"Us big boys gotta find a way that works": A qualitative study of casual sexual experiences among larger-bodied, White and Latino sexual minority men

Compared to their heterosexual counterparts, sexual minority men (SMM) are more likely to report that their own body image negatively impacts their sex lives, are more vulnerable to weight stigma, and more frequently experience size-based discrimination. Additionally, in comparison to heterosexual men, SMM report higher levels of anti-fat bias, both directed at themselves and intimate partners. Given this literature, we qualitatively examined how nine larger-bodied SMM (Mage = 37.89, SD = 12.42) experience and navigate weight stigma when seeking out casual sex. Our analytic process revealed four primary themes: Building a Gate, Letting Partners Past the Gate, Joy Inside the Gate, and When the Gate Fails. The gate refers to the protection that participants employed to avoid negative, unsafe, or fatphobic sexual encounters. Participants shared that they were aware of weight stigma within their own community, and many assumed (or were explicitly told) that their bodies were undesirable to potential partners. Further, participants readily delineated between fat attraction and fat fetishization, whereby the latter was universally framed as negative and degrading. These findings highlight the complex experience of engaging in casual sex for larger-bodied SMM and identify strategies these men use to protect themselves from body shame and weight stigma.

"I felt so powerful to have this love in me": A grounded theory analysis of the experiences of people living with and recovering from eating disorders while in diverse romantic relationships

Romantic partners have the potential to influence attitudes and behaviors related to body image and disordered eating. However, the role that romantic relationships can play in eating disorder (ED) recovery has not been comprehensively investigated. The present study aimed to explore the ways that people living with and recovering from EDs experience their romantic relationships, with the specific objective of developing a novel theoretical framework, grounded in the experiences of people in diverse romantic relationships, to guide future research on the topic. Semi-structured individual interviews were conducted with 66 people (45 cisgender women, 11 cisgender men, 9 nonbinary people, and 1 transgender man) living with and recovering from EDs while in romantic relationships. Our grounded theory analysis yielded a theoretical model of ED management in romantic relationships, revealing that Individual and Relationship Characteristics intersected with Relationship-Related Stressors and were navigated using Eating Disorder and Relationship Management Strategies. Combined with Partner Support and Tensions, these management strategies were related to Relationship and Mental Health Outcomes, which affected and were affected by Future Concerns. Future researchers should continue to build on, expand, and modify this model and further explore the role of romantic relationships in the experience of people living with EDs.

SPECT quantification of cerebral ischemia before and after carotid endarterectomy

A method to assess changes in cerebral perfusion following carotid endarterectomy was developed using late (2 hr)/early (20 min) single-photon emission computed tomography (SPECT)/[123I]iodoamphetamine count ratios. Using a ratio greater than 1.0 to indicate redistribution and reversible ischemia, pre- and postoperative studies were compared for 20 patients. Regional polar plots based on 30 degrees angular sectors showed improvement greater than 2 standard deviations (s.d.s) ipsilateral to surgery in 15/19 (79%) and contralateral to the side of surgery in 8/19 (42%) patients with significant hemodynamic lesions. Using a hemispheric perfusion index (mean of four 30 degrees sectors) ipsilateral perfusion improved in 11/19 (58%) with bilateral improvement in 6/19 (32%). Visual interpretation was similar to the regional analysis with 14/19 (74%) improving on the operative side; however, it was less sensitive for contralateral changes, 4/19 (21%). We conclude that quantitation of redistribution can provide an objective index of improved perfusion and is especially important to detect contralateral changes.

Evaluation of a complementarity-determining region-grafted (humanized) anti-carcinoembryonic antigen monoclonal antibody in preclinical and clinical studies

