Effectiveness and diagnostic accuracy of teledermatology for the assessment of skin conditions.

BACKGROUND: Teledermatology provides a platform for swift specialist advice without the potential need for face-to-face review. Our objectives were to investigate the effectiveness, accuracy and diagnostic concordance of the platform with regard to the remote management of skin conditions. METHODS: We undertook a single-centre, retrospective chart review over a 1-year period, comprising a total of 1703 teledermatology referrals. Two physicians independently assessed the diagnostic concordance between telederm diagnosis (TD), in-person diagnosis (ID) and histopathological diagnosis (HD). RESULTS: There were a total of 1703 TD referrals, of which 341 were rejected, leaving 1362 referrals for evaluation. Sixty-five per cent of these referrals were managed remotely and discharged with advice, although 4.6% of these were later re-referred for an in-person review. A total of 20% of referrals were rejected, of which the majority was due to a lack of appropriate imaging. The total concordance of TD compared to ID was 76.4%. When comparing the TD and ID/HD, we obtained a Kappa value of 0.636 indicating substantial agreement. In terms of accuracy, there were 49 biopsy-proven skin cancers picked up by the service in this cohort of data. Of these, 61.2% were given an accurate diagnosis on first impression via teledermatology, 14.3% were given a different diagnosis but correctly categorised as skin cancer and 24.5% could not be assessed; however, they were triaged and escalated based upon clinical suspicion. CONCLUSION: Our study demonstrates that teledermatology is an effective platform in terms of diagnosis and remote management, with adequate diagnostic accuracy and concordance to in-person diagnosis.

Light-up split aptamers: binding thermodynamics and kinetics for sensing.

Due to their programmable structures, many aptamers can be readily split into two halves while still retaining their target binding function. While split aptamers are prevalent in the biosensor field, fundamental studies of their binding are still lacking. In this work, we took advantage of the fluorescence enhancement property of a new aptamer named OTC5 that can bind to tetracycline antibiotics to compare various split aptamers with the full-length aptamer. The split aptamers were designed to have different stem lengths. Longer stem length aptamers showed similar dissociation constants (Kd) to the full-length aptamer, while a shorter stem construct showed an 85-fold increase in Kd. Temperature-dependent fluorescence measurements confirmed the lower thermostability of split aptamers. Isothermal titration calorimetry indicated that split aptamer binding can release more heat but have an even larger entropy loss. Finally, a colorimetric biosensor using gold nanoparticles was designed by pre-assembling two thiolated aptamer halves, which can then link gold nanoparticles to give a red-to-blue color change.

Anogenital dermatology: caseload analysis of new outpatient referrals at a single dermatology centre.

Little is known about the volume of outpatient referrals for anogenital dermatoses received by NHS dermatology departments. We undertook a caseload analysis at our centre and found 6.0% of GP referrals to Dermatology were for anogenital dermatoses. This has important implications for training in this field of dermatology as well as for service provision.

Rewriting nature's assembly manual for a ssRNA virus.

Satellite tobacco necrosis virus (STNV) is one of the smallest viruses known. Its genome encodes only its coat protein (CP) subunit, relying on the polymerase of its helper virus TNV for replication. The genome has been shown to contain a cryptic set of dispersed assembly signals in the form of stem-loops that each present a minimal CP-binding motif AXXA in the loops. The genomic fragment encompassing nucleotides 1-127 is predicted to contain five such packaging signals (PSs). We have used mutagenesis to determine the critical assembly features in this region. These include the CP-binding motif, the relative placement of PS stem-loops, their number, and their folding propensity. CP binding has an electrostatic contribution, but assembly nucleation is dominated by the recognition of the folded PSs in the RNA fragment. Mutation to remove all AXXA motifs in PSs throughout the genome yields an RNA that is unable to assemble efficiently. In contrast, when a synthetic 127-nt fragment encompassing improved PSs is swapped onto the RNA otherwise lacking CP recognition motifs, assembly is partially restored, although the virus-like particles created are incomplete, implying that PSs outside this region are required for correct assembly. Swapping this improved region into the wild-type STNV1 sequence results in a better assembly substrate than the viral RNA, producing complete capsids and outcompeting the wild-type genome in head-to-head competition. These data confirm details of the PS-mediated assembly mechanism for STNV and identify an efficient approach for production of stable virus-like particles encapsidating nonnative RNAs or other cargoes.

