Optimizing Tissue Engineering for Clinical Relevance in Rotator Cuff Repair

Rotator cuff tear (RCT) is the most common cause of disability in the upper extremity. It results in 4.5 million physician visits in the United States every year and is the most common etiology of shoulder conditions evaluated by orthopedic surgeons. Over 460,000 RCT repair surgeries are performed in the United States annually. Rotator cuff (RC) retear and failure to heal remain significant postoperative complications. Literature suggests that the retear rates can range from 29.5% to as high as 94%. Weakened and irregular enthesis regeneration is a crucial factor in postsurgical failure. Although commercially available RC repair grafts have been introduced to augment RC enthesis repair, they have been associated with mixed clinical outcomes. These grafts lack appropriate biological cues such as stem cells and signaling molecules at the bone-tendon interface. In addition, they do little to prevent fibrovascular scar tissue formation, which causes the RC to be susceptible to retear. Advances in tissue engineering have demonstrated that mesenchymal stem cells (MSCs) and growth factors (GFs) enhance RC enthesis regeneration in animal models. These models show that delivering MSCs and GFs to the site of RCT enhances native enthesis repair and leads to greater mechanical strength. In addition, these models demonstrate that MSCs and GFs may be delivered through a variety of methods including direct injection, saturation of repair materials, and loaded microspheres. Grafts that incorporate MSCs and GFs enhance anti-inflammation, osteogenesis, angiogenesis, and chondrogenesis in the RC repair process. It is crucial that the techniques that have shown success in animal models are incorporated into the clinical setting. A gap currently exists between the promising biological factors that have been investigated in animal models and the RC repair grafts that can be used in the clinical setting. Future RC repair grafts must allow for stable implantation and fixation, be compatible with current arthroscopic techniques, and have the capability to deliver MSCs and/or GFs.

Host and microbial characteristics associated with recurrent prosthetic joint infections

Approximately 20% of patients after resection arthroplasty and antibiotic spacer placement for prosthetic joint infection develop repeat infections, requiring an additional antibiotic spacer before definitive reimplantation. The host and bacterial characteristics associated with the development of recurrent infection is poorly understood. A case-control study was conducted for 106 patients with intention to treat by two-stage revision arthroplasty for prosthetic joint infection at a single institution between 2009 and 2020. Infection was defined according to the 2018 Musculoskeletal Infection Society criteria. Thirty-nine cases ("recurrent-periprosthetic joint infection [PJI]") received at least two antibiotic spacers before clinical resolution of their infection, and 67 controls ("single-PJI") received a single antibiotic cement spacer before infection-free prosthesis reimplantation. Patient demographics, McPherson host grade, and culture results including antibiotic susceptibilities were compared. Fifty-two (78%) single-PJI and 32 (82%) recurrent-PJI patients had positive intraoperative cultures at the time of their initial spacer procedure. The odds of polymicrobial infections were 11-fold higher among recurrent-PJI patients, and the odds of significant systemic compromise (McPherson host-grade C) were more than double. Recurrent-PJI patients were significantly more likely to harbor Staphylococcus aureus. We found no differences between cases and controls in pathogen resistance to the six most tested antibiotics. Among recurrent-PJI patients, erythromycin-resistant infections were more prevalent at the final than initial spacer, despite no erythromycin exposure. Our findings suggest that McPherson host grade, polymicrobial infection, and S. aureus infection are key indicators of secondary or persistent joint infection following resection arthroplasty and antibiotic spacer placement, while bacterial resistance does not predict infection-related arthroplasty failure.

Growth and differentiation factor-7 immobilized, mechanically strong quadrol-hexamethylene diisocyanate-methacrylic anhydride polyurethane polymer for tendon repair and regeneration

Biological and mechanical cues are both vital for biomaterial aided tendon repair and regeneration. Here, we fabricated mechanically tendon-like (0 s UV) QHM polyurethane scaffolds (Q: Quadrol, H: Hexamethylene diisocyanate; M: Methacrylic anhydride) and immobilized them with Growth and differentiation factor-7 (GDF-7) to produce mechanically strong and tenogenic scaffolds. In this study, we assessed QHM polymer cytocompatibility, amenability to fibrin-coating, immobilization and persistence of GDF-7, and capability to support GDF-7-mediated tendon differentiation in vitro as well as in vivo in mouse subcutaneous and acute rat rotator cuff tendon resection models. Cytocompatibility studies showed that QHM facilitated cell attachment, proliferation, and viability. Fibrin-coating and GDF-7 retention studies showed that mechanically tendon-like 0 s UV QHM polymer could be immobilized with GDF-7 and retained the growth factor (GF) for at least 1-week ex vivo. In vitro differentiation studies showed that GDF-7 mediated bone marrow-derived human mesenchymal stem cell (hMSC) tendon-like differentiation on 0 s UV QHM. Subcutaneous implantation of GDF-7-immobilized, fibrin-coated, QHM polymer in mice for 2 weeks demonstrated de novo formation of tendon-like tissue while implantation of GDF-7-immobilized, fibrin-coated, QHM polymer in a rat acute rotator cuff resection injury model indicated tendon-like tissue formation in situ and the absence of heterotopic ossification. Together, our work demonstrates a promising synthetic scaffold with human tendon-like biomechanical attributes as well as immobilized tenogenic GDF-7 for tendon repair and regeneration. STATEMENT OF SIGNIFICANCE: Biological activity and mechanical robustness are key features required for tendon-promoting biomaterials. While synthetic biomaterials can be mechanically robust, they often lack bioactivity. To biologically augment synthetic biomaterials, numerous drug and GF delivery strategies exist but the large tissue space within the shoulder is constantly flushed with saline during arthroscopic surgery, hindering efficacious controlled release of therapeutic molecules. Here, we coated QHM polymer (which exhibits human tendon-to-bone-like biomechanical attributes) with fibrin for GF binding. Unlike conventional drug delivery strategies, our approach utilizes immobilized GFs as opposed to released GFs for sustained, localized tissue regeneration. Our data demonstrated that GF immobilization can be broadly applied to synthetic biomaterials for enhancing bioactivity, and GDF-7-immobilized QHM exhibit high clinical translational potential for tendon repair.

Continuous interscalene versus phrenic nerve-sparing high-thoracic erector spinae plane block for total shoulder arthroplasty: a randomized controlled trial

PURPOSE

The high-thoracic erector spinae plane block (HT-ESPB) has been reported as an effective analgesic modality for the shoulder region without phrenic nerve palsy. The goal of this study was to compare the HT-ESPB as a phrenic nerve-sparing alternative to an interscalene block for total shoulder arthroplasty.

