De novo design of buttressed loops for sculpting protein functions

In natural proteins, structured loops have central roles in molecular recognition, signal transduction and enzyme catalysis. However, because of the intrinsic flexibility and irregularity of loop regions, organizing multiple structured loops at protein functional sites has been very difficult to achieve by de novo protein design. Here we describe a solution to this problem that designs tandem repeat proteins with structured loops (9-14 residues) buttressed by extensive hydrogen bonding interactions. Experimental characterization shows that the designs are monodisperse, highly soluble, folded and thermally stable. Crystal structures are in close agreement with the design models, with the loops structured and buttressed as designed. We demonstrate the functionality afforded by loop buttressing by designing and characterizing binders for extended peptides in which the loops form one side of an extended binding pocket. The ability to design multiple structured loops should contribute generally to efforts to design new protein functions.

De novo design of buttressed loops for sculpting protein functions

In natural proteins, structured loops play central roles in molecular recognition, signal transduction and enzyme catalysis. However, because of the intrinsic flexibility and irregularity of loop regions, organizing multiple structured loops at protein functional sites has been very difficult to achieve by de novo protein design. Here we describe a solution to this problem that generates structured loops buttressed by extensive hydrogen bonding interactions with two neighboring loops and with secondary structure elements. We use this approach to design tandem repeat proteins with buttressed loops ranging from 9 to 14 residues in length. Experimental characterization shows the designs are folded and monodisperse, highly soluble, and thermally stable. Crystal structures are in close agreement with the computational design models, with the loops structured and buttressed by their neighbors as designed. We demonstrate the functionality afforded by loop buttressing by designing and characterizing binders for extended peptides in which the loops form one side of an extended binding pocket. The ability to design multiple structured loops should contribute quite generally to efforts to design new protein functions.

Deploying synthetic coevolution and machine learning to engineer protein-protein interactions

Fine-tuning of protein-protein interactions occurs naturally through coevolution, but this process is difficult to recapitulate in the laboratory. We describe a platform for synthetic protein-protein coevolution that can isolate matched pairs of interacting muteins from complex libraries. This large dataset of coevolved complexes drove a systems-level analysis of molecular recognition between Z domain-affibody pairs spanning a wide range of structures, affinities, cross-reactivities, and orthogonalities, and captured a broad spectrum of coevolutionary networks. Furthermore, we harnessed pretrained protein language models to expand, in silico, the amino acid diversity of our coevolution screen, predicting remodeled interfaces beyond the reach of the experimental library. The integration of these approaches provides a means of simulating protein coevolution and generating protein complexes with diverse molecular recognition properties for biotechnology and synthetic biology.

Patients not taking a previously prescribed bone active medication now prescribed medication through Ontario FLS

In an Ontario fracture liaison service (FLS), we compared medication prescription rates among patients not taking a previously prescribed bone active medication to those with no previous prescription. Prescription rates were similar between these two groups of patients. The FLS provided a secondary opportunity for patients to initiate bone active medication.

PURPOSE

We compared bone active medication prescription rates among patients presenting to an Ontario fracture liaison service (FLS) who reported not taking a previously prescribed bone active medication to those with no history of prescription.

METHODS

Eligible patients were those screened in 39 fracture clinics between July 1, 2017, and September 15, 2019, who were not taking bone active medication at the time of screening and classified as high risk for future fracture based on CAROC or FRAX. Sociodemographic and clinical risk factor variables were assessed at screening. Bone active medication prescription rate was assessed within 6 months of screening and defined as having received a prescription for the medication from either a specialist or primary care provider. In cases where a specialist report was not available, patient self-reported data were collected. The chi-square test of independence was used to assess differences in prescription rates.

RESULTS

Of 17,575 patients screened, eligible patients were 350 with a previous prescription and 2644 without a previous prescription. Compared with patients who reported no previous prescription, those who had a previous prescription were older, more likely to be female and to report a previous fracture, and less likely to smoke. There was no statistically significant difference between the medication prescription rate of patients with a previous prescription (73.7%) compared to patients with no previous prescription (70.7%) (p = 0.157).

CONCLUSION

A large jurisdiction-wide FLS approach provided a secondary opportunity to patients who were not taking a previously prescribed bone active medication to initiate that medication.

