David M. Segal

Up-regulation of D3 dopamine receptor mRNA in the nucleus accumbens of human cocaine fatalities

The effects of chronic cocaine use on D3 receptor mRNA expression in the human nucleus accumbens was assessed by reverse transcription-polymerase chain reaction. D3 receptor/cyclophilin mRNA ratios in the nucleus accumbens were increased 6-fold in cocaine overdose victims as compared to age-matched and drug-free control subjects. This finding demonstrates that chronic cocaine exposure leads to adaptive increases in the expression of D3 receptor mRNA in a critical reward center in brain.

Independent evolution of HIV type 1 in different brain regions

HIV-1-associated brain pathology exhibits regional variability and we therefore studied the genetic differences in the V1-V5 domains of the HIV env gene in up to four regions of brain (frontal lobe, basal ganglia, medial temporal lobe, and nonmedial temporal lobe) from three patients. We found that in each separate brain region HIV-1 forms different quasispecies and that there is little gene flow among these regions. In further support of brain region-specific evolution of HIV-1, we analyzed amino acid signatures in these clones. In addition to known amino acid signatures associated with macrophage tropism and the lack of syncytium formation, we found 15 majority amino acid signature patterns from the V1-V5 env sequences associated with the neuroanatomical regions analyzed from the three individuals. Furthermore, on average, intrabrain genetic distances for the HIV-1 env were estimated to be much smaller than genetic distances between brain regions. Specific strains of HIV-1 may be neurotropic or neuroinvasive (replication preference in brain tissue) and may contribute to pathology, cognitive loss, and neuropsychiatric disease.

HIV-1 RNA load in needles/syringes from shooting galleries in Miami: a preliminary laboratory report

We quantified HIV-1 RNA load in rinses from needles/syringes (N/S) obtained at shooting galleries in Miami and also analyzed the rinses for antibodies for viral proteins. In rinses from 36 N/S that contained visible blood, 14 (39%) had detectable amounts of HIV-1 RNA. Numbers of copies of HIV-1 RNA ranged from the detection limit (400 copies/ml) to 268,000 copies/ml. We also detected antibodies to HIV-1 polypeptides in 34/36 (94%) of rinses from visibly contaminated N/S using Western blots specific for the HIV-1 proteins. No antibodies were detected in laboratory rinses from six visibly clean needles. The presence of HIV-1 RNA in N/S is an important indication of the risk created by N/S sharing as well as by shared paraphernalia and wash waters by injecting drug users.

Dopamine transporter mRNA in autopsy studies of chronic cocaine users

The effects of chronic cocaine abuse on transcriptional regulation of human dopamine transporter (DAT) mRNA in midbrain dopaminergic neurons was assessed by reverse transcription-polymerase chain reaction (RT-PCR). DAT/cyclophilin mRNA ratios in the substantia nigra (SN) were unchanged in cocaine overdose (CO) victims as compared to age-matched and drug-free control (CTRL) subjects. In contrast, DAT mRNA levels were decreased significantly in agitated cocaine delirium victims (67%, p<0.05). These findings demonstrate the lack of a regulatory influence by cocaine on the steady state content of DAT mRNA in cocaine abusers. In contrast, DAT gene expression was altered significantly in cocaine abusers at risk for agitated delirium.

Oxandrolone, used for treatment of wasting disease in HIV-1-infected patients, does not diminish the antiviral activity of deoxynucleoside analogues in lymphocyte and macrophage cell cultures.

Antiviral agents are the primary therapy for patients infected with HIV-1. However, supportive therapies are often necessary in addition to antiviral drugs because of the devastating wasting process associated with HIV-1 infection and AIDS. Oxandrolone, an anabolic steroid, is used in promoting weight gain and, most important lean body mass (LBM), in patients with HIV-1 disease. We investigated whether oxandrolone interferes with the antiviral activity of zidovudine (ZDV), dideoxyinosine (ddI), and dideoxycytidine (ddC) on HIV-1 replication in peripheral blood lymphocytes and macrophage-monocytes. The nucleoside analogues had nanomolar 50% inhibitory concentrations (IC50) in peripheral lymphocytes. Combinations of nucleoside analogues and oxandrolone did not result in increased IC50 values. Oxandrolone used alone exhibited micromolar IC50 values in peripheral blood lymphocytes. Lack of interference was consistent for nucleoside concentrations up to 5 microM and for oxandrolone concentrations up to 100 microM in several combinations of drugs, viral strains, and peripheral lymphocytes and macrophages. We conclude that oxandrolone can be used for the promotion of weight gain in patients with AIDS-related wasting without interference with the antiviral effects of ZDV, ddI, or ddC.

Dopamine Transporter mRNA in Human Brain

Midbrain dopamine (DA)-containing neurons have effects on a number of distinct behavioral functions, including sensorimotor integration, motivation and affect, and cognition. Disruption of normal DA cell function occurs in Parkinson’s disease, neuropsychiatric disorders, and psychostimulant dependence. Drugs of abuse and dependence, such as cocaine and amphetamines, act as psychostimulants in humans. Psychiatric complications of cocaine and amphetamine include paranoia, agitated delirium, delusional disorder, and the depressed mood and dysphoria associated with abrupt withdrawal. Amphetamine psychosis and cocaine arousal and reinforcement are presumed consequences of the stimulation of the mesolimbic DA pathway (for a review, see ref. 1).

Viral and Host Determinants of Neurovirulence of HIV-1 Infection

HIV-1 infection of the brain is often associated with impairment in cognition, motor performance, and behavior in adults, and in addition, slowed milestones of brain growth and development in children(33,42,79). These may range in severity from subtle, mild deficits to conspicuous decline in performance diagnosed as HIV-1 associated dementia (HAD) and may occur in about 25% of AIDS patients independently of opportunistic infections, neoplasms, or metabolic derangements(44,85,104,120). However, close correlations between the clinical course of HAD and laboratory findings are not yet established(43,l40).