A novel process for H&E, immunofluorescence, and imaging mass cytometry on a single slide with a concise analytics pipeline

Imaging mass cytometry (IMC) is a powerful spatial technology that utilizes cytometry time of flight to acquire multiplexed image datasets with up to 40 markers, via metal-tagged antibodies. Recent advances in IMC have led to the inclusion of RNAScope probes and multiple new analysis pipelines have led to faster analyses and better results. However, IMC still suffers from lower resolution (1 μm2 pixels) and relatively small regions of interest (ROIs) (<2 mm2 ) compared to other, light-based microscope technologies. Capturing higher-resolution images on serial sections causes great difficulty when attempting to align cells and structures across serial sections, especially when observing smaller cell types and structures. Therefore, we demonstrate the combination of H&E and multiplex immunofluorescence imaging, for much higher resolution of the structural and cellular compartments found throughout the entire tissue section, with the high-dimensionality of IMC for specific ROIs on a single slide. Additionally, we demonstrate a simple and effective open-source cell segmentation and IMC analysis pipeline with previously published and freely available software.

Imaging mass cytometry reveals tissue-specific cellular immune phenotypes in the mouse knee following ACL injury

Objective

To develop an imaging mass cytometry method for identifying complex cell phenotypes, inter-cellular interactions, and population changes in the synovium and infrapatellar fat pad (IFP) of the mouse knee following a non-invasive compression injury.

Design

Fifteen male C57BL/6 mice were fed a high-fat diet for 8 weeks prior to random assignment to sham, 0.88 ​mm, or 1.7 ​mm knee compression displacement at 24 weeks of age. 2-weeks after loading, limbs were prepared for histologic and imaging mass cytometry analysis, focusing on myeloid immune cell populations in the synovium and IFP.

Results

1.7 ​mm compression caused anterior cruciate ligament (ACL) rupture, development of post-traumatic osteoarthritis, and a 2- to 3-fold increase in cellularity of synovium and IFP tissues compared to sham or 0.88 ​mm compression. Imaging mass cytometry identified 11 myeloid cell subpopulations in synovium and 7 in IFP, of which approximately half were elevated 2 weeks after ACL injury in association with the vasculature. Notably, two monocyte/macrophage subpopulations and an MHC IIhi population were elevated 2-weeks post-injury in the synovium but not IFP. Vascular and immune cell interactions were particularly diverse in the synovium, incorporating 8 unique combinations of 5 myeloid cell populations, including a monocyte/macrophage population, an MHC IIhi population, and 3 different undefined F4/80+ myeloid populations.

Conclusions

Developing an imaging mass cytometry method for the mouse enabled us to identify a diverse array of synovial and IFP vascular-associated myeloid cell subpopulations. These subpopulations were differentially elevated in synovial and IFP tissues 2-weeks post injury, providing new details on tissue-specific immune regulation.

Closing the theory to practice gap for newly qualified doctors: evaluation of a peer-delivered practical skills training course for newly qualified doctors in preparation for clinical practice

PURPOSE

The Good Intern Programme (GIP) in Sri Lanka has been implemented to bridge the 'theory to practice gap' of doctors preparing for their internship. This paper evaluates the impact of a 2-day peer-delivered Acute Care Skills Training (ACST) course as part of the GIP.

STUDY DESIGN

The ACST course was developed by an interprofessional faculty, including newly graduated doctors awaiting internship (pre-intern), focusing on the recognition and management of common medical and surgical emergencies. Course delivery was entirely by pre-intern doctors to their peers. Knowledge was evaluated by a pre- and post-course multiple choice test. Participants' confidence (post-course) and 12 acute care skills (pre- and post-course) were assessed using Likert scale-based questions. A subset of participants provided feedback on the peer learning experience.

RESULTS

Seventeen courses were delivered by a faculty consisting of eight peer trainers over 4 months, training 320 participants. The mean (SD) multiple choice questionnaire score was 71.03 (13.19) pre-course compared with 77.98 (7.7) post-course (p<0.05). Increased overall confidence in managing ward emergencies was reported by 97.2% (n=283) of respondents. Participants rated their post-course skills to be significantly higher (p<0.05) than pre-course in all 12 assessed skills. Extended feedback on the peer learning experience was overwhelmingly positive and 96.5% would recommend the course to a colleague.

