Homocysteine modifies the association of coronary stenosis and HIV infection in an inner city African American population

BACKGROUND AND AIMS

People with HIV (PWH) whose disease is controlled on anti-retroviral regimens remain at an increased risk for coronary artery disease (CAD). Traditional cardiovascular risk factors do not fully explain the residual risk in PWH suggesting contributions from nontraditional factors. Homocysteine (Hcy) may be one of these as prior work in adults without HIV demonstrate that Hcy may impair endothelial function by decreasing the availability of nitric oxide, promoting the development of atherosclerosis. In addition, plasma Hcy levels are higher in PWH than in individuals living without HIV. The aim of this study was to investigate whether Hcy levels influence the association between HIV and coronary stenosis in an inner city African American population.

METHODS

African Americans from the Heart Study in Baltimore, with and without HIV, recruited from inner-city Baltimore between June 2004 and February 2015, were included in this analysis. Participants underwent coronary CT angiography to evaluate the presence of coronary stenosis, defined as luminal stenosis >10%. Hcy was measured from stored serum samples.

RESULTS

In this analysis, the median [IQR] age of the 664 participants was 56 [50-66] years; 68.1% were living with HIV and 43.1% were women. Elevated Hcy (>15 µmol/L) was more prevalent in those with coronary stenosis (23.3%, 95% CI: 18.4%-28.2%) than in those without coronary stenosis (13.1%, 95% CI: 9.7%-16.5%) (p = 0.0007), and HIV was associated with coronary stenosis in those participants with an elevated Hcy (Prevalence Ratio: 1.94, 95% CI: 1.04-3.64, p = 0.0038) and not in those with a Hcy ≤15 µmol/L (Prevalence Ratio: 1.02, 95% CI: 0.83-1.25, p = 0.87).

CONCLUSIONS

Our data suggest an association between elevated Hcy levels (>15 µmol/L) and the prevalence of coronary stenosis in PWH from this inner city African American population.

Elevated homocysteine levels may moderate and mediate the association between HIV and cognitive impairment among middle-aged and older adults in an underserved population in Baltimore, Maryland

Background: In the antiretroviral therapy (ART) era, HIV-associated neurocognitive disorders (HAND) remain a considerable challenge for people with HIV, yet not all such disorders can be attributed to HIV alone. This study aimed to: (1) identify factors influencing neurocognitive impairment (NCI) utilizing the NIH Toolbox Cognition Battery (NIHTB-CB) as per the revised research criteria for HAND; (2) ascertain the moderating role of high homocysteine levels in the association between NCI and HIV; and (3) assess the mediating effect of elevated homocysteine levels on this association.Methods: We analyzed data from 788 adults (≥45 years) participating in a study on HIV-related comorbidities in underserved Baltimore communities, using NIHTB-CB to gauge neurocognitive performance. Special attention was given to results from the Dimensional Change Card Sort (DCCS) test within the executive function domain during causal mediation analysis.Results: Overall, HIV was not associated with NCI presence. However, HIV was associated with NCI among individuals with homocysteine >14 μmol/L. Furthermore, HIV was both directly and indirectly associated with NCI in DCCS test scores. Notably, the mediating role of elevated homocysteine in DCCS scores was only observable among individuals who had never used cocaine or had used it for ≤ 10 years, suggesting that extended cocaine use may have a substantial influence on cognitive performance.Conclusions: The findings from this study suggest elevated homocysteine levels may moderate and mediate the association between HIV and neurocognitive impairment.