Fragility fracture patients with a history of prior fractures more likely to present with multiple risk factors: findings from a province-wide fracture liaison service

We examined the demographic characteristics and risk factors of FLS fragility fracture patients who had sustained prior fragility fracture(s) and found that this is an important high-risk subgroup that warrants further attention within FLS priority pathways in order to disrupt their fragility fracture cycle.

PURPOSE

Our primary objective was to examine whether fragility fracture patients presenting to a provincial fracture liaison service (FLS) having a history of prior fractures, versus those without, differ in demographic characteristics and risk factors for future fracture. A secondary objective was to understand if those who report two or more prior fractures differ from those reporting one prior fracture.

METHODS

This cohort study included fragility fracture patients aged 50 + enrolled in the Ontario FLS between July 2017 and September 2019. Patients with versus those without prior fractures were compared on age, sex, index fracture site, biological parents' history of hip fracture, current fracture due to a fall, history of feeling unsteady when walking, history of falls in the past year, smoking, oral steroid use, and comorbid chronic conditions. Pearson's chi-square, Fischer's exact, and analysis of variance tests were used to assess differences.

RESULTS

Among 14,454 patients, 16.8% (n = 2428) reported a history of one or more prior fractures after the age of 40. They were significantly more likely to be older, female, with a higher number of comorbidities, with greater incidence of falls, and feel unsteady when walking. Compared to those with one prior fracture, patients with greater than one prior fracture were more likely to report falls in the past year and feel unsteady when walking.

CONCLUSION

Findings suggest that FLS fragility fracture patients who had sustained prior fragility fracture are an important high-risk subgroup that warrants further attention within FLS priority pathways in order to disrupt their fragility fracture cycle.

Design of protein-binding proteins from the target structure alone

The design of proteins that bind to a specific site on the surface of a target protein using no information other than the three-dimensional structure of the target remains a challenge1-5. Here we describe a general solution to this problem that starts with a broad exploration of the vast space of possible binding modes to a selected region of a protein surface, and then intensifies the search in the vicinity of the most promising binding modes. We demonstrate the broad applicability of this approach through the de novo design of binding proteins to 12 diverse protein targets with different shapes and surface properties. Biophysical characterization shows that the binders, which are all smaller than 65 amino acids, are hyperstable and, following experimental optimization, bind their targets with nanomolar to picomolar affinities. We succeeded in solving crystal structures of five of the binder-target complexes, and all five closely match the corresponding computational design models. Experimental data on nearly half a million computational designs and hundreds of thousands of point mutants provide detailed feedback on the strengths and limitations of the method and of our current understanding of protein-protein interactions, and should guide improvements of both. Our approach enables the targeted design of binders to sites of interest on a wide variety of proteins for therapeutic and diagnostic applications.

Patients 80 + have similar medication initiation rates to those aged 50-79 in Ontario FLS

Among individuals presenting to an Ontario FLS, we compared bone active medication initiation rates of patients 80 years and older with those 50-79 years old. After accounting for fracture risk status, there was no statistically significant difference in medication initiation rates between the two age groups INTRODUCTION: A Fracture Liaison Service (FLS) offers post-fracture services to individuals over the age of 50 years and could potentially address age inequities in pharmacotherapy often observed for older adults. Among individuals presenting to an Ontario FLS and classified as being at high risk for future fracture, our objective was to compare bone active medication initiation rates of patients 80 years and older with those 50-79 years old.

METHODS

In 39 FLS fracture clinics across Ontario, Canada, fracture prevention coordinators identified, assessed, and facilitated the referral of eligible patients for bone densitometry, fracture risk assessment, and implementation of pharmacotherapy in patients classified as high risk for future fracture. Variables assessed at baseline included age, sex, marital status, living location, fracture location, history of previous fracture, parent's history of hip fracture, history of falls, and fracture risk status. At 6 months, bone active medication initiation was assessed in patients classified as high risk for future fracture. The Chi-square test of independence was used to compare medication initiation rates between patients 80 + and those 50-79 years old.