A complementarity-determining region-grafted (humanized) version of MN-14 (hMN-14), a high-affinity, anti-carcinoembryonic antigen (CEA) murine monoclonal antibody (mMAb), was selected from several clones that differed slightly in their framework composition. One clone was selected based on its similar binding affinity to CEA as that observed with mMN-14 MAb and its production yields. Targeting studies, using 131I-labeled humanized MN-14 (hMN-14)/125I-labeled mMN-14 IgG in GW-39 tumor-bearing nude mice, showed excellent tumor uptake and tumor: nontumor ratios, similar to the mMN-14. A pilot clinical imaging trial was initiated to determine the targeting, pharmacokinetics, and dosimetry for 131I-labeled hMN-14 IgG. Nineteen patients with advanced CEA-producing tumors were given 8 to 30 mCi (0.5 to 20.0 mg). Eleven patients also received 131I-labeled mMN-14 IgG for comparison. The biodistribution, tumor targeting, and pharmacokinetic behavior of the hMN-14 was similar to that seen with the mMN-14. The average time required to clear 50% of the radiolabeled hMN-14 from the blood and total body was 32.9 +/- 25.6 h and 109 +/- 73 h, respectively. Patients with elevated plasma CEA (i.e., > 200 ng/ml) had more than 30% of the labeled antibody complexed within 1 h after injection. In some of these patients, increased complexation resulted in enhanced metabolism of the antibody with more rapid clearance from the blood than that seen in patients with lower plasma CEA. The average radiation absorbed dose measured in 20 tumors (average weight, 204 +/- 205 g) in 14 patients was 7.6 +/- 5.3 cGy/mCi. Tumor: nontumor dose ratios were 2.5 +/- 1.6, 9.5 +/- 5.8, and 2.6 +/- 1.8 for the red marrow, total body, and liver, respectively. One patient, with a highly elevated human anti-mouse antibody response from a prior OncoScint study (murine B72.3 IgG), received 3 injections of the hMN-14 without an adverse experience, and showed no evidence of altered biodistribution characteristic of mMAb-human anti-mouse antibody interactions. An antibody response to hMN-14 (HAhMN14) was not detected in patients who received only the hMN-14 (as many as three injections), but in three patients who received two injections of the mMN-14, a HAhMN14 response was detected. With similar, excellent targeting properties as the mMN-14 and the potential for reduced immunogenicity, hMN-14 is an attractive candidate for further clinical imaging and therapy applications.

Tc-99m HIDA dosimetry in patients with various hepatic disorders

The pharmacodynamics of Tc-99m dimethyliminodiacetic acid were studied for normal subjects and for patients with a variety of hepatobiliary disorders. It was determined that, in normal subjects, approximately 65% of the gallbladder agent bypassed the gallbladder and was excreted directly from the liver into the small intestine. This bypassing of the gallbladder was even higher in patients with cystic-duct or common-duct obstruction. The radiation burdens to the gallbladder wall and other critical organs were calculated using the dynamic data obtained from patients with a variety of gallbladder disease. The dose to the gallbladder wall was found to be significantly lower than previously reported. Gallbladder ejection and clearance characteristics when stimulated by food intake were studied for normal subjects. Dosimetry calculations demonstrated a fivefold reduction of absorbed dose to the gallbladder wall when the gallbladder was stimulated to contract using a fatty meal. Accordingly, a fatty meal is recommended for patients at the end of all gallbladder imaging studies.

A qualitative analysis of relationship advice from the perspective of people living with and recovering from eating disorders while in diverse romantic relationships

Eating disorders (EDs) have adverse consequences across life domains, ranging from physical health to interpersonal relationships. While research suggests that romantic partners have the potential to support ED recovery, partners to those with EDs often report feeling confused and helpless in the face of the condition. The extant literature on EDs in relationships centers on the experiences of cisgender, heterosexual women. The present study aimed to garner a more comprehensive understanding of the types of support people with EDs believe are most helpful from romantic partners by analyzing relationship advice from a diverse group of individuals with EDs who were in romantic relationships. As part of a larger study on romantic relationships in ED recovery, we analyzed responses to the question, "If you had to give one piece of advice to someone who learns that their partner has an ED, what would it be?" Through Consensual Qualitative Research-Modified, we identified 29 themes, which we grouped into 7 domains: Foster Open Communication, Create an Environment of Emotional Intimacy, Let Your Partner Guide You, Educate Yourself, Be Compassionate with Yourself, Use Caution when Discussing Food and Bodies, and a Miscellaneous domain. These findings highlight the importance of patience, flexibility, psychoeducation, and self-compassion for individuals working to support their partner's ED recovery, and can inform future couples-based treatments and interventions for EDs.

