Cocaine Dependence: Behavioral Dimensions and Patterns of Progression

The authors report a longitudinal study describing the progression and circumstances of cocaine dependence within a large group of men with different usage histories, from initiation of use to entrance into a treatment program at a Veterans Affairs medical center several years later. Data illustrating the course of the disorder were retrospectively collected, using a “natural history” methodology successfully used in prior research. Four patterns of escalation of cocaine use are described. Generally, as the cocaine career progressed, there was a decrease in the consumption of alcohol and other drugs.     

Studies on the characterization and inhibition of rat brain phenylethanolamine N-methyltransferase

Summary The existence of phenylethanolamine N-methyltransferase (PNMT) activity in the rat brain and spinal cord was confirmed using both substrate specificity and selective inhibitors of the adrenal enzyme as biochemical tools. The enzyme was not generally localized throughout the central nervous system but was found primarily in the brain stem and spinal cord with lesser amounts occurring in the midbrain. No significant PNMT activity was found in the cerebellum or forebrain. The central enzyme was markedly inhibited both in vitro and in vivo by low concentrations (doses) of SK&F 64139, a potent inhibitor of the adrenal enzyme.     

Noradrenergic role in the self-administration of morphine or amphetamine

The role of brain noradrenergic neurons in mediating the reinforcing properties of small intravenous doses of morphine and d-amphetamine was investigated by pretreatment of rats with the norepinephrine-depleting agents diethyldithiocarbamate and U-14,624, inhibitors of dopamine-β-hydroxylase (DBH). Such treatment prevented the reacquisition of a self-administration response (bar-press) for morphine (32 μg/kg/injection) or d-amphetamine (15 μg/kg/injection) made available on a CRF schedule. Pretreatment with a DBH inhibitor also prevented the development of a secondary (conditioned) reinforcer based on primary reinforcement associated with either drug. Observations indicating that the orienting reflex was intact are taken as evidence that depressant effects of the DBH inhibitors were not severe enough to disrupt the associative process. Therefore, any effect on learning does not seem sufficient to explain the present results. Thus, it is inferred that the mechanisms mediating reinforcement for both morphine and amphetamine were disrupted by the inhibition of central noradrenergic functions.     

The Role of Visual Experience in Individual Differences of Brain Connectivity

Visual cortex organization is highly consistent across individuals. But to what degree does this consistency depend on life experience, in particular sensory experience? In this study, we asked whether visual cortex reorganization in congenital blindness results in connectivity patterns that are particularly variable across individuals, focusing on resting-state functional connectivity (RSFC) patterns from the primary visual cortex. We show that the absence of shared visual experience results in more variable RSFC patterns across blind individuals than sighted controls. Increased variability is specifically found in areas that show a group difference between the blind and sighted in their RSFC. These findings reveal a relationship between brain plasticity and individual variability; reorganization manifests variably across individuals. We further investigated the different patterns of reorganization in the blind, showing that the connectivity to frontal regions, proposed to have a role in the reorganization of the visual cortex of the blind toward higher cognitive roles, is highly variable. Further, we link some of the variability in visual-to-frontal connectivity to another environmental factor—duration of formal education. Together, these findings show a role of postnatal sensory and socioeconomic experience in imposing consistency on brain organization. By revealing the idiosyncratic nature of neural reorganization, these findings highlight the importance of considering individual differences in fitting sensory aids and restoration approaches for vision loss.SIGNIFICANCE STATEMENT The typical visual system is highly consistent across individuals. What are the origins of this consistency? Comparing the consistency of visual cortex connectivity between people born blind and sighted people, we showed that blindness results in higher variability, suggesting a key impact of postnatal individual experience on brain organization. Further, connectivity patterns that changed following blindness were particularly variable, resulting in diverse patterns of brain reorganization. Individual differences in reorganization were also directly affected by nonvisual experiences in the blind (years of formal education). Together, these findings show a role of sensory and socioeconomic experiences in creating individual differences in brain organization and endorse the use of individual profiles for rehabilitation and restoration of vision loss.     

