Clinical Outcomes and Immunotoxicity in People with HIV (PWH) after Definitive Chemoradiation (CRT) for Anal Squamous Cell Carcinoma

PURPOSE/OBJECTIVE(S)

Anal cancer disproportionately affects PWH despite antiretroviral therapy. Data on CRT outcomes are limited. Modern IMRT CRT decreases acute toxicity but may exacerbate immune dysregulation from chronic HIV. Although historical CRT has been associated with prolonged CD4 count suppression, little is known about late immunotoxicity in PWH after contemporary CRT. We report clinical outcomes and long term immunotoxicity.

MATERIALS/METHODS

Single-center retrospective review of all PWH confirmed on chart review with anal squamous cell carcinoma without prior pelvic irradiation treated with definitive IMRT CRT. Patient and CRT factors including HIV suppression (<200 copies/mL), mean CD4 count (cells/µL), and receipt of capecitabine (C) or 5-fluorouracil (F) +/- mitomycin (M) were summarized with n (%) or median (interquartile range). Progression-free and overall survival (PFS; OS) were estimated per Kaplan-Meier with 95% confidence intervals and compared with log-rank tests. Mean CD4 count and CD4:CD8 were compared by HIV suppression status (Welch's t-test); longitudinal changes in median CD4 count and CD4:CD8 were compared between baseline vs. nadir (within 6 months of CRT start) and 1-year follow-up for patients with complete data (Wilcoxon signed-rank test).

RESULTS

A total of 23 PWH were treated between 2010-2022, median age 52, median 16 (13 - 19) years after HIV diagnosis; 4 had unsuppressed HIV; AJCC 8th stage I/II/III/IV 5/5/12/1. Radiation dose was median 54 Gy in 30 fractions over 42 (40 - 44) days. Most had C+M (57%); only 43% had 2×M with either C or F. One had neoadjuvant carboplatin/paclitaxel/pembrolizumab. With 2.9 (1.03 - 3.3) years follow-up, median OS was 6.6 (6.2 - unreached [UR]) years. With 2.2 (0.67 - 2.7) years follow-up, median PFS was UR. OS and PFS were similar regardless of HIV suppression status (both P ≥ 0.09). Overall baseline CD4 count was 458 (226 - 484), and CD4:CD8 was 0.54 (0.2 - 0.7). Nadir CD4 was 100 (59 - 126) and CD4:CD8 was 0.3 (0.2 - 0.4). Baseline and nadir CD4 count and CD4:CD8 were lower if HIV-unsuppressed (each P ≤ 0.04). One year after CRT, CD4 count was 252 (102 - 276), while CD4:CD8 was 0.5 (0.2 - 0.7). For 7 patients with repeated values the change in median from baseline to nadir, 6-, and 12-months post-CRT was -282, -549 (both P = 0.02), -480 (P = 0.9) for CD4 counts, and -0.7, -0.5, -0.4 (each P > 0.5) for CD4:CD8 ratios; none had unsuppressed HIV.

CONCLUSION

Definitive IMRT CRT with guideline-concordant doublet chemotherapy for anal cancer in PWH is effective despite unsuppressed HIV. Treatment leads to prolonged immunological changes that may increase the risk of HIV-related morbidity and mortality. Modifiable treatment-related causes of hematoimmunologic toxicity should be investigated further, and immune surveillance after CRT should be considered to better understand impact on quality of life.

Use of a Mylar filter to eliminate vacuum ultraviolet pulse pileup in low-energy x-ray measurements

We describe a method to reduce vacuum ultraviolet (VUV) pulse pileup (PPU) in x-ray pulse-height Silicon Drift Detector (SDD) signals. An Amptek FAST SDD, with C1 (Si₃N₄) window, measures bremsstrahlung emitted from PFRC-2 plasma to extract the electron temperature (T_e) and density (n_e). The C1 window has low transmissivity for photons with energy below 200 eV though will transmit some VUV and soft x-ray photons, which PFRC-2 plasmas abundantly emit. Multi-VUV-photon PPU contaminates the interpretation of x rays with energy > 100 eV, particularly in a low-energy exponential tail. The predicted low transmissivity of ∼1 μm thick Mylar [polyethylene terephthalate (PET)] to photons of energy <100 eV led to the selection of Mylar as the candidate filter to reduce VUV PPU. Experiments were conducted on an x-ray tube with a graphite target and on a quasi-Maxwellian tenuous plasma (n_e ∼ 10⁹ cm^-3) with effective temperatures reaching 1500 eV. A Mylar filter thickness of 850 nm is consistent with the results. The Mylar-filter-equipped SDD was then used on the PFRC-2 plasma, showing a substantial reduction in the low-energy x-ray signal, supporting our hypothesis of the importance of VUV PPU. We describe the modeling and experiments performed to characterize the effect of the Mylar filter on SDD measurements.

