Fast, High-Fidelity Addressed Single-Qubit Gates Using Efficient Composite Pulse Sequences.

We use electronic microwave control methods to implement addressed single-qubit gates with high speed and fidelity, for ^{43}Ca^{+} hyperfine "atomic clock" qubits in a cryogenic (100 K) surface trap. For a single qubit, we benchmark an error of 1.5×10^{-6} per Clifford gate (implemented using 600 ns π/2 pulses). For 2 qubits in the same trap zone (ion separation 5 µm), we use a spatial microwave field gradient, combined with an efficient four-pulse scheme, to implement independent addressed gates. Parallel randomized benchmarking on both qubits yields an average error 3.4×10^{-5} per addressed π/2 gate. The scheme scales theoretically to larger numbers of qubits in a single register.

Magneto-hydrodynamics of multi-phase flows in heterogeneous systems with large property gradients.

The complex interplay between thermal, hydrodynamic, and electromagnetic, forces governs the evolution of multi-phase systems in high technology applications, such as advanced manufacturing and fusion power plant operation. In this work, a new formulation of the time dependent magnetic induction equation is fully coupled to a set of conservation laws for multi-phase fluid flow, energy transport and chemical species transport that describes melting and solidification state transitions. A finite-volume discretisation of the resulting system of equations is performed, where a novel projection method is formulated to ensure that the magnetic field remains divergence free. The proposed framework is validated by accurately replicating a Hartmann flow profile. Further validation is performed through correctly predicting the experimentally observed trajectory of Argon bubbles rising in a liquid metal under varying applied magnetic fields. Finally, the applicability of the framework to technologically relevant processes is illustrated through the simulation of an electrical arc welding process between dissimilar metals. The proposed framework addresses an urgent need for numerical methods to understand the evolution of multi-phase systems with large electromagnetic property contrast.

Obesity and surgical complications of pancreaticoduodenectomy: An observation study utilizing ACS NSQIP.

BACKGROUND: An estimated 38% of US adults are obese. Obesity is associated with socioeconomic disparities and increased rates of comorbidities, and is a known risk factor for development of pancreatic cancer. As a fourth leading cause of death in the United States, pancreatic cancer is commonly treated with a pancreatico-duodenectomy (PD), or Whipple procedure. Data regarding the effects of obesity on post-operative complication rate primarily comes from specialized centers, however the results are mixed. Our aim is to elucidate the effects that obesity has on outcomes after PD for pancreatic head cancer using a national prospectively maintained clinical database. METHOD: The 2010-2015 American College of Surgeons National Surgical Quality Improvement Project (ACS NSQIP) Participant Use Files (PUF) were used as the data source. We identified cases in which PD was performed (CPT code 48150) in the setting of a postoperative diagnosis of pancreatic cancer (ICD9 code 157.0). We excluded cases that had emergency admissions, BMI ≤18.5 kg/m2, intraoperative wound classification of III or IV, and disseminated cancer. Cases with missing BMI, preoperative albumin, operative time, LOS data were also excluded. Multiple imputation for missing sex, race, functional status, and ASA classification using chained equations was performed.16 Patients that had BMI ≥30 kg/m2 were considered obese, and patients with BMI <30 kg/m2 were used as control. RESULTS: 3484 patients underwent pancreaticoduodenectomy for pancreatic cancer. 860 patients were identified as obese. Propensity score analysis was performed matching age, sex, race, functional status, presence of dyspnea, diabetes, hypertension, acute renal failure, dialysis dependence, ascites, steroid use, bleeding disorders, history of chronic obstructive pulmonary disease (COPD), congestive heart failure (CHF), weight loss, American Society of Anesthesiologists (ASA) classification, and preoperative albumin levels. After matching, obese patients had higher risk of 30-day postoperative complications compared to control, including organ space wound infections (OR 1.38, 95% CI 1.07-1.79, p = 0.0128), returning to the operating room (OR 1.39, 95% CI 1.01-1.91, p = 0.0461), failure to extubate for greater than 48 h (OR 1.60, 95% CI 1.09-2.34, p = 0.0153), death (OR 1.68, 95% CI 1.01-2.78, p = 0.0453), septic shock (OR 2.22, 95% CI 1.46-3.38, p = 0.0002), pulmonary embolism (OR 2.42, 95% CI 1.07-5.45, p = 0.0332), renal insufficiency (OR 2.67, 95% CI 1.33-5.38, p = 0.0058). Sensitivity analysis yielded similar results with the exception of risk for return to the operating room, death, and pulmonary embolism, P > .05. CONCLUSION: In this large observational study using a national clinical database, obese patients undergoing PD for head of pancreas cancer had increased risk of postoperative complications and mortality in comparison to controls.