METHODS

Thirty patients undergoing total shoulder arthroplasty at Stanford Health Care (Palo Alto, CA, USA) were enrolled in a double-blind randomized controlled trial. We randomized 28 patients to receive either an interscalene or HT-ESPB perineural catheter preoperatively; 26 patients were included in the final analysis. The study was powered for the primary outcome of incidence of hemidiaphragmatic paralysis in the postanesthesia care unit (PACU). Other outcome measures included incentive spirometry volume, brachial plexus motor and sensory exams, adverse events, pain scores, and opioid consumption.

RESULTS

The incidence of hemidiaphragmatic paralysis in the HT-ESPB catheter group was significantly lower than in the interscalene catheter group (0/12, 0% vs 14/14, 100%; P < 0.001). No statistically significant differences were found in pain scores and opioid consumption (in oral morphine equivalents) between the interscalene and HT-ESPB groups through postoperative day (POD) 2. Nevertheless, the mean (standard deviation) point estimates for opioid consumption for the HT-ESPB group were higher than for the interscalene group in the PACU (HT-ESPB: 24.8 [26.7] mg; interscalene: 10.7 [21.7] mg) and for POD 0 (HT-ESPB: 20.5 [25.0] mg; interscalene: 6.7 [12.0] mg). In addition, cumulative postoperative opioid consumption was significantly higher at POD 0 (PACU through POD 0) in the HT-ESPB group (45.3 [39.9] mg) than in the interscalene group (16.6 [21.9] mg; P = 0.04).

CONCLUSIONS

This study suggests that continuous HT-ESPB can be a phrenic nerve-sparing alternative to continuous interscalene brachial plexus blockade, although the latter provided superior opioid-sparing in the immediate postoperative period. This was a small sample size study, and further investigations powered to detect differences in analgesic and quality of recovery score endpoints are needed.

STUDY REGISTRATION

www.

CLINICALTRIALS

gov (NCT03807505); registered 17 January 2019.

Multicentre study of hospitalised patients with sports- and recreational cycling-related traumatic brain injury in Hong Kong

INTRODUCTION

Cycling is associated with a greater risk of traumatic brain injury (TBI) than other recreational activities. This study aimed to investigate the epidemiology of sports-related TBI in Hong Kong and to examine predictors for recreational cycling-induced intracranial haemorrhage.

METHODS

This retrospective multicentre study included patients diagnosed with sports-related TBI in public hospitals in Hong Kong from 2015 to 2019. Computed tomography scans were reviewed by an independent assessor. The primary endpoint was traumatic intracranial haemorrhage. The secondary endpoint was an unfavourable Glasgow Outcome Scale (GOS) score at discharge from hospital.

RESULTS

In total, 720 patients were hospitalised with sports-related TBI. The most common sport was cycling (59.2%). The crude incidence of cycling-related TBI was 1.1 per 100 000 population. Cyclists were more likely to exhibit intracranial haemorrhage and an unfavourable GOS score, compared with patients who had TBI because of other sports. Although 47% of cyclists had intracranial haemorrhage, only 15% wore a helmet. In multivariate analysis, significant predictors for intracranial haemorrhage were age ≥60 years, antiplatelet medication, moderate or severe TBI, and skull fracture. Among 426 cyclists, 375 (88%) had mild TBI, and helmet wearing was protective against intracranial haemorrhage, regardless of age, antiplatelet medication intake, and mechanism of injury. Of 426 cyclists, 31 (7.3%) had unfavourable outcomes on discharge from hospital.

CONCLUSIONS

The incidence of sports-related TBI is low in Hong Kong. Although cycling-related head injuries carried greater risks of intracranial haemorrhage and unfavourable outcomes compared with other sports, most cyclists experienced good recovery. Helmet wearing among recreational cyclists with mild TBI was protective against intracranial haemorrhage and skull fracture.

Clinical effect of normal saline injectate into interscalene nerve block catheters given within one hour of local anesthetic bolus on analgesia and hemidiaphragmatic paralysis

BACKGROUND

Previous case reports describe the reversal of phrenic nerve blockade from the interscalene nerve block using normal saline injectate washout. This randomized clinical trial aimed to evaluate whether using normal saline injectate to wash out local anesthetic from an interscalene nerve block catheter would restore phrenic nerve and diaphragm function, while preserving analgesia.

METHODS

Institutional review board approval, clinical trial registration and consent were obtained for patients undergoing shoulder surgery with an interscalene nerve block catheter. 16 patients were randomized to receive three 10 mL aliquots of normal saline injectate (intervention group, n=8) or three sham injectates (control group, n=8) via their perineural catheters in the postanesthesia care unit (PACU). Primary outcome measures were the effects on ipsilateral hemidiaphragmatic paralysis, and secondary outcome measures included PACU opioid consumption, pain scores and change in brachial plexus sensory examination and motor function.

RESULTS

There was no significant difference in reversal of hemidiaphragmatic paralysis. However, there was a greater number of patients in the intervention group who ultimately displayed partial, as opposed to full, paralysis of the hemidiaphragm (p=0.03). There was no significant difference in pain scores, PACU opioid requirement, and brachial plexus motor and sensory examinations between the two groups.

CONCLUSIONS

All patients had persistent hemidiaphragmatic paralysis after the intervention, but fewer patients in the intervention group progressed to full paralysis, suggesting that a larger bolus dose of normal saline may be needed to completely reverse hemidiaphragmatic paralysis. Although normal saline injectate in 10mL increments given through the interscalene nerve block catheter had no clinically significant effect on reversing phrenic nerve blockade, it also did not lead to a reduction in analgesia and may be protective in preventing the progression to full hemidiaphragmatic paralysis.

TRAIL REGISTRATION NUMBER

NCT03677778.

eV-Scale Sterile Neutrino Search Using Eight Years of Atmospheric Muon Neutrino Data from the IceCube Neutrino Observatory

The results of a 3+1 sterile neutrino search using eight years of data from the IceCube Neutrino Observatory are presented. A total of 305 735 muon neutrino events are analyzed in reconstructed energy-zenith space to test for signatures of a matter-enhanced oscillation that would occur given a sterile neutrino state with a mass-squared differences between 0.01 and 100  eV^{2}. The best-fit point is found to be at sin^{2}(2θ_{24})=0.10 and Δm_{41}^{2}=4.5  eV^{2}, which is consistent with the no sterile neutrino hypothesis with a p value of 8.0%.

