Radiation Exposure to the Interventional Echocardiographers and Sonographers: A Call to Action.

Interventional echocardiography is a rapidly growing field within the disciplines of cardiology and anesthesiology, with the rise of advanced transcatheter procedures making skilled imagers more important than ever. However, these procedures also involve frequent manipulation of the transesophageal echocardiography probe, which means interventional echocardiographers (IEs) are at risk of long-term occupational radiation exposure. Studies have shown that radiation exposure is linked to various health issues, including cancer, cataracts, hypertension, hyperlipidemia, endothelial dysfunction, vascular aging, and early atherosclerosis. While there is increasing awareness of the occupational radiation dose limits and the need for better shielding methods, the importance of radiation safety for the IE is still not sufficiently prioritized in most cardiac catheterization laboratories/hybrid operating rooms. This is partly due to a paucity of studies looking at long-term radiation exposure to the IE, as this field is newer than that of interventional cardiologists.

Investigation of integrated time nanosecond pulse irreversible electroporation against spontaneous equine melanoma.

Introduction: Integrated time nanosecond pulse irreversible electroporation (INSPIRE) is a novel tumor ablation modality that employs high voltage, alternating polarity waveforms to induce cell death in a well-defined volume while sparing the underlying tissue. This study aimed to demonstrate the in vivo efficacy of INSPIRE against spontaneous melanoma in standing, awake horses. Methods: A custom applicator and a pulse generation system were utilized in a pilot study to treat horses presenting with spontaneous melanoma. INSPIRE treatments were administered to 32 tumors across 6 horses and an additional 13 tumors were followed to act as untreated controls. Tumors were tracked over a 43-85 day period following a single INSPIRE treatment. Pulse widths of 500ns and 2000ns with voltages between 1000 V and 2000 V were investigated to determine the effect of these variables on treatment outcomes. Results: Treatments administered at the lowest voltage (1000 V) reduced tumor volumes by 11 to 15%. Higher voltage (2000 V) treatments reduced tumor volumes by 84 to 88% and eliminated 33% and 80% of tumors when 500 ns and 2000 ns pulses were administered, respectively. Discussion: Promising results were achieved without the use of chemotherapeutics, the use of general anesthesia, or the need for surgical resection in regions which are challenging to keep sterile. This novel therapeutic approach has the potential to expand the role of pulsed electric fields in veterinary patients, especially when general anesthesia is contraindicated, and warrants future studies to demonstrate the efficacy of INSPIRE as a solid tumor treatment.

Role of affinity in plasma cell development in the germinal center light zone.

Protective immune responses to many pathogens depend on the development of high-affinity antibody-producing plasma cells (PC) in germinal centers (GCs). Transgenic models suggest that there is a stringent affinity-based barrier to PC development. Whether a similar high-affinity barrier regulates PC development under physiologic circumstances and the nature of the PC fate decision has not been defined precisely. Here, we use a fate-mapping approach to examine the relationship between GC B cells selected to undergo additional rounds of affinity maturation, GC pre-PC, and PC. The data show that initial PC selection overlaps with GC B cell selection, but that the PC compartment accumulates a less diverse and higher affinity collection of antibodies over time. Thus, whereas the GC continues to diversify over time, affinity-based pre-PC selection sieves the GC to enable the accumulation of a more restricted group of high-affinity antibody-secreting PC.

Memory B cell development elicited by mRNA booster vaccinations in the elderly.

Despite mRNA vaccination, elderly individuals remain especially vulnerable to severe consequences of SARS-CoV-2 infection. Here, we compare the memory B cell responses in a cohort of elderly and younger individuals who received mRNA booster vaccinations. Plasma neutralizing potency and breadth were similar between the two groups. By contrast, the absolute number of SARS-CoV-2-specific memory B cells was lower in the elderly. Antibody sequencing revealed that the SARS-CoV-2-specific elderly memory compartments were more clonal and less diverse. Notably, memory antibodies from the elderly preferentially targeted the ACE2-binding site on the RBD, while those from younger individuals targeted less accessible but more conserved epitopes. Nevertheless, individual memory antibodies elicited by booster vaccines in the elderly and younger individuals showed similar levels of neutralizing activity and breadth against SARS-CoV-2 variants. Thus, the relatively diminished protective effects of vaccination against serious disease in the elderly are associated with a smaller number of antigen-specific memory B cells that express altered antibody repertoires.