A diagnostic to measure neutral-atom density in fusion-research plasmas

A femtosecond two-photon-absorption laser-induced-fluorescence (TALIF) diagnostic was designed, installed, and operated on the Princeton-Field-Reversed Configuration-2 device to provide non-invasive measurements of the time and spatially resolved neutral-atom densities in its plasmas. Calibration of the H^o density was accomplished by comparison with Kr TALIF. Measurements on plasmas formed of either H₂ or Kr fill gases allowed examination of nominally long and short ionization mean-free-path regimes. With multi-kW plasma heating and H₂ fill gas, a spatially uniform H^o density of order 10¹⁷ m^-3 was measured with better than ±2 mm and 10 µs resolution. Under similar plasma conditions but with Kr fill gas, a 3-fold decrease in the in-plasma Kr density was observed.

Evaluation of a collisional radiative model for electron temperature determination in hydrogen plasma

A collisional-radiative (CR) model that extracts the electron temperature, T_e, of hydrogen plasmas from Balmer-line-ratio measurements is examined for the plasma electron density, n_e, and T_e ranges of 10¹⁰-10¹⁵ cm^-3 and 5-500 eV, respectively. The CR code, developed and implemented in Python, has a forward component that computes the densities of excited states up to n = 15 as functions of T_e, n_e, and the molecular-to-atomic neutral ratio r(H₂/H). The backward component provides n_e and r(H₂/H) as functions of the Balmer ratios to predict the T_e. The model assumes Maxwellian electrons. The density profiles of the electrons and of the molecular and atomic hydrogen neutrals are shown to be of great importance, as is the accuracy of the line-ratio measurement method.

Simulating single-particle dynamics in magnetized plasmas: The RMF code

The RMF (Rotating Magnetic Field) code is designed to calculate the motion of a charged particle in a given electromagnetic field. It integrates Hamilton's equations in cylindrical coordinates using an adaptive predictor-corrector double-precision variable-coefficient ordinary differential equation solver for speed and accuracy. RMF has multiple capabilities for the field. Particle motion is initialized by specifying the position and velocity vectors. The six-dimensional state vector and derived quantities are saved as functions of time. A post-processing graphics code, XDRAW, is used on the stored output to plot up to 12 windows of any two quantities using different colors to denote successive time intervals. Multiple cases of RMF may be run in parallel and perform data mining on the results. Recent features are a synthetic diagnostic for simulating the observations of charge-exchange-neutral energy distributions and RF grids to explore a Fermi acceleration parallel to static magnetic fields.

The Association between Physical Activity and Metabolic Syndrome in Older Adults with Obesity

BACKGROUND

Physical activity reduces the likelihood of developing metabolic syndrome (MetS). However, the association between different physical activity levels and MetS remains unclear in older adults with obesity.

METHODS

This cross-sectional study used four waves of data (2007-2008, 2009-2010, 2011-2012, 2013-2014) from two datasets: The National Health and Nutrition Examination Survey and United Sates Department of Agriculture's Food Patterns Equivalents Database. The sample included adults 60+ years of age (n= 613) with obesity who had physical activity and MetS data. Physical activity was assessed using the Global Physical Activity Questionnaire and categorized into three physical activity levels (low, medium, and high); and medium or high physical activity levels are aligned with or exceed current physical activity recommendations. Participants were classified as having MetS using a commonly agreed upon definition. Multiple logistic regression models examined the association between the three physical activity levels and MetS risk factors and MetS. All analyses adjusted for potential confounding variables and accounted for complex sampling.

RESULTS

Of 613 respondents, 72.1% (n=431) were classified as having MetS, and 44.3% (n = 263) had not met physical activity recommendations. Participants with high levels of physical activity had a lower risk of MetS (OR = 0.31, 95%CI: 0.13, 0.72) and more healthful levels of high-density lipoprotein cholesterol (OR = 0.39, 95%CI: 0.18, 0.84), blood pressure (OR = 0.39, 95%CI: 0.20, 0.77), fasting glucose (OR = 0.34, 95%CI: 0.15, 0.78) than participants categorized as having low physical activity.

