The Critical Role of Physical Activity and Weight Management in Knee and Hip Osteoarthritis: A Narrative Review

Physical activity (PA) and weight management are critical components of an effective knee and hip osteoarthritis (OA) management plan, yet most people with OA remain insufficiently active and/or overweight. Clinicians and their care teams play an important role in educating patients with OA about PA and weight management, eliciting patient motivation to engage in these strategies, and referring patients to appropriate self-management interventions. The purpose of this review is to educate clinicians about the current public health and clinical OA guidelines for PA and weight management and highlight a variety of evidence-based self-management interventions available in community and clinical settings and online.

Preventing Osteoarthritis After an Anterior Cruciate Ligament Injury: An Osteoarthritis Action Alliance Consensus Statement

After an anterior cruciate ligament (ACL) injury, people need secondary prevention strategies to identify osteoarthritis at its earliest stages so that interventions can be implemented to halt or slow the progression toward its long-term burden. The Osteoarthritis Action Alliance formed an interdisciplinary Secondary Prevention Task Group to develop a consensus on recommendations to provide clinicians with secondary prevention strategies that are intended to reduce the risk of osteoarthritis after a person has an ACL injury. The group achieved consensus on 15 out of 16 recommendations that address patient education, exercise and rehabilitation, psychological skills training, graded-exposure therapy, cognitive-behavioral counseling (lacked consensus), outcomes to monitor, secondary injury prevention, system-level social support, leveraging technology, and coordinated care models. We hope this statement raises awareness among clinicians and researchers on the importance of taking steps to mitigate the risk of osteoarthritis after an ACL injury.

Evidence Review for Preventing Osteoarthritis After an Anterior Cruciate Ligament Injury: An Osteoarthritis Action Alliance Consensus Statement

CONTEXT

The Osteoarthritis Action Alliance formed a secondary prevention task group to develop a consensus on secondary prevention recommendations to reduce the risk of osteoarthritis after a knee injury.

OBJECTIVE

Our goal was to provide clinicians with secondary prevention recommendations that are intended to reduce the risk of osteoarthritis after a person has sustained an anterior cruciate ligament injury. Specifically, this manuscript describes our methods, literature reviews, and dissenting opinions to elaborate on the rationale for our recommendations and to identify critical gaps.

DESIGN

Consensus process.

SETTING

Virtual video conference calls and online voting.

PATIENTS OR OTHER PARTICIPANTS

The Secondary Prevention Task Group consisted of 29 members from various clinical backgrounds.

MAIN OUTCOME MEASURE(S)

The group initially convened online in August 2020 to discuss the target population, goals, and key topics. After a second call, the task group divided into 9 subgroups to draft the recommendations and supportive text for crucial content areas. Twenty-one members completed 2 rounds of voting and revising the recommendations and supportive text between February and April 2021. A virtual meeting was held to review the wording of the recommendations and obtain final votes. We defined consensus as >80% of voting members supporting a proposed recommendation.

RESULTS

The group achieved consensus on 15 of 16 recommendations. The recommendations address patient education, exercise and rehabilitation, psychological skills training, graded-exposure therapy, cognitive-behavioral counseling (lacked consensus), outcomes to monitor, secondary injury prevention, system-level social support, leveraging technology, and coordinated care models.

CONCLUSIONS

This consensus statement reflects information synthesized from an interdisciplinary group of experts based on the best available evidence from the literature or personal experience. We hope this document raises awareness among clinicians and researchers to take steps to mitigate the risk of osteoarthritis after an anterior cruciate ligament injury.

Barriers and facilitators to the adoption and implementation of evidence-based injury prevention training programmes: a narrative review

While there is a multitude of evidence supporting the efficacy of injury prevention training programmes, the literature investigating the implementation of these programmes is, in contrast, rather limited. This narrative review sought to describe the commonly reported barriers and facilitators of the implementation of injury prevention training programmes among athletes in organised sport. We also aimed to identify necessary steps to promote the uptake and sustainable use of these programmes in non-elite athletic communities. We identified 24 publications that discussed implementing evidence-based injury prevention training programmes. Frequently reported barriers to implementation include the perceived time and financial cost of the programme, coaches lacking confidence in their ability to implement it, and the programme including exercises that were difficult or confusing to follow. Frequently reported facilitators to implementation include the coach being aware of programme efficacy, shared motivation to complete the programme from both coaches and athletes, and the ability to easily integrate the programme into practice schedules. The current literature is focused on high-income, high-resource settings. We recommend that future studies focus on understanding the best practices of programme dissemination in culturally and economically diverse regions. Programmes ought to be of no financial burden to the user, be simply adaptable to different sports and individual athletes and be available for use in easily accessible forms, such as in a mobile smartphone application.