Characteristics of the Diffuse Astrophysical Electron and Tau Neutrino Flux with Six Years of IceCube High Energy Cascade Data

We report on the first measurement of the astrophysical neutrino flux using particle showers (cascades) in IceCube data from 2010-2015. Assuming standard oscillations, the astrophysical neutrinos in this dedicated cascade sample are dominated (∼90%) by electron and tau flavors. The flux, observed in the sensitive energy range from 16 TeV to 2.6 PeV, is consistent with a single power-law model as expected from Fermi-type acceleration of high energy particles at astrophysical sources. We find the flux spectral index to be γ=2.53±0.07 and a flux normalization for each neutrino flavor of ϕ_{astro}=1.66_{-0.27}^{+0.25} at E_{0}=100  TeV, in agreement with IceCube's complementary muon neutrino results and with all-neutrino flavor fit results. In the measured energy range we reject spectral indices γ≤2.28 at ≥3σ significance level. Because of high neutrino energy resolution and low atmospheric neutrino backgrounds, this analysis provides the most detailed characterization of the neutrino flux at energies below ∼100  TeV compared to previous IceCube results. Results from fits assuming more complex neutrino flux models suggest a flux softening at high energies and a flux hardening at low energies (p value ≥0.06). The sizable and smooth flux measured below ∼100  TeV remains a puzzle. In order to not violate the isotropic diffuse gamma-ray background as measured by the Fermi Large Area Telescope, it suggests the existence of astrophysical neutrino sources characterized by dense environments which are opaque to gamma rays.

Time-Integrated Neutrino Source Searches with 10 Years of IceCube Data

This Letter presents the results from pointlike neutrino source searches using ten years of IceCube data collected between April 6, 2008 and July 10, 2018. We evaluate the significance of an astrophysical signal from a pointlike source looking for an excess of clustered neutrino events with energies typically above ∼1  TeV among the background of atmospheric muons and neutrinos. We perform a full-sky scan, a search within a selected source catalog, a catalog population study, and three stacked Galactic catalog searches. The most significant point in the northern hemisphere from scanning the sky is coincident with the Seyfert II galaxy NGC 1068, which was included in the source catalog search. The excess at the coordinates of NGC 1068 is inconsistent with background expectations at the level of 2.9σ after accounting for statistical trials from the entire catalog. The combination of this result along with excesses observed at the coordinates of three other sources, including TXS 0506+056, suggests that, collectively, correlations with sources in the northern catalog are inconsistent with background at 3.3σ significance. The southern catalog is consistent with background. These results, all based on searches for a cumulative neutrino signal integrated over the 10 years of available data, motivate further study of these and similar sources, including time-dependent analyses, multimessenger correlations, and the possibility of stronger evidence with coming upgrades to the detector.

Clinical and radiographic comparison of a hybrid cage glenoid to a cemented polyethylene glenoid in anatomic total shoulder arthroplasty

BACKGROUND

This study reports the clinical and radiographic outcomes of a hybrid cage glenoid compared with an age-matched, sex-matched, and follow-up-matched cohort of cemented all-polyethylene peg glenoids in patients undergoing anatomic total shoulder arthroplasty with 2 years' minimum follow-up.

MATERIALS AND METHODS

We reviewed 632 primary anatomic total shoulder arthroplasty patients from an international multi-institutional database; 316 patients received hybrid cage glenoids and were matched for age, sex, and follow-up with 316 patients with cemented all-polyethylene peg glenoids. Each cohort received the same humeral component. Scoring was performed in all patients preoperatively and at latest follow-up using 5 outcome scoring metrics and 4 active range-of-motion measurements. A Student 2-tailed unpaired t test identified differences in outcomes; P < .05 denoted a significant difference.

RESULTS

Cage glenoid patients had significantly lower rates of radiolucent glenoid lines (9.0% vs. 37.6%, P < .0001) and radiolucent humeral lines (3.0% vs. 9.1%, P = .0088) than all-polyethylene peg glenoid patients. In the cage glenoid cohort, 4 cases of aseptic glenoid loosening (1.3%) and 4 cases of articular surface dissociation (1.3%) occurred. In the all-polyethylene peg cohort, 12 cases of aseptic loosening (3.8%) occurred. Cage glenoid patients had a significantly lower revision rate than all-polyethylene peg glenoid patients (2.5% vs. 6.9%, P = .0088).

CONCLUSION

At 50 months' mean follow-up, cage glenoids demonstrated equally good clinical outcomes to all-polyethylene peg glenoids. Cage glenoids had significantly fewer radiolucent lines around both the glenoid and humeral components and a lower revision rate. Longer-term follow-up is required to confirm these promising short-term results.

Impact of screw length and screw quantity on reverse total shoulder arthroplasty glenoid fixation for 2 different sizes of glenoid baseplates

Background

Little guidance exists regarding the minimum screw length and screw quantity necessary to achieve fixation in reverse total shoulder arthroplasty (rTSA); to that end, this study quantified the displacement of 2 different sizes of glenoid baseplates using multiple different screw lengths and quantities of screws in a low-density polyurethane bone-substitute model.

Methods

Testing of rTSA glenoid loosening was conducted according to ASTM F 2028-17. To independently evaluate the impact of screw quantity and screw length on rTSA glenoid fixation for 2 different sizes of glenoid baseplates, baseplates were constructed using 2 screws, 4 screws, or 6 screws (with the latter being used for the larger baseplate only) with 3 different poly-axial locking compression screw lengths.

Results

Both sizes of glenoid baseplates remained well fixed after cyclic loading regardless of screw length or screw quantity. Baseplates with 2 screws had significantly greater displacement than baseplates with 4 or 6 screws. No differences were observed between baseplates with 4 screws and those with 6 screws (used for the larger baseplate). Both sizes of baseplates with 18-mm screws had significantly greater displacement than baseplates with 30- or 46-mm screws. For larger baseplates, those with 30-mm screws had significantly greater displacement than those with 46-mm screws in the superior-inferior direction.

Discussion

For the 2 different sizes of baseplates tested in this study, rTSA glenoid fixation was impacted by both screw quantity and screw length. Irrespective of screw quantity, longer screws showed significantly better fixation. Irrespective of screw length, the use of more screws showed significantly better fixation, up to a point, as the use of more than 4 screws showed no incremental benefit. Finally, longer screws can be used as a substitute for additional fixation if it is not feasible to use more screws.

Abstract PD1-01: Trilaciclib (T), a CDK4/6 inhibitor, dosed with gemcitabine (G), carboplatin (C) in metastatic triple negative breast cancer (mTNBC) patients: Preliminary phase 2 results

Background: Cytotoxic chemotherapy-induced damage of hematopoietic stem and progenitor cells (HSPCs) results in acute toxicities consisting of multi-lineage myelosuppression, and late onset toxicities consisting of progressive bone marrow suppression with increased incidence of therapy-related myeloid neoplasms. T is an IV CDK4/6 inhibitor in development to preserve HSPC and immune system function during cytotoxic chemotherapy (myelopreservation). Proof of concept for myelopreservation with T was observed in a randomized, placebo-controlled Phase 2 trial in small-cell lung cancer patients receiving 1st-line chemotherapy. This trial in mTNBC patients (NCT02978716) was designed to explore the utility of T in combination with GC.

