Michael E May

Vanderbilt University, Nashville, MI, United States

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Publications (18)52.59 Total impact

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    ABSTRACT: Deleting the tailless (TLX) gene in mice produces a highly aggressive phenotype yet to be characterized in terms of heterozygous animals or neurotransmitter mechanisms. We sought to establish pharmacological control over aggression and study the role of serotonin (5-HT)2A/C receptors in mediating changes in aggression. We analyzed aggression in mice heterozygous (+/-) or homozygous (-/-) for the TLX gene and wild-types (+/+) using a resident-intruder paradigm. No +/+ mice were aggressive, 36% of +/- TLX and 100% of -/- TLX mice showed aggression. Dose-effect functions were established for clozapine (0.1-1.5mg/kg, ip), ketanserin (0.3-1.25mg/kg, ip), and (±)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane [(±)DOI] (0.5-2.0mg/kg, ip). Injecting clozapine decreased the frequency and duration of attacks for +/- TLX and -/- TLX mice. Clozapine did not decrease grooming in either +/- TLX or -/- TLX mice but may have increased locomotion for -/- TLX mice. Injecting ketanserin, a 5-HT2A/C receptor antagonist, produced differential decreases in frequency and latency to aggression between genotypes and corresponding increases in locomotor behavior. Injecting (±)DOI, a 5-HT2A/C receptor agonist, increased the frequency and duration of attacks, decreased the latency to attacks, and decreased locomotion in +/- and -/- TLX mice. Results of the current study suggest aggression displayed by TLX null and heterozygous mice involves 5-HT2A/C receptors.
    Behavioural brain research 08/2013; · 3.22 Impact Factor
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    ABSTRACT: OBJECTIVE To determine if long-term mortality rates in early-onset insulin-treated diabetes differ by race among adults of similar socioeconomic status.RESEARCH DESIGN AND METHODSA total of 391 (299 African Americans, 92 whites) mostly low-income adults 40-79 years of age with insulin-treated diabetes diagnosed before 30 years of age were recruited from community health centers in the southeast U.S. Cox models were used to estimate hazard ratios (HRs) of all-cause mortality among African Americans compared with whites. Additionally, standardized mortality ratios (SMRs) were used to compare the mortality experience of the individuals with diabetes with both national and general community health center sex- and race-specific population norms.RESULTSMean age at diabetes diagnosis and cohort entry, respectively, was 21 and 50 years in African Americans and 19 and 51 years in whites. During an average of 6.7 years of follow-up, 29% of African Americans and 35% of whites died. In multivariable analysis, no significant mortality difference was observed among African Americans compared with whites (HR 0.83 [95% CI 0.53-1.30]; P = 0.51). Compared with the race-specific U.S. general population, SMRs for those with diabetes were 5.7 in African Americans and 11.7 in whites. However, when compared with the same source population (i.e., the community health center population), SMRs were 3.5 and 3.7 in African Americans and whites, respectively.CONCLUSIONS Elevated mortality persists in men and women with long duration of early-onset insulin-treated diabetes, but given survival to 40 years of age and similarly low economic status and access to health care, our data do not suggest a racial disparity in mortality.
    Diabetes care 07/2013; · 7.74 Impact Factor
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    ABSTRACT: OBJECTIVE To estimate mortality rates and risk factors for mortality in a low-socioeconomic status (SES) population of African Americans and whites with diabetes. RESEARCH DESIGN AND METHODS We determined mortality among African Americans and whites aged 40-79 years with (n = 12,498) and without (n = 49,914) diabetes at entry into a cohort of participants recruited from government-funded community health centers. Multivariable Cox analysis was used to estimate mortality hazard ratios (HRs) (95% CI) among those with versus those without diabetes and among those with diabetes according to patient characteristics. RESULTS During follow-up (mean 5.9 years), 13.5% of those with and 7.3% of those without diabetes died. All-cause mortality risk was higher among those with versus without diabetes for both African Americans (HR 1.84 [95% CI 1.71-1.99]) and whites (1.80 [1.58-2.04]), although among those with diabetes, mortality was lower among African Americans than whites (0.78 [0.69-0.87]). Mortality risk increased with duration of diabetes and was greater among patients on insulin therapy and reporting histories of cardiovascular disease (CVD), hypertension, and stroke. The HRs associated with these multiple risk factors tended to be similar by sex and race, with the exception of a differentially higher impact of prevalent CVD on mortality among African Americans (interaction P value = 0.03), despite a lower baseline prevalence of CVD. CONCLUSIONS In this population with similarly low SES and access to health care, strong and generally similar predictors of mortality were identified for African Americans and whites with diabetes, with African Americans at a moderately but significantly lower mortality risk.