Antibody feedback regulates immune memory after SARS-CoV-2 mRNA vaccination.

Feedback inhibition of humoral immunity by antibodies was first documented in 19091. Subsequent studies showed that, depending on the context, antibodies can enhance or inhibit immune responses2,3. However, little is known about how pre-existing antibodies influence the development of memory B cells. Here we examined the memory B cell response in individuals who received two high-affinity anti-SARS-CoV-2 monoclonal antibodies and subsequently two doses of an mRNA vaccine4-8. We found that the recipients of the monoclonal antibodies produced antigen-binding and neutralizing titres that were only fractionally lower compared than in control individuals. However, the memory B cells of the individuals who received the monoclonal antibodies differed from those of control individuals in that they predominantly expressed low-affinity IgM antibodies that carried small numbers of somatic mutations and showed altered receptor binding domain (RBD) target specificity, consistent with epitope masking. Moreover, only 1 out of 77 anti-RBD memory antibodies tested neutralized the virus. The mechanism underlying these findings was examined in experiments in mice that showed that germinal centres formed in the presence of the same antibodies were dominated by low-affinity B cells. Our results indicate that pre-existing high-affinity antibodies bias germinal centre and memory B cell selection through two distinct mechanisms: (1) by lowering the activation threshold for B cells, thereby permitting abundant lower-affinity clones to participate in the immune response; and (2) through direct masking of their cognate epitopes. This may in part explain the shifting target profile of memory antibodies elicited by booster vaccinations9.

HEMOLYMPH COLLECTION AND ISOFLURANE ANESTHESIA OF THE EMPEROR SCORPION (PANDINUS IMPERATOR).

With captive invertebrates increasing in popularity, a safe and effective anesthesia protocol is required for their veterinary care. This study investigated the safety and efficacy of 5% isoflurane anesthesia and 0.26 ml hemolymph collection in subadult to adult emperor scorpions (Pandinus imperator; n = 14). Each scorpion was placed in a 2-L anesthetic chamber and induced with 5% isoflurane at a flow rate of 2 L/min oxygen. Anesthetic depth was assessed by rolling the animal into dorsal recumbency and rating the response from one to four: 1 = successful coordinated righting movement, 2 = successful uncoordinated righting movement, 3 = unsuccessful righting movement, 4 = no movement. Ratings 3 and 4 were both adequate for the hemolymph collection. The mean induction time was 4.2 min to reach a level 3 depth and 10.5 min to reach a level 4 depth. All animals were clinically normal for at least 1 yr post experiment. A mean hemolymph volume drawn of 1.92% of body weight, and an anesthetic induction with 5% isoflurane, appear safe in subadult to adult emperor scorpions.

Memory B cell responses to Omicron subvariants after SARS-CoV-2 mRNA breakthrough infection in humans.

Individuals who receive a third mRNA vaccine dose show enhanced protection against severe COVID-19, but little is known about the impact of breakthrough infections on memory responses. Here, we examine the memory antibodies that develop after a third or fourth antigenic exposure by Delta or Omicron BA.1 infection, respectively. A third exposure to antigen by Delta breakthrough increases the number of memory B cells that produce antibodies with comparable potency and breadth to a third mRNA vaccine dose. A fourth antigenic exposure with Omicron BA.1 infection increased variant-specific plasma antibody and memory B cell responses. However, the fourth exposure did not increase the overall frequency of memory B cells or their general potency or breadth compared to a third mRNA vaccine dose. In conclusion, a third antigenic exposure by Delta infection elicits strain-specific memory responses and increases in the overall potency and breadth of the memory B cells. In contrast, the effects of a fourth antigenic exposure with Omicron BA.1 are limited to increased strain-specific memory with little effect on the potency or breadth of memory B cell antibodies. The results suggest that the effect of strain-specific boosting on memory B cell compartment may be limited.