CONCLUSIONS

A peer-delivered ACST course was extremely well received and can improve newly qualified medical graduates' knowledge, skills and confidence in managing medical and surgical emergencies. This peer-based model may have utility beyond pre-interns and beyond Sri Lanka.

Patient and system factors of mortality after hip fracture: a scoping review

Background

Several patient and health system factors were associated with the risk of death among patients with hip fracture. However, without knowledge of underlying mechanisms interventions to improve survival post hip fracture can only be designed on the basis of the found statistical associations.

Methods

We used the framework developed by Arksey and O’Malley and Levac et al. for synthesis of factors and mechanisms of mortality post low energy hip fracture in adults over the age of 50 years, published in English, between September 1, 2009 and October 1, 2014 and indexed in MEDLINE. Proposed mechanisms for reported associations were extracted from the discussion sections.

Results

We synthesized the evidence from 56 articles that reported on 35 patient and 9 system factors of mortality post hip fracture. For 21 factors we found proposed biological mechanisms for their association with mortality which included complications, comorbidity, cardiorespiratory function, immune function, bone remodeling and glycemic control.

Conclusions

The majority of patient and system factors of mortality post hip fracture were reported by only one or two articles and with no proposed mechanisms for their effects on mortality. Where reported, underlying mechanisms are often based on a single article and should be confirmed with further study. Therefore, one cannot be certain whether intervening on such factors may produce expected results.

HIV/AIDS, STIs and condom use beliefs among male prison inmates in two South African provinces: Mpumalanga and KwaZulu-Natal

The purpose of this study was to describe the characteristics of a random sample of prison inmates from two provinces in South Africa with respect to correct knowledge regarding HIV/AIDS and sexual transmitted infection (STI) risk and beliefs about condom use. This cross-sectional descriptive study of 357 prison inmates formed part of a larger longitudinal investigation designed to implement a health education intervention for prison inmates in the KwaZulu-Natal (KZN) and Mpumalanga (MP) provinces of South Africa. Mean differences for groups were compared across sites using Analysis of Variance (ANOVA). Inmates from KZN were less likely to agree that 'It is important to use condoms every time you have sex' F (1355) = 25.8, p<0.0001 when compared with inmates in MP. However, they were more likely to agree that 'Condoms work well to prevent the spread of HIV' F (1355) = 11.7, p<0.001; 'Condoms also prevent pregnancy' F (1355) = 5.1, p<0.05. Overall, the demonstrated differences in condom use behaviour suggested that future prevention efforts focus on the importance of using condoms to prevent the spread of HIV/AIDS and other STIs.

Tattooing and body piercing among adolescent detainees: relationship to alcohol and other drug use

PURPOSE

The purpose of this preliminary study was to document self-reported tattooing and body piercing behavior among a sample of 860 adolescent detainees. Additionally, the study examined the relationship of alcohol and drug use to tattooing and body piercing--an often overlooked HIV risk behavior.

METHODS

Adolescents (N = 860) participating in a substance use and HIV risk reduction intervention were surveyed upon entrance to a Youth Development Campus (YDC).

RESULTS

Twenty-nine percent of the sample (N = 245) had at least one tattoo, and more than half (69%) had at least one body piercing. Fifteen percent had two or more tattoos, while 28% had three or more piercings. Although a small percentage of the youth reported knowingly sharing needles for tattoos or piercings (2% and 1.5%, respectively), 21% had tattoos that had been administered unprofessionally and 20% had unprofessionally administered piercings. Marijuana and alcohol were the highest reported substances used in this sample, 62% and 54%, respectively. Alcohol, marijuana, antidepressants, and sedatives were significant correlates of having tattoos. Alcohol was found to be a marginally significant (P = .052) correlate of body piercing.

CONCLUSION

The popularity of tattooing and piercing and the risk involved with these activities make them an HIV risk behavior worthy of address. Risk reduction messages to youth should consistently address these behaviors and focus on them as they relate to substance use.

Comprehensive tobacco control policies and the smoking behaviour of Canadian adults

OBJECTIVE

To examine the associations of cigarette prices, restrictions on public smoking, and health education with the odds of adult smoking and amount smoked daily.

DESIGN

Multi-level analysis of adult (age 25+) smoking patterns in Canada's National Population Health Survey, after adding administrative data on prices, bylaws, and health education according to the survey respondent's place of residence.