Tumor, red marrow, and organ dosimetry for 131I-labeled anti-carcinoembryonic antigen monoclonal antibody

Tumor-, red marrow-, and organ-absorbed doses were calculated for patients receiving 131I-labeled monoclonal antibodies against carcinoembryonic antigen for either diagnosis or therapy. Ten patients with confirmed liver tumors who received doses ranging from 10.79 to 200 mCi were evaluated. Urine and blood samples were taken in order to determine total body and red marrow activity, respectively. Anterior and posterior gamma camera images were obtained at multiple times postinjection in order to quantitate activity uptake using the conjugate view counting method for the following organs and regions: lungs, liver, spleen, kidneys, and the liver tumors. In addition, sacral regions of interest were drawn to generate red marrow-absorbed dose estimates for comparison to those obtained by blood sampling. Tumor volumes were obtained from volumetric analysis of the patient's computed tomographic study and tumor S values were obtained by assuming uniform distribution of the 131I-labeled monoclonal antibody in spherical tumor regions considering all emitted electrons, beta-particles, and photons. The following mean absorbed doses in rads/mCi injected were obtained: lungs, 2.3 +/- 1.6 (SD); liver, 1.4 +/- 0.7; spleen, 2.6 +/- 1.4; kidneys, 3.1 +/- 1.5; total body, 0.7 +/- 0.5; red marrow from blood sampling, 2.9 +/- 1.9; red marrow from sacral scintigraphy, 1.7 +/- 1.2; and liver tumors, 69.3 +/- 92.5. Tumor volumes ranged from 1 to 216 g and the percentage of uptake/g of monoclonal antibody into these tumors ranged from 0.0006 to 1.040. There was a statistically significant difference between the two techniques for estimation of red marrow dose (P less than 0.01). This methodology, permits calculation of tumor, red marrow, and organ dosimetry using planar gamma camera imaging.

Effect of proximal vagotomy and Roux-en-Y diversion on gastric emptying kinetics in asymptomatic patients

The role of the distal stomach in gastric emptying was studied. Ten patients with proximal gastric vagotomy (PV) and 10 age-matched patients with Roux-en-Y gastro-jejunostomy (R-Y) were compared with 10 healthy controls. Gastric emptying of solids and liquids was determined by the use of Tc-99m SC scrambled eggs and In-111 DTPA. In PV, gastric emptying of both solids and liquids was delayed; the prolongation with solids was mainly accounted for by an abnormal lag phase. In R-Y patients, no lag phase was observed, and the solid emptying curve pattern was characterized by early rapid emptying followed by very slow emptying. Both the solid and liquid phases were prolonged. The lag phase is affected by proximal vagotomy and is mainly determined by the distal stomach, which appears to be essential for normal emptying.

Nonmyeloablative iodine-131 anti-B1 radioimmunotherapy as outpatient therapy

The expected effective dose equivalent to an individual from contact with 131I anti-B1 radioimmunotherapy (RIT) patients released immediately after therapeutic infusion was estimated.

METHODS

Effective dose equivalents were calculated retrospectively using data acquired on 46 patients treated with 1311 anti-B1 RIT as inpatients. Effective dose equivalents to members of the public were estimated using the method published in the Nuclear Regulatory Commission (NRC) Regulatory Guide 8.39, assuming the administered activity, the patient-specific effective half-life, the 0.25 occupancy factor, and no photon attenuation. Effective dose equivalents also were estimated using ionization chamber dose rates, measured immediately after therapeutic infusion and integrated to total decay based on the measured effective half-life.

RESULTS

For the whole-body treatment absorbed dose limit of 75 cGy (75 rad), the administered 131I activity ranged from 2.1 to 6.5 GBq (56 to 175 mCi), and the measured dose rate at 1 m ranged from 70 to 190 microSv/hr (7 to 19 mrem/hr). The total-body effective half-life for these patients ranged from approximately 40 to 88 hr. Using the NRC method and not accounting for the attenuation of photons, the mean dose equivalent to the public exposed to an 131I anti-B1 patient discharged without hospitalization was 4.9 +/- 0.9 mSv (490 +/- 90 mrem). The range was 3.2-6.6 mSv (320 to 660 mrem), where 48% of patients would deliver a dose to another individual that is <5 mSv (500 mrem) (i.e., 48% of the patients would be allowed to return home immediately following the infusion). Using the measured dose rate method, the mean dose equivalent to an individual exposed to the same RIT patients was 2.9 +/- 0.4 mSv (290 +/- 40 mrem). The range was 2.0-3.7 mSv (200-370 mrem), where 100% of the estimated effective dose equivalents were <5 mSv (500 mrem).