Cocaine Use May Moderate the Associations of HIV and Female Sex with Neurocognitive Impairment in a Predominantly African American Population Disproportionately Impacted by HIV and Substance Use

HIV-associated neurocognitive disorders (HAND) remain a major challenge for people with HIV in the antiretroviral therapy era. Cocaine use may trigger/exacerbate HAND among African American (AA) adults, especially women. Between 2018 and 2019, 922 adults, predominantly AAs, with/without HIV and with/without cocaine use in Baltimore, Maryland, were enrolled in a study investigating the association of HIV and cocaine use with neurocognitive impairment (NCI). Neurocognitive performance was assessed with the NIH Toolbox Cognition Battery (NIHTB-CB). NCI was considered to be present if the fully adjusted standard score for at least two cognitive domains was 1.0 standard deviation below the mean. Although the overall analysis showed HIV and female sex were associated with NCI, the associations were dependent on cocaine use. Neither HIV [adj prevalence ratio (PR): 1.12, confidence interval (95% CI): 0.77-1.64] nor female sex (adj PR: 1.07, 95% CI: 0.71-1.61) was associated with NCI among cocaine nonusers, while both HIV (adj PR: 1.39, 95% CI: 1.06-1.81) and female sex (adj PR: 1.53, 95% CI: 1.18-1.98) were associated with NCI in cocaine users. HIV was associated with two NIHTB-CB measures overall. In addition, HIV was associated with a lower dimensional change card sort score (an executive function measure) in cocaine users and not in nonusers. Cognitive performance was poorer in female than in male cocaine users. The adverse effect of HIV on cognitive performance predominantly affected cocaine users. However, cocaine use may moderate the impact of HIV and female sex on cognitive performance, highlighting the importance of reducing cocaine use in NCI prevention among the AA population.

Diet-Related and Gut-Derived Metabolites and Health Outcomes: A Scoping Review

Objectives

To conduct a scoping review to map available evidence about the health impact of gut microbiota-derived metabolites in humans.

Methods

We searched PubMed and Embase for studies that assessed the health impact of gut microbiota-derived metabolites in humans. We included case-control studies, cross-sectional studies, cohort studies, and clinical trials. Any health condition was considered. Based on an initial prioritization phase informed by preliminary searching and expert input, we narrowed our scope to ten metabolites: deoxycholate or deoxycholic acid (DCA), lithocholate or lithocholic acid (LCA), glycolithocholate or glycolithocholic acid, glycodeoxycholate or glycodeoxycholic acid, tryptamine, putrescine, d-alanine, urolithins, N-acetylmannosamine, and phenylacetylglutamine. We used evidence mapping to identify evidence gaps and associations that may permit future systematic reviews. The screening was conducted in PICO Portal aided by artificial intelligence.

Results

Overall, for these 10 metabolites, we identified 352 studies with 168,072 participants. Most (326, 92.6%) were case-control studies, followed by cohort studies (14, 4.0%), clinical trials (8, 2.3%), and cross-sectional studies (6, 1.7%). Most studies assessed the following associations: DCA on hepatobiliary disorders (64 studies, 7,976 participants), colorectal cancer (19 studies, 7,461 participants), and other digestive disorders (27 studies, 2,463 participants); LCA on hepatobiliary disorders (34 studies, 4,297 participants), colorectal cancers (14 studies, 4,955 participants), and other digestive disorders (26 studies, 2,117 participants); putrescine on colorectal cancers (16 studies, 94,399 participants) and cancers excluding colorectal and hepatobiliary cancers (42 studies, 4,250 participants).

Conclusions

The association of gut microbiota-derived metabolites and human health is being examined in an increasing number of studies, most of which are case-control studies. As these metabolites hold considerable potential for elucidating microbiome-disease associations, there is a need to conduct more prospective studies including clinical trials. Moreover, systemic reviews are needed to characterize the metabolite-disease associations.

Funding Sources

Institute for the Advancement of Food and Nutrition Sciences (IAFNS).