SETTING/SUBJECTS

Population based sample of Canadians age 25+ in households (n = 14 355).

OUTCOME MEASURES

Smoking status, amount consumed daily.

ANALYSIS

Logistic regression for smoking status, multiple regression for amount smoked, with controls for age, education, marital status; separate analyses for men and women.

RESULTS

Cigarette prices were positively associated with the odds of being a non-smoker and negatively with amount smoked, for adults of both sexes. Per capita health education expenditures were positively associated with the odds of being a non-smoker and negatively with amount smoked--for men but not women. The restrictiveness of municipal bylaws limiting public smoking was positively associated with the odds of being a non-smoker and negatively with amount smoked--for women but not men. These results are independent of age, education, and marital status.

CONCLUSIONS

To be effective, tobacco control must comprise a mix of strategies as men and women respond differently to health education and restrictions on public smoking; taxation, reflected in higher cigarette prices, is the only one of these measures related to smoking for both sexes. This model permits calculations of the level of increase in each measure that is required to reduce the prevalence of smoking by a specified amount.

Apolipoprotein E: possible therapeutic target for atherosclerosis

Human apolipoprotein E (apoE) consists of a single polypeptide chain with 299 amino acids and is best known for its role in the transport of cholesterol and other lipids between peripheral tissues and the liver. However, more direct effects of apoE on the vascular wall may well contribute to arterial protection from atherosclerosis. This review will focus on: (a) the ability of apoE to direct cholesterol efflux mechanisms with the aid of apoA1 and the ATP binding cassette transporter 1 (ABC1); (b) the ability of apoE to prevent platelet aggregation by facilitating the production of endogenous nitric oxide (NO); (c) the ability of apoE to inhibit the proliferation of T-lymphocytes by internalization of the IL-2 receptor; and (d) the ability of apoE to inhibit proliferation of endothelial cells by out competing growth factors for interaction with cell surface heparan sulfate proteoglycans (HSPG's). The characterization of apoE and its many functions has provided insight into the ultimate potential of this protein as a possible therapeutic agent for the treatment of atherosclerosis. This review will examine key scientific advances, which focus on possible therapeutic strategies that encompass the use of apoE in the amelioration of atherosclerosis.

The economic burden of mental health problems in Canada

This study provides a comprehensive estimate of the economic burden of mental health problems in Canada in 1998. In particular, it estimates the cost of non-medical services that have not been previously published and the value of short-term disability associated with mental health problems that were previously underestimated according to the definitions used here. The costs of consultations with psychologists and social workers not covered by public health insurance was $278 million, while the value of reduced productivity associated with depression and distress over the short term was $6 billion. Several data limitations suggest that these are underestimates. The estimated total burden of $14.4 billion places mental health problems among the costliest conditions in Canada.

Commentary. monitoring tobacco use in canada: the need for a surveillance strategy

Smoking behaviour has been monitored nationally through population surveys for 35 years in Canada, but these surveys have not been as consistent or rigorous as the magnitude of the smoking problem demands. Inconsistent methods and irregular survey intervals are just two of the characteristics that have made it difficult to know exactly how smoking is changing. Further, an absence of routine data on tobacco control policies (other than the price of cigarettes) has hampered understanding of the determinants of changing prevalence. The advent of two survey series--Canadian Tobacco Use Monitoring Survey (CTUMS) and Canadian Community Health Survey (CCHS) promises to change this situation for the better. We suggest that both are critical elements of a national smoking surveillance system and that, with a commitment to CTUMS in particular, Health Canada could set a new international standard for surveillance.

School-based smoking prevention: economic costs versus benefits

The objective of this study was to conduct a cost-benefit analysis to compare the costs of developing and delivering an effective school-based smoking prevention program with the savings to be expected from reducing the prevalence of smoking in the Canadian population over time. A smoking prevention program that meets published criteria for effectiveness, implemented nationally in Canada, would cost $67 per student (1996 dollars). Assuming such a program would reduce smoking by 6% initially and 4% indefinitely, lifetime savings on health care would be $3,400 per person and on productivity, almost $14,000. The benefit-cost ratio would be 15.4 and the net savings $619 million annually. Sensitivity analyses reveal that considerable economic benefits could accrue from an effective smoking prevention program under a wide range of conditions.

