Error-related brain potentials are differentially related to awareness of response errors: evidence from an antisaccade task

The error negativity (Ne/ERN) and error positivity (Pe) are two components of the event-related brain potential (ERP) that are associated with action monitoring and error detection. To investigate the relation between error processing and conscious self-monitoring of behavior, the present experiment examined whether an Ne and Pe are observed after response errors of which participants are unaware. Ne and Pe measures, behavioral accuracy, and trial-to-trial subjective accuracy judgments were obtained from participants performing an antisaccade task, which elicits many unperceived, incorrect reflex-like saccades. Consistent with previous research, subjectively unperceived saccade errors were almost always immediately corrected, and were associated with faster correction times and smaller saccade sizes than perceived errors. Importantly, irrespective of whether the participant was aware of the error or not, erroneous saccades were followed by a sizable Ne. In contrast, the Pe was much more pronounced for perceived than for unperceived errors. Unperceived errors were characterized by the absence of posterror slowing. These and other results are consistent with the view that the Ne and Pe reflect the activity of two separate error monitoring processes, of which only the later process, reflected by the Pe, is associated with conscious error recognition and remedial action.     

Analysis of neomycins A, B and C by high-performance liquid chromatography with post-column reaction detection

The analysis of the antibiotics neomycins A, B and C was investigated. The separation of the components was studied using reversed-phase and reversed-phase ion-pair chromatography. The optimum separation was obtained utilizing a Lichrosorb RP-2 column with a mobile phase consisting of 75 mg/l sodium dodecyl sulphate, 0.5M Na2SO4 and 0.015 M sodium acetate buffer at pH 7.0. Using this mobile phase, baseline separation was obtained for all three compounds in approximately 20 min. Detection was via post-column derivatization of the analytes with ortho-phthalaldehyde in the presence of mercaptoethanol to form fluorescent iso-indole products. This system is applied to the analysis of a number of formulated products containing neomycin.     

Right-sided colonic diverticular disease as a source of lower gastrointestinal bleeding

Right-sided colonic diverticular disease is a distinct disease entity uncommon in the West. Occasionally, the condition may be complicated by hemorrhage and present as lower gastrointestinal bleeding. We report a series of 25 cases of bleeding right colon diverticulosis and discuss its presentation and management. Patients were selected from the colonoscopic reports of all 190 patients presented with suspected acute lower gastrointestinal bleeding in National University Hospital, Singapore, from 1988 to 1994. Fifty-seven patients (30%) had bleeding diverticulosis in which 25 patients (44%) suffered from right-sided disease. Sixty-four per cent of patients had a history of hypertension. Patients presented with either fresh blood in stools or melena. Fifteen patients (60%) required blood transfusion (median, 2 units). Colonoscopy showed blood clots in the right colon in 15 cases (60%) and active bleeding from the right colon diverticula in 3 patients (12%). The bleeding stopped spontaneously in 16 patients (64%). The other 9 patients required surgery because of continuous or recurrent bleeding. All had a right hemicolectomy performed. The hospital stay was 13 days in this group, compared with 5 days for those undergoing conservative treatment (P = 0.0004). There were no deaths. No patients had further bleeding episodes during a median 7-month follow-up.     

Needlescopic or minisite cholecystectomy

Needlescopic or minisite cholecystectomy is laparoscopic cholecystectomy done through tiny ports from 1.4 mm to 3 mm in size. This refinement of conventional laparoscopic cholecystectomy reduces further the invasiveness of the operation and gives an improved cosmetic effect. This series describes the result of 36 needlescopic cholecystectomies done between February 1996 and April 1997. Patients with acute cholecystitis were excluded. There were two conversions to conventional laparoscopic surgery and no conversions to open surgery. Thirty-four patients were successfully treated by this technique. Analgesic consumption and cosmetic result was superior compared to a previous published series of conventionally done cases in the same department.     

Cell type-specific acquired protection from crystal adherence by renal tubule cells in culture

BACKGROUND: Adherence of crystals to the surface of renal tubule epithelial cells is considered an important step in the development of nephrolithiasis. Previously, we demonstrated that functional monolayers formed by the renal tubule cell line, Madin-Darby canine kidney (MDCK), acquire protection against the adherence of calcium oxalate monohydrate crystals. We now examined whether this property is cell type specific. The susceptibility of the cells to crystal binding was further studied under different culture conditions. METHODS: Cell-type specificity and the influence of the growth substrate was tested by comparing calcium oxalate monohydrate crystal binding to LLC-PK1 cells and to two MDCK strains cultured on either permeable or impermeable supports. These cell lines are representative for the renal proximal tubule (LLC-PK1) and distal tubule/collecting duct (MDCK) segments of the nephron, in which crystals are expected to be absent and present, respectively. RESULTS: Whereas relatively large amounts of crystals adhered to subconfluent MDCK cultures, the level of crystal binding to confluent monolayers was reduced for both MDCK strains. On permeable supports, MDCK cells not only obtained a higher level of morphological differentiation, but also acquired a higher degree of protection than on impermeable surfaces. Crystals avidly adhered to LLC-PK1 cells, irrespective of their developmental stage or growth substrate used. CONCLUSIONS: These results show that the prevention of crystal binding is cell type specific and expressed only by differentiated MDCK cells. The anti-adherence properties acquired by MDCK cells may mirror a specific functional characteristic of its in situ equivalent, the renal distal tubule/collecting ducts.     