Phase-Field Simulation of Grain Boundary Evolution In Microstructures Containing Second-Phase Particles with Heterogeneous Thermal Properties.

Understanding the interaction between complex thermal fields and metallic structures at the meso-scale is crucial for the prediction of microstructural evolution during thermomechanical processing. The competitive growth of crystal grains, driven by thermodynamic forces at the grain boundaries, is one of the most fundamental phenomena in metallurgy and solid state physics. The presence of second phase particles, which act as pinning sites for boundaries, drastically alters the coarsening behaviour of the system; particularly when considering that these particles have different thermal properties to the primary phase. In this work a multi-phase field model, incorporating thermal gradient and curvature driving forces, is used to predict grain growth in a Ti6Al4V alloy system with second phase particle inclusions representative of oxide and carbide precipitates. The multi-phase field framework is fully coupled to the heat equation. The incorporation of the thermal gradient driving force enables the detailed behaviour of the grain boundaries around the particles to be predicted. It is shown that the inclusion of particles with a lower thermal conductivity has a significant influence on the coarsening behaviour of various systems of grains, due to the combined effects of thermal shielding and the generation of thermal gradient driving forces between the boundaries and pinning particles.

Timings for HbA1c testing in people with diabetes are associated with incentive payments: an analysis of UK primary care data.

AIMS: Guidelines recommend testing HbA1c every 3-6 months in people with diabetes. In the United Kingdom (UK), primary care clinics are financially incentivized to monitor HbA1c at least annually and report proportions of patients meeting targets on 31 March. We explored the hypothesis that this reporting deadline may be associated with over-frequent or delayed HbA1c testing. METHODS: This analysis used HbA1c results from 100 000 people with diabetes during 2005-2014 in the Clinical Practice Research Datalink UK primary care database. Logistic regression was used to explore whether the four months prior to the deadline for quality reporting (December to March) or individual's previous HbA1c were aligned with retesting HbA1c within 60 days or > 1 year from the previous test, and identify other factors associated with the timing of HbA1c testing. RESULTS: Retesting HbA1c within 60 days or > 1 year was more common in December to March compared with other months of the year (odds ratio 1.06, 95% confidence interval 1.04-1.08 for retesting within 60 days). Those with higher HbA1c were more likely to have a repeat test within 60 days and less likely to have a repeat test > 1 year from the previous test. CONCLUSIONS: We have found that retesting HbA1c within 60 days and > 1 year from the previous test was more common in December to March compared with the other months of the year. This work suggests that both practice-centred administrative factors and patient-centred considerations may be influencing diabetes care in the UK.

Surgical treatment of chronic ear disease in remote or resource-constrained environments.

BACKGROUND: Surgery for chronic suppurative otitis media performed in low- and middle-income countries creates specific challenges. This paper describes the equipment and a variety of techniques that we find best suited to these conditions. These have been used over many years in remote areas of Nepal. RESULTS AND CONCLUSION: Extensive chronic suppurative otitis media is frequently encountered, with limited pre-operative investigation or treatment possible. Techniques learnt in better-resourced settings with good follow up need to be modified. The paper describes surgical methods suitable for resource-poor conditions, with rationales. These include methods of tympanoplasty for subtotal wet perforations, hearing reconstruction in wet ears and open cavities, large aural polyps, and canal wall down mastoidectomy with cavity obliteration. Various types of autologous ossiculoplasty are described in detail for use in the absence of prostheses. The following topics are discussed: decision-making for surgery on wet or best hearing ears, children, bilateral surgery, working with local anaesthesia, and obtaining adequate consent in this environment.

Rates of hip and knee joint replacement amongst different ethnic groups in England: an analysis of National Joint Registry data.