RESULTS

Our sample size consisted of 808 patients aged 50-79 years and 346 aged 80 + years. After accounting for fracture risk status, there was no statistically significant difference in medication initiation rates of patients 50-79 and 80 + years old (76.9% versus 73.7%, p = 0.251).

CONCLUSION

A systematic approach to identifying patients at high risk for future fracture and tailoring treatment recommendations to these patients appeared to eliminate differences in treatment initiation rates based on older age.

Vibrio harveyi isolated from marine aquaculture species in eastern China and virulence to the large yellow croaker (Larimichthys crocea)

AIMS

Diseases of maricultured species caused by Vibrio harveyi are increasing in China and other regions. This study examined the genetic diversity, antimicrobial susceptibility, plasmid profiles and virulence potential of the V. harveyi isolated from marine organisms farmed in two provinces in eastern China between 2014 and 2019.

METHODS AND RESULTS

A total of 54 V. harveyi were obtained from seven marine species. Enterobacterial repetitive intergenic consensus (ERIC)-PCR fingerprinting revealed substantial genetic heterogeneity among the V. harveyi isolates. There was no significant correlation between ERIC-PCR genotypes and host origins or fish farms. All the isolates were resistant to amoxicillin and ampicillin, and 79·6% to kanamycin. We found that 61·1% of the V. harveyi isolates had plasmid(s) and there were 14 different plasmid profiles. Most isolates from fish hosts (76·5%) contained plasmids; however, 75% of isolates from nonfish hosts lacked plasmids. Experimental infection results showed that isolates with plasmid(s) were more virulent to large yellow croaker than isolates lacking plasmids (P < 0·05).

CONCLUSIONS

This study confirmed that V. harveyi isolates obtained from animals farmed in the coastal region of east China were genetically diverse. Our results suggest that the virulence of various V. harveyi strains to fish is associated with the plasmids they carry.

SIGNIFICANCE AND IMPACT OF THE STUDY

More than 50% of the V. harveyi isolates carried one to 11 plasmids. The plasmid-borne traits of V. harveyi strains might be important for host adaptation and virulence, but they were not associated with susceptibility to the tested antibiotics.

A graphical method for breaking logical loops based on multi-tree structure

Logical loops or circular logics, interpreted as circular supporting relations among systems, remain a longstanding challenge in the probabilistic safety assessment (PSA). Logical loops are commonly found in complex industrial systems. Due to the existence of the logical loops, the minimal cut sets cannot be directly obtained. In order to solve this problem, the logical loops should be broken properly. This paper proposes a graphical method based on multi-tree structure. By constructing the simplified multi-tree, logical loops both in linearly and non-linearly interrelated systems are solved. To illustrate this method, examples of linearly interrelated systems and non-linearly interrelated systems are given in this paper. As a supplement, this method is applied to the well-known complex logical loops in the nuclear power plant. It shows that this method is highly intuitive and efficient by means of graphs.

A graphical method for breaking logical loops based on multi-tree structure

Logical loops or circular logics, interpreted as circular supporting relations among systems, remain a longstanding challenge in the probabilistic safety assessment (PSA). Logical loops are commonly found in complex industrial systems. Due to the existence of the logical loops, the minimal cut sets cannot be directly obtained. In order to solve this problem, the logical loops should be broken properly. This paper proposes a graphical method based on multi-tree structure. By constructing the simplified multi-tree, logical loops both in linearly and non-linearly interrelated systems are solved. To illustrate this method, examples of linearly interrelated systems and non-linearly interrelated systems are given in this paper. As a supplement, this method is applied to the well-known complex logical loops in the nuclear power plant. It shows that this method is highly intuitive and efficient by means of graphs.

Pilot validation of blood-based biomarkers during pregnancy and postpartum in women with prior or current depression