Humoral immunity to SARS-CoV-2 elicited by combination COVID-19 vaccination regimens.

The SARS-CoV-2 pandemic prompted a global vaccination effort and the development of numerous COVID-19 vaccines at an unprecedented scale and pace. As a result, current COVID-19 vaccination regimens comprise diverse vaccine modalities, immunogen combinations, and dosing intervals. Here, we compare vaccine-specific antibody and memory B cell responses following two-dose mRNA, single-dose Ad26.COV.2S, and two-dose ChAdOx1, or combination ChAdOx1/mRNA vaccination. Plasma-neutralizing activity, as well as the magnitude, clonal composition, and antibody maturation of the RBD-specific memory B cell compartments, showed substantial differences between the vaccination regimens. While individual monoclonal antibodies derived from memory B cells exhibited similar binding affinities and neutralizing potency against Wuhan-Hu-1 SARS-CoV-2, there were significant differences in epitope specificity and neutralizing breadth against viral variants of concern. Although the ChAdOx1 vaccine was inferior to mRNA and Ad26.COV.2S in several respects, biochemical and structural analyses revealed enrichment in a subgroup of memory B cell neutralizing antibodies with distinct RBD-binding properties resulting in remarkable potency and breadth.

Antibody feedback regulation of memory B cell development in SARS-CoV-2 mRNA vaccination.

Feedback inhibition of humoral immunity by antibodies was initially documented in guinea pigs by Theobald Smith in 1909, who showed that passive administration of excess anti-Diphtheria toxin inhibited immune responses1. Subsequent work documented that antibodies can enhance or inhibit immune responses depending on antibody isotype, affinity, the physical nature of the antigen, and engagement of immunoglobulin (Fc) and complement (C') receptors2,3. However, little is known about how pre-existing antibodies might influence the subsequent development of memory B cells. Here we examined the memory B cell response in individuals who received two high-affinity IgG1 anti-SARS-CoV-2 receptor binding domain (RBD)-specific monoclonal antibodies, C144-LS and C135-LS, and subsequently two doses of a SARS-CoV-2 mRNA vaccine. The two antibodies target Class 2 and 3 epitopes that dominate the initial immune response to SARS-CoV-2 infection and mRNA vaccination4-8. Antibody responses to the vaccine in C144-LS and C135-LS recipients produced plasma antigen binding and neutralizing titers that were fractionally lower but not statistically different to controls. In contrast, memory B cells enumerated by flow cytometry after the second vaccine dose were present in higher numbers than in controls. However, the memory B cells that developed in antibody recipients differed from controls in that they were not enriched in VH3-53, VH1-46 and VH3-66 genes and predominantly expressed low-affinity IgM antibodies that carried small numbers of somatic mutations. These antibodies showed altered RBD target specificity consistent with epitope masking, and only 1 out of 77 anti-RBD memory antibodies tested neutralized the virus. The results indicate that pre-existing high-affinity antibodies bias memory B cell selection and have a profound effect on the development of immunological memory in humans that may in part explain the shifting target profile of memory antibodies elicited by the 3rd mRNA vaccine dose.

Antibody evolution to SARS-CoV-2 after single-dose Ad26.COV2.S vaccine in humans.

The single-dose Ad.26.COV.2 (Janssen) vaccine elicits lower levels of neutralizing antibodies and shows more limited efficacy in protection against infection than either of the two available mRNA vaccines. In addition, Ad.26.COV.2 has been less effective in protection against severe disease during the Omicron surge. Here, we examined the memory B cell response to single-dose Ad.26.COV.2 vaccination. Compared with mRNA vaccines, Ad.26.COV.2 recipients had significantly lower numbers of RBD-specific memory B cells 1.5 or 6 mo after vaccination. Despite the lower numbers, the overall quality of the memory B cell responses appears to be similar, such that memory antibodies elicited by both vaccine types show comparable neutralizing potency against SARS-CoV-2 Wuhan-Hu-1, Delta, and Omicron BA.1 variants. The data help explain why boosting Ad.26.COV.2 vaccine recipients with mRNA vaccines is effective and why the Ad26.COV2.S vaccine can maintain some protective efficacy against severe disease during the Omicron surge.