Single-Incision Laparoscopic Deroofing and Omentalization of a Cystic Renal Adenoma in a Dog.

A 12 yr old 13.5 kg male castrated Pembroke Welsh corgi was presented for evaluation of a suspected renal cyst following multiple episodes of lethargy and abdominal pain. Abdominal imaging revealed a large, thin-walled, hypoechoic cystic lesion associated with the cranial pole of the left kidney and a second smaller cystic lesion on the caudal pole. The larger cystic lesion was repeatedly drained percutaneously, but the lesion returned to initial size and clinical signs returned within weeks. Percutaneous ethanol sclerotherapy achieved only transient improvement in lesion size and abdominal discomfort. Laparoscopic deroofing and omentalization of the larger left renal cystic lesion was performed. The resected cystic wall was histopathologically consistent with a renal adenoma. Abdominal ultrasonography performed 1 mo postoperatively found no recurrence of the cystic renal adenoma. Repeated ultrasonography at 3 mo postoperatively detected a small cystic lesion at the cranial pole of the left kidney, which remained static in appearance at 11 and 18 mo postoperatively. During all follow-up visits, the dog was reported to be doing well with no recurrence of clinical signs. Renal cysts causing clinical signs and renal adenomas are rare in veterinary medicine; laparoscopic deroofing and omentalization provides a minimally invasive treatment approach.

Revealing the density of encoded functions in a viral RNA.

We present direct experimental evidence that assembly of a single-stranded RNA virus occurs via a packaging signal-mediated mechanism. We show that the sequences of coat protein recognition motifs within multiple, dispersed, putative RNA packaging signals, as well as their relative spacing within a genomic fragment, act collectively to influence the fidelity and yield of capsid self-assembly in vitro. These experiments confirm that the selective advantages for viral yield and encapsidation specificity, predicted from previous modeling of packaging signal-mediated assembly, are found in Nature. Regions of the genome that act as packaging signals also function in translational and transcriptional enhancement, as well as directly coding for the coat protein, highlighting the density of encoded functions within the viral RNA. Assembly and gene expression are therefore direct molecular competitors for different functional folds of the same RNA sequence. The strongest packaging signal in the test fragment, encodes a region of the coat protein that undergoes a conformational change upon contact with packaging signals. A similar phenomenon occurs in other RNA viruses for which packaging signals are known. These contacts hint at an even deeper density of encoded functions in viral RNA, which if confirmed, would have profound consequences for the evolution of this class of pathogens.

Observation of unpaired substrate DNA in the flap endonuclease-1 active site.

The structure- and strand-specific phosphodiesterase flap endonuclease-1 (FEN1), the prototypical 5'-nuclease, catalyzes the essential removal of 5'-single-stranded flaps during replication and repair. FEN1 achieves this by selectively catalyzing hydrolysis one nucleotide into the duplex region of substrates, always targeting the 5'-strand. This specificity is proposed to arise by unpairing the 5'-end of duplex to permit the scissile phosphate diester to contact catalytic divalent metal ions. Providing the first direct evidence for this, we detected changes induced by human FEN1 (hFEN1) in the low-energy CD spectra and fluorescence lifetimes of 2-aminopurine in substrates and products that were indicative of unpairing. Divalent metal ions were essential for unpairing. However, although 5'-nuclease superfamily-conserved active-site residues K93 and R100 were required to produce unpaired product, they were not necessary to unpair substrates. Nevertheless, a unique arrangement of protein residues around the unpaired DNA was detected only with wild-type protein, suggesting a cooperative assembly of active-site residues that may be triggered by unpaired DNA. The general principles of FEN1 strand and reaction-site selection, which depend on the ability of juxtaposed divalent metal ions to unpair the end of duplex DNA, may also apply more widely to other structure- and strand-specific nucleases.