OBJECTIVE: Despite a health care system that is free at the point of delivery, ethnic minorities may not always get care equitable to that of White patients in England. We examined whether ethnic differences exist in joint replacement rates and surgical practice in England. DESIGN: 373,613 hip and 428,936 knee National Joint Registry (NJR) primary replacement patients had coded ethnicity in Hospital Episode Statistics (HES). Age and gender adjusted observed/expected ratios of hip and knee replacements amongst ethnic groups were compared using indirect standardisation. Associations between ethnic group and type of procedure were explored and effects of demographic, clinical and hospital-related factors examined using multivariable logistic regression. RESULTS: Adjusted standardised observed/expected ratios were substantially lower in Blacks and Asians than Whites for hip replacement (Blacks 0.33 [95% CI, 0.31-0.35], Asians 0.20 [CI, 0.19-0.21]) and knee replacement (Blacks 0.64 [CI, 0.61-0.67], Asians 0.86 % [CI, 0.84-0.88]). Blacks were more likely to receive uncemented hip replacements (Blacks 52%, Whites 37%, Asians 44%; P < 0.001). Black men and women aged <70 years were less likely to receive unicondylar or patellofemoral knee replacements than Whites (men 10% vs 15%, P = 0.001; women 6% vs 14%, P < 0.001). After adjustment for demographic, clinical and hospital-related factors, Blacks were more likely to receive uncemented hip replacement (OR 1.43 [CI, 1.11-1.84]). CONCLUSIONS: In England, hip and knee replacement rates and prosthesis type given differ amongst ethnic groups. Whether these reflect differences in clinical need or differential access to treatment requires urgent investigation.

Evaluation of Errors Associated with Cutting-Induced Plasticity in Residual Stress Measurements Using the Contour Method.

Cutting-induced plasticity can lead to elevated uncertainties in residual stress measurements made by the contour method. In this study plasticity-induced stress errors are numerically evaluated for a benchmark edge-welded beam to understand the underlying mechanism. Welding and cutting are sequentially simulated by finite element models which have been validated by previous experimental results. It is found that a cutting direction normal to the symmetry plane of the residual stress distribution can lead to a substantially asymmetrical back-calculated stress distribution, owing to cutting-induced plasticity. In general, the stresses at sample edges are most susceptible to error, particularly when the sample is restrained during cutting. Inadequate clamping (far from the plane of cut) can lead to highly concentrated plastic deformation in local regions, and consequently the back-calculated stresses have exceptionally high values and gradients at these locations. Furthermore, the overall stress distribution is skewed towards the end-of-cut side. Adequate clamping (close to the plane of cut) minimises errors in back-calculated stress which becomes insensitive to the cutting direction. For minimal constraint (i.e. solely preventing rigid body motion), the plastic deformation is relatively smoothly distributed, and an optimal cutting direction (i.e. cutting from the base material towards the weld region in a direction that falls within the residual stress symmetry plane) is identified by evaluating the magnitude of stress errors. These findings suggest that cutting process information is important for the evaluation of potential plasticity-induced errors in contour method results, and that the cutting direction and clamping strategy can be optimised with an understanding of their effects on plasticity and hence the back-calculated stresses.

Magnetic Nanodrug Delivery Through the Mucus Layer of Air-Liquid Interface Cultured Primary Normal Human Tracheobronchial Epithelial Cells.

Superparamagnetic iron oxide (Fe3O4) and highly anisotropic barium hexaferrite (BaFe12O19) nanoparticles were coated with an anti-inflammatory drug and magnetically transported through mucus produced by primary human airway epithelial cells. Using wet planetary ball milling, dl-2-amino-3-phosphonopropionic acid-coated BaFe12O19 nano-particles (BaNPs) of 1-100 nm in diameter were prepared in water. BaNPs and conventional 20-30-nm Fe3O4 nanoparticles (FeNPs) were then encased in a polymer (PLGA) loaded with dexamethasone (Dex) and tagged for imaging. PLGA-Dex-coated BaNPs and FeNPs were characterized using dynamic light scattering (DLS), transmission electron microscopy (TEM), and superconducting quantum interference device (SQUID) magnetometry. Both PLGA-Dex-coated BaNPs and FeNPs were transferred to the surface of a ~100-µm thick mucus layer of air-liquid interface cultured primary normal human tracheobronchial epithelial (NHTE) cells. Within 30 min, the nanoparticles were pulled successfully through the mucus layer by a permanent neodymium magnet. The penetration time of the nanomedicine was monitored using confocal microscopy and tailored by varying the thickness of the PLGA-Dex coating around the particles.

The influence of cemented femoral stem choice on the incidence of revision for periprosthetic fracture after primary total hip arthroplasty: an analysis of national joint registry data.

