Rostral and dorsal anterior cingulate cortex make dissociable contributions during antisaccade error commission

The anterior cingulate cortex (ACC) participates in both performance optimization and evaluation, with dissociable contributions from dorsal (dACC) and rostral (rACC) regions. Deactivation in rACC and other default-mode regions is important for performance optimization, whereas increased rACC and dACC activation contributes to performance evaluation. Errors activate both rACC and dACC. We propose that this activation reflects differential error-related involvement of rACC and dACC during both performance optimization and evaluation, and that these two processes can be distinguished by the timing of their occurrence within a trial. We compared correct and error antisaccade trials. We expected errors to correlate with an early failure of rACC deactivation and increased activation of both rACC and dACC later in the trial. Eighteen healthy subjects performed a series of prosaccade and antisaccade trials during event-related functional MRI. We estimated the hemodynamic responses for error and correct antisaccades using a finite impulse-response model. We examined ACC activity by comparing error and correct antisaccades with a fixation baseline and error to correct antisaccades directly. Compared with correct antisaccades, errors were characterized by an early bilateral failure of deactivation of rACC and other default-mode regions. This difference was significant in rACC. Errors also were associated with increased activity in both rACC and dACC later in the trial. These results show that accurate performance involves deactivation of the rACC and other default mode regions and suggest that both rACC and dACC contribute to the evaluation of error responses.     

In vitro reversal of hyperglycemia normalizes insulin action in fat cells from type 2 diabetes patients: is cellular insulin resistance caused by glucotoxicity in vivo?

Chronic hyperglycemia promotes the development of insulin resistance. The aim of this study was to investigate whether cellular insulin resistance is secondary to the diabetic state in human type 2 diabetes. Subcutaneous fat biopsies were taken from 3 age-, sex-, and body mass index (BMI)-matched groups with 10 subjects in each group: type 2 diabetes patients with either good (hemoglobin A(1c) [HbA(1c)] < 7%, G) or poor (HbA(1c) > 7.5%, P) metabolic control and healthy control subjects (C). Insulin action in vitro was studied by measurements of glucose uptake both directly after cell isolation and following a 24-hour incubation at a physiological glucose level (6 mmol/L). The relationship with insulin action in vivo was addressed by employing the euglycemic clamp technique. Freshly isolated fat cells from type 2 diabetes patients with poor metabolic control had approximately 55% lower maximal insulin response (1,000 microU/mL) on glucose uptake (P <.05) compared to C. Cells from P were more insulin-resistant (P <.05) than cells from G at a low (5 microU/mL) but not at a high (1,000 microU/mL) insulin concentration, suggesting insulin insensitivity. However, following 24 hours of incubation at physiological glucose levels, insulin resistance was completely reversed in the diabetes cells and no differences in insulin-stimulated glucose uptake were found among the 3 groups. Insulin sensitivity in vivo assessed with hyperinsulinemic, euglycemic clamp (M-value) was significantly associated with insulin action on glucose uptake in fresh adipocytes in vitro (r = 0.50, P <.01). Fasting blood glucose at the time of biopsy and HbA(1c), but not serum insulin, were negatively correlated to insulin's effect to stimulate glucose uptake in vitro (r = -0.36, P =.064 and r = - 0.41, P <.05, respectively) in all groups taken together. In the in vivo situation, fasting blood glucose, HbA(1c), and serum insulin were all negatively correlated to insulin sensitivity (M-value; r = -0.62, P<.001, r= -0.61, P<.001, and r = -0.56, p <.01, respectively). Cell size, waist-to-hip ration (WHR), and BMI correlated negatively with insulin's effect to stimulate glucose uptake both in vitro (r = -0.55, P <.01, r = -0.54, P <.01, and r = -0.43, P <.05, respectively) and in vivo (r = -0.43, P <.05, r = -0.50, P <.01, and r = -0.36, P <.05, respectively). Multiple regression analyses revealed that adipocyte cell size and WHR independently predicted insulin resistance in vitro. Furthermore, insulin sensitivity in vivo could be predicted by fasting blood glucose and serum insulin levels. We conclude that insulin resistance in fat cells from type 2 diabetes patients is fully reversible following incubation at physiological glucose concentrations. Thus, cellular insulin resistance may be mainly secondary to the hyperglycemic state in vivo.     