Benefits of leisure-time physical activity on the cardiovascular risk profile at older age.

BACKGROUND: Intensity, frequency and duration of physical activity may contribute in different ways to the maintenance of cardiovascular health. Their relative importance may also change at different stages in life and this should be taken into account for activity recommendations. METHODS: The relationship of frequency and duration of leisure-time physical activities with cardiovascular risk factors was studied in 4942 male and 5885 female participants aged 50-69, of the German Cardiovascular Prevention Study (1984-1991). RESULTS: After adjustment for several possible confounders, women with modest levels (2-12 times per month, 0.5-2 h per week) of moderate-to-vigorous activity (> or =5 kcal/kg/h) had significantly lower systolic blood pressure (-1.8%), resting heart rate (-3.1%) and body mass index (-3.2%) values than sedentary women. Beneficial differences increased with frequency and duration of activity. Light activities (3-4.5 kcal/kg/h), conducted > or =5 times a week, were significantly associated with favourable lower diastolic blood pressure (-1.4%), resting heart rate (-2.3%) among women, and body mass index (women -2.9%, men -2.2%) among both genders. Recommended activity levels (> or =5 times, > or =3.5 h weekly) were associated with a lower prevalence of multiple risk factors (odds ratio [OR] = 0.55, 95% CI: 0.41-0.75 for men and OR = 0.44 95% CI: 0.31-0.63 for women). CONCLUSIONS: For sedentary elderly, even less physical activity than currently recommended, is likely to improve the cardiovascular risk profile.     

The theory of planned behavior: a review of its applications to health-related behaviors

PURPOSE: To review applications of Ajzen's theory of planned behavior in the domain of health and to verify the efficiency of the theory to explain and predict health-related behaviors. METHODS: Most material has been drawn from Current Contents (Social and Behavioral Sciences and Clinical Medicine) from 1985 to date, together with all peer-reviewed articles cited in the publications thus identified. FINDINGS: The results indicated that the theory performs very well for the explanation of intention; an averaged R2 of .41 was observed. Attitude toward the action and perceived behavioral control were most often the significant variables responsible for this explained variation in intention. The prediction of behavior yielded an averaged R2 of .34. Intention remained the most important predictor, but in half of the studies reviewed perceived behavioral control significantly added to the prediction. CONCLUSIONS: The efficiency of the model seems to be quite good for explaining intention, perceived behavioral control being as important as attitude across health-related behavior categories. The efficiency of the theory, however, varies between health-related behavior categories.     

Virgidivarine, a New Alkaloid of Virgilia divaricata

Virgidivarine, C (15)H (26)N (2)O (2), is a new dipiperidine alkaloid, isolated from the South African VIRGILIA DIVARICATA Leguminosae. Its systematic name is 3-carboxy-N-(4'-butenyl)-5-(2'-piperidyl) piperidine.     

Dietary fructans modulate polyamine concentration in the cecum of rats

Nondigestible but fermentable dietary fructans such as oligofructose exert many effects on gut physiology through their fermentation end products such as short-chain fatty acids. Could other metabolites be produced in the gut and contribute to the physiologic effects of dietary fructans? The aim of the study was to evaluate the influence of oligofructose on putrescine, spermidine and spermine concentrations in the cecum, the portal vein and the liver of rats and to assess their involvement in cecal enlargement and the modulation of hepatic lipid metabolism. Putrescine, spermidine and spermine were quantified by HPLC in samples obtained from male Wistar rats fed a nonpurified standard diet (controls) or the same diet enriched with 10 g/100 g oligofructose (OFS) for 4 wk. OFS-fed rats had significantly greater cecal content and tissue weights. OFS almost doubled the concentration of putrescine in the cecal contents. The concentration of all three polyamines in the cecal tissue was significantly greater than in controls. The concentration of spermidine in portal plasma was lower in rats fed OFS, whereas the treatment did not affect the polyamine concentrations in the liver. The fermentation of dietary fructans contributed to an increase in the concentration of putrescine in the gut without modifying putrescine concentration in either the portal blood or liver. Moreover, the greater levels of polyamines in cecal tissue may be related to the cell proliferation resulting from OFS fermentation in the gut.