AIMS: Periprosthetic fracture (PF) after primary total hip arthroplasty (THA) is an uncommon but potentially devastating complication. This study aims to investigate the influence of cemented stem designs on the risk of needing a revision for a PF. PATIENTS AND METHODS: We analysed data on 257 202 primary THAs with cemented stems and 390 linked first revisions for PF recorded in the National Joint Registry (NJR) of England, Wales and Northern Ireland to determine if a cemented femoral stem brand was associated with the risk of having revision for a PF after primary THA. All cemented femoral stem brands with more than 10 000 primary operations recorded in the NJR were identified. The four most commonly used cemented femoral stems were the Exeter V40 (n = 146 409), CPT (n = 24 300), C-Stem (n = 15 113) and Charnley (n = 20 182). We compared the revision risk ratios due to PF amongst the stems using a Poisson regression model adjusting for patient factors. Compared with the Exeter V40, the age, gender and ASA grade adjusted revision rate ratio was 3.89 for the cemented CPT stem (95% confidence interval (CI) 3.07 to 4.93), 0.89 for the C-Stem (95% CI 0.57 to 1.41) and 0.41 for the Charnley stem (95% CI 0.24 to 0.70). CONCLUSIONS: The limitations of the study include incomplete data capture, analysis of only PF requiring revision and that observation does not imply causality. Nevertheless, this study demonstrates that the choice of a cemented stem may influence the risk of revision for PF. Cite this article: Bone Joint J 2016;98-B:1347-54.

Knowledge, attitudes, beliefs and practices related to chronic suppurative otitis media and hearing impairment in Pokhara, Nepal.

BACKGROUND: Nepal has a high prevalence of chronic suppurative otitis media and hearing impairment. An improved understanding of patients' knowledge, attitudes, beliefs and practices is therefore important for effective healthcare planning and intervention. METHOD: Questionnaires designed to explore their current knowledge, attitudes, beliefs and practices were completed by 153 participants: 71 were affected by a known ear disease and 82 were unaffected. RESULTS: In the unaffected group, 31.7 per cent considered breast milk to be a risk factor for ear infection. Home remedies (e.g. leaf paste, oils, and urine and/or bodily fluids) had been used by 42.3 per cent of the affected group. Most participants (71.9 per cent) believed that society discriminates against those with hearing impairment. CONCLUSION: Knowledge deficits and false beliefs were found in both groups, along with a significant use of home remedies and a perception of discrimination against people with hearing impairment. These findings are relevant for healthcare providers and may aid the development of policy, interventions and public education initiatives.

Practicality of using galvanic skin response to measure intraoperative physiologic autonomic activation in operating room team members.

BACKGROUND: Physiologic and psychological stress are commonly experienced by operating room (OR) personnel, yet there is little research about the stress levels in OR teams and their impact on performance. Previously published procedures to measure physiologic activation are invasive and impractical for the OR. The purpose of this study was to determine the practicality of a new watch-sized device to measure galvanic skin response (GSR) in OR team members during high-fidelity surgical simulations. METHODS: Interprofessional OR teams wore sensors on the wrist (all) and ankle (surgeons and scrub nurses/technicians) during the orientation, case, and debriefing phases for 17 simulations of a surgical airway case. Data were compared across all simulation phases, collectively and for each professional group. RESULTS: Forty anesthesiology residents, 35 surgery residents, 27 OR nurses, 12 surgical technicians, and 7 CRNAs participated. Collectively, mean wrist GSR levels significantly increased from orientation phase to the case (0.40-0.62 µS; P < .001) and remained elevated even after the simulation was over (0.40-0.67 µS; P < .001). Surgery residents were the only group that demonstrated continued increases in wrist GSR levels throughout the entire simulation (change in GSR = 0.21 to 0.32 to 0.11 µS; P < .01). Large intraindividual differences (≤ 200 times) were found in both wrist and ankle GSR. There was no correlation between wrist and ankle data. CONCLUSION: Continuous GSR monitoring of all professionals during OR simulations is feasible, but would be difficult to implement in an actual OR environment. Large variation in individual levels of physiologic activation suggests complementary qualitative research is needed to better understand how people respond to stressful OR situations.

Postinflammatory medial meatal fibrosis: early and late surgical outcomes.