    Diabetes care 08/2012; 35(11):2293-9. · 7.74 Impact Factor
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    ABSTRACT: In young-onset diabetes, insulin therapy status is a rough marker of diabetes type. We describe the mortality experience of a low-income, predominantly minority population with diabetes diagnosed before age 30 years, stratified by insulin therapy. A total of 1,098 adults aged 40-79 years (median 49) diagnosed with diabetes before age 30 years and 49,914 without diabetes were recruited from community health centers. Individuals with diabetes were categorized by insulin therapy at baseline: group A, insulin therapy only; group B, insulin therapy and an oral hypoglycemic agent; and group C, no insulin therapy. Cox models were used to compute hazard ratios (HRs) and 95% CI for cause-specific mortality based on both underlying and contributing causes of death from death certificates. During follow-up (mean 3.9 years), 15.0, 12.5, and 7.3% of groups A, B, and C, respectively, and 4.6% without diabetes died. Compared with individuals without diabetes, HRs (CI) for all-cause mortality were 4.3 (3.4-5.6), 4.2 (2.8-6.3), and 2.0 (1.4-2.8) in groups A, B, and C, respectively. The leading cause of death was renal failure (end-stage renal disease [ESRD]) in group A, ESRD and coronary artery disease (CAD) in group B, and CAD in group C and individuals without diabetes. HRs for these conditions were at least twice as high as the HRs for all-cause mortality, reaching 17.3 (10.2-29.3), 17.9 (8.3-38.7), and 5.1 (2.3-11.7) in groups A, B, and C, respectively, for ESRD. Excess mortality persists among people with young-onset diabetes of long duration, with ESRD and CAD as the leading contributors to mortality.
    Diabetes care 03/2012; 35(3):542-8. · 7.74 Impact Factor
  • Michael E May
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    ABSTRACT: From an applied behavior-analytic perspective, aggression in people with intellectual disabilities is mostly maintained by social reinforcement consequences. However, nonsocial consequences have also been identified in functional assessments on aggression. Behaviors producing their own reinforcement have been labeled "automatic" or "nonsocial" in the behavior-analytic literature, a label that bares a striking resemblance to biobehavioral explanations of reward-seeking behaviors. Biobehavioral studies have revealed that aggression activates the same endogenous brain mechanisms as primary reinforcers like food. Therefore, integrating brain-environment explanations would result in a better understanding of the functional mechanisms associated with nonsocial aggression. The purpose of this paper was to explore aggression as a reinforcing consequence for reinforcement-seeking behaviors in people with intellectual disabilities. First, the literature establishing aggression as reinforcement for arbitrary responding will be reviewed. Next, the reward-related biological process associated with aggression was described. Finally, the paper discusses what might be done to assess and treat aggression maintained by nonsocial reinforcement.