Methods: This Phase 2, randomized, open-label study enrolled patients in the US and EU with mTNBC who had received 0-2 prior systemic cytotoxic therapies in the locally recurrent or metastatic setting and had no symptomatic brain metastases. Patients were randomized (1:1:1) to GC alone (Group 1) or T plus GC (Group 2) using a standard schedule (D1, 8 every 21 days) or to an alternative schedule (T on D1, 2, 8 and 9 with GC on D2 and 9 every 21 days; Group 3). On those days when both T and GC were scheduled, T was administered iv prior to GC infusion. Prophylactic growth factors were not administered in cycle 1; otherwise supportive care was allowed as needed. Primary objectives were safety and tolerability; tumor response was evaluated using RECIST v1.1 and PFS and OS were assessed. Myelopreservation endpoints reflecting the potential effects of T on multiple cellular lineages include occurrence of Grade 4 neutropenia (primary), RBC and platelet transfusions (primary), and lymphocyte counts with immune profiling (secondary and exploratory). A signature of CDK4/6 independence developed from preclinical data will be used to evaluate archival tumor tissue samples and data analysis is ongoing.

Results: 95 patients were dosed; median age 57 years (range 32,86), ECOG PS 0 (53%) or 1 (47%), 25% had liver metastases at baseline, and approximately 50% had received no systemic therapy in the recurrent/metastatic setting. Fifty-five patients remain on treatment. Disease progression was the most common reason for drug discontinuation (22/40; 55%). Overall the most common (≥ 25%) TEAEs were anemia (47%), nausea (35%), fatigue (34%), neutropenia (32%), platelet count decreased (25%), and vomiting (25%). The most frequent (≥ 15%) Grade 3 or 4 TEAEs were hematologic toxicities, i.e. neutropenia (28%), anemia (21%), neutrophil count decreased (21%) and thrombocytopenia (16%). These were also the most frequent drug-related TEAEs observed. Tumor efficacy data are being evaluated.

Conclusions: This trial, assessing the myelopreservation effects of T when combined with GC in patients with mTNBC, has completed enrollment. Myelopreservation data, immune profiling, as well as ORR and preliminary PFS results will be presented by study arm at the meeting.

Citation Format: O'Shaughnessy J, Wright GS, Thummala AR, Danso MA, Popovic L, Pluard TJ, Cheung E, Han HS, Daniel BR, Vojnovic Z, Vasev N, Ling M, Richards DA, Wilks ST, Milenkovic D, Sorrentino JA, Roberts PJ, Bomar M, Yang Z, Antal JM, Malik RK, Morris SR, Tan A. Trilaciclib (T), a CDK4/6 inhibitor, dosed with gemcitabine (G), carboplatin (C) in metastatic triple negative breast cancer (mTNBC) patients: Preliminary phase 2 results [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD1-01.

Constraints on Minute-Scale Transient Astrophysical Neutrino Sources

High-energy neutrino emission has been predicted for several short-lived astrophysical transients including gamma-ray bursts (GRBs), core-collapse supernovae with choked jets, and neutron star mergers. IceCube's optical and x-ray follow-up program searches for such transient sources by looking for two or more muon neutrino candidates in directional coincidence and arriving within 100 s. The measured rate of neutrino alerts is consistent with the expected rate of chance coincidences of atmospheric background events and no likely electromagnetic counterparts have been identified in Swift follow-up observations. Here, we calculate generic bounds on the neutrino flux of short-lived transient sources. Assuming an E^{-2.5} neutrino spectrum, we find that the neutrino flux of rare sources, like long gamma-ray bursts, is constrained to <5% of the detected astrophysical flux and the energy released in neutrinos (100 GeV to 10 PeV) by a median bright GRB-like source is <10^{52.5}  erg. For a harder E^{-2.13} neutrino spectrum up to 30% of the flux could be produced by GRBs and the allowed median source energy is <10^{52}  erg. A hypothetical population of transient sources has to be more common than 10^{-5}  Mpc^{-3}  yr^{-1} (5×10^{-8}  Mpc^{-3}  yr^{-1} for the E^{-2.13} spectrum) to account for the complete astrophysical neutrino flux.

Safety and Efficacy of Intraoperative Computer-Navigated Versus Non-Navigated Shoulder Arthroplasty at a Tertiary Referral

Emerging technologies in shoulder arthroplasty, such as 3-dimensional planning software and real-time intraoperative navigation, are now available for surgeons to perform more accurate placement of the glenoid component without malposition or perforation. Using these tools, the surgeon can visualize the version, inclination, and containment of the implant and determine whether augmented components would be necessary. This review provides an updated investigation of the present literature to elucidate the role of computer navigation in modern shoulder arthroplasty.

Elbow Trauma Sequelae: Instability, Stiffness, Non-arthroplasty, and Arthroplasty Options

Sequelae of elbow trauma are complicated to manage. Undiagnosed instability patterns are important to recognize to get the elbow into concentric alignment for further reconstructive efforts. Stiffness is also common after elbow trauma. Surgeons should be familiar with the different approaches to the elbow to safely address stiffness. Non-arthroplasty and arthroplasty salvage options are also important to understand because the indications are expanding and outcomes for these procedures are being better understood.

Search for neutrinos from decaying dark matter with IceCube: IceCube Collaboration

With the observation of high-energy astrophysical neutrinos by the IceCube Neutrino Observatory, interest has risen in models of PeV-mass decaying dark matter particles to explain the observed flux. We present two dedicated experimental analyses to test this hypothesis. One analysis uses 6 years of IceCube data focusing on muon neutrino 'track' events from the Northern Hemisphere, while the second analysis uses 2 years of 'cascade' events from the full sky. Known background components and the hypothetical flux from unstable dark matter are fitted to the experimental data. Since no significant excess is observed in either analysis, lower limits on the lifetime of dark matter particles are derived: we obtain the strongest constraint to date, excluding lifetimes shorter than10 28 s at 90% CL for dark matter masses above 10 TeV .

Functionally Graded, Bone- and Tendon-Like Polyurethane for Rotator Cuff Repair

Critical considerations in engineering biomaterials for rotator cuff repair include bone-tendon-like mechanical properties to support physiological loading and biophysicochemical attributes that stabilize the repair site over the long-term. In this study, UV-crosslinkable polyurethane based on quadrol (Q), hexamethylene diisocyante (H), and methacrylic anhydride (M; QHM polymers), which are free of solvent, catalyst, and photoinitiator, is developed. Mechanical characterization studies demonstrate that QHM polymers possesses phototunable bone- and tendon-like tensile and compressive properties (12-74 MPa tensile strength, 0.6-2.7 GPa tensile modulus, 58-121 MPa compressive strength, and 1.5-3.0 GPa compressive modulus), including the capability to withstand 10 000 cycles of physiological tensile loading and reduce stress concentrations via stiffness gradients. Biophysicochemical studies demonstrate that QHM polymers have clinically favorable attributes vital to rotator cuff repair stability, including slow degradation profiles (5-30% mass loss after 8 weeks) with little-to-no cytotoxicity in vitro, exceptional suture retention ex vivo (2.79-3.56-fold less suture migration relative to a clinically available graft), and competent tensile properties (similar ultimate load but higher normalized tensile stiffness relative to a clinically available graft) as well as good biocompatibility for augmenting rat supraspinatus tendon repair in vivo. This work demonstrates functionally graded, bone-tendon-like biomaterials for interfacial tissue engineering.