Clinical solutions to chronic pain and the opiate epidemic

The current opiate epidemic has caused tens of thousands of deaths annually and hundreds of billions in economic losses. From 1979 to 2015, accidental opiate-related deaths increased by 4250%. Despite its magnitude, the driving forces remain poorly understood. A narrow understanding by physicians, administrators and policy makers has resulted in a clinical approach to chronic pain treatment misguided by expediency, shortsighted cost reduction, pharmaceutical profit, and patient satisfaction. Until the broken elements are well understood, effective policy solutions will remain elusive. In this review, we describe the first comprehensive timeline of significant contributing factors between 1979 and the present. To address the complexity of treating patients with chronic pain and its contribution to opiate overuse, we outline an alternative clinical and health systems approach to chronic pain therapy. Addressing the underlying drivers will require empowering physicians to use clinical judgment over guidelines and algorithms to provide holistic, high-quality healthcare to individual victims of the opiate epidemic.

Cocaine use may induce telomere shortening in individuals with HIV infection

BACKGROUND

Although cocaine use may induce/accelerate HIV-associated comorbidities in HIV-infected individuals on antiretroviral therapy (ART), and that HIV itself may accelerate aging, the issue of whether cocaine use plays a role in HIV-associated aging in HIV-infected cocaine users has not been reported. The goals of this study were (1) to explore factor(s) associated with peripheral blood leukocyte telomere length, a marker of cellular replicative history, and telomere shortening in HIV-infected individuals, and (2) to assess whether cocaine use plays a role in accelerating telomere shortening in cocaine users with HIV infection.

METHODS

Between June 2010 and December 2016, 147 HIV-infected participants in Baltimore, Maryland, were enrolled in a cross-sectional study investigating factor(s) associated with telomere length. Of these 147, 93 participated in a follow-up study to examine factor(s) associated with telomere shortening. Robust regression model was used to analyze cross-sectional data and the generalized estimating equation approach was used to analyze follow-up data.

RESULTS

Cross-sectional analyses demonstrated that (1) both daily alcohol consumption and use of non-nucleoside reverse transcriptase inhibitors (NNRTIs) were independently associated with telomere length, and cocaine use modified the associations of daily alcohol use and NNRTI use with telomere length. Longitudinal analyses suggested that both daily alcohol consumption and duration of NNRTI use were independently associated with telomere shortening, and (2) cocaine use induced/accelerated telomere shortening in HIV-infected individuals.

CONCLUSIONS

Our findings suggest that cocaine use may promote premature aging in HIV-infected individuals who are on ART. Our results emphasize the importance of cocaine abstinence/reduced use, which may retard HIV-associated premature aging.

Cocaine use may modify HIV/ART-associated myocardial steatosis and hepatic steatosis

BACKGROUND

It has been recognized that myocardial and hepatic steatosis may be more prevalent in HIV-infected individuals on antiretroviral therapy (ART); however, factors associated with these conditions have not been thoroughly investigated. The goals of this study were (1) to identify the risk factors for myocardial and hepatic steatosis in HIV-infected African Americans (AAs) and explore whether ART use is independently associated with myocardial and hepatic steatosis, and (2) to examine whether and how cocaine use influences any associations of ART use with myocardial and hepatic steatosis.

METHODS

Between June 2010 and December 2013, 220 HIV-infected AAs in Baltimore, Maryland, were enrolled in a study investigating HIV/ART-associated myocardial and hepatic damage. Proton magnetic resonance spectroscopy was performed to quantify myocardial and hepatic triglyceride contents. Sociodemographic, medical and laboratory data were also obtained. Robust regression model was employed to perform primary statistical analysis.

RESULTS

Robust regression analyses showed that (1) duration of protease inhibitor (PI) use was independently associated with myocardial and hepatic triglyceride contents, (2) duration of PI use was independently associated with myocardial triglyceride in cocaine users (p=0.025), but not in cocaine never-users (p=0.84), and (3) duration of PI use was independently associated with hepatic triglyceride in cocaine users, but not in cocaine never-users (p=0.52).

CONCLUSIONS

Cocaine use may trigger/exacerbate the toxicity of PI in ART-associated myocardial and hepatic steatosis, suggesting that cocaine abstinence/reduced use may retard these ART-associated comorbidities. Clinical trials should be conducted to examine whether reduced cocaine use improves HIV/AIDS-associated myocardial and hepatic steatosis.