Proline scanning mutagenesis reveals a role for the flap endonuclease-1 helical cap in substrate unpairing.

The prototypical 5'-nuclease, flap endonuclease-1 (FEN1), catalyzes the essential removal of single-stranded flaps during DNA replication and repair. FEN1 hydrolyzes a specific phosphodiester bond one nucleotide into double-stranded DNA. This specificity arises from double nucleotide unpairing that places the scissile phosphate diester on active site divalent metal ions. Also related to FEN1 specificity is the helical arch, through which 5'-flaps, but not continuous DNAs, can thread. The arch contains basic residues (Lys-93 and Arg-100 in human FEN1 (hFEN1)) that are conserved by all 5'-nucleases and a cap region only present in enzymes that process DNAs with 5' termini. Proline mutations (L97P, L111P, L130P) were introduced into the hFEN1 helical arch. Each mutation was severely detrimental to reaction. However, all proteins were at least as stable as wild-type (WT) hFEN1 and bound substrate with comparable affinity. Moreover, all mutants produced complexes with 5'-biotinylated substrate that, when captured with streptavidin, were resistant to challenge with competitor DNA. Removal of both conserved basic residues (K93A/R100A) was no more detrimental to reaction than the single mutation R100A, but much less severe than L97P. The ability of protein-Ca(2+) to rearrange 2-aminopurine-containing substrates was monitored by low energy CD. Although L97P and K93A/R100A retained the ability to unpair substrates, the cap mutants L111P and L130P did not. Taken together, these data challenge current assumptions related to 5'-nuclease family mechanism. Conserved basic amino acids are not required for double nucleotide unpairing and appear to act cooperatively, whereas the helical cap plays an unexpected role in hFEN1-substrate rearrangement.

Flap endonucleases pass 5'-flaps through a flexible arch using a disorder-thread-order mechanism to confer specificity for free 5'-ends.

Flap endonucleases (FENs), essential for DNA replication and repair, recognize and remove RNA or DNA 5'-flaps. Related to FEN specificity for substrates with free 5'-ends, but controversial, is the role of the helical arch observed in varying conformations in substrate-free FEN structures. Conflicting models suggest either 5'-flaps thread through the arch, which when structured can only accommodate single-stranded (ss) DNA, or the arch acts as a clamp. Here we show that free 5'-termini are selected using a disorder-thread-order mechanism. Adding short duplexes to 5'-flaps or 3'-streptavidin does not markedly impair the FEN reaction. In contrast, reactions of 5'-streptavidin substrates are drastically slowed. However, when added to premixed FEN and 5'-biotinylated substrate, streptavidin is not inhibitory and complexes persist after challenge with unlabelled competitor substrate, regardless of flap length or the presence of a short duplex. Cross-linked flap duplexes that cannot thread through the structured arch react at modestly reduced rate, ruling out mechanisms involving resolution of secondary structure. Combined results explain how FEN avoids cutting template DNA between Okazaki fragments and link local FEN folding to catalysis and specificity: the arch is disordered when flaps are threaded to confer specificity for free 5'-ends, with subsequent ordering of the arch to catalyze hydrolysis.

Social Risk Factors and Racial and Ethnic Disparities in Health Care Resource Utilization Among Medicare Advantage Beneficiaries With Psychiatric Disorders.

