Interactive memory systems and category learning in schizophrenia

Schizophrenia is a devastating mental disorder with multiple facets, including the impairment of learning and memory. Recent evidence suggests that information is processed and represented by multiple interacting memory systems in the brain, including prefrontal cortex, basal ganglia, and medial temporal lobe. These structures are critical in the pathophysiology of schizophrenia. Whereas executive and declarative memory dysfunctions are well known in schizophrenia, habit learning deficits related to the basal ganglia are less clear, despite the fact that dopaminergic and other neurochemical processes in the basal ganglia may play a crucial role in the pathophysiology and pharmacology of schizophrenia. In this article, I propose that the investigation of different classification learning functions, including reward- and feedback-guided learning and acquired equivalence learning, may shed light on the neuropsychology, pathophysiology, pharmacology, and behavioral genetics of schizophrenia.     

Hyperlipidemia induced by a cholesterol-rich diet aggravates necrotizing pancreatitis in rats

The aim of the present study was to investigate whether hyperlipidemia can cause acute pancreatitis or alter its severity. Male Wistar rats were fed a 3% cholesterol-enriched diet or a normal diet for 16 weeks. Edematous and necrotizing pancreatitis was induced with 3x75 mug/kg body weight of cholecystokinin s.c. and 2x2 g/kg body weight of L-arginine i.p., respectively, in separate groups of normal and hyperlipidemic rats. The severity of the pancreatitis was assessed. We studied the influence of hyperlipidemia on the formation of oxygen-derived free radicals, endogenous scavengers, nitric oxide synthases (NOS), peroxynitrite (ONOO(-)), heat shock protein 72 (HSP72) and nuclear factor-kappa B (NF-kappaB) activation in the pancreas during acute edematous and necrotizing pancreatitis. Hyperlipidemia did not worsen edematous, but aggravated necrotizing pancreatitis. The cholesterol-enriched diet significantly reduced the catalase and Mn-superoxide dismutase (SOD) and constitutive NOS (cNOS) activities and increased the inducible NOS (iNOS) in the pancreas relative to those in the rats on the normal diet. The pancreatic nitrotyrosine level, as a marker of ONOO(-), and the NF-kappaB DNA-binding activity in the pancreas, were significantly elevated in the cholesterol-fed rats. The pancreatic HSP72 expression during necrotizing pancreatitis was not influenced by the hyperlipidemia. The pancreatic Mn-SOD, Cu, Zn-SOD, glutathione peroxidase, total glutathione and cNOS activities were significantly reduced, while the catalase, iNOS and NF-kappaB DNA-binding activities were significantly increased in the animals with necrotizing pancreatitis on the cholesterol diet as compared with those with pancreatitis and receiving the normal diet. Hyperlipidemia induced with this cholesterol-enriched diet leads to decreases in endogenous scavenger and cNOS activities, results in iNOS and NF-kappaB activation and stimulates ONOO(-) generation in the pancreas, which may be responsible for the aggravation of acute necrotizing pancreatitis.     

Fundamentals of stationary phase optimized selectivity LC (SOS-LC)

A new procedure (SOS-LC) is described for the optimization of the HPLC stationary phase, using serially connected columns and the principle of the "PRISMA" model. In the course of the base measurements the retention factors (k) of the analytes were determined on three different base stationary phases; other parameters were fixed. By use of these data the k values were predicted in the cases of all theoretically combined stationary phases. These predictions resulted in numerous intermediate theoretical separations but only the optimal one was compiled and tested applying other parameters fixed as in the case of the base measurements. The overall selectivity of this separation was better than that of any individual stationary phase. SOS-LC is independent of the mechanism and the scale of separation and will be very advantageous in the case of hyphenated techniques (LC-MS and LC-NMR) due to stable mobile phase background.     

Planar chromatography: Current status and future perspectives in pharmaceutical analysis — I. Applicability, quantitation and validation

The most important features of capillary action planar chromatographic methods are summarized. Certain properties such as case in operation, sensitivity to experimental conditions, stationary and mobile phase selection, phase system optimization, separation efficiency and detection possibilities are discussed only briefly. Other aspects such as the applicability of planar chromatographic methods in pharmaceutical analysis, quantitation and validation are considered in more detail. The advantages and limitations of different evaluation techniques (visual comparison, spot elution techniques and in situ densitometry) are also discussed. Validation steps specific to planar chromatographic methods are emphasized.     