CXCL5-secreting pulmonary epithelial cells drive destructive neutrophilic inflammation in tuberculosis

Successful host defense against numerous pulmonary infections depends on bacterial clearance by polymorphonuclear leukocytes (PMNs); however, excessive PMN accumulation can result in life-threatening lung injury. Local expression of CXC chemokines is critical for PMN recruitment. The impact of chemokine-dependent PMN recruitment during pulmonary Mycobacterium tuberculosis infection is not fully understood. Here, we analyzed expression of genes encoding CXC chemokines in M. tuberculosis–infected murine lung tissue and found that M. tuberculosis infection promotes upregulation of Cxcr2 and its ligand Cxcl5. To determine the contribution of CXCL5 in pulmonary PMN recruitment, we generated Cxcl5^–/– mice and analyzed their immune response against M. tuberculosis. Both Cxcr2^–/– mice and Cxcl5^–/– mice, which are deficient for only one of numerous CXCR2 ligands, exhibited enhanced survival compared with that of WT mice following high-dose M. tuberculosis infection. The resistance of Cxcl5^–/– mice to M. tuberculosis infection was not due to heightened M. tuberculosis clearance but was the result of impaired PMN recruitment, which reduced pulmonary inflammation. Lung epithelial cells were the main source of CXCL5 upon M. tuberculosis infection, and secretion of CXCL5 was reduced by blocking TLR2 signaling. Together, our data indicate that TLR2-induced epithelial-derived CXCL5 is critical for PMN-driven destructive inflammation in pulmonary tuberculosis.     

The Allergy Pricker

Skin prick test has advantages over other diagnostic tests in allergy, and attempts to increase the reproducibility are warranted. A standardised disposable precision needle with a needle point of 1.0 mm has recently become available. Based on 960 tests with histamine and grass pollen ( Phleum pratense ) the reproducibility of the skin prick weal area was calculated. Using histamine 10 mg/ml and grass pollen (1000 and 5000 PNU) A significantly lower coeffcient of variation was found compared with a stadard blood lancet with a point of 4 mm. The mean weal reaction is reduced to about 80% of the size obtained with the blood lancet. Testing with the precision needle resulted in a significantly reduced incidence of bleedings. The precision needle simplifies the skin test and does not require as much skill as other needles, and is recommended for both routine tests and the biological standardization of allergen extracts.     

Representativity of a postal public health questionnaire survey in Sweden, with special reference to ethnic differences in participation

AIM: Non-participation in health surveys is a common phenomenon. When differences between participants and non-participants are considerable, the external validity of the sample survey may decrease and false conclusions might be drawn about the health status of the population. For this reason, the authors aimed to investigate the representativity of a postal questionnaire survey performed in the county of Scania, Sweden, in 1999-2000. The survey, which was based on an 18- to 80-year-old population sample, had a 58% response rate (n = 13 604). METHODS: For some variables, the information obtained using the questionnaire was compared with information obtained from a population register that covers all the population in the county (for the 18- to 80-year-old group, n = 850 476). The population register includes, among other data, information on age, gender, educational level, country of birth, and healthcare expenditure. RESULTS: Men, individuals with a low level of education, and immigrants were under-represented in the survey. However, except for immigrants, the under-representation was not large. Among immigrants, particularly those born in former Yugoslavia, the Arabic-speaking countries, and Poland were very significantly under-represented in the study. By contrast, immigrants born in other Nordic countries had responded to almost the same extent as respondents born in Sweden. The survey sample had about the same healthcare utilization costs as did the general population. CONCLUSIONS: In summary, the "Health Survey for Scania, 2000" seems largely representative of the total Scanian population. A major concern, however, is the under-representation of the immigrant population.