OBJECTIVES: To evaluate the primary and long-term surgical outcomes of patients with postinflammatory medial meatal fibrosis. METHODS: A retrospective study was conducted of 14 ears (in 12 patients) with postinflammatory medial meatal fibrosis managed surgically. Outcome measures were primary (i.e. less than six months) and long-term (i.e. greater than five years) closure of the air-bone gap, and the incidence of otorrhoea and restenosis. RESULTS: At primary review, the mean air-bone gap ± standard deviation had decreased from 29.9 ± 11.6 dB to 12 ± 8.4 dB (p < 0.0006). Seven (50 per cent) ears had closure of the air-bone gap to within 10 dB. However, for the 9 ears receiving long-term review, the mean air-bone gap ± standard deviation increased to 19.3 ± 15.2 dB; there was no significant difference between this result and pre-operative values (p = 0.06). Of the 9 long-term review ears, 3 (33 per cent) showed closure of the air-bone gap to within 10 dB. Recurrent otorrhoea was the most common complication, occurring in 5 of the 9 long-term review ears (56 per cent); in addition, 3 (33 per cent) of these 9 ears developed restenosis. CONCLUSION: Over time, the success of surgery for postinflammatory medial meatal fibrosis diminishes. This was demonstrated in the present study by progressive post-operative hearing decline and a high prevalence of otorrhoea and restenosis.

Discovery and characterization of LY2784544, a small-molecule tyrosine kinase inhibitor of JAK2V617F.

Owing to the prevalence of the JAK2V617F mutation in myeloproliferative neoplasms (MPNs), its constitutive activity, and ability to recapitulate the MPN phenotype in mouse models, JAK2V617F kinase is an attractive therapeutic target. We report the discovery and initial characterization of the orally bioavailable imidazopyridazine, LY2784544, a potent, selective and ATP-competitive inhibitor of janus kinase 2 (JAK2) tyrosine kinase. LY2784544 was discovered and characterized using a JAK2-inhibition screening assay in tandem with biochemical and cell-based assays. LY2784544 in vitro selectivity for JAK2 was found to be equal or superior to known JAK2 inhibitors. Further studies showed that LY2784544 effectively inhibited JAK2V617F-driven signaling and cell proliferation in Ba/F3 cells (IC50=20 and 55 nM, respectively). In comparison, LY2784544 was much less potent at inhibiting interleukin-3-stimulated wild-type JAK2-mediated signaling and cell proliferation (IC50=1183 and 1309 nM, respectively). In vivo, LY2784544 effectively inhibited STAT5 phosphorylation in Ba/F3-JAK2V617F-GFP (green fluorescent protein) ascitic tumor cells (TED50=12.7 mg/kg) and significantly reduced (P<0.05) Ba/F3-JAK2V617F-GFP tumor burden in the JAK2V617F-induced MPN model (TED50=13.7 mg/kg, twice daily). In contrast, LY2784544 showed no effect on erythroid progenitors, reticulocytes or platelets. These data suggest that LY2784544 has potential for development as a targeted agent against JAK2V617F and may have properties that allow suppression of JAK2V617F-induced MPN pathogenesis while minimizing effects on hematopoietic progenitor cells.

Severe glottic stenosis in a parturient with ectodermal dysplasia.

Airway stenosis in pregnancy is challenging and the literature does not offer consensus regarding its evaluation and anesthetic management. A 21-year-old nulliparous woman with ectodermal dysplasia and severe glottic stenosis was referred to the obstetric anesthesia team for evaluation and peripartum management recommendations. She had a history of a congenital complete glottic web that required a tracheostomy at birth. After decannulation at age four, she was lost to follow-up. On examination in early pregnancy, she was found to have a dangerously narrow airway with fixed vocal cords and a glottic aperture of 2-3mm. At nine weeks of gestation an elective tracheostomy was performed under local anesthesia. She later underwent an uneventful cesarean delivery under spinal anesthesia. Ultimately, early interdisciplinary planning for an elective tracheostomy helped assure patient safety during advancing pregnancy and delivery.

Patterns of alcohol use and multiple risk behaviour by gender during early and late adolescence: the ALSPAC cohort.

BACKGROUND: Adolescent risk behaviours such as smoking, alcohol use and antisocial behaviour are associated with increased risk of morbidity and mortality. Patterns of risk behaviour may vary between genders during adolescence. METHODS: Analysis of data from a longitudinal birth cohort to assess the prevalence and distribution of multiple risk behaviours by gender at age 15-16 years with a focus on alcohol use at age 10, 13 and 15 years. RESULTS: By age 15 years, over half of boys and girls had consumed alcohol and one-fifth had engaged in binge drinking with no clear difference by gender. At age 15-16 years, the most prevalent risk behaviours were physical inactivity (74%), antisocial and criminal behaviour (42%) and hazardous drinking (34%). Boys and girls engaged in a similar number of behaviours but antisocial and criminal behaviours, cannabis use and vehicle-related risk behaviours were more prevalent among boys, whilst tobacco smoking, self-harm and physical inactivity were more prevalent among girls. CONCLUSION: Multiple risk behaviour is prevalent in both genders during adolescence but the pattern of individual risk behaviour varies between boys and girls. Effective interventions at the individual, family, school, community or population level are needed to address gender-specific patterns of risk behaviour during adolescence.