The Link between Cannabis Use,Immune System,and Viral Infections

Cannabis continues to be the most used drug in the world today. Research shows that cannabis use is associated with a wide range of adverse health consequences that may involve almost every physiological and biochemical system including respiratory/pulmonary complications such as chronic cough and emphysema, impairment of immune function, and increased risk of acquiring or transmitting viral infections such as HIV, HCV, and others. The review of published research shows that cannabis use may impair immune function in many instances and thereby exerts an impact on viral infections including human immune deficiency virus (HIV), hepatitis C infection (HCV), and human T-cell lymphotropic type I and II virus (HTLV-I/II). The need for more research is also highlighted in the areas of long-term effects of cannabis use on pulmonary/respiratory diseases, immune dysfunction and the risk of infection transmission, and the molecular/genetic basis of immune dysfunction in chronic cannabis users.     

Heart rate dynamics during three forms of meditation

OBJECTIVE: This study was designed to quantify and compare the instantaneous heart rate dynamics and cardiopulmonary interactions during sequential performance of three meditation protocols with different breathing patterns. BACKGROUND: We analyzed beat-to-beat heart rate and continuous breathing signals from 10 experienced meditators (4 females; 6 males; mean age 42 years; range 29-55 years) during three traditional interventions: relaxation response, breath of fire, and segmented breathing. RESULTS: Heart rate and respiratory dynamics were generally similar during the relaxation response and segmented breathing. We observed high amplitude, low frequency (approximately 0.05-0.1 Hz) oscillations due to respiratory sinus arrhythmia during both the relaxation response and segmented breathing, along with a significantly (p<0.05) increased coherence between heart rate and breathing during these two maneuvers when compared to baseline. The third technique, breath of fire, was associated with a different pattern of response, marked by a significant increase in mean heart rate with respect to baseline (p<0.01), and a significant decrease in coherence between heart rate and breathing (p<0.05). CONCLUSIONS: These findings suggest that different meditative/breathing protocols may evoke common heart rate effects, as well as specific responses. The results support the concept of a "meditation paradox," since a variety of relaxation and meditative techniques may produce active rather than quiescent cardiac dynamics, associated with prominent low frequency heart rate oscillations or increases in mean resting heart rate. These findings also underscore the need to critically assess traditional frequency domain heart rate variability parameters in making inferences about autonomic alterations during meditation with slow breathing.     

Prevalence of chronic kidney disease risk factors among low birth weight adolescents

Background

By adulthood, low birth weight infants have an increased risk for chronic kidney disease (CKD). The extent to which objective CKD risk factors are present at earlier ages is unclear.

Methods

We analyzed 5352 participants aged 12–15 years in the National Health and Nutrition Examination Survey, 1999–2012. Participants were classified as low birth weight (LBW; < 2500 g), very low birth weight (VLBW; < 1500 g), or normal (2500–4000 g) by parental/proxy recall. Albuminuria (albumin/creatinine 30 – <300 mg/g), decreased estimated glomerular filtration rate (eGFR; < 90 ml/min/1.73 m²; Counahan–Barratt), and elevated systolic blood pressure (BP; ≥ 95th percentile for age, height, and sex) were considered CKD risk factors.

Results

While albuminuria did not vary by birth weight, elevated blood pressure (BP) and decreased eGFR occurred more frequently in LBW/VLBW adolescents (elevated BP: LBW 6.0 %, VLBW 11.2 %, normal 2.4 %; decreased eGFR: LBW 23.2 %, VLBW 32.5 %, normal 16.1 %). After multivariable adjustment, LBW/VLBW adolescents had greater odds for both elevated BP (LBW: OR 2.90, 95 % CI 1.48–5.71; VLBW: 5.23; 1.11–24.74) and decreased eGFR (LBW: 1.49, 95 % CI 1.06–2.10; VLBW 2.49, 95 % CI 1.20–5.18).

Conclusions

In the U.S. population, both decreased eGFR and elevated systolic BP occur frequently among adolescents with history of LBW/VLBW.