Feature uncertainty activates anterior cingulate cortex

In visual discrimination tasks, the relevant feature to discriminate is defined before stimulus presentation. In feature uncertainty tasks, a cue about the relevant feature is provided after stimulus offset. We used (15)O-butanol positron emission tomography (PET) in order to investigate brain activation during a feature uncertainty task. There was greater activity during the feature uncertainty task, compared with stimulus detection and discrimination of orientation and spatial frequency, in the lateral and medial prefrontal cortex, the cuneus, superior temporal and inferior parietal cortex, cortical motor areas, and the cerebellum. The most robust and consistent activation was observed in the dorsal anterior cingulate cortex (Brodmann area 32; x = 0 y = 16, z = 40). The insula, located near the claustrum (x = -38, y = 8, z = 4), was activated during the discrimination tasks compared with the feature uncertainty condition. These results suggest that the dorsal anterior cingulate cortex is important in feature uncertainty conditions, which include divided attention, expectancy under uncertainty, and cognitive monitoring.     

The role of ventromedial prefrontal cortex in addiction disorders

Recently a significant conceptual change emerged in the interpretation of addictological disorders. Despite this significant progress, the exact neuronal mechanisms of these disorders are still unknown. By the development of cognitive neuroscience novel clinical tests became available which are devoted to the evaluation of more properly defined neuronal structures. These novel approaches are designed to separately investigate memory/attention-related and affective processes in decision-making. These investigations along with animal models and functional neuroimaging approaches suggest the crucial role of a complex neuronal network in the pathomechanism of addictological disorders, including the ventromedial prefrontal cortex and the amygdala-accumbens system. The aim of this paper is to review these novel findings in order to gain insight into the neurocognitive mechanisms of addictological disorders.     

Severe nephrotic syndrome in a young man taking anabolic steroid and creatine long term

Anabolic steroids and creatine supplementation is one of the current abuse used by body builders. It is less known that this combination beside of many deleterious effects may also cause renal damage. Authors report a case of diffuse membranoproliferative glomerulonephritis type I in a 22-year-old man who had been taking continuously methandion in a large quantity and 200 grams of creatine daily, and was sent to the outpatient nephrologic unit with typical clinical signs of nephrosis syndrome. They also call attention to the role of the continuously consumed creatine in the renal failure.     

Thoracic epidural anesthesia improves the gastric microcirculation during experimental gastric tube formation

BACKGROUND: Gastric tube formation is a surgical technique to reestablish the continuity of the gastrointestinal tract after esophagectomy. Our aims were to study the microcirculatory consequences of experimental gastric tube formation and characterize the effects of thoracic epidural anesthesia (TEA) during this condition. METHODS: The experiments were performed on mongrel dogs anesthetized with pentobarbital. The stomach was prepared for replacement according to the method of Akiyama, and TEA was induced with bupivacaine (1 mg/kg). Macrohemodynamics, intramucosal pH, and gastric motility changes were monitored, and intravital video-microscopy with orthogonal polarization spectral imaging technique was used to observe the gastric microcirculation. RESULTS: The gastric pull-up induced a significant decrease in intramucosal pH. The functional capillary density of the mucosa or subserosa did not change; the red blood cell velocity in the capillaries of the upper part of the gastric tube was decreased in the mucosa, as well as on the serosal side. After epidural anesthesia the red blood cell velocity returned to the baseline, and the gastric and intestinal motility index was significantly increased. CONCLUSIONS: TEA significantly improves the microcirculation of the distal portion of the gastric tube and increases the intestinal and gastric motility after gastric pull-up. The procedure is favorable and should be recommended during reconstructive esophageal surgery.     

hMLHl and hMSH2 somatic inactivation mechanisms in sporadic colorectal cancer patients

Much is known about the role of germline inactivation in mismatch repair (MMR) genes in hereditary non-polyposis colorectal cancer (HNPCC), but the impact of somatic MMR gene changes on sporadic colorectal cancer remains to be elucidated. In hereditary cases the hMLHl and hMSH2 genes were shown to have a great importance, and in order to examine the somatic inactivation mechanisms of the two MMR genes hMLHl and hMSH2 we screened 37 Hungarian sporadic colorectal cancer patients for allelic imbalance (AI), microsatellite instability (MSI), hMLHl promoter hypermethylation and somatic mutations. Thirteen of the examined tumours (35%) were characterized by low-level MSI and none of the cases belonged to the high MSI group. Nine (24%) and seven (19%) cases had AI at the hMLHl and hMSH2 genes, respectively. Seven tumours (19%) showed dense promoter hypermethylation of hMLHl, but only two patients had somatic mutations, one for each MMR gene. According to our study on this limited set of cases the most prominent mismatch repair inactivation mechanism in sporadic colorectal cancer patients is the hMLHl promoter hypermethylation which may have a role in the carcinogenesis of sporadic colorectal cancer.     

The C270T polymorphism of the brain-derived neurotrophic factor gene is associated with schizophrenia

We investigated a novel polymorphism of single nucleotide substitution (C270T) of the brain-derived neurotrophic factor (BDNF) gene in schizophrenia patients (n=101) and in controls (n=68). The frequency of the C/T genotype and the T allele were significantly higher in the schizophrenia patients (25.7% and 13.9%, respectively) compared with the controls (5.9% and 2.9%). There were no significant differences in Positive and Negative Symptom Scale (PANSS) items and Global Assessment of Functioning (GAF) scores between the patients with C/C and C/T genotypes. Further studies are warranted to elucidate the significance of this finding in the pathophysiology of schizophrenia.     

Four facets of a single brain: behaviour,cerebral blood flow/metabolism,neuronal activity and neurotransmitter dynamics

Is functional neuroimaging a royal way to understand brain function or is it a new phrenology without an exact understanding what we measure? After two decades of imaging revolution, more and more authors ask this question. Brain functions are multidimensional, which can be approached from the point of (1) behavioural measures, (2) brain activation as reflected by blood flow and metabolic changes, (3) electrical activity of cells and cell-populations, and (4) neurotransmitter dynamics (release, receptor binding and reuptake). Using imaging techniques, we must take into consideration that even during the simplest task all of these processes operate in a closely interacting manner. Therefore, before drawing final conclusions about brain functions on the basis of a single aspect of these mechanisms, we must clarify the exact relationship among them. In this paper, we address this issue in order to draw attention to a number of uncertainties and controversies in the relationship of the four facets of brain functions.