The intersection of social risk and race and ethnicity on mental health care utilization is understudied. This study examined disparities in health care treatment, adjusting for clinical need, among 25,780 Medicare Advantage beneficiaries with a diagnosis of a psychiatric disorder. We assessed contributions to disparities from racial and ethnic differences in the composition and returns of social risk variables. Black and Hispanic beneficiaries had lower rates of mental health outpatient visits than Whites. Assessing composition, Black and Hispanic beneficiaries experienced greater financial, food, and housing insecurity than White beneficiaries, factors associated with greater mental health treatment. Assessing returns, food insecurity was associated with an exacerbation of Hispanic-White disparities. Health care systems need to address the financial, food and housing insecurity of racial and ethnic minority groups with psychiatric disorder. Accounting for racial and ethnic differences in social risk adjustment-based payment reforms has significant implications for provider reimbursement and outcomes.

Concern for Increased Prevalence of Heyde's Syndrome in Patients on Hemodialysis.

The association between aortic stenosis and increased gastrointestinal arteriovenous malformations is known as Heyde's syndrome. An acquired von Willebrand deficiency mediates the connection between these two seemingly dispersed pathologies. As von Willebrand factor passes through a stenosed aorta, it is broken down and can no longer inhibit angiogenesis, leading to angiodysplasias. Heyde's syndrome can manifest with chronic, refractory anemia requiring multiple hospitalizations for symptomatic gastrointestinal bleeding and transfusion. Hitherto, Heyde's syndrome has been considered exceptionally rare, with 1-3% of populations with aortic stenosis. However, given that 31.7% of patients with gastrointestinal angioplasty have aortic stenosis and gastrointestinal arteriovenous malformations are not screened for in patients without anemia, the prevalence of Heyde's syndrome is most likely higher than currently reflected in the literature. Also, the prevalence of Heyde's syndrome in populations who are predisposed to angiodysplasias, such as those on hemodialysis, is understudied. We aim to impart a need for increased research on the prevalence of Heyde's syndrome, especially in high-risk patients. This case report presents a patient with severe Heyde's syndrome on hemodialysis, showing an unconsidered risk factor for Heyde's syndrome in need of further research.

Improving Quantum Well Tube Homogeneity Using Strained Nanowire Heterostructures.

Bottom-up grown nanostructures often suffer from significant dimensional inhomogeneity, and for quantum confined heterostructures, this can lead to a corresponding large variation in electronic properties. A high-throughput characterization methodology is applied to >15,000 nanoskived sections of highly strained GaAsP/GaAs radial core/shell quantum well heterostructures revealing high emission uniformity. While scanning electron microscopy shows a wide nanowire diameter spread of 540-60+60 nm, photoluminescence reveals a tightly bounded band-to-band transition energy of 1546-3+4 meV. A highly strained core/shell nanowire design is shown to reduce the dependence of emission on the quantum well width variation significantly more than in the unstrained case.

Evaluation of the Panbio™ COVID-19 IgG rapid test device performance.

Background: The Panbio™ COVID-19 IgG Rapid Test Device ("Panbio™") detects IgG antibodies against the SARS-CoV-2 spike protein from viral infection or vaccination. Objectives: To determine the diagnostic sensitivity and specificity of the Panbio™ professional use test, using fingerstick whole blood and venous plasma. Study design: Fingerstick whole blood and venous plasma from each participant were tested with Panbio™ and compared against the SARS-CoV-2 IgG II assay on the Abbott Architect™ platform (Europe) or the equivalent AdviseDx SARS-CoV-2 IgG II Abbott Alinity i™ platform (US). 447 evaluable participants were enrolled across 6 US and 9 European clinical centers. Results: For unvaccinated participants with PCR-confirmed infection ≥21 days post-symptom onset, the Panbio™ sensitivity with fingerstick whole blood was 92.6 % (95 % CI: 85.9, 96.7), and the specificity was 97.0 % (95 % CI: 93.1, 99.0). For venous plasma, the sensitivity was 90.0 % (95 % CI: 79.5, 96.2) for participants with PCR-confirmed infection and symptom onset 22-180 days ago; the specificity was 96.3 % (92.2, 98.6). For vaccinated participants, the sensitivity was 98.4 % (95 % CI: 91.2, 100.0) for fingerstick whole blood and 96.7 % (95 % CI: 88.7, 99.6) for venous plasma. Conclusion: The Panbio™ test had high sensitivity and specificity for detecting IgG against the SARS-CoV-2 spike protein.