Risks associated with tattooing and body piercing

The purpose of this article is to highlight the importance of including cosmetic body-piercing and tattooing in HIV prevention and education. Little information about risks associated with tattoos or having one's body pierced is evident in the health promotion and disease prevention literature, particularly among adolescents, ethnic groups, and incarcerated populations. It is incumbent that preventionists address behaviors such as tattooing and body piercing as possible vectors for HIV transmission in addition to typical concerns (homosexuality, i.v. drug use, condom use and safer sex practices). This article draws attention to the need for formation of regulatory policy issues related to body piercing and tattooing parlors. Currently, 26 percent of the states have regulatory authority over tattooing establishments, while only 4 states exercise such authority over body-piercing establishments. Implications for future research and policy initiatives are identified.

Mental health of the Canadian population: a comprehensive analysis

This study examines eight measures of mental health and looks for associations with nine potential demographic and psychosocial determinants. Data from the National Population Health Survey (NPHS), analyzed by logistic regression, reveal consistently strong, graded, independent associations of current stress, social support, life events, education and childhood traumas with both positive and negative indicators of mental health status. Sex differences exist for four of eight measures. For most indicators, mental health is relatively poor among youth and improves with age. Physical and mental health problems are associated. There is no independent relation between mental health and income adequacy or province of residence. Two measures used in several previous Canadian surveys are recommended for inclusion in the NPHS to better monitor population mental health.

Predictors of homelessness among participants in a substance abuse treatment program

Risk factors for homelessness were examined prospectively among recent participants in a substance abuse treatment program. Low levels of support from friends, greater depression, and recent substance use were bivariately associated with homelessness two months following completion of the program. However, friend support was the only factor associated with homelessness after controlling for other significant bivariate predictors.

Transsexual orientation in HIV risk behaviours in an adult male prison

The present study examined the consequences of being a self-reported transsexual male and HIV risk behaviours in a state penal system. The specific research question was whether or not sexual orientation of inmates influences the level to which they evidence HIV risk behaviours. A total of 153 participants volunteered to participate in the study of which 31 described themselves as being transsexual. Based on risk ratios and using transsexual inmates (TIs) as the reference group, they were 13.7 times more likely to have a main sex partner while in prison [95% CI=5.28, 35.58]. Moreover, TIs were 5.8 times more likely than non-transsexual inmates (NTIs) to report having more than one sex partner while in prison [95% CI=2.18, 15.54]. It is obvious from these findings that TIs require more preventive support than their NTI confederates. In addition to TIs being protected from assault and battery by NTIs, they need social support and carefully developed preventive informational materials.

Dynamic positron emission tomography with F-18 fluorodeoxyglucose imaging in differentiation of benign from malignant lung/mediastinal lesions

PURPOSE

This study was done to evaluate the diagnostic utility of dynamic positron emission tomography (PET) with F-18 fluorodeoxyglucose (FDG) imaging in patients with suspected malignant pulmonary lesions. We wanted to test the hypothesis that the rate of FDG uptake (FDG influx constant values) would differentiate malignant from benign lung or mediastinal lesions.

MATERIALS AND METHODS

We performed segmental dynamic PET imaging studies following administration of FDG in 19 patients with indeterminate pulmonary lesions based on chest radiograph and/or CT scans. Patlak analysis was done to compute Ki (FDG influx constant) values and compared with FDG standardized uptake values (SUVs) and histology.

RESULTS

FDG Ki values (mean+/-SD) were significantly greater (p < 0.01) in all 12 malignant lesions (0.029+/-0.02) as compared with 7 benign lesions (0.0024+/-0.0011) with good correlation to the SUV values. Distinct time activity curve patterns were identified in malignant and benign lesions with continued uptake in malignant lesions.

CONCLUSION

Dynamic PET-FDG imaging accurately differentiates malignant from benign pulmonary lesions. In certain cases with equivocal findings on visual analysis and SUV values, dynamic imaging may be further helpful in differentiating benign and malignant lesions.