Exercise prescription for weight management in obese adults at risk for osteoarthritis: synthesis from a systematic review

BACKGROUND

The aim of this systematic review was to identify principles of exercise interventions associated with improved physical function, weight management or musculoskeletal pain relief among young and middle-aged adults with obesity and propose an evidence-based exercise prescription that could assist in secondary prevention of osteoarthritis.

METHODS

A structured electronic review was conducted using MEDLINE, PubMed, and SPORTDiscus. The search string included 1) "obes*" AND "exercise" AND "interven*" AND "musculoskeletal pain OR knee pain OR hip pain". Studies 1) were randomized controlled trials of humans, with a non-exercise control, 2) included participants aged 18-50 years, and 3) had outcomes that included physical function, musculoskeletal pain, and/or body composition. Studies were excluded if participants had peri-menopausal status, cancer, or obesity-related co-morbidities. A recommended exercise prescription was developed based on common principles used in the included exercise interventions with greatest change in function or pain.

RESULTS

Seven studies were included. Similarities in exercise intensity (40-80% VO_2max), frequency (three times per week), duration (30-60 min), and exercise mode (treadmill, cross-trainer, stationary bike, aquatic exercise) were observed in exercise interventions that resulted in improved physical function and/or pain, compared to non-exercise control groups.

CONCLUSION

Common principles in exercise prescription for improvements in weight management, physical function and pain relief among otherwise healthy people with obesity. Exercise prescription including moderate intensity exercise for 30-60 min, three times per week can be considered an effective treatment for weight management and obesity-related musculoskeletal symptoms. Exercise should be recommended to at-risk individuals as part of secondary prevention of osteoarthritis.

Public Health Interventions for Osteoarthritis - updates on the Osteoarthritis Action Alliance's efforts to address the 2010 OA Public Health Agenda Recommendations

Osteoarthritis (OA) is a painful joint disease affecting more than 32.5 million adults in the US and over 350 million adults worldwide. The prevalence is expected to rise continually over the next several decades with significant impacts to societal health and economic costs as well as individuals' daily activities and quality of life. In 2008, the Centers for Disease Control and Prevention (CDC) and the Arthritis Foundation (AF) led a collaborative effort to address approaches to reduce the burden of OA via public health interventions, policies (systems and environmental), and communication strategies. This collaboration resulted in the National Public Health Agenda for OA (OA Agenda), which was vetted by more than 75 stakeholder organisations and released in 2010. The OA Agenda listed ten recommendations focused on public health interventions for OA including weight management, physical activity, self-management education, and injury prevention, and policies, systems, communication, research and evaluation. In 2011, the CDC and AF mobilised the OA Action Alliance (OAAA), a national coalition of organisations concerned with mitigating the public health impact of OA, to operationalise the recommendations set forth in the OA Agenda. Since then, the OAAA has grown to include more than 110 organisations that work collectively to increase awareness about the prevention and management of OA, provide educational resources, and expand access to evidence-based programmes for target audiences including individuals with OA, community-based organisations, healthcare systems and providers, and policymakers. This review highlights the OAAA's progress to date in addressing the OA Agenda recommendations; successes and challenges in delivery of effective communication, programmes, and resources; and future implications.

"Where Does it Hurt?" Implications of Obesity on Musculoskeletal Health

Obesity and musculoskeletal health are inextricably linked across risk factors, prevalence rates, and societal burden. They are also linked across management strategies. It is necessary to consider the mutual impact of musculoskeletal health and obesity in order to inform effective and safe weight management and physical activity solutions.

Physical Activity as a Vital Sign: A Systematic Review

Introduction

Physical activity (PA) is strongly endorsed for managing chronic conditions, and a vital sign tool (indicator of general physical condition) could alert providers of inadequate PA to prompt counseling or referral. This systematic review examined the use, definitions, psychometric properties, and outcomes of brief PA instruments as vital sign measures, with attention primarily to studies focused on arthritis.

Methods

Electronic databases were searched for English-language literature from 1985 through 2016 using the terms PA, exercise, vital sign, exercise referral scheme, and exercise counseling. Of the 838 articles identified for title and abstract review, 9 articles qualified for full text review and data extraction.

Results

Five brief PA measures were identified: Exercise Vital Sign (EVS), Physical Activity Vital Sign (PAVS), Speedy Nutrition and Physical Activity Assessment (SNAP), General Practice Physical Activity Questionnaire (GPPAQ), and Stanford Brief Activity Survey (SBAS). Studies focusing on arthritis were not found. Over 1.5 years of using EVS in a large hospital system, improvements occurred in relative weight loss among overweight patients and reduction in glycosylated hemoglobin among diabetic patients. On PAVS, moderate physical activity of 5 or more days per week versus fewer than 5 days per week was associated with a lower body mass index (−2.90 kg/m²). Compared with accelerometer-defined physical activity, EVS was weakly correlated (r = 0.27), had low sensitivity (27%–59%), and high specificity (74%–89%); SNAP showed weak agreement (κ = 0.12); GPPAQ had moderate sensitivity (46%) and specificity (50%), and SBAS was weakly correlated (r = 0.10–0.28), had poor to moderate sensitivity (18%–67%), and had moderate specificity (58%–79%).