    Research in developmental disabilities 06/2011; 32(6):2214-24. · 4.41 Impact Factor
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    ABSTRACT: A thermal preference task was used to assess the effects of sleep deprivation on nociceptive behavior using hot and cool stimuli. The thermal preference apparatus allowed male rats to move freely from a hot thermal plate (44.7°C) to an adjacent plate at neutral (33.5°C) or cold temperatures (1.3-11°C). Investigators recorded occupancy on the colder side, frequency of movements between the 2 compartments, and first escape latency from the cold side. Parametric analysis of thermal preference indicated that behavioral allocation was related to temperature ranges previously associated with activation of thermal nociceptors. A 50% occupancy rate was determined from a stimulus-response function identifying 1.3°C vs. 44.7°C as optimal temperatures. This temperature combination was then used to test the effects of sleep deprivation for 48h using the pedestal-over-water method on response allocation to the 2 temperature zones. Sleep deprivation decreased time spent on the cooled plate. Cumulative occupancy indicated differential effects for sleep deprivation with the rats preferring to remain on the hot side vs. the cold side, suggesting that sleep deprivation increased the nociceptive properties of the cold stimulus.
    Neuroscience Letters 11/2010; 485(2):98-101. · 2.03 Impact Factor
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    ABSTRACT: Research on aggression over the past two decades has focused on gene-environment interaction models to explain the relative contribution of each to this behavioral phenotype in various clinical populations. Recent investigations suggest a link between aggression in people with intellectual disabilities the functionality of the serotonin transporter. The aims in this study were to examine the possible association of the STin2 and/or the 5-HTTLPR serotonin transporter polymorphisms in adult males with and without intellectual disabilities, and to examine the association of these polymorphisms with aggression in people with intellectual disabilities. DNA samples and behavioral records were obtained from adult males with intellectual disabilities, distinguished only by the presence or absence of aggression. No association was found between either transporter polymorphism for aggression. However, the long 5-HTTLPR allele, and not the short allele or the heterozygous state, was associated with the severity of aggression. The association with aggression appears to be genetically complex, suggesting there may be other genes, interactions between genes, and/or environmental relations occasioning aggression in people with intellectual disabilities.
    Brain research 10/2010; 1357:97-103. · 2.46 Impact Factor
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    Michael E May, Craig H Kennedy
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    ABSTRACT: Good health significantly improves a person's quality of life. However, people with intellectual disabilities disproportionately have more health problems than the general population. Further complicating the matter is that people with more severe disabilities often cannot verbalize health complications they are experiencing, which leads to health problems being undiagnosed and untreated. It is plausible these conditions can interact with reinforcement contingencies to maintain problem behavior because of the increased incidence of health problems among people with intellectual disabilities. This paper reviews common health problems influencing problem behavior and reinforcement processes. A clear implication of this review is the need for comprehensive functional assessments of problem behavior involving behavior analysts and health professionals.
    Behavior analysis in practice. 01/2010; 3(2):4-12.
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    ABSTRACT: A functional polymorphism in the promoter of the gene encoding monoamine oxidase A has been associated with problem behavior in various populations. We examined the association of MAOA alleles in adult males with intellectual/developmental disabilities with and without established histories of problem behavior. These data were compared with a gender, ethnicity, and age-matched contrast sample. About 43% (15/35) of adults with intellectual/developmental disabilities and problem behavior possessed the low-efficiency version of the MAOA gene. In comparison, 20% (7/35) of adults with intellectual/developmental disabilities and no problem behavior and 20% (7/35) of the contrast group had the short-allele MAOA polymorphism. Therefore, a common variant in the MAOA gene may be associated with problem behavior in adults with intellectual/developmental disabilities.