Model for using hip-hop music for small group HIV/AIDS prevention counseling with African American adolescents and young adults

Currently little attention has been directed, with the exception of peer education efforts, to constructively develop new and innovative ways to promote HIV/AIDS primary prevention among African American (AA) adolescents and young adults. With this in mind, the aim of this conceptual effort is to present a HIV/AIDS preventive counseling protocol developed for use with AA young adults that makes use of hip-hop music, a form of music popularized by young AAs. The author contend that an increased understanding of the relationships that many AA young adults have with hip-hop music may be used by disease prevention personnel to educate these populations about protective factors for HIV. Making use of hip-hop music is one strategy for integrating counseling in prevention and health maintenance. The overall implications of using hip-hop music in health promotion are unlimited. First, this method makes use of cultural relevant materials to address the educational and health needs of the target community. Second, it is grounded in an approach that serves to stimulate cooperative learning based on peer developed content. Moreover, the use of this medium can be applied to other health promotion activities such as violence/harm reduction and substance abuse prevention, upon reviews of songs for appropriate content. The authors contend that such an approach holds heuristic value in dealing with HIV/AIDS prevention among AA young adults. Additional testing of the intervention is warranted in the refinement of this innovative intervention.

A relevant dose of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone is extensively metabolized and rapidly absorbed in the canine tracheal mucosa

Lung cancer is largely a site-of-entry disease caused by inhaled carcinogenic agents, especially tobacco smoke. Two major groups of procarcinogens, tobacco-specific nitrosamines and polycyclic aromatic hydrocarbons, are putative agents, but their relative contributions are disputed. An important indicator of relative potency for these compounds is the dose to the target epithelial cells. Although we have reported the dose of polycyclic aromatic hydrocarbons to the canine tracheal epithelium [Gerde et al., Carcinogenesis (Lond.), 18: 1825-1832, 1997; Gerde et al., Carcinogenesis (Lond.), in press, 1998], the purpose of the current study was to characterize the absorption and metabolism of low levels of one tobacco-specific nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), in the canine trachea. One hundred ng of tritiated NNK were instilled in the distal trachea of the dog. Blood was repeatedly sampled from the azygous vein and both sides of the systemic circulation from 15 s to 30 min after instillation. Tissues were then removed and analyzed for the tritiated NNK and its metabolites. Autoradiography was used to determine the depth distribution of tritium in the tracheal mucosa. Most NNK appeared rapidly in the blood draining the airway mucosa, but there was also a slow clearance phase. During absorption, NNK was distributed within the entire depth of the mucosa to the tracheal cartilage; however, a portion was conspicuously bound to the mucin component of the mucous lining layer. Reversible binding to mucin may be largely responsible for the slow clearance phase. Despite the rapid absorption of most of the tritium, NNK was nonetheless extensively metabolized in the tracheal mucosa. Systemic metabolism was also rapid: within 18 min of instillation, the NNK parent compound had disappeared from the systemic circulation, and 45 min after instillation, no NNK was found in the trachea or any distal tissue. Although the rapid absorption and distribution of NNK and its metabolites ensured widespread and extensive distal binding in all tissues, first-pass metabolism and activation of NNK in the airway mucosa were sufficiently rapid to cause levels of binding at the site of absorption to be approximately 20-fold those of distal tissues. NNK may thus act as a site-of-entry carcinogen. This observation may be important in estimating the contribution of NNK to lung cancer relative to other carcinogens and for explaining increased incidences of oral cancers in users of snuff and chewing tobacco in which NNK is present in high concentrations.

Comparison of plasma and tissue levels of ZD1694 (Tomudex), a highly polyglutamatable quinazoline thymidylate synthase inhibitor, in preclinical models