Conclusion

Few studies have examined a brief physical activity tool as a vital sign measure. Initial investigations suggest the promise of these simple and quick assessment tools, and research is needed to test the effects of their use on chronic disease outcomes.

Assessor Status Influences Pain Recall

Anecdotal clinical reports suggest that patients report differing levels of pain, depending on the status within the medical hierarchy of the individual gathering the pain rating. This observation has clinical relevance, given the practice of delegating the assessment of pain to lower status clinic staff members. In this study, both pain and mood were assessed in 70 patients diagnosed with low back pain at pretreatment, immediately after epidural lumbar injection, and again 2 weeks later by phone. At the 2-week follow-up, patients were also asked to recall the postprocedural rating that they had given immediately after the injection. This rating was obtained by either the treating physician or by a research assistant who was present at the time of injection, on a randomly determined basis. Current ratings of pain and mood did not differ for either group before the epidural injection, after the epidural injection, or at the 2-week follow-up. Two-week recall of postprocedural pain did, however, differ depending on assessor status. Those called by the physician provided recalled pain ratings that closely matched the ratings provided immediately after the procedure. Those called by the research assistant provided ratings that were 86% higher (that is, worse) than their original ratings. This status-driven bias in recalled postprocedural pain reporting is discussed in the context of social demands inherent in the physician-patient relationship, with implications for assessing treatment effectiveness in clinical practice and research.

PERSPECTIVE

Accurate assessment of patients' pain is critical to effective pain management and treatment planning. This study found evidence of a status-based bias in which physicians elicited lower ratings of previously experienced pain associated with treatment procedures than did staff members of lower status.

Pharmacokinetics and metabolism of the methyl-branched fatty acid (BMIPP) in animals and humans

The aim of this study was to further characterize the major metabolite of 15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid (BMIPP).

METHODS

Radioactive components of 131I-BMIPP were evaluated in Langendorff-perfused rat hearts, as well as in blood samples from 20 patients after injection of 123I-BMIPP. Rat hearts were perfused with pH 7.4 Krebs-Henseleit buffer with or without 0.4 mmol/L bovine serum albumin (BSA) or 0.4 mmol/L palmitate. Lipids were Folch extracted and hydrolyzed from samples of the outflow, as well as from homogenized hearts. Radioactive components were determined by thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) analyses. The major metabolite of BMIPP was then further characterized by electrospray mass spectrometry.

RESULTS

The rat heart perfusate showed one major polar metabolite observed by TLC (Rf = 0.35; solvent = benzene-dioxane-acetic acid 80:18:2). The addition of BSA/palmitate to the perfusate buffer significantly increased backdiffusion of BMIPP (Rf = 0.55), as well as reduced BMIPP uptake and metabolism. The major metabolite was identified by mass spectral analysis as 2-(p-iodophenyl)acetic acid (IPC2). From TLC and HPLC analyses of the serum lipids obtained from patients, the same metabolite could be identified with levels increasing over time (0%, 5.2% and 11.8% of the injected dose; 3 min, 20 min and 3 h postinjection, respectively). In addition to the identification of unmetabolized BMIPP (53.9%), the rat heart lipid hydrolysate also contained alpha-methyl-14-(p-iodophenyl)tetradecanoic acid (20.8%), 12-(p-iodophenyl)-substituted-dodecanoic (17.1%), -hexanoic acid (5.2%) and IPC2 (1.1%).

CONCLUSION

The animal results show the complexity of uptake, metabolism and release of BMIPP from which a part is metabolized through alpha- and subsequent beta-oxidation to the final IPC2 metabolite as confirmed by mass spectral analysis. The results from patient studies suggest that the slow myocardial washout observed in vivo after intravenous administration of BMIPP may represent a similar process, because both unmetabolized BMIPP and the final metabolite were also identified in serum samples.

Effects of configuration on the myocardial uptake of radioiodinated 3(R)-BMIPP and 3(S)-BMIPP in rats

Radioiodinated 3(R)-(+)- and 3(S)-(-)-15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid (BMIPP) were prepared and evaluated in rats to investigate the effects of absolute configuration of the 3(beta)-methyl group on myocardial uptake and release kinetics.

METHODS

The 3(R)-(+)-BMIPP analog was synthesized by initial acylation of a thiophene template with the acid chloride of ethyl 3(R)-methylglutarate. 3(S)-(-)-BMIPP was obtained by separation from the mixture of diastereomeric amides prepared from reaction of the acid chloride of racemic BMIPP with the S-(-)-alpha-methylbenzylamine. The amide of synthetic 3(R)-BMIPP prepared from S-(-)-alpha-methylbenzylamine was identical to the chromatographically more polar isomer. Free acids were obtained by acid hydrolysis of the amides, fully characterized and then converted to the radioiodinated BMIPP isomers.