Increased Prevalence of Breast and All-cause Cancer in Female Orthopaedic Surgeons.

INTRODUCTION: Cancer is the second leading cause of death among women in the United States. Previous studies demonstrate a higher prevalence of cancer among female orthopaedic surgeons. This study aimed to provide an updated prevalence of breast and all-cause cancer among female orthopaedic surgeons using a larger and more current study population. METHODS: We distributed surveys to female orthopaedic surgeons in national orthopaedic specialty societies. Six hundred seventy-two survey responses were collected. We calculated standardized prevalence ratios (SPRs) and 95% confidence intervals (CIs) based on gender-specific, race-specific, and age-specific cancer prevalence statistics in the US population. We compared the distribution of breast cancer risk factors with that of women in the 2018 and 2009 California Health Interview Survey. RESULTS: Fifty-one of the 672 surveyed surgeons reported a diagnosis of invasive cancer. Twenty reported breast cancer with a prevalence higher among female orthopaedic surgeons compared with the US female population (SPR: 2.89, 95% CI: 2.16 to 3.81, P < 0.001). The breast cancer prevalence was also higher among orthopaedic surgeons compared with the US female population (SPR: 3.97, 95% CI: 2.43 to 6.14, P = 0.003). DISCUSSION: The increased prevalence of breast and all-cause cancer among a larger and more diverse cohort of female orthopaedic surgeons confirms previous studies and provides an update regarding a concerning public health issue within this specialty.

Disease Ecology of a Low-Virulence Mycoplasma ovipneumoniae Strain in a Free-Ranging Desert Bighorn Sheep Population.

Infectious pneumonia associated with the bacterial pathogen Mycoplasma ovipneumoniae is an impediment to bighorn sheep (Ovis canadensis) population recovery throughout western North America, yet the full range of M. ovipneumoniae virulence in bighorn sheep is not well-understood. Here, we present data from an M. ovipneumoniae introduction event in the Zion desert bighorn sheep (Ovis canadensis nelsoni) population in southern Utah. The ensuing disease event exhibited epidemiology distinct from what has been reported elsewhere, with virtually no mortality (0 adult mortalities among 70 animals tracked over 118 animal-years; 1 lamb mortality among 40 lambs tracked through weaning in the two summers following introduction; and lamb:ewe ratios of 34.9:100 in the year immediately after introduction and 49.4:100 in the second year after introduction). Individual-level immune responses were lower than expected, and M. ovipneumoniae appeared to fade out approximately 1.5 to 2 years after introduction. Several mechanisms could explain the limited burden of this M. ovipneumoniae event. First, most work on M. ovipneumoniae has centered on Rocky Mountain bighorn sheep (O. c. candensis), but the Zion bighorns are members of the desert subspecies (O. c. nelsoni). Second, the particular M. ovipneumoniae strain involved comes from a clade of strains associated with weaker demographic responses in other settings. Third, the substructuring of the Zion population may have made this population more resilient to disease invasion and persistence. The limited burden of the disease event on the Zion bighorn population underscores a broader point in wildlife disease ecology: that one size may not fit all events.

Increased memory B cell potency and breadth after a SARS-CoV-2 mRNA boost.