CONCLUSIONS

Physical activity is associated with lower risk of MetS only for participants with the highest level of physical activity, which suggests that physical activity dosage is important to reduce MetS risk in older adults with obesity.

Relationship between Diet Quality, Physical Activity and Health-Related Quality of Life in Older Adults: Findings from 2007-2014 National Health and Nutrition Examination Survey

BACKGROUND

A growing body of research shows that diet quality and physical activity (PA) are associated with health-related quality of life (HRQOL). However, no study to date has assessed this association using the Healthy Eating Index-2015 as a measure of diet quality. Furthermore, few studies have examined the association between PA dose and HRQOL among a nationally representative sample of older adults.

OBJECTIVES

To investigate the relationship between diet quality, physical activity, and HRQOL.

DESIGN

A cross-sectional analysis was conducted using data obtained from 5,311 adults aged 60+ years who took part in the National Health and Nutrition Examination Survey between 2007 and 2014.

MEASUREMENTS

HRQOL was assessed by general health status, and number of physically unhealthy days, mentally unhealthy days, and inactive days in past 30 days. Diet quality was assessed by the Healthy Eating Index-2015 using data generated by two 24-hour dietary recalls. PA was measured by the Global Physical Activity Questionnaire. Multivariate logistic/or linear regression models were used to examine the association between diet quality, PA and HRQOL controlling for confounders and accounting for complex sampling.

RESULTS

Approximately half of the participants (55.2%) were women, 45.1% met current PA recommendations, 65% had less healthful diets according to the Healthy Eating Index-2015. Diet quality was associated with HROQL. For every 1-point diet quality score increase, the likelihood of respondents rating their general health as being excellent/good increased by 3% (OR=1.03, 95%CI: 1.02, 1.04), and number of inactive days (β =-0.03, 95%CI: -0.05, 0.00) and mental unhealthy days (β =-0.03, 95%CI: -0.05, -0.01) declined by 0.03 days. PA was associated with all HROQL measures and respondents with high PA levels reported better general health (OR=3.53, 95%CI: 2.69, 4.63), fewer inactive days (β =-1.53, 95%CI: -2.11, -0.95), fewer physical unhealthy days (β =-1.88, 95%CI: -2.74, -1.02) than individuals with low PA levels but not fewer mentally unhealthy days.

CONCLUSIONS

Among older adults in this study, eating a healthier diet and being physically active were associated with better general health and reporting fewer physical unhealthy days and inactive days. Study results provide valuable information that could inform policies, programs and interventions designed to improve HRQOL in older adults and reduce potentially preventable health disparities.

Incidence and outcomes of bloodstream infections among hematopoietic cell transplant recipients from species commonly reported to be in over-the-counter probiotic formulations

BACKGROUND

Probiotic supplementation has been promoted for numerous health conditions; however, safety in immunosuppressed patients is unknown. We evaluated bloodstream infections (BSIs) caused by common probiotic organisms in hematopoietic cell transplant recipients.

METHODS

All blood culture (BC) results from a cohort of hematopoietic cell transplant recipients transplanted at Fred Hutchinson Cancer Research Center in Seattle, Washington, between 2002 and 2011 were reviewed. Patients with at least 1 positive BC for common probiotic organisms (Lactobacillus species, Bifidobacterium species, Streptococcus thermophilus, and Saccharomyces species) within 1 year post hematopoietic cell transplantation (HCT) were considered cases. Data were collected from center databases, which contain archived laboratory data, patient demographics, and clinical summaries.

RESULTS

A total of 19/3796 (0.5%) patients developed a BSI from one of these organisms within 1 year post HCT; no Bifidobacterium species or S. thermophilus were identified. Cases had a median age of 49 years (interquartile range [IQR]: 39-53), and the majority were allogeneic hematopoietic cell transplant recipients (14/19, 74%). Most positive BCs were Lactobacillus species (18/19) and occurred at a median of 84 days (IQR: 34-127) post transplant. The incidence rate of Lactobacillus bacteremia was 1.62 cases per 100,000 patient-days; the highest rate occurred within 100 days post transplant (3.3 per 100,000 patient-days). Eight patients (44%) were diagnosed with acute graft-versus-host disease of the gut prior to the development of bacteremia. No mortality was attributable to any of these infections.