CONCLUSION

Based on calculated and patient-specific exposure data, outpatient RIT with nonmyeloablative doses of 131I should be feasible for all patients under current NRC regulations. Implementing outpatient RIT should make the therapy more widely available and more convenient and should lower patient care costs without exceeding accepted limits for public exposure to radiation.

Outpatient treatment with (131)I-anti-B1 antibody: radiation exposure to family members

The Nuclear Regulatory Commission (NRC) regulations that govern release of patients administered radioactive material have been revised to include dose-based criteria in addition to the conventional activity-based criteria. A licensee may now release a patient if the total effective dose equivalent to another individual from exposure to the released patient is not likely to exceed 5 mSv (500 mrem). The result of this dose-based release limit is that now many patients given therapeutic amounts of radioactive material no longer require hospitalization. This article presents measured dose data for 26 family members exposed to 22 patients treated for non-Hodgkin's lymphoma with (131)I-anti-B1 antibody after their release according to the new NRC dose-based regulations.

METHODS

The patients received administered activities ranging from 0.94 to 4.77 GBq (25--129 mCi). Family members were provided with radiation monitoring devices (film badges, thermoluminescent or optically stimulated luminescent dosimeters, or electronic digital dosimeters). Radiation safety personnel instructed the family members on the proper wearing and use of the devices. Instruction was also provided on actions recommended to maintain doses to potentially exposed individuals as low as is reasonably achievable.

RESULTS

Family members wore the dosimeters for 2--17 d, with the range of measured dose values extending from 0.17 to 4.09 mSv (17--409 mrem). The average dose for infinite time based on dosimeter readings was 32% of the predicted doses projected to be received by the family members using the NRC method provided in regulatory guide 8.39.

CONCLUSION

Therapy with (131)I-anti-B1 antibody can be conducted on an outpatient basis using the established recommended protocol. The patients can be released immediately with confidence that doses to other individuals will be below the 5-mSv (500 mrem) limit.

Gender identity-based disparities in self-injurious thoughts and behaviors among pre-teens in the United States

INTRODUCTION

Transgender individuals are at heightened risk for self-injurious thoughts and behaviors (SITBs). Evidence suggests that middle childhood-aged transgender individuals experience elevated rates of non-suicidal self-injury (NSSI) and passive suicidal ideation (SI), compared to cisgender children. Little is known about gender identity-based disparities in SI more broadly and suicidal behavior (SB) in children aged 9 and 10. The aim of this study was to examine gender identity-based disparities in SITBs among children in middle childhood (pre-teens) in a US-based sample.

METHODS

Using data from the 3.0 baseline release of the Adolescent Brain Cognitive Development (ABCD) study, logistic regression models, unadjusted and adjusted for covariates, were performed to examine gender identity-based disparities in SITBs.

RESULTS

In a model adjusted for birth sex, race/ethnicity, and household income, transgender children were at significantly higher odds for current (adjusted odds ratio [AOR] = 6.34) but not lifetime NSSI compared with cisgender children. Transgender children were at significantly higher odds for current and lifetime SI (AOR = 13.03; AOR = 5.39, respectively) and SB (AOR = 14.21; AOR = 12.64, respectively) compared with cisgender children.

CONCLUSIONS

Gender identity-based disparities in SITBs may be present as early as age 9 and 10, demonstrating the need for SITB prevention and intervention efforts specific to transgender children.

The association between minority stressors, intraminority stressors, and borderline personality disorder symptomatology among sexual minority men

Sexual minority men are more likely to be diagnosed with borderline personality disorder compared to their heterosexual counterparts. Minority stressors have been associated with criteria for borderline personality disorder (e.g., substance use, suicidality, impulsive behaviors, and interpersonal difficulties with rejection). However, to date, there are no known studies examining the association between traditional minority and intraminority stressors and borderline personality disorder symptomatology. The purpose of the study is to examine the association between traditional and intraminority stressors and borderline personality disorder symptomatology among sexual minority men. Data were collected from 312 sexual minority men (Mage = 24.00, SD = 4.04) via Qualtrics panels across the United States. A hierarchical linear regression was conducted with borderline personality disorder symptomatology as the outcome variable. Minority stressors (i.e., internalized homophobia, sexual orientation concealment, major discrimination, and day-to-day discrimination) were entered in Step 1, and intraminority stress was entered in Step 2. In Step 1, both major and day-to-day discrimination were significantly positively associated with borderline personality disorder symptomatology. In Step 2, intraminority stress was significantly positively associated with borderline personality disorder symptomatology, and day-to-day discrimination remained significant. These findings warrant clinicians to evaluate both minority and intraminority stressors, which may be an additional risk factor in the development and/or maintenance of borderline personality disorder symptomatology. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Indium-111-labeled white blood cells: dosimetry in children