RESULTS

Biodistribution studies in rats with the dual-labeled [(131)I]-3(S)-BMIPP/[(125)I]-3(R)-BMIPP mixture demonstrated greater myocardial uptake of 3(R)-BMIPP compared with the 3(S)-BMIPP isomer [60 min: 3(R)-BMIPP = 4.37 %ID/g; 3(S)-BMIPP = 3.44; p < 0.05; 180 min, 2.31 and 1.78 %ID/G, respectively, p < 0.01], although both isomers had similar myocardial washout curves (5-180 min). Percent ID/g values for other tissues which were examined (blood, lungs, thyroid) were similar.

CONCLUSION

Higher myocardial uptake of the 3(R)-BMIPP isomer observed in these animal studies may suggest differences in carrier-mediated myocyte uptake of the two isomers. These studies suggest that [(123)I]-3(R)-BMIPP is a candidate for clinical evaluation and may show greater myocardial uptake than the 3(S)-BMIPP isomer and may thus require reduced injected dose.

Both total chain length and position of dimethyl-branching effect the myocardial uptake and retention of radioiodinated analogues of 15-(p-iodophenyl)-3,3-dimethylpentadecanoic acid (DMIPP)

Introduction of geminal dimethyl-branching into the 3-position of 15-(p-iodophenyl) pentadecanoic acid (IPPA) significantly delays myocardial clearance in rats and dogs following intravenous administration. Several new analogues of DMIPP have been synthesized and evaluated in fasted rats. The effects of both the position of dimethyl-branching and the total chain-length of 3, 3-dimethyl analogues on heart uptake and clearance kinetics have been studied. In the first series of compounds, two methyl groups were introduced into the 3-, 4-, 6-, or 9- position. Tissue distribution studies of the 15-(p-[I-125] iodophenyl)-analogues demonstrated that the position of dimethyl-branching is an important factor affecting both myocardial specificity and retention. The [I-125] labeled 3,3- and 4,4-DMIPP analogues showed higher myocardial uptake and faster blood clearance than the 6,6- and 9,9-DMIPP analogues [heart, % dose/gm heart: blood), 30 min: 3,3-DMIPP = 5.06 (12:1); 4,4-DMIPP = 8.03 (16.7: 1); 6,6-DMIPP = 2.26 (3.1:1); 9,9-DMIPP = 3.06 (2.77)]. In the second series, the effects of total fatty acid chain length were evaluated with 3,3-dimethyl-substituted analogues with C11, C12, C13, C14, C15, and C19 chain lengths. The C14 and C15 chain length analogues showed the best properties [global heart: blood ratios): 30 min: C11, 0.70 (0.82); C12, 1.25 (0.68); C13, 0.47 (0.90); C14, 1.63 (3.54); C15, 5.06 (12); C19. 1.29 (0.82). These detailed studies have demonstrated that both total chain length and the position of geminal dimethyl-branching are important structural parameters which affect myocardial specificity and retention of omega-(p-iodophenyl)-substituted fatty acid analogues and that 3,3-DMIPP and 4,4-DMIPP are the best candidates with optimal properties for further study.

Evaluation of pancreatic lipase activity by simple urine analysis after oral administration of a new iodine-131-labeled triglyceride

A new iodine-131-labeled triglyceride analogue called "MIPAG" [1,2-dipalmitoyl-3-[(15-p-iodophenyl) pentadecan-1-oyl]rac-glycerol] has been prepared in which 15-(p-iodophenyl)pentadecanoic acid (IPPA) is attached to position-3. MIPAG has been developed for the evaluation of pancreatic exocrine function by simple urine analysis and has been evaluated in rats and humans. After oral administration, IPPA is released from the triglyceride by the action of pancreatic lipases followed by intestinal absorption and the principal IPPA metabolite (p-iodobenzoic acid, IBA) is primarily excreted in the urine. Excretion in the urine and feces was evaluated in rats, as well as the biodistribution in various organs over 21 days. Twenty patients without pancreatic disease (normals) and four patients without pancreatic insufficiency were also investigated. Following oral administration of 30 microCi of MIPAG, urine was collected for two successive 24-h periods. Blood samples were drawn and thin-layer chromatographic (TLC) analysis was performed on the serum lipid extracts. Urine from normals contained 44.9% +/- 7.7% and 61.8% +/- 8.4% of the administered activity after 24 and 48 h, respectively. The patients with pancreatic insufficiency excreted 13.1 +/- 5.6% and 18.9% +/- 6.2%, respectively, which was significantly decreased (P < 0.001) compared with normals. The TLC profiles showed an increasing proportion of IBA with time. Urine analysis after oral administration of MIPAG thus appears to be an attractive new techniques for the evaluation of pancreatic lipase activity by a simple urine analysis.