The Omicron variant of SARS-CoV-2 infected many vaccinated and convalescent individuals1-3. Despite the reduced protection from infection, individuals who received three doses of an mRNA vaccine were highly protected from more serious consequences of infection4. Here we examine the memory B cell repertoire in a longitudinal cohort of individuals receiving three mRNA vaccine doses5,6. We find that the third dose is accompanied by an increase in, and evolution of, receptor-binding domain (RBD)-specific memory B cells. The increase is due to expansion of memory B cell clones that were present after the second dose as well as the emergence of new clones. The antibodies encoded by these cells showed significantly increased potency and breadth when compared with antibodies obtained after the second dose. Notably, the increase in potency was especially evident among newly developing clones of memory cells, which differed from persisting clones in targeting more conserved regions of the RBD. Overall, more than 50% of the analysed neutralizing antibodies in the memory compartment after the third mRNA vaccine dose neutralized the Omicron variant. Thus, individuals receiving three doses of an mRNA vaccine have a diverse memory B cell repertoire that can respond rapidly and produce antibodies capable of clearing even diversified variants such as Omicron. These data help to explain why a third dose of a vaccine that was not specifically designed to protect against variants is effective against variant-induced serious disease.

Increased Potency and Breadth of SARS-CoV-2 Neutralizing Antibodies After a Third mRNA Vaccine Dose.

The omicron variant of SARS-CoV-2 infected very large numbers of SARS-CoV-2 vaccinated and convalescent individuals 1-3 . The penetrance of this variant in the antigen experienced human population can be explained in part by the relatively low levels of plasma neutralizing activity against Omicron in people who were infected or vaccinated with the original Wuhan-Hu-1 strain 4-7 . The 3 rd mRNA vaccine dose produces an initial increase in circulating anti-Omicron neutralizing antibodies, but titers remain 10-20-fold lower than against Wuhan-Hu-1 and are, in many cases, insufficient to prevent infection 7 . Despite the reduced protection from infection, individuals that received 3 doses of an mRNA vaccine were highly protected from the more serious consequences of infection 8 . Here we examine the memory B cell repertoire in a longitudinal cohort of individuals receiving 3 mRNA vaccine doses 9,10 . We find that the 3 rd dose is accompanied by an increase in, and evolution of, anti-receptor binding domain specific memory B cells. The increase is due to expansion of memory B cell clones that were present after the 2 nd vaccine dose as well as the emergence of new clones. The antibodies encoded by these cells showed significantly increased potency and breadth when compared to antibodies obtained after the 2 nd vaccine dose. Notably, the increase in potency was especially evident among newly developing clones of memory cells that differed from the persisting clones in targeting more conserved regions of the RBD. Overall, more than 50% of the analyzed neutralizing antibodies in the memory compartment obtained from individuals receiving a 3 rd mRNA vaccine dose neutralized Omicron. Thus, individuals receiving 3 doses of an mRNA vaccine encoding Wuhan-Hu-1, have a diverse memory B cell repertoire that can respond rapidly and produce antibodies capable of clearing even diversified variants such as Omicron. These data help explain why a 3 rd dose of an mRNA vaccine that was not specifically designed to protect against variants is effective against variant-induced serious disease.

Short-term outcomes following dehydrated micronized allogenic cartilage versus isolated microfracture for treatment of medial talar osteochondral lesions.

BACKGROUND: Osteochondral lesions of the talus (OLTs) have been traditionally treated with bone marrow stimulation techniques such as microfracture. However, conventional microfracture results in a biomechanically weaker repair tissue of predominantly type I collagen. Acellular micronized cartilage matrix (MCM) serves as a bioactive scaffold to restore hyaline cartilage. The purpose was to compare short-term outcomes after microfracture with and without augmentation with MCM for medial-sided OLTs. METHODS: A retrospective review was performed between 2010-2019 for medial-sided OLTs undergoing treatment with either microfracture augmented with MCM or isolated microfracture. The MCM was hydrated with either bone marrow aspirate concentrate (BMAC) or platelet-rich plasma (PRP). Outcomes included visual analogue scale (VAS) pain scores, Foot and Ankle Activity Measure (FAAM) scores, return-to-daily activities, and return-to-sport. RESULTS: 48 patients (14 MCM with PRP, 6 MCM with BMAC; 28 isolated microfracture) with average age 35.5 years (range: 13.8-67.2 years) and mean follow-up 4.0 ± 3.4 years (range,.13-10.7) were included. There was no difference in average lesion size between MCM and microfracture groups (64.0 ± 49.4 mm2 versus 57.3 ± 44.2 mm2, P = .63) and a trend toward larger lesion size for BMAC compared to PRP (106.5 ± 59.2 versus 45.9 ± 32.1 mm2, P = .056). There was no difference in time to return-to-activity (83.5 ± 18.8 versus 87.3 ± 49.1 days) or return-to-sports (151.9 ± 62.2 versus 165 ± 99.2 days) with MCM versus isolated microfracture. However, the MCM group had a significantly greater improvement in VAS pain score at final follow-up (4.9 ± 2.2 versus 2.7 ± 2.6, P = .0032) and significantly higher post-operative FAAM-Activities of Daily Living subscale scores (97.2 ± 8.2 versus 79.7 ± 32.8, P = .033). CONCLUSIONS: Augmenting microfracture with MCM hydrated with PRP or BMAC may result in beneficial changes in pain scores and activities of daily living, but similar return-to-activities and return-to-sport times compared to microfracture alone in management of medial OLT. LEVEL OF EVIDENCE: IV.