The distribution of [111In]oxine-labeled leukocytes was studied by whole-body gamma camera imaging in nine pediatric patients. Images were obtained at approximately 24 hr after administration of the material. Organ distribution was estimated from stored data by manual region of interest assignment. Dosimetry estimates based on geometric mean and conjugate view absolute activity calculations showed close agreement in these patients. Leukocytes were distributed in liver, spleen and marrow. The mean percent uptakes +/- s.d. were: spleen, 31.2 +/- 18.3%; liver, 26.3 +/- 10.8%; and marrow, 14.2 +/- 5.7%. A significant portion (28.3 +/- 9.9%) of administered white cell activity was found outside these organs in the remainder of the body. Mean organ absorbed doses (rad/mCi) were: spleen, 115.0 +/- 84.8; liver, 13.9 +/- 7.8; marrow, 7.6 +/- 3.8; and total body 2.5 +/- 1.0. The mean organ absorbed doses (rad/dose administered) were: spleen, 13.7 +/- 10.6; liver, 1.48 +/- 0.62; marrow, 0.79 +/- 0.26; and total body, 0.28 +/- 0.09.

Radiation dose estimates for oral agents used in upper gastrointestinal disease

Radiation dosimetry was calculated for a number of orally administered radiopharmaceuticals used for study of upper gastrointestinal function. These include: Tc-99m sulfur colloid in water, in a cooked egg, and in chicken liver labeled in vivo; In-111 DTPA; Tc-99m DTPA; In-113m DTPA; Tc-99m ovalbumin in cooked egg; and In-111 colloid in chicken liver labeled in vivo. Radiation burdens to the stomach, small intestine, upper and lower large intestine, ovaries, testes, and total body are calculated for each preparation.

Absorbed fractions for electrons and beta particles in spheres of various sizes

The use of electron-emitting radionuclides in tumor imaging and therapy has presented some new challenges to conventional radiation dosimetry. The fraction of electron energy absorbed in most source regions has usually been assumed to be unity. In small structures such as localized tumors or isolated regions containing moderate to high energy electron emitters, however, this may not always be the case.

METHODS

Using an extension of Berger's scaled absorbed dose distributions for point sources to represent a spherical geometry, absorbed fractions of electron energy for sources uniformly distributed in spheres of various sizes have been calculated.

RESULTS

Beta particle and monoenergetic electron energies studied range from 0.025 to 4.0 MeV and sphere masses range from 0.01 to 1000 g. S values have also been calculated for 90Y, 123I and 131I based on the results of the absorbed fraction calculations.

CONCLUSION

These calculated absorbed fractions are valuable in estimating electron energy loss from small spherical structures and may be useful in estimating the radiation dose to these small volumes.

Absolute organ activity estimated by five different methods of background correction

Accurate absorbed dose estimates in radionuclide therapy require patient-specific dosimetry. In patient-based dosimetry, estimation of absolute organ uptake is essential. The methods used should be reasonably accurate as well as easy to perform in routine clinical practice. One of the major sources of uncertainty in quantification of organ or tumor activity from planar images is the activity present in the tissue surrounding the source.

METHODS

To estimate organ activity as a function of organ-to-background activity concentration ratio, a cylindrical phantom, filled with 5.6 liters of water was used to simulate the abdomen of a patient. Two other cylinders of 150 ml each, representing the kidneys, were each filled with 19 MBq 99mTC and were positioned in the abdomen phantom. The phantom was imaged with a dual-head gamma camera with the kidneys placed at posterior depths of 1-, 5- and 10-cm at kidney-to-background activity concentration ratios of infinity, 10:1, 5:1 and 2:1. The conjugate view geometric mean counting method was used to quantify activity. Five methods for background correction were applied: (1) no correction; (2) conventional background correction (simple subtraction of the background counting rate from the source region counting rate); (3) Kojima method (background corrected for organ thickness and depth); (4) Thomas method (analytical solution); and (5) Buijs method (background corrected for organ and total-body thickness).