CONCLUSION

Organisms frequently incorporated in available over-the-counter probiotics are infrequent causes of bacteremia after HCT. Studies evaluating the use of probiotics among high-risk patients are needed.

A New Vision for Fusion Energy Research: Fusion Rocket Engines for Planetary Defense

We argue that it is essential for the fusion energy program to identify an imagination-capturing critical mission by developing a unique product which could command the marketplace. We lay out the logic that this product is a fusion rocket engine, to enable a rapid response capable of deflecting an incoming comet, to prevent its impact on the planet Earth, in defense of our population, infrastructure, and civilization. As a side benefit, deep space solar system exploration, with greater speed and orders-of-magnitude greater payload mass would also be possible.

Examining trends in the treatment of ureterocele yields no definitive solution

INTRODUCTION

The surgical management of ureteroceles is extremely variable. Some have hypothesized that if these patients were treated with 'definitive' staged surgical intervention, the need for further revision surgery would be eliminated.

OBJECTIVE

The present study sought to determine if the rate of revision surgery differed among patients who have undergone different surgical approaches for the ureterocele complex.

STUDY DESIGN

A large retrospective chart review was conducted, identifying all patients having undergone ureterocele surgery at a single institution over the past 41 years. The cohort was divided into four groups based on surgical approach: upper tract approach (UTA), lower tract reconstruction (LTR), simultaneous upper and lower tract approach (ULTA), and staged lower tract reconstruction (SLTR). Demographics, the presence of preoperative/postoperative VUR, postoperative morbidity and the need for revision surgery were compared using the Chi- squared test, Fisher's exact test, Kruskal-Wallis test, Mann-Whitney U test (Bonferroni correction), logistic regression modeling and survival analyses (Kaplan-Meier and Cox proportional Hazards regression with unplanned revision operation as the outcome event).

RESULTS

Between 1969 and 2010, 180 patients were identified as having undergone surgical management of ureteroceles, of which 120 had complete demographic data available for analysis. The median age at the time of initial surgical intervention was 5.8 months and the majority of patients (83.3%) were female. The median follow-up was 33.1 months. Surgical management was as follows: 18 (15.0%) patients underwent UTA, 47 (39.2%) underwent LTR, 23 (19.2%) underwent ULTA, and 32 (26.6%) underwent SLTR. Among these groups, the only difference in median age was between the LTR and SLTR groups (6.3 months vs 3.7 months, P=0.012). Additional revision surgery was required in: nine (50.0%) of UTA, ten (21.3%) of LTR, four (17.4%) of ULTA, and three (9.4%) of SLTR. The only statistically significant difference in unplanned revision surgery was noted in the UTA group versus each of the other groups with VUR as the predominant indication (88.9%). The likelihood of requiring revision surgery in comparison to the SLTR group was significantly increased in the UTA group (OR 9.67, CI 2.15-43.56), but not in the LTR (OR 2.61, CI 0.66-10.37) or the ULTA group (OR 2.04, CI 0.41-10.13). Obstruction, recurring UTIs and VUR were the main indications for revision surgery overall.

DISCUSSION

There is a large body of literature examining the surgical management of ureteroceles. It most recently primarily focuses on an endoscopic approach to the lower tract. The present retrospective review examined the need for re-operative intervention by comparing four different surgical approaches, and found that there is no panacea. Although heminephrectomy (UTA) was a definitive procedure in some patients without reflux at presentation, many who underwent heminephrectomy, went on to require later bladder surgery for either recurrent UTI or persistent reflux. The present study has multiple limitations. Although VUR was an indication for revision surgery in the early part of the series, the current treatment of VUR is not necessarily as stringent. In addition, no distinction was made between an orthotopic or ectopic ureterocele, although some authors have reported differing outcomes in these two groups. However, it is felt that given the large data set of a relatively uncommon condition, the lack of superiority of one approach is apparent.

CONCLUSION

There is no definitive surgical repair for the ureterocele complex. All groups except UTA had statistically similar rates of revision surgery. The widespread variability in current management echoes the lack of one superior approach found in this comprehensive series.