HIV Infection Itself May Not Be Associated With Subclinical Coronary Artery Disease Among African Americans Without Cardiovascular Symptoms

Background

The key objectives of this study were to examine whether HIV infection itself is associated with subclinical coronary atherosclerosis and the potential contributions of cocaine use and antiretroviral therapies (ARTs) to subclinical coronary artery disease (CAD) in HIV‐infected persons.

Methods and Results

Between June 2004 and February 2015, 1429 African American (AA) adults with/without HIV infection in Baltimore, Maryland, were enrolled in an observational study of the effects of HIV infection, exposure to ART, and cocaine use on subclinical CAD. The prevalence of subclinical coronary atherosclerosis was 30.0% in HIV‐uninfected and 33.7% in HIV‐infected (P=0.17). Stratified analyses revealed that compared to HIV‐uninfected, HIV‐infected ART naïve were at significantly lower risk for subclinical coronary atherosclerosis, whereas HIV‐infected long‐term ART users (≥36 months) were at significantly higher risk. Thus, an overall nonsignificant association between subclinical coronary atherosclerosis and HIV was found. Furthermore, compared to those who were ART naïve, long‐term ART users (≥36 months) were at significantly higher risk for subclinical coronary atherosclerosis in chronic cocaine users, but not in those who never used cocaine. Cocaine use was independently associated with subclinical coronary atherosclerosis.

Conclusions

Overall, HIV infection, per se, was not associated with subclinical coronary atherosclerosis in this population. Cocaine use was prevalent in both HIV‐infected and ‐uninfected individuals and itself was associated with subclinical disease. In addition, cocaine significantly elevated the risk for ART‐associated subclinical coronary atherosclerosis. Treating cocaine addiction must be a high priority for managing HIV disease and preventing HIV/ART‐associated subclinical and clinical CAD in individuals with HIV infection.

Routine depression screening in an HIV clinic cohort identifies patients with complex psychiatric co-morbidities who show significant response to treatment

This study described characteristics, psychiatric diagnoses and response to treatment among patients in an outpatient HIV clinic who screened positive for depression. Depressed (25 %) were less likely to have private insurance, less likely to have suppressed HIV viral loads, had more anxiety symptoms, and were more likely to report current substance abuse than not depressed. Among depressed, 81.2 % met diagnostic criteria for a depressive disorder; 78 % for an anxiety disorder; 61 % for a substance use disorder; and 30 % for co-morbid anxiety, depression, and substance use disorders. Depressed received significantly more treatment for depression and less HIV primary care than not depressed patients. PHQ-9 total depression scores decreased by 0.63 from baseline to 6-month follow-up for every additional attended depression treatment visit. HIV clinics can routinely screen and treat depressive symptoms, but should consider accurate psychiatric diagnosis as well as co-occurring mental disorders.

Lifetime depressive disorders and adherence to anti-retroviral therapy in HIV-infected Ugandan adults: a case-control study

BACKGROUND

There is limited information on the impact of lifetime depressive disorders on adherence to ART.

AIM

We examined the association between lifetime depressive disorders and adherence to anti-retroviral therapy (ART) among a rural clinic-based HIV positive population. We further explored whether this association was mediated by current depression and moderated by gender.

METHODS

Two hundred HIV positive individuals who had<95% adherence and two hundred HIV positive individuals who had ≥95% adherence were screened for depression using the self-reporting questionnaire (SRQ-20) and evaluated with the Mini neuropsychiatric interview (MINI). Multivariate logistic regression was used to assess the association between lifetime depressive disorders and adherence to ART. The logistic regression model of Baron and Kenny was used to evaluate the mediating effect of current depression. Hierarchical binomial logistic regression was used to evaluate the moderating effect of gender.

RESULTS

HIV positive individuals with lifetime depressive disorders had an increased risk of non-adherence to ART after controlling for education status, income, self-efficacy, perceived social support, cognitive impairment and current alcohol use disorders [AOR=1.68, 95%CI (1.02-2.79), p=0.04]. This association was stronger in females than males [AOR= 4.76, 95%CI (1.52-14.97), p=0.008].