RESULTS

Since the results were identical for both kidneys, only the left kidney activity measurements are presented. The accuracy of the five background correction methods is given as the percentage difference between the actual and measured activity in the left kidney. For Method 1, the percentage difference ranged from 2% with an infinite kidney-to-background activity concentration ratio to +413% with a 2:1 ratio. For Method 2, these values ranged from -1% to -80%, for Method 3 from +11% to -18%, for Method 4 from -2% to +120% and for Method 5 from -4% to +39%.

CONCLUSION

Even though quantitative SPECT is the most rigorous method for activity quantification in conditions of low organ-to-background activity concentration ratio, planar scintigraphy can be applied accurately if appropriate attention is paid to background correction. Using relatively simple background subtraction methods, the quantitative planar imaging technique can result in reasonably accurate activity estimates (Methods 3 and 5). The use of Kojima's method is preferable, especially at very low source-to-background activity concentration ratios.

Aggressive behavior among women sexually abused as children

Although research shows that sexually abused children appear to be at risk of subsequent aggressive behavior, few investigations address whether such behavior persists beyond childhood. This research describes the self-reported adolescent and adult fighting behavior of 136 women sexually abused as children and examines the role of intervening variables in the risk of such behavior. The women are part of a longitudinal study of 206 primarily low-income, urban women whose abuse was documented at the time it occurred. Fighting was common, particularly during adolescence. Adult aggression was strongly associated with being a victim of violence by an intimate partner. A history of exposure to other forms of violence significantly increased the risk of fighting while strong maternal attachments mitigated the risk, primarily by reducing the likelihood of involvement in an abusive intimate relationship.

The effect of source size on the buildup factor calculation of absolute volume

A general scheme for generating attenuation-corrected images for use in absolute volume measurements has been developed. The technique is based on a buildup factor approach for Compton scatter compensation and requires anterior and posterior count-rate measurements. The scatter correction requires evaluation of the attenuation factor (1-(1-e-mu d)B(infinity), where mu is the linear attenuation coefficient in cm-1 and B(infinity) is the buildup factor at infinite depth. The attenuation factors for four different source sizes using 99mTcO4- and a 20% scintillation camera energy window are reported. The results indicated that B(infinity) was constant while mu varied as a function of size (S) in pixels according to mu = 0.151 cm-1 X exp(-1.18 X 10(-4) pixels-1 X S). Once the appropriate value of mu was determined, a pair of anterior-posterior count rate equations was used to generate attenuation-corrected count rate data for use in absolute volume measurements. The method was validated by calculating three separate phantom volumes. The results showed that the method provides less than +/- 6.0% error for volume determinations at all investigated depths.

Radioimmunotherapy of the GW-39 human colonic tumor xenograft with 131I-labeled murine monoclonal antibody to carcinoembryonic antigen

We have investigated the therapeutic efficacy of a single injection of 131I-labeled murine mouse monoclonal antibody (NP-4) against carcinoembryonic antigen using the human colonic tumor xenograft, GW-39, grown in the cheek pouches of adult hamsters. Therapeutic efficacy was dependent on the dose of radioactivity, the specificity of the antibody for the tumor, and the size of the tumor when the radioantibody was administered. A dose of 1 mCi of 131I-labeled NP-4 given 1 day after tumor transplantation completely inhibited the growth of 6 of 11 tumors over a 12-week period, and histological evidence indicated that viable tumor was absent in the tissue remaining at the injection site. Lower doses (0.5 mCi) of 131I-labeled NP-4 inhibited tumor growth over 90% in comparison to untreated animals, but the tumors eventually resumed growth. Delaying the administration of radioantibody for 4 or 7 days after tumor transplantation significantly reduced the therapeutic efficacy. Although the same dose of 131I-labeled irrelevant immunoglobulin G also inhibited tumor growth, 131I-labeled NP-4 was generally 2-3 times more effective in reducing tumor growth than was the control IgG. There was a 13% loss in body weight within 7 days after treatment with 1 mCi, but all the animals regained their weight by day 14, indicating that the level of radioactivity was tolerated well. Dosimetric calculations predicted that over 14 days a dose of nearly 2400 rads was delivered to the tumors with 131I-labeled NP-4. These results confirm our previous studies that 131I-labeled antibody can effectively inhibit tumor growth, but suggest that radioantibody therapy is most effectively administered when there is a low tumor burden.