    American Journal on Intellectual and Developmental Disabilities 08/2009; 114(4):269-73. · 2.08 Impact Factor
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    Michael E May, Craig H Kennedy
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    ABSTRACT: There is evidence suggesting aggression may be a positive reinforcer in many species. However, only a few studies have examined the characteristics of aggression as a positive reinforcer in mice. Four types of reinforcement schedules were examined in the current experiment using male Swiss CFW albino mice in a resident-intruder model of aggression as a positive reinforcer. A nose poke response on an operant conditioning panel was reinforced under fixed-ratio (FR 8), fixed-interval (FI 5-min), progressive ratio (PR 2), or differential reinforcement of low rate behavior reinforcement schedules (DRL 40-s and DRL 80-s). In the FR conditions, nose pokes were maintained by aggression and extinguished when the aggression contingency was removed. There were long postreinforcement pauses followed by bursts of responses with short interresponse times (IRTs). In the FI conditions, nose pokes were maintained by aggression, occurred more frequently as the interval elapsed, and extinguished when the contingency was removed. In the PR conditions, nose pokes were maintained by aggression, postreinforcement pauses increased as the ratio requirement increased, and responding was extinguished when the aggression contingency was removed. In the DRL conditions, the nose poke rate decreased, while the proportional distributions of IRTs and postreinforcement pauses shifted toward longer durations as the DRL interval increased. However, most responses occurred before the minimum IRT interval elapsed, suggesting weak temporal control of behavior. Overall, the findings suggest aggression can be a positive reinforcer for nose poke responses in mice on ratio- and time-based reinforcement schedules.
    Journal of the Experimental Analysis of Behavior 03/2009; 91(2):185-96. · 1.07 Impact Factor
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    ABSTRACT: We analyzed the effects of four conventional antiepileptic drugs (AEDs) - carbamazepine (CBZ), ethosuximide (ETH), phenytoin (PHT), and valproate (VPA) - on operant behavior maintained by negative or positive reinforcement contingencies. Rats were trained to lever press on a free-operant avoidance schedule or variable-interval (VI) schedule of appetitive reinforcement. Dose-effect functions were separately established on each reinforcement contingency for CBZ (12.5-100 mg/kg), ETH (25-200 mg/kg), PHT (12.5-50 mg/kg), and VPA (50-400 mg/kg). CBZ and PHT reduced responding on free-operant avoidance and VI appetitive reinforcement tasks, with positively reinforced behavior reduced at lower drug dosages than negatively reinforced responding. ETH and VPA reduced responding on the VI appetitive reinforcement task, but did not alter behavior maintained on the free-operant avoidance schedule. Our results suggest that conventional AEDs vary in their effect on operant behavior, depending on the type of reinforcement process maintaining responding.
    Physiology & Behavior 03/2008; 93(3):612-21. · 3.16 Impact Factor
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    The Primary Care Companion to The Journal of Clinical Psychiatry 02/2008; 10(1):73-5.
  • The Primary Care Companion to The Journal of Clinical Psychiatry 01/2008; 10(01):73-74.
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    ABSTRACT: Hyperglycemia worsens clinical outcomes in critically ill patients. Precise glycemia control using intravenous insulin improves outcomes. To determine if we could improve glycemia control over a previous paper-based, manual protocol, authors implemented, in a surgical intensive care unit (SICU), an intravenous insulin protocol integrated into a care provider order entry (CPOE) system. Retrospective before-after study of consecutive adult patients admitted to a SICU during pre (manual protocol, 32 days) and post (computer-based protocol, 49 days) periods. Percentage of glucose readings in ideal range of 70-109 mg/dl, and minutes spent in ideal range of control during the first 5 days of SICU stay. The computer-based protocol reduced time from first glucose measurement to initiation of insulin protocol, improved the percentage of all SICU glucose readings in the ideal range, and improved control in patients on IV insulin for > or =24 hours. Hypoglycemia (<40 mg/dl) was rare in both groups. The CPOE-based intravenous insulin protocol improved glycemia control in SICU patients compared to a previous manual protocol, and reduced time to insulin therapy initiation. Integrating a computer-based insulin protocol into a CPOE system achieved efficient, safe, and effective glycemia control in SICU patients.