Measurement of the ν μ energy spectrum with IceCube-79: IceCube Collaboration

IceCube is a neutrino observatory deployed in the glacial ice at the geographic South Pole. The ν μ energy unfolding described in this paper is based on data taken with IceCube in its 79-string configuration. A sample of muon neutrino charged-current interactions with a purity of 99.5% was selected by means of a multivariate classification process based on machine learning. The subsequent unfolding was performed using the software Truee. The resulting spectrum covers an E ν -range of more than four orders of magnitude from 125 GeV to 3.2 PeV. Compared to the Honda atmospheric neutrino flux model, the energy spectrum shows an excess of more than 1.9 σ in four adjacent bins for neutrino energies E ν ≥ 177.8 TeV . The obtained spectrum is fully compatible with previous measurements of the atmospheric neutrino flux and recent IceCube measurements of a flux of high-energy astrophysical neutrinos.

Constraints on Ultrahigh-Energy Cosmic-Ray Sources from a Search for Neutrinos above 10 PeV with IceCube

We report constraints on the sources of ultrahigh-energy cosmic rays (UHECRs) above 10^{9}  GeV, based on an analysis of seven years of IceCube data. This analysis efficiently selects very high- energy neutrino-induced events which have deposited energies from 5×10^{5}  GeV to above 10^{11}  GeV. Two neutrino-induced events with an estimated deposited energy of (2.6±0.3)×10^{6}  GeV, the highest neutrino energy observed so far, and (7.7±2.0)×10^{5}  GeV were detected. The atmospheric background-only hypothesis of detecting these events is rejected at 3.6σ. The hypothesis that the observed events are of cosmogenic origin is also rejected at >99% CL because of the limited deposited energy and the nonobservation of events at higher energy, while their observation is consistent with an astrophysical origin. Our limits on cosmogenic neutrino fluxes disfavor the UHECR sources having a cosmological evolution stronger than the star formation rate, e.g., active galactic nuclei and γ-ray bursts, assuming proton-dominated UHECRs. Constraints on UHECR sources including mixed and heavy UHECR compositions are obtained for models of neutrino production within UHECR sources. Our limit disfavors a significant part of parameter space for active galactic nuclei and new-born pulsar models. These limits on the ultrahigh-energy neutrino flux models are the most stringent to date.

Searches for Sterile Neutrinos with the IceCube Detector

The IceCube neutrino telescope at the South Pole has measured the atmospheric muon neutrino spectrum as a function of zenith angle and energy in the approximate 320 GeV to 20 TeV range, to search for the oscillation signatures of light sterile neutrinos. No evidence for anomalous ν_{μ} or ν[over ¯]_{μ} disappearance is observed in either of two independently developed analyses, each using one year of atmospheric neutrino data. New exclusion limits are placed on the parameter space of the 3+1 model, in which muon antineutrinos experience a strong Mikheyev-Smirnov-Wolfenstein-resonant oscillation. The exclusion limits extend to sin^{2}2θ_{24}≤0.02 at Δm^{2}∼0.3  eV^{2} at the 90% confidence level. The allowed region from global analysis of appearance experiments, including LSND and MiniBooNE, is excluded at approximately the 99% confidence level for the global best-fit value of |U_{e4}|^{2}.

Evidence for Astrophysical Muon Neutrinos from the Northern Sky with IceCube

Results from the IceCube Neutrino Observatory have recently provided compelling evidence for the existence of a high energy astrophysical neutrino flux utilizing a dominantly Southern Hemisphere data set consisting primarily of ν(e) and ν(τ) charged-current and neutral-current (cascade) neutrino interactions. In the analysis presented here, a data sample of approximately 35,000 muon neutrinos from the Northern sky is extracted from data taken during 659.5 days of live time recorded between May 2010 and May 2012. While this sample is composed primarily of neutrinos produced by cosmic ray interactions in Earth's atmosphere, the highest energy events are inconsistent with a hypothesis of solely terrestrial origin at 3.7σ significance. These neutrinos can, however, be explained by an astrophysical flux per neutrino flavor at a level of Φ(E(ν))=9.9(-3.4)(+3.9)×10(-19)  GeV(-1) cm(-2) sr(-1) s(-1)(E(ν)/100  TeV(-2), consistent with IceCube's Southern-Hemisphere-dominated result. Additionally, a fit for an astrophysical flux with an arbitrary spectral index is performed. We find a spectral index of 2.2(-0.2)(+0.2), which is also in good agreement with the Southern Hemisphere result.

Flavor Ratio of Astrophysical Neutrinos above 35 TeV in IceCube

A diffuse flux of astrophysical neutrinos above 100 TeV has been observed at the IceCube Neutrino Observatory. Here we extend this analysis to probe the astrophysical flux down to 35 TeV and analyze its flavor composition by classifying events as showers or tracks. Taking advantage of lower atmospheric backgrounds for showerlike events, we obtain a shower-biased sample containing 129 showers and 8 tracks collected in three years from 2010 to 2013. We demonstrate consistency with the (fe:fμ:fτ)⊕≈(1:1:1)⊕ flavor ratio at Earth commonly expected from the averaged oscillations of neutrinos produced by pion decay in distant astrophysical sources. Limits are placed on nonstandard flavor compositions that cannot be produced by averaged neutrino oscillations but could arise in exotic physics scenarios. A maximally tracklike composition of (0:1:0)⊕ is excluded at 3.3σ, and a purely showerlike composition of (1:0:0)⊕ is excluded at 2.3σ.

Development of a general analysis and unfolding scheme and its application to measure the energy spectrum of atmospheric neutrinos with IceCube: IceCube Collaboration

We present the development and application of a generic analysis scheme for the measurement of neutrino spectra with the IceCube detector. This scheme is based on regularized unfolding, preceded by an event selection which uses a Minimum Redundancy Maximum Relevance algorithm to select the relevant variables and a random forest for the classification of events. The analysis has been developed using IceCube data from the 59-string configuration of the detector. 27,771 neutrino candidates were detected in 346 days of livetime. A rejection of 99.9999 % of the atmospheric muon background is achieved. The energy spectrum of the atmospheric neutrino flux is obtained using the TRUEE unfolding program. The unfolded spectrum of atmospheric muon neutrinos covers an energy range from 100 GeV to 1 PeV. Compared to the previous measurement using the detector in the 40-string configuration, the analysis presented here, extends the upper end of the atmospheric neutrino spectrum by more than a factor of two, reaching an energy region that has not been previously accessed by spectral measurements.