LIMITATIONS

Findings cannot be generalized to ART naïve individuals or those using ART for less than six months.

CONCLUSION

Lifetime depressive disorders are associated with increased risk of non-adherence to ART in rural women with HIV infection in southern Uganda. Detection and treatment of depression can potentially improve adherence with HIV treatment in this setting.

Medical consequences of drug abuse and co-occurring infections: research at the National Institute on Drug Abuse

Substance abuse still remains one of the major problems in the world today, with millions of people abusing legal and illegal drugs. In addition, a billion people may also be infected with one or more infections. Both drugs of abuse and infections are associated with enormous burden of social, economic, and health consequences. This article briefly discusses a few medical consequences of drugs of abuse and infections such as human immunodeficiency virus, hepatitis C virus, psychiatric complications in hepatitis C infection, pharmacokinetic drug-drug interactions among medications used in the treatment of addiction and infections, and new drugs in development for the treatment of infections. Research is encouraged to study interactions between infections, drugs of abuse, and underlying pathophysiologic and molecular/genetic mechanisms of these interactions.

Interrelation between psychiatric disorders and the prevention and treatment of HIV infection

Psychiatric disorders, particularly major depression, have a profound affect on the use of and adherence to highly active antiretroviral therapy (HAART) among patients with human immunodeficiency virus (HIV) infection. Because some of the symptoms of HIV infection are similar to those of major depression, efforts to diagnose and treat major depression are further complicated. Moreover, major depression increases vulnerability to HIV infection by provoking high-risk behaviors, and it interferes with a patient's ability to comply with protocols for the prevention and treatment of HIV infection. HIV infection itself can disguise, help initiate, or exacerbate major depression. In this report, the interrelation between major depression and HIV infection is evaluated, the impact of this interrelation on adherence to HAART is described, and methods for effective treatment of psychiatric conditions in HIV-infected persons are discussed.

PTSD: a problematic diagnostic category

Since the publication of Diagnostic and Statistical Manual of Mental Disorders (DSM)-III, posttraumatic stress disorder (PTSD) has become a remarkably dominant theme in mental health discourse and diagnostic practice. This development has been encouraged by the diagnosis being officially presumed to exist in acute, chronic, delayed, complex, subdromal, and even "masked" forms. Here, we present an historical and clinical review that indicates how, since 1980, the term PTSD (along with its dubious embellishments) replaced established views on mental responses to trauma to the detriment of patient care and psychiatric investigation. From this historical perspective, we review and evaluate the natural course of emotional and behavioral reactions to traumatic experiences, and as well their assessment, formulation, and therapeutic management in both civilian and military situations. From this we conclude that the concept of PTSD has moved the mental health field away from, rather than towards a better understanding of the natural psychological responses to trauma. A return to prior standards of diagnostic practice and therapeutic planning would greatly benefit patient care, rehabilitative services to veterans, and epidemiologic research.

Psychotropic medications and HIV

Patients with human immunodeficiency virus (HIV) infection and acquired immune deficiency syndrome have high rates of psychiatric illness. The effective management of these psychiatric conditions can improve a patient's quality of life and may improve antiretroviral adherence. Care providers for patients with HIV infection frequently encounter clinical situations in which psychotropic medications are needed or are being used. Those clinical situations require familiarity with the broad category of medications termed "psychotropic." That familiarity should include a basic understanding of indications, adverse effects, and drug interactions. In particular, it is very important to recognize the many potential interactions based on cytochrome P450 metabolism, which is common to many psychotropics, the protease inhibitors, and the nonnucleoside reverse-transcriptase inhibitors. In a brief review of the use of psychotropic medications in patients with HIV infection, we discuss indications, adverse effects, and drug interactions for commonly used antidepressants, mood stabilizers, anxiolytics, antipsychotics, psychostimulants, and drugs of abuse.

