preclotted with plasma and then lined with microvascular endothelial cells derived from the patient's subcutaneous adipose tissue. The patient did well initially but 9 months later required resection of a mechanical stricture of the graft that occurred as it passed beneath the costochondral junction. Grossly, the luminal surface of the resected graft was free of thrombus, with a smooth, glistening, white surface. Light microscopy demonstrated a surface layer of cells morphologically consistent with an endothelial cell monolayer, a subendothelial layer composed of extracellular matrix and spindle-shaped cells, and granulation tissue around the Dacron fabric. Immunohistochemistry and electron microscopy confirmed the presence of vascular endothelium on the luminal surface. This report documents the successful achievement of a human endothelial cell monolayer that persisted for 9 months in the midportion of a Dacron vascular graft.

Human microvessel endothelial cell isolation and vascular graft sodding in the operating room

We have evaluated multiple factors inherent to an operating room-compatible endothelial cell procurement and sodding procedure. Microvessel endothelial cell isolations have been performed on fat tissue obtained from over 140 patients with a 100% success rate. Liposuction-derived fat was optimal with respect to cell yield, and isolation time. The devices and equipment used were acceptable to the operating room and the complete cell procurement procedure was successful even in the hands of personnel with minimal training. Fat digestion was achieved using crude clostridial collagenase, with an average cell yield of 1 x 10(6) microvessel endothelial cells/gm of fat. Evaluation of this procedure with canine fat using an operating room acceptable procedure resulted in a 100% procurement success rate requiring 1.5 hours (+/- .5 hrs) for completion of the fat isolation, and cell isolation procedure. Microvessel EC could subsequently be used in graft seeding or sodding techniques to establish endothelial cell monolayers on vascular grafts. Our results indicate that one person with minimal cell isolation background can reproducibly isolate large quantities of sterile autologous endothelial cells in the operating room for immediate use in endothelial cell seeding/sodding procedures.

Carbon Dioxide Partial Pressure in the Columbia River

Columbia River water is supersaturated with respect to atmospheric carbon dioxide by 200 to 870 parts per million. An equilibrium exists between the carbon dioxide partial pressure and pH, and Henry's law is obeyed in this natural water. The carbon dioxide pressure can be calculated by a determination of the pH, total carbon dioxide, and temperature.

Seawater Hydrogen-Ion Concentration: Vertical Distribution

Two major processes that affect the vertical distribution of hydrogen-ion concentration in the sub-Arctic region of the northeastern Pacific Ocean are the apparent oxygen utilization by marine organisms and, to a lesser extent, carbonate dissolution.