Partial penile amputation using a thoracoabdominal stapler in nine dogs.

OBJECTIVES: To describe a novel technique for partial anatomic penile amputation using a thoracoabdominal stapler in dogs and to report any associated short-term peri-operative complications and clinical outcomes associated with the procedure. MATERIALS AND METHODS: Medical records from a tertiary referral hospital were reviewed for dogs undergoing penile amputation and scrotal urethrostomy between October 2007 and December 2019. Data collected included patient signalment, clinical signs on presentation, indication for penile amputation, surgical technique, duration of surgery, post-operative complications, and short-term outcome. RESULTS: Nine dogs were included in the study. Indications for surgery were for treatment of chronic paraphimosis and priapism (n = 3), recurrent urethral prolapse (n = 2), balanoposthitis (n = 1), masses arising from the penis, prepuce, and/or urethra (n = 2), and penile trauma (n = 1). All dogs underwent a scrotal urethrostomy followed by a partial penile amputation with a thoracoabdominal stapler. All dogs suffered mild post-operative haemorrhage from the urethrostomy stoma. On recovery from general anaesthesia, 2/9 dogs were painful and another 2/9 dogs were dysphoric. Two dogs experienced incisional complications with mild swelling around the urethrostomy stoma. One dog experienced an infection of the penile amputation site 21 days after surgery. The short-term outcomes for this procedure were excellent in 8/9 dogs. These outcomes were based on owner assessment of comfort and monitoring throughout the recovery period, manual palpation of the surgical site at the time re-evaluation, and surgeon visualization of successful voluntary urination 14-35 days after surgery. CLINICAL SIGNIFICANCE: Use of a thoracoabdominal stapler is effective in achieving partial anatomic penile amputation in dogs.

Dysregulation of Hepatitis B Virus Nucleocapsid Assembly in vitro by RNA-binding Small Ligands.

RNA sequences/motifs dispersed across the genome of Hepatitis B Virus regulate formation of nucleocapsid-like particles (NCPs) by core protein (Cp) in vitro, in an epsilon/polymerase-independent fashion. These multiple RNA Packaging Signals (PSs) can each form stem-loops encompassing a Cp-recognition motif, -RGAG-, in their loops. Drug-like molecules that bind the most important of these PS sites for NCP assembly regulation with nanomolar affinities, were identified by screening an immobilized ligand library with a fluorescently-labelled, RNA oligonucleotide encompassing this sequence. Sixty-six of these "hits", with affinities ranging from low nanomolar to high micromolar, were purchased as non-immobilized versions. Their affinities for PSs and effects on NCP assembly were determined in vitro by Surface Plasmon Resonance. High-affinity ligand binding is dependent on the presence of an -RGAG- motif within the loop of the PS, consistent with ligand cross-binding between PS sites. Simple structure-activity relationships show that it is also dependent on the presence of specific functional groups in these ligands. Some compounds are potent inhibitors of in vitro NCP assembly at nanomolar concentrations. Despite appropriate logP values, these ligands do not inhibit HBV replication in cell culture. However, modelling confirms the potential of using PS-binding ligands to target NCP assembly as a novel anti-viral strategy. This also allows for computational exploration of potential synergic effects between anti-viral ligands directed at distinct molecular targets in vivo. HBV PS-regulated assembly can be dysregulated by novel small molecule RNA-binding ligands opening a novel target for developing directly-acting anti-virals against this major pathogen.

Dataset of high-throughput ligand screening against the RNA Packaging Signals regulating Hepatitis B Virus nucleocapsid formation.