    Journal of the American Medical Informatics Association 01/2007; 14(3):278-87. · 3.57 Impact Factor
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    ABSTRACT: REM sleep deprivation (REMSD) has been shown to increase rates of negatively reinforced operant behavior, but not operant responding maintained by positive reinforcement. The reason for this differential effect is currently unknown. We hypothesize that REMSD can increase sensitivity to noxious stimuli. In the present study, we sought to determine if REMSD was associated with a change in response to noxious heat (i.e., altered nociceptive sensitivity). Two groups of rats, aged 6 and 22 months, were subjected to hotplate algesia testing at two different temperatures (44 and 52 degrees C). Initially, baseline numbers of responses and total response time were obtained at 44 degrees C. Animals then were exposed to 48 h of REMSD or control conditions. The frequency and duration of hindpaw responses (licking and guarding) increased for young animals only after REMSD and none of the control conditions. Old rats showed increased duration of nocifensive responding after REMSD and tank control conditions without a change in the number of responses at 44 degrees C. Latency to first nocifensive response was significantly longer in the 44 degrees C hotplate tests, but decreased to levels observed throughout the 52 degrees C hotplate tests following REMSD and TC conditions. These findings suggest that REMSD increases nociceptive sensitivity under conditions of sustained, selective C nociceptor activation (42 degrees C), but not under conditions of phasic A-delta activation (52 degrees C). The findings also indicate that age can be a significant variable in REMSD studies.
    Behavioural Brain Research 05/2005; 159(1):89-94. · 3.33 Impact Factor
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    ABSTRACT: REM sleep deprivation (REMSD) has been shown to increase rates of free-operant avoidance responding. Depletion of 5-hydroxytryptamine (5-HT, serotonin) levels produces similar effects on responding. We studied whether the pharmacological activation of the 5-HT1A receptor would produce effects on avoidance responding similar to REMSD and depleted 5-HT levels. Rats were trained to lever press on a free-operant avoidance task. Dose-effect functions were established for 8-OH-DPAT (a 5-HT1A receptor agonist) (0.1-1.0 mg/kg) and WAY 100635 (a 5-HT1A receptor antagonist) (0.1-1.0 mg/kg). Rats were then exposed to REMSD (48 h) or equivalent control conditions, and then administered 8-OH-DPAT (0.6 mg/kg) and/or WAY 100635 (0.025-0.1 mg/kg). Injections of 8-OH-DPAT increased rates of avoidance responding in a dose-dependent manner, while WAY 100635 did not alter responding. The effect of 8-OH-DPAT was antagonized by pre-injection of WAY 100635. REMSD and injections of 8-OH-DPAT increased rates of avoidance responding and the effects of both manipulations were reversed by pre-injection of WAY 100635. Activation of the 5-HT1A receptor may be a mechanism by which REMSD increases rates of free-operant avoidance responding.
    Psychopharmacology 12/2004; 176(2):123-8. · 4.06 Impact Factor
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    Mark T. Harvey, Michael E. May, Craig H. Kennedy
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    ABSTRACT: Important findings are often a balance between the rigor of the experimental design and innovativeness of the experimental question. One broad topic area that has received a great deal of discussion, but little empirical study, is the evaluation of educational systems. Experimental designs that permit the analysis of practices used by state education agencies, local education agencies, and schools have the potential for yielding socially significant findings that could improve education. In this article we discuss the use of nonconcurrent multiple baseline designs as an option for studying the activities and effects of educational programs. Nonconcurrent multiple baseline designs stagger the timing of baseline-to-intervention changes across various entities, but the baselines and intervention phases are not contemporaneous across each of the tiers. Although considered less rigorous than concurrent multiple baseline designs, nonconcurrent designs have a degree of flexibility that may allow for their use in studying complex social contexts, such as educational settings, that might otherwise go unanalyzed.
    Journal of Behavioral Education 11/2004; 13(4):267-276.

Publication Stats

98 Citations
52.59 Total Impact Points

Institutions

  • 2004–2013
    • Vanderbilt University
      • Department of Special Education
      Nashville, MI, United States
  • 2009–2011
    • Southern Illinois University Carbondale
      • Department of Educational Psychology and Special Education
      Carbondale, IL, United States
  • 2010
    • Southern Illinois University Edwardsville
      Illinois, United States