Vibrio cholerae's mysterious Seventh Pandemic island (VSP-II) encodes novel Zur-regulated zinc starvation genes involved in chemotaxis and cell congregation.

Vibrio cholerae is the causative agent of cholera, a notorious diarrheal disease that is typically transmitted via contaminated drinking water. The current pandemic agent, the El Tor biotype, has undergone several genetic changes that include horizontal acquisition of two genomic islands (VSP-I and VSP-II). VSP presence strongly correlates with pandemicity; however, the contribution of these islands to V. cholerae's life cycle, particularly the 26-kb VSP-II, remains poorly understood. VSP-II-encoded genes are not expressed under standard laboratory conditions, suggesting that their induction requires an unknown signal from the host or environment. One signal that bacteria encounter under both host and environmental conditions is metal limitation. While studying V. cholerae's zinc-starvation response in vitro, we noticed that a mutant constitutively expressing zinc starvation genes (Δzur) congregates at the bottom of a culture tube when grown in a nutrient-poor medium. Using transposon mutagenesis, we found that flagellar motility, chemotaxis, and VSP-II encoded genes were required for congregation. The VSP-II genes encode an AraC-like transcriptional activator (VerA) and a methyl-accepting chemotaxis protein (AerB). Using RNA-seq and lacZ transcriptional reporters, we show that VerA is a novel Zur target and an activator of the nearby AerB chemoreceptor. AerB interfaces with the chemotaxis system to drive oxygen-dependent congregation and energy taxis. Importantly, this work suggests a functional link between VSP-II, zinc-starved environments, and energy taxis, yielding insights into the role of VSP-II in a metal-limited host or aquatic reservoir.

Evaluation of Pexion® (imepitoin) for treatment of storm anxiety in dogs: A randomised, double-blind, placebo-controlled trial.

BACKGROUND: While often grouped with other noise aversions, fearful behaviour during storms is considered more complex than noise aversion alone. The objective here was to assess the effect of imepitoin for the treatment of storm anxiety in dogs. METHODS: In this double-blind, placebo-controlled randomised study, eligible dogs completed a baseline then were randomised to receive either imepitoin (n = 30; 30 mg/kg BID) or placebo (n = 15) for 28 days. During storms, owners rated their dog's intensity for 16 behaviours using a Likert scale. Weekly, owners rated intensity and frequency of these behaviours. Summary scores were compared to baseline and between groups. RESULTS AND CONCLUSIONS: Imepitoin was significantly superior to placebo in storm logs and weekly surveys for weeks 2 and 4, and in the end-of-study survey. Mild/moderate adverse events were reported in 26 patients (24 active: two placebo); the most frequent adverse event was ataxia. Owners of dogs in the imepitoin group, compared to placebo, were significantly more likely to report that treatment reduced their dogs fear and anxiety during storms (p < 0.001) and other noise events (p < 0.001). Twice daily administration of imepitoin decreased anxiety scores in dogs with storm anxiety. Future work may evaluate optimal dosage regimens.