Possible FRAX-based intervention thresholds for a cohort of Chinese postmenopausal women

SUMMARY

A total of 2,266 postmenopausal Chinese women were followed for 4.5 years to determine the incidence of new fractures. The positive predictive value, negative predictive value, sensitivity and specificity of different treatment strategies were compared. Using a fixed optimal threshold calculated from receiver operating characteristics (ROC) curve had the highest sensitivity but lowest specificity.

INTRODUCTION

There is no specific intervention threshold based on FRAX to guide treatment for Asian populations. This prospective study sought to determine the impact of applying different intervention thresholds to a cohort of Chinese postmenopausal women.

METHODS

This study was part of the Hong Kong Osteoporosis Study. A total of 2,266 treatment-naïve postmenopausal women underwent clinical risk factor and BMD assessments. The subjects were followed to assess fractures. We calculated the FRAX probability of major osteoporotic fractures corresponding to women with prior fractures but no other clinical risk factors. Different treatment strategies which include treating women with prior fractures, women with age-specific FRAX probability corresponding to those with prior fractures, women with osteoporosis as well as women with FRAX probability above a fixed cut-off based on optimizing sensitivity and specificity on the ROC curve were compared.

RESULTS

The mean age at baseline was 62.1 ± 8.5 years, and the mean follow-up time was 4.5 ± 2.8 years. One hundred six new major osteoporotic fractures were reported. An optimal (FRAX, with BMD) cut-off point of 9.95 % was identified. All strategies had negative predictive value of >90 %. Using a fixed cut-off had the highest sensitivity (62.3 %) but lowest specificity (73.5 %) and positive predictive value (10.3 %). Using a fixed cut-off would direct treatment from younger women with lower absolute risk to elderly women with higher absolute risk.

CONCLUSION

Targeting only women with prior fractures is unlikely to reduce fracture burden. Other treatment strategies with higher sensitivity need to be considered but they have different shortcomings.

MRI detection of forearm soft tissue injuries with radial head fractures

BACKGROUND

This study aims to evaluate the incidence of forearm soft tissue abnormalities associated with radial head fracture severity based on the Mason classification system.

METHODS

Eighteen patients (age 18-45 years) were prospectively evaluated with elbow radiographs and magnetic resonance imaging (MRI) following longitudinal forearm trauma. MRI was performed within 10 days of the initial injury. Radiographs and MR images were evaluated in a blinded fashion by two musculoskeletal radiologists.

RESULTS

Thirteen of 18 patients presented with Mason type I radial head fractures. In all patients with Mason type I fractures, the interosseous membrane (IOM) was intact. Two patients had Mason type II fractures with associated partial and compete tearing of the IOM and three patients had Mason type III fractures with complete tearing of the IOM. Edema was noted in the pronator quadratus in six of 13 type I injuries and seen in all type II and III injuries. No structural forearm soft tissue abnormalities were present in patients with Mason type I injuries. The presence of edema within the pronator quadratus correlated with distal forearm pain.

CONCLUSIONS

The severity of radial head fracture correlates with longitudinal forearm injury evidenced by the presence of IOM tearing. The findings suggest patients with Mason type II or III fractures of the radial head should undergo further evaluation of the forearm for associated soft tissue injuries. Edema within the pronator quadratus was present following forearm trauma regardless of the severity of fracture and was related to symptomatic forearm pain.

Exploratory bioinformatics study of lncRNAs in Alzheimer's disease mRNA sequences with application to drug development

Long noncoding RNA (lncRNA) within mRNA sequences of Alzheimer's disease genes, namely, APP, APOE, PSEN1, and PSEN2, has been analyzed using fractal dimension (FD) computation and correlation analysis. We examined lncRNA by comparing mRNA FD to corresponding coding DNA sequences (CDSs) FD. APP, APOE, and PSEN1 CDSs select slightly higher FDs compared to the mRNA, while PSEN2 CDSs FDs are lower. The correlation coefficient for these sequences is 0.969. A comparative study of differentially expressed MAPK signaling pathway lncRNAs in pancreatic cancer cells shows a correlation of 0.771. Selection of higher FD CDSs could indicate interaction of Alzheimer's gene products APP, APOE, and PSEN1. Including hypocretin sequences (where all CDSs have higher fractal dimensions than mRNA) in the APP, APOE, and PSEN1 sequence analyses improves correlation, but the inclusion of erythropoietin (where all CDSs have higher FD than mRNA) would suppress correlation, suggesting that HCRT, a hypothalamus neurotransmitter related to the wake/sleep cycle, might be better when compared to EPO, a glycoprotein hormone, for targeting Alzheimer's disease drug development. Fractal dimension and entropy correlation have provided supporting evidence, consistent with evolutionary studies, for using a zebrafish model together with a mouse model, in HCRT drug development.

Ethnic difference of clinical vertebral fracture risk

Vertebral fractures are the most common osteoporotic fractures. Data on the vertebral fracture risk in Asia remain sparse. This study observed that Hong Kong Chinese and Japanese populations have a less dramatic increase in hip fracture rates associated with age than Caucasians, but the vertebral fracture rates were higher, resulting in a high vertebral-to-hip fracture ratio. As a result, estimation of the absolute fracture risk for Asians may need to be readjusted for the higher clinical vertebral fracture rate.

INTRODUCTION

Vertebral fractures are the most common osteoporotic fractures. Data on the vertebral fracture risk in Asia remain sparse. The aim of this study was to report the incidence of clinical vertebral fractures among the Chinese and to compare the vertebral-to-hip fracture risk to other ethnic groups.

METHODS

Four thousand, three hundred eighty-six community-dwelling Southern Chinese subjects (2,302 women and 1,810 men) aged 50 or above were recruited in the Hong Kong Osteoporosis Study since 1995. Baseline demographic characteristics and medical history were obtained. Subjects were followed annually for fracture outcomes with a structured questionnaire and verified by the computerized patient information system of the Hospital Authority of the Hong Kong Government. Only non-traumatic incident hip fractures and clinical vertebral fractures that received medical attention were included in the analysis. The incidence rates of clinical vertebral fractures and hip fractures were determined and compared to the published data of Swedish Caucasian and Japanese populations.

RESULTS

The mean age at baseline was 62 ± 8.2 years for women and 68 ± 10.3 years for men. The average duration of follow-up was 4.0 ± 2.8 (range, 1 to 14) years for a total of 14,733 person-years for the whole cohort. The incidence rate for vertebral fracture was 194/100,000 person-years in men and 508/100,000 person-years in women, respectively. For subjects above the age of 65, the clinical vertebral fracture and hip fracture rates were 299/100,000 and 332/100,000 person-years, respectively, in men, and 594/100,000 and 379/100,000 person-years, respectively, in women. Hong Kong Chinese and Japanese populations have a less dramatic increase in hip fracture rates associated with age than Caucasians. At the age of 65 or above, the hip fracture rates for Asian (Hong Kong Chinese and Japanese) men and women were less than half of that in Caucasians, but the vertebral fracture rate was higher in Asians, resulting in a high vertebral-to-hip fracture ratio.