Biodegradability of injection molded bioplastic pots containing polylactic acid and poultry feather fiber.

The biodegradability of three types of bioplastic pots was evaluated by measuring carbon dioxide produced from lab-scale compost reactors containing mixtures of pot fragments and compost inoculum held at 58 °C for 60 days. Biodegradability of pot type A (composed of 100% polylactic acid (PLA)) was very low (13 ± 3%) compared to literature values for other PLA materials. Near infrared spectroscopy (NIRS) results suggest that the PLA undergoes chemical structural changes during polymer extrusion and injection molding. These changes may be the basis of the low biodegradability value. Biodegradability of pot types B (containing 5% poultry feather, 80% PLA, 15% starch), and C (containing 50% poultry feather, 25% urea, 25% glycerol), were 53 ± 2% and 39 ± 3%, respectively. More than 85% of the total biodegradation of these bioplastics occurred within 38 days. NIRS results revealed that poultry feather was not degraded during composting.

Chronic suppurative otitis media in Nepal: ethnicity does not determine whether disease is associated with cholesteatoma or not.

OBJECTIVES: To determine the frequency of cholesteatoma in a population of patients with chronic suppurative otitis media, and to determine whether this frequency is affected by ethnicity. PATIENTS: The study included 6005 patients with chronic suppurative otitis media seen during the course of 30 charitable surgical 'ear camps' in Nepal. MAIN OUTCOME MEASURES: Proportion of patients with each subtype of disease, and their ethnicity. A secondary outcome measure was concordance of surname with Nepalese ethnic affiliation. RESULTS: A total of 762 patients were grouped as being of Tibeto-Mongolian origin, and 4875 as Indo-Caucasian. The rate of chronic suppurative otitis media with cholesteatoma, expressed as a proportion of the rate of all chronic suppurative otitis media subtypes, was 17.8 per cent in Tibeto-Mongolian patients and 18.6 per cent in Indo-Caucasian patients (p > 0.05). The effect of other risk factors (i.e. age, gender and geographical district) on disease distribution was also non-significant. Analysis of secondary outcome measures indicated that patients' surnames were a reliable predictor of ethnicity in this Nepalese population. CONCLUSION: There is almost complete concordance in proportions of patients with significant genetic, cultural, and even geographical heterogeneity, suggesting that, in Nepal, the aetiology of cholesteatoma owes little to these factors.

Contributions of conventional and heavy-chain IgG to immunity in fetal, neonatal, and adult alpacas.

In addition to conventional immunoglobulins, camelids produce antibodies that do not incorporate light chains into their structures. These so-called heavy-chain (HC) antibodies have incited great interest in the biomedical community, as they have considerable potential for biotechnological and therapeutic application. Recently, we have begun to elucidate the immunological functions of HC antibodies, yet little is known about their significance in maternal immunity or about the B lymphocytes that produce them. This study describes the application of isotype-specific reagents toward physiological assessments of camelid IgGs and the B cells that produce them. We document the specificities of monoclonal antibodies that distinguish two conventional IgG1 isotypes and two HC IgG3 variants produced by alpacas. Next, we report that the relative concentrations of five isotypes are similar in serum, milk, and colostrum; however, following passive transfer, the concentrations of HC IgG2 and IgG3 declined more rapidly than the concentration of conventional IgG1 in the sera of neonates. Finally, we assessed the distribution of B cells of distinct isotypes within lymphoid tissues during fetal and adult life. We detected IgG1, IgG2, and IgG3 in lymphocytes located in lymph node follicles, suggesting that HC B cells affinity mature and/or class switch. One IgG3 isotype was present in B cells located in ileal Peyer's patches, and one conventional IgG1 isotype was detected in splenic marginal zone B cells. Our findings contribute to the growing body of knowledge pertaining to HC antibodies and are compatible with functional specialization among conventional and HC IgGs in the alpaca.