Multiple ssRNA viruses which infect bacteria, plants or humans use RNA Packaging Signal (PS)-mediated regulation during assembly to package their genomes faithfully and efficiently. PSs typically comprise short nucleotide recognition motifs, most often presented in the unpaired region of RNA stem-loops, and often bind their cognate coat proteins (CPs) with nanomolar affinity. PSs identified to date are resilient in the face of the typical error prone replication of their virus-coded polymerases, making them potential drug targets. An immobilised array of small molecular weight, drug-like compounds was panned against a fluorescently-labelled oligonucleotide encompassing the most conserved Hepatitis B Virus (HBV) PS, PS1, known to be a major determinant in nucleocapsid formation. This identified > 70 compounds that bind PS1 uniquely in the array. The commercially available 66 of these were tested for their potential effect(s) on HBV nucleocapsid-like particle (NCP) assembly in vitro, which identified potent assembly inhibitors. Here, we describe a high-throughput screen for such effects using employing fluorescence anisotropy in a 96-well microplate format. HBV genomic RNAs (gRNA) and short oligonucleotides encompassing PS1 were 5' labelled with an Alexa Fluor 488 dye. Excess (with respect to stoichiometric T = 4 NCP formation) HBV core protein (Cp) dimers were titrated robotically into solutions containing each of these RNAs stepwise, using a Biomek 4000 liquid handling robot. The anisotropy values of these mixtures were monitored using a POLARstar microplate reader. NCP-like structures were challenged with RNase A to identify reactions that did not result in complete NCP formation. The results imply that ∼50% of the compounds prevent complete NCP formation, highlighting both PS-meditated assembly and the PS-binding compounds as potential directly-acting anti-virals with a novel molecular target. Importantly, this method allows high-throughput in vitro screening for assembly inhibitors in this major human pathogen.

Evolution of a virus-like architecture and packaging mechanism in a repurposed bacterial protein.

Viruses are ubiquitous pathogens of global impact. Prompted by the hypothesis that their earliest progenitors recruited host proteins for virion formation, we have used stringent laboratory evolution to convert a bacterial enzyme that lacks affinity for nucleic acids into an artificial nucleocapsid that efficiently packages and protects multiple copies of its own encoding messenger RNA. Revealing remarkable convergence on the molecular hallmarks of natural viruses, the accompanying changes reorganized the protein building blocks into an interlaced 240-subunit icosahedral capsid that is impermeable to nucleases, and emergence of a robust RNA stem-loop packaging cassette ensured high encapsidation yields and specificity. In addition to evincing a plausible evolutionary pathway for primordial viruses, these findings highlight practical strategies for developing nonviral carriers for diverse vaccine and delivery applications.

In vitro functional analysis of gRNA sites regulating assembly of hepatitis B virus.

The roles of RNA sequence/structure motifs, Packaging Signals (PSs), for regulating assembly of an HBV genome transcript have been investigated in an efficient in vitro assay containing only core protein (Cp) and RNA. Variants of three conserved PSs, within the genome of a strain not used previously, preventing correct presentation of a Cp-recognition loop motif are differentially deleterious for assembly of nucleocapsid-like particles (NCPs). Cryo-electron microscopy reconstruction of the T = 4 NCPs formed with the wild-type gRNA transcript, reveal that the interior of the Cp shell is in contact with lower resolution density, potentially encompassing the arginine-rich protein domains and gRNA. Symmetry relaxation followed by asymmetric reconstruction reveal that such contacts are made at every symmetry axis. We infer from their regulation of assembly that some of these contacts would involve gRNA PSs, and confirmed this by X-ray RNA footprinting. Mutation of the ε stem-loop in the gRNA, where polymerase binds in vivo, produces a poor RNA assembly substrate with Cp alone, largely due to alterations in its conformation. The results show that RNA PSs regulate assembly of HBV genomic transcripts in vitro, and therefore may play similar roles in vivo, in concert with other molecular factors.