Major depressive disorder (MDD) is more common in women than in men, and evidence of gender-related subtypes of depression is emerging. Previously identified blood-based transcriptomic biomarkers distinguished male and female subjects with MDD from those without the disorder. In the present pilot study, we investigated the performance of these biomarkers in pregnant and postpartum women with prior major depressive episodes, some of whom had current symptomatology. The symptom scores of 13 pregnant and 15 postpartum women were identified by the Inventory of Depressive Symptoms (IDS-SR-30) at the time of blood sampling. Blood levels of the 20 transcriptomic biomarkers and that of estrogen receptor 2 (ESR2), membrane progesterone receptor alpha and beta (mPRα, mPRβ) were measured. In pregnant women, transcript levels of ADCY3, ASAH1, ATP11C, CDR2, ESR2, FAM46A, mPRβ, NAGA, RAPH1, TLR7, and ZNF291/SCAPER showed significant association with IDS-SR-30 scores, of which ADCY3, FAM46A, RAPH1, and TLR7 were identified in previous studies for their diagnostic potential for major depression. ASAH1 and ATP11C were previously also identified as potential markers of treatment efficacy. In postpartum women, transcript levels of CAT, CD59, and RAPH1 demonstrated a trend of association with IDS-SR-30 scores. Transcript levels of ADCY3, ATP11C, FAM46A, RAPH1, and ZNF291/SCAPER correlated with ESR2 and mPRβ expressions in pregnant women, whereas these associations only existed for mPRβ in postpartum women. These results suggest that a blood biomarker panel can identify depression symptomatology in pregnant women and that expression of these biomarker genes are affected by estrogen and/or progesterone binding differently during pregnancy and postpartum.

Transcervical dissection of metastatic suprahyoid retropharyngeal lymph nodes from papillary thyroid carcinoma through three anatomical barriers

Papillary thyroid carcinoma (PTC) rarely metastasizes to the suprahyoid retropharyngeal lymph nodes (SRPLNs). Studies on SRPLN metastasis from PTC and a description of the dissection of the SRPLNs via the transcervical approach are rare in the literature. In this study, the cases of six patients diagnosed with PTC with SRPLN metastasis, who underwent dissection of the SRPLNs between 2001 and 2017, were reviewed retrospectively. A transcervical approach was applied for exposure and dissection of the SRPLNs in all patients. All patients were successfully treated by transcervical resection of the metastatic SRPLNs. No patient needed a mandibulotomy or presented severe complications. The median duration of follow-up after dissection of the SRPLNs was 83 months. No recurrence of SRPLN metastasis was identified during follow-up, and none of the patients died of the disease. Surgery might be the best treatment for SRPLN metastasis from PTC. The transcervical route to the retropharyngeal space is through three anatomical barriers, including the submandibular gland, the posterior belly of the digastric muscle, and the blood vessels branching from the external carotid artery and internal jugular vein. Surgical removal of metastatic SRPLNs through the transcervical approach was safe and effective.

Impact of the extent of axillary surgery in patients with N2-3 disease in the de-escalation era: a propensity score-matched study

BACKGROUND

Reduction of surgeries in axillary has been proved feasible in breast cancer with negative and limited involved axillary lymph nodes. However, for women with a heavy axillary burden, the extent of dissection is still arguable.

PATIENTS AND METHODS

From a total of 7042 patients with breast cancer who underwent surgical treatments between 2008 and 2014, 692 (9.85%) patients with the axillary staging of N2-3M0 were classified into Level I-II dissection group and Level I-III dissection group. 203 pairs of patients were matched by the propensity score.

RESULTS

The positive rate of level-III lymph nodes is 62.4% in patients who underwent Level I-III dissection. There are 67 (22.1%) patients who experienced rise in staging from N2 to N3 due to level-III dissection. With a median follow-up of 62.4 months, no significant difference was observed in RFS (P = 0.897), MFS (P = 0.610) and OS (P = 0.755) between level I-II group and level I-III group. The same results were observed in the independent analysis of neoadjuvant and non-neoadjuvant subgroups. The binary regression model showed the positivity of level-III is only associated with involved lymph nodes in level-II.

CONCLUSION

Additional level-III dissection has a limited impact on survival but still valuable in an accurate stage. The reduction of surgeries in axillary should be treated with discretion in breast cancer patients with a heavy axillary burden.

0532 Cognitive Behavioral Therapy Delivered Via Telemedicine vs. Face-to-Face: Results from a Randomized Controlled Non-Inferiority Trial

Introduction

Telemedicine is increasingly an option for delivery of healthcare services, but its efficacy and acceptability for delivering CBT for insomnia has not been adequately tested. In a randomized controlled non-inferiority trial, we compared face-to-face and telemedicine delivery (via the AASM SleepTM platform) of CBT for insomnia for improving sleep and daytime functioning at post-treatment and 12-week follow-up.