Characterization of Thin Dielectric Films as Copper Diffusion Barriers Using Triangular Voltage Sweep

As technology progresses, the need for thinner Cu diffusion barrier caps is becoming more important, and it is advantageous if these barriers have low dielectric constants (κ). Towards this end, we characterized Cu penetration in several thin (35 nm to 70 nm) dielectrics, including silicon nitrides, silicon oxynitrides, an amorphous hydrogenated carbon film, and a methyl silsesquioxane layer. Metal Insulator Silicon (MIS) structures were used as the test vehicle. The barrier dielectrics were deposited on 100 nm thermal oxide which was grown on 2 Ω-cm, n-type Si wafers. After the deposition of 50 nm TEOS capping layers, both Al and Cu dots were evaporated on each wafer through a mask. Both Al and Cu dot samples were stressed at +2.7 MV/cm at 300°C for 10 minutes. For Cu dots, the applied stress pushed Cu ions into the dielectric stack. Stressing Al dots characterized the effects of the stress on the dielectric stacks and the quantity of Na ions in the films. Since C-V shifts are subject to stress-related instabilities in the interfaces as well as within the dielectrics themselves, triangular voltage sweep (TVS) was used after the applied stress to measure the concentration of Cu which reached the underlying thermal oxide film. The sensitivity of the TVS test with the structures used is about 5×109/cm2. Secondary ion mass spectroscopy (SIMS) analyses were performed on some of these samples to verify the electrical results.

Formation of field-reversed-configuration plasma with punctuated-betatron-orbit electrons

We describe ab initio, self-consistent, 3D, fully electromagnetic numerical simulations of current drive and field-reversed-configuration plasma formation by odd-parity rotating magnetic fields (RMF{o}). Magnetic-separatrix formation and field reversal are attained from an initial mirror configuration. A population of punctuated-betatron-orbit electrons, generated by the RMF{o}, carries the majority of the field-normal azimuthal electrical current responsible for field reversal. Appreciable current and plasma pressure exist outside the magnetic separatrix whose shape is modulated by the RMF{o} phase. The predicted plasma density and electron energy distribution compare favorably with RMF{o} experiments.

Formation of collisionless high-beta plasmas by odd-parity rotating magnetic fields

Odd-parity rotating magnetic fields (RMFo) applied to mirror-configuration plasmas have produced average electron energies exceeding 200 eV at line-averaged electron densities of approximately 10(12) cm-3. These plasmas, sustained for over 10(3)tauAlfven, have low Coulomb collisionality, vc* triple bond L/lambdaC approximately 10(-3), where lambdaC is the Coulomb scattering mean free path and L is the plasma's characteristic half length. Divertors allow reduction of the electron-neutral collision frequency to values where the RMFo coupling indicates full penetration of the RMFo to the major axis.

Reduction of murine osteosarcoma lung metastases using the dipeptidyl peptidase inhibitor talabostat

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Background: Dipeptidyl peptidases comprise a family of serine proteases that includes the genes dipeptidyl peptidase IV (DPP-IV) and fibroblast activation protein (FAP). FAP is expressed in stromal fibroblasts that surround sites of metastatic carcinomas, but not in the tumor cells themselves. Talabostat (valine-proline-boronic acid) is a potent and long-acting inhibitor of dipeptidyl peptidases. It has previously been shown to have anti-tumor activity in preclinical studies. We utilized this compound to determine whether inhibition of dipeptidyl peptidases leads to a decrease in lung metastases using a murine model of osteosarcoma metastasis. Methods: 1×106 K7M3-luciferase murine osteosarcoma cells were injected by tail vein into female Balb/C mice. Mice were then treated by gavage with talabostat (20 ug/dose) twice daily, talabostat once daily, or normal saline twice daily, 5 days on and 2 days off. Half of the mice were analyzed once a week using luminescent imaging. All animals were euthanized on day 24 and the number of lung metastases counted. Results: For the control mice, the average number of surface lung nodules was 75.6 (SD 45.4). Mice treated with talabostat had a ten-fold reduction in the number of nodules (twice daily - average 7.0, SD 6.1, p-value <0.01, once daily - average 3.4, SD 2.4, p-value <0.01). The number of resulting metastatic nodules correlated with luminescent intensity. Conclusions: Mice treated with the dipeptidyl peptidase inhibitor, talabostat, had a ten-fold decrease in the number of visible metastatic lung nodules. Experiments to elucidate the mechanism that links treatment with talabostat and inhibition of metastases are currently being performed.