Site-specific/stable radioiodination of 1,2-Pal-3-IPPA: an agent for the potential clinical evaluation of pancreatic insufficiency by urine analysis

To measure pancreatic lipase activity, we synthesized a triglyceride containing a radioiodinated fatty acid. The urinary excretion of radioactivity was measured in five rats following administration of the agent by feeding tube. We attached 15-phenylpentadecanoic acid (PPA) to position-3 of 1,2-dipalmitoyl-rac-glycerol (1,2-Pal) to form 1,2-Pal-3-PPA. The 1,2-Pal-3-IPPA (expected lipase substrate) was prepared by the thallation-iodide displacement method. In a dual-label study, the 125I-1,2-Pal-3-IPPA triglyceride was administered with the 131I-IPPA free acid to rats (n = 5) by oral gavage. Urine and feces were collected daily and the tissue distribution of both tracers was evaluated over a five-day period. A significant portion of the administered activity was excreted in 24 hr in the urine (125I, 30.31% + 4.32%; 131I, 35.0% + 7.29%), which cochromatographed with hippuric acid by thin layer chromatography. Release of the acidic components from the conjugated excretory products by acid hydrolysis of the urine provided the radioactive acidic metabolites. Analysis of the Folch extracts of fat samples demonstrated that the radioactive components cochromatographed in the triglyceride region. This agent appears useful for the evaluation of various gastrointestinal diseases.

Incorporation of radioiodinated IPPA and BMIPP fatty acid analogues into complex lipids from isolated rat hearts

Heart lipids were extracted by the Folch technique from Langendorff-perfused rat hearts after administration of 15-(p-[131I]iodophenyl)pentadecanoic acid and 15-(p-[125I]iodophenyl)-3-R,S-methylpentadecanoic acid. Techniques utilizing successive high performance liquid chromatographic (HPLC) analyses have been developed for the evaluation of the uptake of the tracers into neutral lipids and phospholipids of the rat hearts. Phospholipids were separated on a SiO2 column eluted with a gradient of acetonitrile/water (97.5/2.5) and acetonitrile/water (85/15) followed by separation of the neutral lipids on a C-18 reversed phase column with a gradient consisting of acetonitrile and 2-propanol/hexane (60/40) containing 1 N H2SO4 (5 microL/100 mL). Both tracers show the incorporation into the expected major lipid classes.

Treating exposure to chemical warfare agents: implications for health care providers and community emergency planning

Current treatment protocols for exposure to nerve and vesicant agents found in the U.S. stockpile of unitary chemical weapons are summarized, and the toxicities of available antidotes are evaluated. The status of the most promising of the new nerve agent antidotes is reviewed. In the U.S. atropine and pralidoxime compose the only approved antidote regimen for organophosphate nerve agent poisoning. Diazepam may also be used if necessary to control convulsions. To avoid death, administration must occur within minutes of substantial exposure together with immediate decontamination. Continuous observation and repeated administration of antidotes are necessary as symptoms warrant. Available antidotes do not necessarily prevent respiratory failure or incapacitation. The toxicity of the antidotes themselves and the individualized nature of medical care preclude recommending that autoinjectors be distributed to the general public. In addition, precautionary administration of protective drugs to the general population would not be feasible or desirable. No antidote exists for poisoning by the vesicant sulfur mustard (H, HD, HT); effective intervention can only be accomplished by rapid decontamination followed by palliative treatment of symptoms. British anti-Lewisite (BAL) (2,3-dimercapto-1-propanolol) is the antidote of choice for treatment of exposure to Lewisite, another potent vesicant. Experimental water-soluble BAL analogues have been developed that are less toxic than BAL. Treatment protocols for each antidote are summarized in tabular form for use by health care providers.

Effect of 3-methyl-branching on the myocardial retention of radioiodinated 19-iodo-18-nonadecenoic acid analogues

The effect of methyl-branching at the 3(beta-)-position on myocardial uptake and retention of fatty acids where radioiodide has been stabilized as a terminal trans-(E)-vinyl iodide has been evaluated in fasted rats. The syntheses of two new dimethyl-branched fatty acids, 17-iodo-3,3-dimethylheptadecanoic acid (14) and (E)-19-iodo-3,3-dimethyl-18-nonadecenoic acid (19), are described. Tissue distribution studies in fasted rats with [125I]-19 showed significant heart uptake (2 min, 4.56% dose/g), and prolonged retention (60 min 4.10% dose-g). These results suggest that [123I]-19 is a good candidate for further studies of regional myocardial fatty acid uptake patterns by SPECT.