Does the presence of a current psychiatric disorder in AIDS patients affect the initiation of antiretroviral treatment and duration of therapy?

BACKGROUND

Psychiatric disorders are common in HIV patients, and previous work suggests that these patients experience delays in treatment with highly active antiretroviral therapy (HAART). We investigated whether a current psychiatric disorder (1) affected the time to initiation of HAART, (2) predicted the likelihood of being prescribed HAART for at least 6 months, and (3) affected survival in urban AIDS patients.

METHODS

We conducted a retrospective cohort study of AIDS patients with no prior history of HAART who were enrolled and followed at the Johns Hopkins University HIV clinic between January 1996 and January 2002. Patients were stratified based on the presence of a psychiatric disorder. Cox proportional hazards regression models estimated the relative risk of receiving HAART and survival, whereas multivariate logistic regression models estimated the relative odds of remaining on HAART.

RESULTS

During the study period, 549 patients with AIDS and no prior antiretroviral treatment were enrolled in the clinic. Eighteen percent (n = 100) were defined as having a current psychiatric disorder, 39% (n = 215) were defined as having no psychiatric disorder, and 43% (n = 34) were indeterminate. Patients with a psychiatric disorder were 37% more likely to receive HAART (Cox adjusted hazard ratio [95% confidence interval (CI)]: 1.37 [1.01-1.87]), had greater than twice the odds of being prescribed HAART for at least 6 months (adjusted odds ratio [95% CI]: 2.14 [1.24-3.69]), and were 40% more likely to survive (Cox adjusted hazard ratio [95% CI]: 0.61[0.37-0.99]) as compared with those without a psychiatric disorder.

CONCLUSION

Patients with psychiatric disorders are receiving HAART and are able to reap the survival benefit by remaining on it.

The effectiveness of psychiatric treatment for HIV-infected patients

The study sought to determine the effectiveness of a model program of psychiatric care for human immunodeficiency virus (HIV)-infected patients. This was a cohort study of 126 HIV-positive outpatients referred for psychiatric evaluation and treatment (average follow up of 14 months) in a HIV-dedicated primary-care outpatient clinic in the inner city. A global outcome measure (encompassing symptom relief, functioning, and HIV-risk behaviors), and a measure of abstinence from alcohol and illicit substances were used. Fifty percent of patients improved, with 19% "nearly well" at follow-up. Abstinence was achieved 48% of the time. Good compliance with treatment and the absence of injection drug use were the primary predictors of good outcomes. Of the compliant patients, 94% improved, with 45.7% being nearly well. Psychiatric treatment of HIV-infected patients is effective when located in the HIV primary-care setting and administered by a multidisciplinary team under the direction of a psychiatrist, using evidence-based interventions.

AIDS mania

Twenty patients with HIV infection and mania were grouped according to whether their first manic episode occurred when CD4 count was < 200 (late onset) or > or = 200 (early onset). The late-onset patients were less likely to have personal or family histories of mood disorder and more likely to have dementia or cognitive slowing. They also exhibited a different manic symptom profile. The different sociodemographic and symptom profiles associated with early-onset and late-onset mania may reflect differences in pathophysiology.

Sertraline in the treatment of severe aggressiveness in Huntington's disease

Sertraline, a selective serotonin reuptake inhibitor, was used to treat two consecutive cases of genetically confirmed Huntington's disease in which severe irritability and aggressiveness required inpatient admission. The complete cessation of aggressive behavior in both cases has been maintained on follow-up. This report adds to the literature implicating serotonergic mechanisms in irritability and aggressiveness in both neuropsychiatric and idiopathic psychiatric disorders.

Psychiatric issues and emergencies in HIV infection

Emergency departments are frequently the entry point for patients infected with HIV. Psychiatric conditions may be the initial predominant presentation or an important concomitant factor. Because of the complexities of HIV infection, the serious medical nature of its associated psychiatric complications, the frequent presence of comorbid substance use and other behavioral disorders, and the multiple sites of treatment involved, psychiatrists, emergency physicians, and other professionals must work in collaboration in screening patients infected with HIV for mental disorders and in providing careful and rational care.