ZD1694 (Tomudex, raltitrexed) is a specific quinazoline antifolate thymidylate synthase inhibitor that relies on polyglutamation for high potency. Antibodies to ZD1694 have been used to establish a sensitive radioimmunoassay as an alternative to high-performance liquid chromatography (HPLC). The radioimmunoassay is reproducible, accurate and provides a means of determining low levels of ZD1694 in plasma (< 1 nM). By virtue of the high cross-reactivity of the antibodies with polyglutamated forms of ZD1694, it is also possible to measure the total concentration of drug in tissues. Results obtained in L1210 mouse leukaemia cells and in mouse tissues were similar to those previously determined using radiolabelled drug. Pharmacokinetic studies in mice have confirmed that the compound is rapidly eliminated from the plasma and that there is a prolonged terminal elimination phase. ZD1694 was measured in plasma (0.56 ng ml(-1); 1.2 pmol ml(-1)) up to 7 days after a single i.p. dose of 100 mg kg(-1) ZD1694. Liver, kidney and gut epithelium had a substantially higher level of ZD1694 immunoreactivity than plasma. For example, 24 h after a single i.p. dose at 1, 10 and 100 mg kg(-1), total drug levels in the liver were 480, 325 and 152 times higher than plasma levels respectively. In kidney and gut epithelium, total drug levels at these doses were approximately 55 and 34 times those of plasma. The high tissue to plasma ratios were maintained for at least 7 days after administration. Similarly, high tissue to plasma ratios (> 100) were found in dogs treated with a clinically relevant dose of ZD1694. These were maintained for 4 weeks in liver and kidney tissue (> 100). Total gastrointestinal concentrations of ZD1694 were approximately 10 times higher than plasma 3 days after administration, but levels were near to the limit of detection at 4 weeks. These results are consistent with extensive polyglutamation of ZD1694 within tissues in both mice and dog and provide further support for the infrequent schedule that has been used clinically. Although it has not been possible to measure individual polyglutamated forms of ZD1694, the radioimmunoassay provides a convenient means of assessing total drug levels in tissues and is currently the only method suitable for measuring the extent of drug retention in normal tissue and tumour biopsies obtained from patients treated with ZD1694.

The relationship of cigarette prices and no-smoking bylaws to the prevalence of smoking in Canada

OBJECTIVES

The aim of this study was to analyze the association of cigarette prices and no-smoking bylaws with the prevalence of smoking.

METHODS

Data on individual smoking status were taken from two national household surveys in Canada. Current cigarette price, the 1-year and 10-year increase in price, and the extent of local restrictions on public smoking were added to the model. Logistic regression was used to estimate the odds of being a smoker.

RESULTS

The odds ratio for being a smoker was 1.21 where no-smoking by-laws were relatively infrequent and 1.26 when cigarettes were relatively inexpensive, after adjusting for individual age, sex, education, and marital status.

CONCLUSIONS

Both cigarette prices and no-smoking bylaws are effective in controlling smoking; either alone will likely have less impact than the two measures together.

Phototoxic reactions caused by sodium fluorescein

PURPOSE

To report three cases of phototoxic reactions to intravenous fluorescein for retinal angiography and to describe provocative testing in a volunteer.

METHODS

Three patients with phototoxic reactions were interviewed, and one volunteer underwent a controlled challenge test by applying a potent sunscreen and exposing skin areas to direct sunlight before and after fluorescein administration.

RESULTS

All patients experienced marked cutaneous erythema, edema, and pain to sun-exposed areas within 1 hour of exposure. The reaction faded during a variable period of time, and one case resulted in mild epidermal desquamation and prolonged discomfort. We noted minimal skin changes in the volunteer who was exposed to the sun before fluorescein administration; however, marked blanching erythema and pain were noted after fluorescein administration and sunlight.

CONCLUSIONS

Consistent with its in vitro properties as a photodynamic dye, fluorescein may rarely act as a phototoxic agent in humans at doses employed for fluorescein angiography.

Leptin and thermogenesis in humans

We examined changes in serum leptin concentrations and thermogenesis in 12 healthy men (39 +/- 2 years, BMI 22.8 +/- 0.3 kg m-2) during a 4 h euglycaemic hyperinsulinaemia performed on a control day and after a day of competitive marathon runs. As compared with the control day, after the marathon, baseline FFA concentration (543 +/- 0.73 vs. 955 +/- 96 mumol L-1, P < 0.05), lipid oxidation rate (0.8 +/- 0.1 vs. 1.2 +/- 0.1 mg kg-1 min-1, P < 0.01) and energy expenditure (5.2 +/- 0.1 vs. 5.5 +/- 0.1 kJ min-1, P < 0.01) were elevated. Baseline serum leptin concentrations were similar on the control and postexercise days and increased during insulin infusion by 35-45% on both days (P < or = 0.01). Baseline serum leptin concentration correlated directly with serum insulin (r = 0.65, P < 0.05) and cortisol (r = 0.64, P < 0.05), and inversely with serum growth hormone concentration (r = -0.66, P < 0.05). In the postexercise study, the rise in energy expenditure during insulin clamp correlated with serum leptin concentration as determined before (r = 0.61, P < 0.05) or at the end of insulin infusion (r = 0.55, P < 0.05). Thus, in healthy individuals with normal body weight: (1) hyperinsulinaemia increases serum leptin concentrations; (2) a rise in energy expenditure correlates with serum leptin concentration. These data suggest that leptin is involved in the regulation of energy expenditure in humans.