Effects of fasting on the myocardial subcellular distribution and lipid distribution of terminal p-iodophenyl-substituted fatty acids in rats

The myocardial lipid pool distribution and subcellular distribution of radiolabeled methyl-branched fatty acids in rats was evaluated under conditions of fasting (24 h) and feeding. With the unbranched iodophenyl fatty acid, fasting resulted in increased myocardial extraction and clearance time with a decrease in the incorporation into triglycerides and greater radioactivity in the mitochondrial fraction. With the monomethyl-branched analogue, the effects of fasting on lipid and subcellular distribution were minor except for a decrease in triglyceride incorporation. Like the unbranched analogue, the dimethyl-branched iodophenyl fatty acid showed increased myocardial extraction with fasting, however, this structurally-modified fatty acid showed increased rather than decreased incorporation into triglycerides.

Evaluation of the metabolism in rat hearts of two new radioiodinated 3-methyl-branched fatty acid myocardial imaging agents

The biological fate of two new radioiodinated 3-methyl-branched fatty acids has been evaluated in rat hearts following intravenous administration. Methyl-branching was introduced in [15-(p-iodophenyl)-3-R,S-methylpentadecanoic acid (BMIPP) and 15-(p-iodophenyl)-3,3-dimethylpentadecanoic acid (DMIPP) to inhibit beta-oxidation. The goals of these studies were to correlate the effects of methyl-branching on the incorporation of these agents into the various fatty acid pools and subcellular distribution profiles, and to relate these data to the myocardial retention properties. The properties of BMIPP and DMIPP were compared with the 15-(p-iodophenyl)pentadecanoic acid straight-chain analogue (IPP). Differences in the heart retention of the analogues after intravenous administration in rats correlated with differences observed in subcellular distribution patterns. The dimethyl DMIPP analogue showed the longest retention and the highest association with the mitochondrial and microsomal fractions (34%, 38%) 30 min after injection. These data are in contrast to the rapid clearance of the straight-chain IPP analogue which showed much lower relative association with the mitochondria and microsomes (18%, 15%). The distribution patterns of each analogue in the various lipid pools appeared consistent with the expected capacity of the analogues to be metabolized by beta-oxidation. In contrast to the rapid oxidation of the straight-chain IPP analogue, the 3-monomethyl BMIPP analogue appeared to undergo slower oxidation and clearance, whereas the dimethyl-branched DMIPP analogue was apparently not catabolized by the myocardium. All three analogues showed some incorporation into triglycerides. The metabolism patterns of the branched analogues reported here may provide useful information in the description of the mechanisms by which BMIPP and DMIPP are retained in rat myocardium.

Effect of 3-methyl-branching on the metabolism in rat hearts of radioiodinated iodovinyl long chain fatty acids

The metabolism of two new 3-methyl-branched iodovinyl fatty acids in rat hearts was evaluated by determining the subcellular and lipid pool distribution of these radiolabeled analogues after intravenous injection. Methyl branching had been introduced into the straight chain analogue, 19-iodo-18-nonadecenoic acid (IVN), to produce the monomethyl analogue, 19-iodo-3-(R,S)-methyl-18-nonadecenoic acid (BMIVN) and the dimethyl derivative, 19-iodo-3,3-dimethyl-18-nonadecenoic acid (DMIVN) in the hope of inhibiting beta oxidation. Since the presence of 3-methyl branching results in delayed myocardial clearance in rats, differences were sought in the lipid and subcellular distribution of these branched analogues that might correlate with the prolonged retention and reflect differences in metabolism. Hearts of rats injected intravenously with the radiolabeled fatty acids were removed and homogenized and the homogenates partitioned between the chloroform-methanol (organic) fraction and the aqueous fraction. Comparison of the distribution of radioactivity between the organic and aqueous fractions showed that most of the DMIVN and BMIVN activity was in the organic fraction with IVN activity initially divided equally between the two fractions. Identification of the lipid components of these organic fractions showed that there was slow incorporation of DMIVN into the triglyceride and polar lipid fractions with a slow loss from the free fatty acid fraction. With the straight chain IVN analogue which shows rapid washout from rat hearts, there was loss of activity from all 3 lipid components during the 60 min. The monomethyl branched BMIVN analogue demonstrated predominant storage in the polar lipid fraction with some incorporation into triglycerides.(ABSTRACT TRUNCATED AT 250 WORDS)

New radioiodinated methyl-branched fatty acids for cardiac studies

The effects of 3-methyl substitution on the heart retention and metabolism of 3-R,S-methyl-(BMIPP) and 3,3-dimethyl-(DMIPP) analogues of 15-(p-iodophenyl)-pentadecanoic acid (IPP) were studied in rats. Methyl substitution considerably increased the myocardial half-time values in fasted rats: IPP, 5-10 min; BMIPP, 30-45 min; DMIPP, 6-7 h. Because of the observed differences in the relative myocardial uptake and retention of these agents, an evaluation of the subcellular distribution profiles and the distribution of radioactivity within various lipid pools extracted from cell components was performed. Studies with DMIPP in food-deprived rats have shown high levels of the free fatty acid and only slow conversion to triglycerides. These data are in contrast to the rapid clearance of the straight chain IPP analogue and rapid incorporation into triglycerides, and suggest that the prolonged myocardial retention observed with DMIPP in vivo may result from inhibition of beta oxidation. Subcellular distribution studies have shown predominant association of DMIPP and BMIPP with the mitochondrial and microsomal fractions, while IPP was primarily found in the cytoplasm. Because of the unique "trapping" properties and the high heart:blood ratios, [123I]DMIPP should be useful for evaluation of aberrations in regional myocardial uptake.