CONCLUSIONS

The incidences of vertebral and hip fractures, as well as the vertebral-to-hip fracture ratios vary in Asians and Caucasians. Estimation of the absolute fracture risk for Asians may need to be readjusted for the higher clinical vertebral fracture rate.

Kruppel-like factor 5 modulates p53-independent apoptosis through Pim1 survival kinase in cancer cells

Although Kruppel-like factor 5 (KLF5) is a transcription factor that has been implicated in pathways critical to carcinogenesis, controversy persists as to whether it functions as a tumor suppressor or as an oncogene. Here, we describe a novel role for KLF5 in a p53-independent apoptotic pathway. Using RNA-interference technology, we show that cells deficient in KLF5 have increased sensitivity to DNA damage, regardless of p53 status. Both p53 and p53-dependent factors are unaffected by KLF5 depletion. Instead, the apoptotic phenotype consequent to damage is associated with reduced bad phosphorylation, and downregulation of Pim1. Consistently, transfection of wild-type Pim1 is sufficient to rescue this phenotype. Previous data have shown a number of putative Sp1-binding consensus sequences on the Pim1 promoter. Remarkably, chromatin immunoprecipitation studies show that KLF5 binds to the Pim1 promoter, and that binding increases soon after damage. These results identify a novel, p53-independent apoptotic pathway through which KLF5 functions in response to DNA damage. Therapeutic deregulation of this pathway could be used to modulate chemosensitivity.

Embryogenesis in the glass sponge Oopsacas minuta: Formation of syncytia by fusion of blastomeres

Sponges (Porifera) are unusual animals whose body plans make interpreting phylogenetic relationships within the group and with other basal metazoan taxa a difficult task. Although molecular approaches have offered new insights, some questions require a morphological approach using detailed ultrastructural or light microscopical studies of developing embryos and larvae. Glass sponges (Hexactinellida) have perhaps the most unusual body plan within the Metazoa because the majority of the tissue of the adult consists of a single giant multinucleated syncytium that forms the inner and outer layers of the sponge and is joined by cytoplasmic bridges to uninucleate cellular regions. Here we have used serial section transmission and high-resolution scanning electron microscopy to examine when syncytia first form in the cave-dwelling glass sponge Oopsacas minuta. We confirm that in O. minuta blastomeres are separate until the 32-cell stage; cleavage is equal but asynchronous until a hollow blastula is formed. The sixth division yields a collection of variously sized micromeres at the surface of the embryo and large yolk- and lipid-filled macromeres lining the blastocoel. Syncytia then form by the fusion of micromeres to form cytoplasmic bridges with each other and the fusion of macromeres to form the future multinucleated trabecular tissue of the larva and adult sponge. The multinucleated trabecular tissue envelops and forms cytoplasmic bridges with all uninucleate cells, covering the developing larva with a continuous syncytial epithelium. Differentiation of tissues occurs very early during embryogenesis with the separation of uninucleate and multinucleate lineages, but all cells and syncytia are joined by cytoplasmic bridges such that there is cytoplasmic continuity throughout the entire larva. Although glass sponges begin life as a cellular embryo, the unusual mechanism of syncytia formation at such an early stage in development distinguishes this group of animals from their closest multicellular relatives, the Demospongiae. Most important, however, these data lend support to the hypothesis that the original metazoans were cellular, not syncytial.

Transcriptional landscape of the human and fly genomes: nonlinear and multifunctional modular model of transcriptomes

Regions of the genome not coding for proteins or not involved in cis-acting regulatory activities are frequently viewed as lacking in functional value. However, a number of recent large-scale studies have revealed significant regulated transcription of unannotated portions of a variety of plant and animal genomes, allowing a new appreciation of the widespread transcription of large portions of the genome. High-resolution mapping of the sites of transcription of the human and fly genomes has provided an alternative picture of the extent and organization of transcription and has offered insights for biological functions of some of the newly identified unannotated transcripts. Considerable portions of the unannotated transcription observed are developmental or cell-type-specific parts of protein-coding transcripts, often serving as novel, alternative 5' transcriptional start sites. These distal 5' portions are often situated at significant distances from the annotated gene and alternatively join with or ignore portions of other intervening genes to comprise novel unannotated protein-coding transcripts. These data support an interlaced model of the genome in which many regions serve multifunctional purposes and are highly modular in their utilization. This model illustrates the underappreciated organizational complexity of the genome and one of the functional roles of transcription from unannotated portions of the genome.

(90)Y and (177)Lu labeling of a DOTA-conjugated vitronectin receptor antagonist useful for tumor therapy

The (90)Y and (177)Lu complexes (RP697 and RP688, respectively) of a DOTA-conjugated vitronectin receptor antagonist (SU015: 2-(1,4,7,10-tetraaza-4,7,10-tris(carboxymethyl)-1-cyclododecyl)acetyl-Glu(cyclo[Lys-Arg-Gly-Asp-D-Phe])-cyclo[Lys-Arg-Gly-Asp-D-Phe]) were prepared by reacting SU015 with the radiometal chloride in ammonium acetate buffer (pH > 7.2) in the presence of an antioxidant (sodium gentisate, GA). Through a series of radiolabeling experiments, it was found that there are many factors influencing the rate of (90)Y chelation and the radiolabeling efficiency of SU015. These include the purity of SU015, the pH, reaction temperature, and heating time, as well as the presence of trace metal contaminants, such as Ca(2+), Fe(3+), and Zn(2+). The chelation of (90)Y by SU015 is slow, so that heating at elevated temperatures (50-100 degrees C) is needed to complete the (90)Y-labeling. The rate of (90)Y chelation is also dependent on the pH of the reaction mixture. Under optimized radiolabeling conditions (pH 7.2-7.8 and heating at 50-100 degrees C for 5-10 min), the minimum amount of SU015 required to achieve 95% RCP for RP697 is approximately 25 microg for 20 mCi of (90)YCl(3) corresponding to a SU015:(90)Y ratio of approximately 30:1.