Serum leptin concentration and fuel homeostasis in healthy man

We studied the interrelationship between the obese gene product serum leptin, insulin and counter-regulatory hormone concentrations and glycogen synthesis in 26 healthy men. A 4-h euglycaemic insulin clamp with muscle biopsies was performed after a resting control day in 26 subjects, and in 14 of them also after heavy, glycogen-depleting (32%, P < 0.01) exercise. Serum leptin concentrations were at baseline 34% (0.67 +/- 0.18 vs. 1.03 +/- 0.13 ng L-1, P < 0.05) lower after the exercise, and rose during hyperinsulinaemia by 56% (to 1.38 +/- 0.19 ng L-1, P < 0.001) and 34% (to 1.05 +/- 0.20 ng L-1, P < 0.01) after the post-exercise and control studies respectively. Basal serum leptin concentration correlated positively with body mass index (r = 0.42, P < 0.05), serum cortisol concentration (r = 0.70, P < 0.001) and the rise in muscle glycogen content during the clamp (r = 0.43, P < 0.05) and inversely with serum growth hormone concentration (r = -0.43, P < 0.05). There was a positive correlation between serum leptin after hyperinsulinaemia and serum insulin concentration during the hyperinsulinaemia (r = 0.42, P < 0.05). After exercise, basal serum leptin level correlated with serum triglyceride concentration (r = 0.82, P < 0.001) and after hyperinsulinaemi serum leptin correlated positively with muscle glycogen content (r = 0.56, P < 0.05). It was concluded that serum leptin concentrations correlate directly with serum insulin, cortisol and triglyceride and inversely with growth hormone concentrations. They are decreased by glycogen-depleting exercise and increase during hyperinsulinaemic clamp. These data suggest that leptin is associated with factors regulating fuel homeostasis and its hormonal control in man.

Using pretreatment and posttreatment assessments to enhance and evaluate existing treatment packages

Pretreatment assessment data were used to enhance an existing treatment package to reduce aggression and to increase positive social interactions between a young boy and his peers. Based on the results of pretreatment assessments, additional reinforcement (differential reinforcement of alternative behavior with adult attention) and punishment (performing a nonpreferred task during time-out) components were added to an existing nonresetting differential reinforcement of other behavior (access to peers unless aggression occurred) plus time-out procedure. A posttreatment component analysis of the additional treatment components indicated that the reinforcement component facilitated positive social interactions and the punishment component suppressed aggression towards peers.

Ultradian oscillations of leptin secretion in humans

We have recently demonstrated the nocturnal increase in leptin secretion in humans. In the present study we have examined the pulsatile pattern of leptin secretion using two different experimental protocols. The first protocol utilized blood samples withdrawn at 30 minute intervals immediately after meals, at 1 hour intervals between meals, and at 2 hour intervals during the night from 4 lean, 11 obese, and 5 obese NIDDM subjects. Analysis of circulating leptin levels by ULTRA algorithmic program and using matched intra-assay coefficient of variations demonstrated 1 to 7 ultradian oscillations with a mean of 3.25 +/- 0.36 (SEM) pulses per 24 hour period (period: 10.0 +/- 1.5 hours; mean relative amplitude: 0.52 +/- 0.06, n = 20). Significant positive correlations were observed for changes in absolute amplitude with body mass index (p < 0.025) and fasting leptin levels (< 0.0001). In the second series of experiments utilizing 15 minute blood sampling from 10 overnight fasted obese subjects (BMI 35.9 +/- 2.0 kg/m2), ultradian oscillations for leptin were more frequent, i.e., 2 to 7 oscillations (4.20 +/- 0.59), over a 12 hour duration (period: 3.44 +/- 0.49; mean relative amplitude: 0.28 +/- 0.03). The number of oscillations over a 12 hour period correlated significantly with BMI (p < 0.001), fasting leptin levels (p < 0.01), and absolute amplitude (p < 0.005) in a 15 minute sampling protocol. In summary, similar to other hormones, ultradian oscillations of leptin are observed in humans, although the physiological significance in relation to obesity or feeding behavior is not yet understood.