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Onset and saturation of ion heating by odd-parity rotating magnetic fields in a field-reversed configuration

Heating of figure-8 orbit ions by odd-parity rotating magnetic fields (RMF(O)) applied to an elongated field-reversed configuration (FRC) is investigated. The largest energy gain occurs at resonances (s congruent to omega(R)/omega) of the RMF(O) frequency, omega(R), with the figure-8 orbital frequency, omega, and is proportional to s2 for s-even resonances and to s for s-odd resonances. The threshold for the transition from regular to stochastic orbits explains both the onset and saturation of heating. The FRC magnetic geometry lowers the threshold for heating below that in the tokamak by an order of magnitude.

A prospective assessment of mortality in chronic spinal cord injury

STUDY DESIGN

Prospective mortality study.

OBJECTIVE

To assess the relationship between comorbid medical conditions and other health-related factors to mortality in chronic spinal cord injury (SCI).

SETTING

Boston, MA, USA.

METHODS

Between 1994 and 2000, 361 males >/=1 year after injury completed a respiratory health questionnaire and underwent pulmonary function testing. Cause-specific mortality was assessed over a median of 55.6 months (range 0.33-74.4 months) through 12/31/2000 using the National Death Index.

RESULTS

At entry, mean (+/-SD) age was 50.6+/-15.0 years (range 23-87) and years since injury was 17.5+/-12.8 years (range 1.0-56.5). Mortality was elevated (observed/expected deaths=37/25.1; SMR=1.47; 95% CI=1.04-2.03) compared to US rates. Risk factors for death were diabetes (RR=2.62; 95% CI=1.19-5.77), heart disease (RR=3.66; 95% CI=1.77-7.78), reduced pulmonary function, and smoking. The most common underlying and contributing causes of death were diseases of the circulatory system (ICD-9 390-459) in 40%, and of the respiratory system in 24% (ICD-9 460-519).

CONCLUSIONS

These results suggest that much of the excess mortality in chronic SCI is related to potentially treatable factors. Recognition and treatment of cardiovascular disease, diabetes, and lung disease, together with smoking cessation may substantially reduce mortality in chronic SCI.

Benign metastasizing leiomyoma

Benign metastasizing leiomyoma is a rare clinical entity that has been described in several previous reports. Although the exact pathophysiology of the disease is unknown, two predominant theories exist: (1) metastasis from an existing leiomyoma (commonly seen with uterine leiomyoma) or (2) multicentric leiomyomatous growths rather than actual metastases. We present an interesting case in which several elements of the patient's history complicated the differential diagnosis.

Epithelioid hemangioendothelioma of the maxilla: case report and review of literature

Epithelioid Hemangioendothelioma (EH) is a rare, low-grade malignant vascular tumor, first defined as a soft tissue tumor by Enzinger and Weiss in 1982. The tumor was later reported in virtually all sites, including liver, lung, brain, and bone. The epithelioid neoplastic cells are of endothelial origin, staining positive for Factor VIII and CD-34. In our review of EH of bone medline literature, and including the present case report, a total of 73 cases were found. Forty-one (56%) patients had multifocal bone involvement and thirty-two (44%) patients had solitary EH of bone. Resection was the primary recommended treatment. Visceral involvement appears to affect prognosis and survival adversely. We report a case of EH of the maxilla, which occurred in a 32-year-old male.

Homogeneous preparation of fluorescent-derivatized insulin and its application to competitive chromatographic immunoassays

A homogeneously labeled insulin sample was prepared using 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) as the fluorescent-labeling reagent, and this was successfully applied to a chromatographic immunoassay. This labeled insulin was prepared by tagging all the three amino groups with AQC. Both CE and chromatographic immunoassay experiments indicated that the prepared insulin still kept its immunoaffinity to its antibody. It was observed that appropriate concentrations of acetonitrile (ACN) were efficient in lowering the quenching of the fluorescent signal of tagged insulin, in keeping the dilute, tagged insulin in solution, and in improving its peak shape during a chromatographic immunoassay. The tagged insulin was found to be 20-400 times more sensitive than native insulin detected under ultraviolet detection conditions. A competitive chromatographic immunoassay system was set up and calibrated. The system was used for analyses of an insulin-spiked urine sample, with a 96% recovery obtained.