The cognitive neuroscience of category learning

Recently, a multidisciplinary approach has provided new insights into the mechanisms of category learning. In this article, results from theoretical modeling, experimental psychology, clinical neuropsychology, functional neuroimaging, and single-cell studies are reviewed. Although the results are not conclusive, some general principles have emerged. Areas localized in the sensory neocortex are responsible for the perceptual representation of category exemplars, whereas lateral and anterior prefrontal structures are necessary for the encoding of category boundaries and abstract rules. The prefrontal cortex may influence categorical representation in the sensory neocortex via top-down control. The neostriatum is important in stimulus–response mapping, and the orbitofrontal cortex/ventral striatum are related to stimulus–reward associations accompanying category learning. Many category learning tasks can be performed implicitly. In conclusion, category learning paradigms provide a unique opportunity to investigate cognitive processes such as perception, memory, and attention in a systematic and interactive manner. Category learning tasks are suitable for mapping damaged brain systems in clinical populations.     

The effect of vestibular nerve section on the expression of the hyaluronan in the frog, Rana esculenta

Following postganglionic lesion of the eighth cranial nerve, the changes in the expression of hyaluronan (HA), one of the extracellular matrix macromolecules, were examined in the medial (MVN) and lateral (LVN) vestibular nuclei and in the entry or transitional zone (TZ) of the nerve in the frog. HA was detected in different survival times by using a specific biotinylated hyaluronan-binding probe. HA expression was defined by the area-integrated optical density (AIOD), calculated from pixel intensities of digitally captured images. During the first postoperative days the perineuronal net (PN), a HA-rich area around the neurons, was not distinguishable from the surrounding neuropil in the MVN and LVN, characterized by a bilateral drop of AIOD specifically on the operated side. From postoperative day 14 onwards AIOD increased whilst the PN reorganized. In contrast, the AIOD wobbled up and down bilaterally without any trend in the TZ. Statistical analysis indicated that AIOD changes in the structures studied ran parallel bilaterally presumably because of the operation. Our results demonstrated for the first time that (1) the lesion of the eighth cranial nerve is accompanied by the modification of AIOD reflected HA expression in the MVN, LVN and TZ, (2) different tendencies exist in the time course of AIOD in the structures studied and (3) these tendencies are similar on the intact and operated sides. Our findings may suggest an area dependent molecular mechanism of HA in the restoration of vestibular function.     

Radical vulvectomy to treat severe vulvar acne inversa

A rare case, when radical vulvectomy had to be done to treat a benign skin disorder is presented. PATIENT AND METHOD: A 56-year-old white woman suffered from severe vulvar acne inversa. The systemic treatments, the incisions and drainages were not successful. The only solution was the radical excision of the seriously damaged vulva, with a satisfactory cosmetic and functional result. The pathology, the diagnosis and the treatment of the disease are also discussed. CONCLUSION: The authors put emphasis on the importance of the interdisciplinary collaboration.     

The state of the colorectal screening in Hungary: lessons of the pilot programs

In Hungary, colorectal cancer is the second most common malignant disease. Due to its natural history, colorectal cancer is particularly suitable for screening. At present, epidemiological evidences of the effectiveness of detection of the symptomless colorectal cancer and its precursors are only available for the demonstration of fecal occult blood, endoscopic methods are also in use. For mass screening, fecal occult blood tests are recommended. Guaiac-type chemical methods are widely criticized because of the lack of specificity. Out of the emerging technologies, immunochemical methods based on the antigenicity of blood proteins (hemoglobin) seem to be the most suitable. In the model programmes organized in the frame of the National Public Health Programme, an immunochemical method using two blood proteins (hemoglobin and albumin) have been used. The compliance was not more than 30-45%. About one-third of those with positive blood test refused colonoscopy. The programmes revealed a great number of adenomatous polyps and early cancers, and in the way, the effectiveness of the method has been proved. The model programmes are still continued. Before the continuous and gradual extension of colorectal screening, the validity of the specific method needs to be tested and proved in order to be recognized as a routine procedure for screening. There is a need to test the feasibility of total colonoscopy, however, to this effect the colonoscopic capacity in the country has to be further developed.