Potential tissue-imaging agents: 23-(trimethyl [117mSn]stannyl)-24-nor-5 alpha-cholan-3 beta-ol

Tin-117m-labeled 23-(trimethylstannyl)-24-nor-5 alpha-cholan-3 beta-ol (2) has been prepared by reaction of trimethyl [117mSn]tin lithium with 3 beta-acetoxy-23-bromo-24-nor-5 alpha-cholane (1). Tin-117m (2) shows pronounced adrenal uptake (2.5% injected dose) in female rats 1 day after injection. Furthermore, the adrenal to liver (9.1:1) and adrenal to blood (33.7:1) ratios are high after this period. The absorbed radiation dose values from [117mSn]2 to human organs have also been estimated by using rat tissue distribution and excretion data. [117mSn]2 is the first reported tissue-specific organic radiopharmaceutical labeled with this nuclide and may have potential as an adrenal imaging agent.

Effect of cis- and trans-dichlorodiammineplatinum(II) on human tumor cell proliferation in diffusion chambers in vivo

The cis and trans isomers of dichlorodiammineplatinum(II) (DDP) were tested for their ability to inhibit human tumor cell proliferation in vivo. Cell-impermeable diffusion chambers containing KB target cells were surgically implanted in the peritoneal cavities of Fischer rats, which were, 1 day later, given i.p. injections of cis-DDP (0.25 to 8.0 mg/kg), trans-DDP (8.0 mg/kg), or 0.9% NaCl solution. Radiolabeled cis- and trans-[195mPt]DDPs were used to monitor the diffusion of DDP within the chamber fluid and the binding or uptake of DDP by the target cells. Cell counts following injection showed that cis-DDP induced a progressive, dose-dependent loss in cell number so that, by the second day, the chambers of animals receiving cis-DDP (8 mg/kg) contained less than 10% of the cell number found in the control or trans-DDP-treated chambers. Despite the relative lack of biological activity of the transisomer, between 2- and 3-fold greater levels of 195mPt activity were detected in the fluid and target cells in chambers of animals receiving trans-[195mPt[DDP compared to cis-[195mPt]-DDP injected animals. Scanning electron micrographs of target cells from cis-DDP treated rats showed certain morphological features (cell surface blebs and the appearance of giant cells) that were not found in control target cell populations. The diffusion chamber system was shown to be a reproducible, sensitive assay system which differentiated between cis-DDP, a potent antitumor drug, and trans-DDP, a biologically ineffective isomer. In addition, it was possible using 195mPt-labeled DDP in this assay system to quantitate the relative concentrations of the two isomers both surrounding and within the target cells.

Effects of chain length and tellurium position on the myocardial uptake of Te-123m fatty acids

A series of Te-123m-labeled fatty acids has been synthesized and studied in rats. In the series of compounds studied, the position of the Te-123m heteroatom was not as important as the total chain length, which dramatically affected the heart uptake. Five minutes after injection, significant heart uptake (1.7-2.3% of injected dose) was observed for agents with C15, C17, and C21 chain lengths, in which Te-123m replaced a methylene group in either the 6, 9, 11, or 17 positions, and the heart-to-blood ratios were high. An important observation was the prolonged retention of radioactivity for at least one hour after injection. In contrast, agents with shorter C13 chain lengths, with Te-123m in either the 6 or the 9 position, exhibited only low heart uptake (0.1-0.3% of injected dose).

Potential pancreatic imaging agents. Tellurium-123m labeled DL-alpha-amino-gamma-(phenyltelluro)butyric acid

This report describes the first successful preparation of a 123mTe-labeled alpha-amino acid as a potential pancreatic imaging agent. Tellurium-123m labeled DL-alpha-amino-gamma-(phenyltelluro)butyric acid was prepared by basic hydrolysis of the radiolabeled 5-[beta-(phenyltelluro)ethyl]hydantoin. The hydantoin was prepared by the reacitron of 123mTe-labeled phenyltellurol, generated by sodium borohydride reduction of diphenyl ditelluride, with 5-(beta-bromoethyl)hydantoin. Tissue distribution studies in rats with the 123mTe-labeled amino acid for periods varying from 30 min to 24 h demonstrated only marginal pancreatic accumulation of radioactivity. The significant result of these studies is that a general synthetic method has been developed for the preparation of 123mTe-labeled amino acids.