Calmodulin stimulates adenylate cyclase activity and increases dopamine activation in bovine retina

Adenylate cyclase activity in bovine retina is highly responsive to Ca2+ and the endogenous Ca2+-binding protein, calmodulin (CaM). CaM stimulated adenylate cyclase activity in washed particulate fractions of bovine retina by 6.6-fold in a Ca2+-dependent manner. Activation of adenylate cyclase activity by CaM was maximal at 0.12 microM free Ca2+. The apparent Ka for calmodulin stimulation of adenylate cyclase was 67 nM and the apparent Vmax was 116 pmol/min/mg of protein above basal activity. Adenylate cyclase activity in bovine retina was stimulated approximately 50% by guanosine 5'-triphosphate (GTP), but the nonhydrolyzable GTP analogue, guanosine-5'-(beta, gamma-imido)triphosphate (Gpp(NH)p), was able to activate the enzyme nearly 5-fold. CaM and Gpp(NH)p appeared to be partially competitive activators of adenylate cyclase in the retina particulate fraction. Dopamine stimulated adenylate cyclase activity in the presence of GTP with an apparent Ka of 1.0 microM and an apparent Vmax of 66 pmol/min/mg of protein. Ca2+ and CaM increased the apparent Vmax of the dopamine-stimulated adenylate cyclase activity more than 2-fold to a level of 146 pmol/min/mg of protein but did not alter the apparent Ka. This suggests that CaM is an endogenous modulator of dopamine-stimulated adenylate cyclase activity in the retina. CaM-stimulated adenylate cyclase activity may be a common component to retina since we found this activity in retinas from rabbit, rat, and goldfish as well as cow.

Calmodulin level in whole blood correlates with the percentage of reticulocytes

We studied the calmodulin-like activity (CaM) level in hemolyzed samples of whole blood after determining the percentage and absolute number of reticulocytes present. Twenty-six samples from 25 people with a range of reticulocyte counts were studied. CaM levels correlated with the percentage (r = 0.63, P less than .01) and absolute number (r = 0.64, P less than .01) of reticulocytes present, indicating that the calmodulin-like activity level in whole blood was inversely related to erythrocyte age.

Chronic sulpiride treatment produces supersensitivity of striatal adenylate cyclase to dopamine in sexually immature or adult castrated rats

Sulpiride, a substituted benzamide antipsychotic drug, is considered to be a selective antagonist at dopamine D-2 receptors, largely because it does not inhibit dopamine-stimulated adenylate cyclase activity. It was found that sulpiride in vitro can block dopamine-stimulated adenylate cyclase activity in rat striatum from sexually immature or adult castrated male rats. Chronic treatment with sulpiride (20 mg/kg i.p. twice daily for 15 days) resulted in supersensitivity of dopamine-stimulated adenylate cyclase activity in striatum from sexually immature (3-4 weeks old) as well as adult castrated rats. The apparent Ka was decreased 4-fold in the sulpiride-treated animals, whereas the apparent Vmax remained unchanged. This treatment did not alter dopamine-stimulated adenylate cyclase activity in the striatum from adult male rats. Acute treatment with sulpiride was slightly inhibitory to dopamine-stimulated adenylate cyclase in striatum from the immature rat, suggesting that the supersensitivity after repeated injections could be a compensatory increase. In in vitro studies it was found that sulpiride at nanomolar levels could inhibit the ability of low concentrations of dopamine to stimulate adenylate cyclase activity in striatal particulate fractions from sexually immature or adult castrated rats. Sulpiride did not affect dopamine-stimulated adenylate cyclase in the adult rat striatum. Our results indicate that sulpiride can affect dopamine-stimulated adenylate cyclase activity in animals that are lacking testosterone, or perhaps estrogen. This suggests that sex hormones could regulate the sensitivity and pharmacological profile of dopamine receptors for their ligands.