DNA binding by the ETS-domain transcription factor PEA3 is regulated by intramolecular and intermolecular protein.protein interactions

The control of DNA binding by eukaryotic transcription factors represents an important regulatory mechanism. Many transcription factors are controlled by cis-acting autoinhibitory modules that are thought to act by blocking promiscuous DNA binding in the absence of appropriate regulatory cues. Here, we have investigated the determinants and regulation of the autoinhibitory mechanism employed by the ETS-domain transcription factor, PEA3. DNA binding is inhibited by a module composed of a combination of two short motifs located on either side of the ETS DNA-binding domain. A second type of protein, Ids, can act in trans to mimic the effect of these cis-acting inhibitory motifs and reduce DNA binding by PEA3. By using a one-hybrid screen, we identified the basic helix-loop-helix-leucine zipper transcription factor USF-1 as an interaction partner for PEA3. PEA3 and USF-1 form DNA complexes in a cooperative manner. Moreover, the formation of ternary PEA3.USF-1.DNA complexes requires parts of the same motifs in PEA3 that form the autoinhibitory module. Thus the binding of USF-1 to PEA3 acts as a switch that modifies the autoinhibitory motifs in PEA3 to first relieve their inhibitory action, and second, promote ternary nucleoprotein complex assembly.

Effect of histological damage on long-term kidney transplant outcome

BACKGROUND

Chronic renal allograft failure remains a major challenge to overcome. Factors such as donor quality, delayed graft function (DGF), acute rejection, and immunosuppression are known to affect long-term outcome, but their relationship to histological damage to graft outcome is unclear.

METHODS

Protocol kidney biopsies (n=112) obtained at 3 months after transplantation yielded 102 with adequate tissue. Histology was scored by the Banff schema, and compared with implantation biopsies (n=91), repeat 12-month histology (n=39), decline in serum creatinine and serial isotopic glomerular filtration rate, onset of chronic allograft nephropathy (CAN), and actuarial graft survival censored for death with a functioning graft.

RESULTS

At a median follow-up of 9.3 years, 20 patients had graft failure and 26 died with a functioning graft. Banff chronic nephropathy was present in 24% of 3-month biopsies, and was predicted by microvascular disease in the donor, cold ischemia, DGF, and acute vascular rejection (P<0.001). Acute glomerulitis at 3 months correlated with segmental glomerulosclerosis at 12 months, subsequent recurrent glomerulonephritis, and graft failure (P<0.01). Subclinical rejection at 3 months occurred in 29% of biopsies, correlated with prior acute rejection and HLA mismatch, and led to chronic histological damage by 12 months (r=0.25-0.67, P<0.05-0.001). Subclinical rejection, arteriolar hyalinosis, and tubulitis present at 3 months had resolved by 12 months. The 10-year survival rates for Banff chronic nephropathy were 90.4% for grade 0, 81.0% grade 1, and 57.9% for grades 2 or greater (P<0.01). Early tubulointerstitial damage at 3 months profoundly influenced graft survival beyond 10 years. CAN was predicted by kidney ischemia, 3-month chronic intimal vascular thickening, tubular injury, proteinuria, and late rejection. Chronic fibrointimal thickening of the small arteries and chronic interstitial fibrosis at 3 months independently predicted graft loss and decline in renal function (P<0.05-0.001).

CONCLUSIONS

Early transplant damage occurs in the tubulointerstitial compartment from preexisting donor kidney injury and discrete events such as vascular rejection and DGF. Subsequent chronic damage and graft failure reflect accumulated previous injury and chronic interstitial fibrosis, vascular impairment, subclinical rejection, and injury from late rejection. CAN may be conceptualized as the sequelae of incremental and cumulative damage to the transplanted kidney. The duration of graft survival is dependent and predicted by the quality of the transplanted donor kidney combined with the intensity, frequency, and irreversibility of these damaging insults.

Specific down-regulation of an engineered human cyclin D1 promoter by a novel DNA-binding ligand in intact cells

Cyclin D1 is expressed at abnormally high levels in many cancers and has been specifically implicated in the development of breast cancer. In this report we have extensively analyzed the cyclin D1 promoter in a variety of cancer cell lines that overexpress the protein and identified two critical regulatory elements (CREs), a previously identified CRE at -52 and a novel site at -30. In vivo footprinting experiments demonstrated factors binding at both sites. We have used a novel DNA-binding ligand, GL020924, to target the site at -30 (-30-21) of the cyclin D1 promoter in MCF7 breast cancer cells. A binding site for this novel molecule was constructed by mutating 2 bp of the wild-type cyclin D1 promoter at the -30-21 site. Treatment with GL020924 specifically inhibited expression of the targeted cyclin D1 promoter construct in MCF7 cells in a concentration-dependent manner, thus validating the -30-21 site as a target for minor groove-binding ligands. In addition, this result validates our approach to regulating the expression of genes implicated in disease by targeting small DNA-binding ligands to key regulatory elements in the promoters of those genes.

Isomerism and solution dynamics of (90)Y-labeled DTPA--biomolecule conjugates

This report describes the synthesis of two DTPA-conjugated cyclic peptides, cyclo(Arg-Gly-Asp-D-Phe-Lys)DTPA (SQ169) and [cyclo(Arg-Gly-Asp-D-Phe-Lys)](2)DTPA (SQ170), and a chromatographic study of their (90)Y complexes (RP762 and RP763, respectively). The goal is to study the solution structure and the possible isomerism of (90)Y-labeled DTPA-biomolecule conjugates at the tracer level (approximately 10(-10) M). RP762 was prepared in high radiochemical purity (RCP > 95%) by reacting 2 microg of SQ169 with 20 mCi of (90)YCl(3) (corresponding to a SQ169:Y ratio of approximately 4:1) in the 0.5 M ammonium acetate buffer (pH 8.0) at room temperature. RP763 was prepared in a similar fashion using SQ170. In both cases, the (90)Y-chelation was instantaneous. By a reversed-phase HPLC method, it was found that RP762 exists in solution as a mixture of two detectable isomers (most likely cis and trans isomers), which interconvert at room temperature. The interconversion of different isomeric forms of RP762 involves a rapid exchange of "wrapping isomers" via the "wagging" of the diethylenetriamine backbone, "shuffling" of the two NO(2) donor sets, and inversion at the ternimal amine-nitrogen atom. The inversion at a terminal nitrogen atom requires simultaneous dissociation of the NO(2) donor set. For RP763, the interconversion of different isomers is much faster than that for RP762 due to the weak bonding of two carbonyl-oxygen donors. Therefore, RP763 shows only one broad radiometric peak in its HPLC chromatogram. The rapid interconversion of different isomers is intramolecular via a partial dissociative mechanism. The results obtained in this study are consistent with the lack of kinetic inertness of (90)Y- and (111)In-labeled DTPA-biomolecule conjugates. Thus, the design of new BFCs should be focused on those which form lanthanide complexes with high thermodynamic stability and more importantly kinetic inertness.

Enantio- and diastereodifferentiating cis,trans-photoisomerization of 2beta,3beta-diphenylcyclopropane-1alpha-carboxylic acid derivatives in organized media

[reaction: see text] Four methods of asymmetric induction in the cis, trans-photoisomerization of 2beta, 3beta-diphenylcyclopropane-1alpha-carboxylic acid derivatives were studied. Best results (ca. 80% de) were obtained by irradiation of chiral esters, amides, and salts in NaY and LiY zeolites and in the pure crystalline state.