Methods

Sixty-five adults with chronic insomnia (46 women, mean age 47.2 ± 16.3 years) were recruited primarily from insomnia clinics and screened for disqualifying sleep, medical, and mental health disorders. Eligible participants were randomized to 6 sessions of CBT for insomnia delivered face-to-face (n=32) or via AASM SleepTM (n=33). Participants completed self-report measures of insomnia (Insomnia Severity Index, ISI) and daytime functioning (fatigue, depression, anxiety, and overall functioning) at pre-treatment, post-treatment, and 12-week follow-up. The ISI was the primary non-inferiority outcome.

Results

Telemedicine was non-inferior to face-to-face delivery of CBT for insomnia, based on a non-inferiority margin of 4 points on the ISI (β = -0.07, 95% CI -2.28 to 2.14). Compared to pre-treatment, ISI scores improved significantly at post-treatment (β = -9.02, 95% CI -10.56 to -7.47) and at 12-week follow-up (β = -9.34, 95% CI -10.89 to -7.79). Similarly, daytime functioning measures improved from pre- to post-treatment, with sustained improvements at 12-week follow-up. Scores on the fatigue scale were lower in the telemedicine group at both post-treatment (F=4.64, df=1,119, p&lt;.03) and follow-up (F=5.79, df=1,119, p&lt;.02).

Conclusion

Insomnia and daytime functioning improve similarly whether CBT for insomnia is delivered via telemedicine or face-to-face. Telemedicine delivery of CBT for insomnia should be implemented more systematically to improve access to this evidence-based treatment.

Support

American Sleep Medicine Foundation Grant # 168-SR-17 (JT Arnedt, PhD)

0513 Comparison of Patient Satisfaction and Therapeutic Alliance for Telemedicine vs. Face-to-Face Delivered Cognitive Behavioral Therapy for Insomnia

Introduction

CBT for insomnia (CBTI) is effective but a barrier to its widespread use is the lack of evidence-based delivery modalities other than face-to-face. The perception and acceptability of telemedicine for the delivery of CBTI is unknown. We conducted a randomized controlled non-inferiority trial comparing face-to-face (F2F) and telemedicine (via AASM SleepTM) delivery of CBTI. We compared measures of patient satisfaction with treatment and the perception of the therapist’s warmth and skills between F2F and SleepTM.

Methods

Adults with insomnia were recruited from insomnia clinics and the community and screened for sleep, medical, and mental health disorders. Eligible participants were randomized to receive CBTI either via AASM SleepTM or F2F in 6 weekly sessions of 45-60 minutes each. Participants completed the Client Satisfaction Questionnaire (CSQ-8) and The Therapy Evaluation Questionnaire (TEQ) after completing treatment. The CSQ-8 score ranges from 8-32 with high scores indicating greater satisfaction. We also analyzed the two items on the TEQ that assess participants’ perception of therapist’s warmth and skills. Item scores ranged from 1-7, with higher scores indicating greater warmth and skills.

Results

Sixty-five adults with chronic insomnia were recruited primarily from insomnia clinics. Sixty-two participants (41 women, mean age 48.9 ± 15.4 years) completed all 6 sessions of CBTI via F2F (n=32) or via AASM SleepTM (n=30). Independent samples t-tests revealed no significant differences between conditions on patient satisfaction (SleepTM, 28.5 +/-4.2 vs F2F 29.9 +/-2.4, t(-1.5), p=.14), therapist warmth (SleepTM, 6.0 ±1.1 vs F2F, 6.4±0.95, t(-1.4), p=.16), or therapist skills (Sleep TM 6.4 ±1.0 vs F2F, 6.7±0.59, t(-1.5), p=.15).

Conclusion

Our findings suggest no differences in patient satisfaction, perception of therapist’s warmth, or confidence in therapist’s skills between telemedicine (via the AASM SleepTM) and F2F delivery of CBTI. Telemedicine-delivered CBTI should be implemented more widely.

Support

Research supported by American Sleep Medicine Foundation Grant # 168-SR-17 (JT Arnedt)