Radiation dosimetry of two new tellurium- 123m-labeled adrenal-imaging agents: concise communication

The absorbed radiation doses to humans from 23-(isopropyl[123mTe]telluro)-24-nor-5 alpha-cholan-3 beta-ol (Te-123m-23-ITC) and 24-(isopropyl[123mTe]telluro)-chol-5-en-3 beta-ol(Te-123m-24-ITC) have been calculated, based on rat biological data, to assess the relative radiation risks to humans from these two new adrenal-imaging agents. The estimated radiation doses to several critical organs have been compared with dose estimates for a variety of other radiolabeled steroids that have been designed as adrenal-imaging agents. Dose estimates to selected organs from Te-123m-23-ITC are as follows (rad/mCi): adrenals 98; ovaries 8.0; liver 1.6. Similar estimated values for Te-123m-24-ITC are: adrenals 210; ovaries 13; liver 2.0. The radiation dose estimates for these two agents are comparable to the calculated radiation doses from 6 beta-[(methyl[75Se]seleno)methyl]-19-nor-cholest-5(10)-en-3 beta-ol (Scintidren) and 19-[131I]iodocholest-5-en-3 beta-ol (NP-59), two agents currently in clinical use for the diagnosis of adrenal disease.

Tellurium- 123m-labeled 23-(isopropyl telluro)-24-nor-5 alpha-cholan-3 beta-ol: a new potential adrenal imaging agent

Tellurium-123m-labeled 23-(isopropyl telluro)-24-nor-5 alpha-cholan-3 beta-ol (24-telluracholestanol, or 23-ITC) has been prepared as a potential adrenal-imaging agent. The new agent was synthesized by the coupling of 3 beta-acetoxy-23-bromo-24-nor-5 alpha-cholan with Te-123m-labeled sodium isopropyl tellurol. Tissue distribution experiments in both male and female rats indicate a high adrenal concentration of a radioactivity following administration of this agent. In female rats the adrenal glands accumulated 4.5% of the injected radioactivity only 1 day after administration of Te-123m-23-ITC. The adrenal-to-liver ratio was 42 after 1 day, and this increased to 100 after 3 days. Chromatographic analyses of lipid extracts from adrenal, ovary, liver, and lungs suggest that this agent is metabolized by these tissues. Examination of the rats' excretory products has indicated that approximately 50% of the administered radioactivity is excreted in the feces within 5 days after injection of Te-123m-23-ITC. Moreover, the adrenals and ovaries of rats have been clearly imaged with this agent, both with a rectilinear scanner and with an RC type of proportional-counter camera.

Characterization of immune responses to spontaneous hamster lymphomas

Tumor resistance could be induced against the transplantation of cell lines derived from spontaneous lymphomas that occurred in the third of three lymphoma epizootics in a hamster colony. Immunization of normal hamsters with irradiated lymphoma cells promoted resistance to homologous lymphoma challenge and prevented the development of spontaneous lymphomas when immunized hamsters were exposed to the contaminated colony. This immunity could be transferred in an adoptive transfer assay. Resistance to direct challenge was not extended to simian virus 40(SV40)-induced sarcomas carrying SV40 tumor-specific transplantation antigen nor to herpesvirus-induced carcinoma cells, indicating specificity. The nature of the antigen(s) involved was discussed.

An epizootic in hamsters of lymphomas of undetermined origin and mode of transmission

An epizootic of lymphomas arose spontaneously on three occasions in a facility containing both inbred and randombred Syrian hamsters. These tumors developed in approximately half the colony-born hamsters and were horizontally transmissible to those brought into the colony.

Forssman antigen and phase specific fetal antigens: an evaluation of their role in SV40 tumor immunity

Forssman heterophile antigen was detected on hamster fetal cells which had been previously shown to be capable of eliciting transplantation resistance to syngeneic hamster SV40 tumors. The expression of Forssman antigen continued throughout fetal development and could be detected postpartum in the tissues of neonate hamsters. In contrast, fetal antigen(s) evoking immunity to SV40 tumors was also present on early fetal cells but, unlike Forssman antigen, was not expressed after the tenth day of gestation. Immunization of hamsters with guinea pig kidney cells or sheep erythrocytes which carry Forssman antigen failed to demonstrate significant protection against SV40 tumor development. Again by contrast, immunization with fetal cells was effective in evoking tumor immunity. Evaluation of serological responses to the FORSSMAN A ANTIGEN IN HAMSTERS INDICATED THAT THE HEMOLYTIC REACTIVITY PRODUCED BY IMMUNIZATION WITH GUINEA PIG KIDNEY CELLS OR SHEEP ERYTHROCYTES WAS ELICITED AGAINST ISOANTIGENS AND NOT THE Forssman antigen. A response to the Forssman determinant could only be detected in the serum from animals receiving exhaustive hyperimmunization with fetal cells or SV40 tumor cells. These data would eliminate a possible role of the Forssman heterophile antigen in the tumor protection evoked by immunization with fetal cells bearing embryonic antigens.