Attenuated Insular Processing During Risk Predicts Relapse in Early Abstinent Methamphetamine-Dependent Individuals

There is some evidence that neuroimaging can be used to predict relapse among abstinent methamphetamine-dependent (MD) individuals. However, it remains unclear what cognitive and neural processes contribute to relapse. This investigation examined whether insula activation during risk-taking decisions—a process shown to be disrupted in MD—is able to predict susceptibility for relapse. Sixty-eight MD enrolled in a treatment program during early abstinence completed a risk-taking task during functional magnetic resonance imaging. Sixty-three of the sixty-eight individuals were followed up 1 year after the study. Of these, 18 MD reported relapse. The 45 abstinent MD showed patterns of insula activation during risky decisions that resembled those found in prior studies of healthy controls, consisting of lower insula activation during safe decisions paired with higher activation during risky decisions. In contrast, the 18 relapsed MD showed similar insula activation during safe and risky decisions. An increase in one standard deviation in the difference in insula activation between risky and safe choices was associated with a 0.34 odds ratio for relapse at any given time. A median split of insula activation (difference between risky and safe) showed that individuals in the bottom half were two times more likely to relapse. In addition, a model that included several other brain regions increased prediction accuracy compared with insula-based model alone. These results suggest that failure to differentially activate the insula as a function of risk is a part of an altered risk-processing network associated with an increased susceptibility to relapse.     

The attractiveness of family medicine among Polish medical students

Background: In many developed countries tuning supply and demand of medical doctors is a continuous challenge to meet the ever changing needs of community and individual patients. The long study period for medical doctors creates the opportunity to observe the current career preferences of medical students and evolution in time.

Objectives: To investigate the career choices of Polish students in different stages of their medical education.

Methods: Medical students at five Polish medical universities were questioned about their career aspirations in the first, third and sixth year.

Results: A total of 2020 students were recruited for the survey. Among first year students 17% preferred family medicine as final career option, compared to 20% in the third year, and 30% in the sixth year (significant trend, P < 0.0001). In particular, female students prefer family medicine: 71% women versus 62% women in the group with a preference for a non-family medicine orientation (P = 0.008). Medical students rejecting a career as a family doctor stated that the impossibility to work in a hospital environment was the determining factor.

Conclusion: The opportunity for professional development seems to be an important determining factor in the choice of a medical specialty in Poland. The proportion of Polish students choosing family medicine increases during their progress in medical education, with one third of students interested in a career in family medicine by year six.     

Recent developments in DXA. Quality of new DXA/MXA-devices for densitometry and morphometry

The introduction of new devices demands the assessment of their capabilities in established terms. The accuracy, reproducibility and spatial resolution of in vitro (phantom) osteodensitometric and morphometric measurements of QDR 2000 Plus and EXPERT are presented. Design details of these DXA/MXA-devices are listed and discussed in combination with the data acquired in the test measurements and calculations. The image quality will improve with further software developments. The long-term reproducibility and in vivo reliability remains to be evaluated.     

Measures of complexity for cancellous bone.

The problem of quantifying the structure of cancellous bone has been addressed in the past by histomorphometry and more recently by imaging techniques using X-ray attenuation. The current approaches compute and describe parts of the construction of the trabecular net. We developed a new technique which quantifies cancellous bone of human lumbar vertebrae as a whole. The interactions, transactions, and interrelationships of all parts of the structural composition of the trabeculae are accounted for and quantified. The method is based on the concept of structural complexity within the framework of nonlinear dynamics. The methodology was developed by using axial high resolution computed tomography images. The technique was transferred to quantitative computed tomography images and is based on the non-invasive assessment of 50 human L3 specimens. The value of Houndsfield units per pixel representing trabecular bone of the vertebrae was transformed into color-encoded and alphabet-encoded symbols. The procedure of transformation of the X-ray attenuation pixels into symbols was necessary as a basis on which measures of complexity were introduced to assess the composition of symbols within the images. The development of a generalization of symbolic dynamics, a mathematical method, to work with two-dimensional images was a prerequisite. The results of this study demonstrate that the structural composition of cancellous bone declines more rapidly than bone mineral density during the loss of bone. This outcome strongly suggests an exponential relationship between bone mineral density and the architectural composition of cancellous bone. Normal trabecular bone has a complex ordered structure. The structural composition during the osteopenic phase of bone loss is characterized by lower structural complexity and a significantly higher level of architectural disorder. A high grade of osteoporosis leads again to an ordered structure, although its structural complexity is minimal.     

Chronic tiagabine administration and aggressive responding in individuals with a history of substance abuse and antisocial behavior

Anticonvulsants, notably those which modulate GABA activity, have shown efficacy in reducing aggressive behavior. Previously, we found dose-related decreases in human aggressive responding following acute tiagabine administration. Here, we examined the effects of chronic tiagabine over a 5-week period. Twelve individuals at increased risk for aggressive and violent behavior (currently on parole/probation with personality and/or substance use disorders) were randomly assigned to placebo (n?=?6) or an escalating dose sequence of placebo, 4?mg, 8?mg, 12?mg, placebo (n?=?6). Data were analyzed using both frequentist and Bayesian mixed models, evaluating aggressive behavior as a function of time, dose condition, and their interaction. For aggressive responding, there was a significant interaction of drug condition and time. Aggression in the tiagabine condition decreased for each additional week in the study, while participants in the placebo condition failed to demonstrate similar change over time. For monetary-reinforced responding, no drug or drug by time interactions were observed, suggesting specificity of drug effects on aggression. The small number of subjects limits the generality of the findings, and previous studies with tiagabine are limited to acute dosing and case report investigations. However, the present data provide an indication that tiagabine merits further examination as an agent for management of impulsive aggression.     

Water and electrolyte content of human intervertebral discs under variable load

The human intervertebral disc acts as an osmotic system. Water, salt, and other low-molecular substances penetrate the cartilage plates and annulus fibrosus. The content of water, sodium, potassium, and ashes in different regions of 69 human lumbar intervertebral discs was examined before and after being loaded with certain weights. Under load, the disc loses water (annulus 11%, nucleus 8%) and gains sodium and potassium. The higher concentration of electrolytes in the disc after a long period of loading increases its osmotic absorption force and enables the disc to hold back the remaining water, even against a considerable pressure. After reduction of the pressure, water is quickly reabsorbed and the disc gains height and volume. The pumping mechanism maintains the nutrition and biomechanical function of the intervertebral disc.