A composite neural network model for perseveration and distractibility in the Wisconsin card sorting test.

A composite artificial neural network model is proposed to simulate the performance of the Wisconsin Card Sorting Test. The Wisconsin Card Sorting Test is a test of executive functions where prefrontal deficits are matched to some quantitative measures such as percentage of perseverative errors and number of failures to maintain set. In this work, the proposed model is used to simulate the performances of healthy subjects and patients with prefrontal involvement particularly on these measures. The model is designed in such a way that one of the subsystems, namely, the Hopfield network, serves as the working memory and the other, the Hamming block, as the hypothesis generator. The results show that the proposed relatively simple model is capable of simulating the wide range of the performances of both normal subjects and prefrontal patients on the Wisconsin Card Sorting Test. While lowering the Hamming distance in the Hamming block gave rise to progressively more perseverative responses, changing the threshold vector of the Hopfield network resulted in more set maintenance failures. The former manipulation disrupts the abstraction or mental flexibility and the latter sustained attention or perseverance both of which are the major functions of the prefrontal system.     

beta2 adrenoceptor (ADRB2) pharmacogenetics and cardiovascular phenotypes during laryngoscopy and tracheal intubation

Pharmacogenetics is the study of genetic variations that cause a variable drug response characterized by alteration in drug metabolism or in pharmacodynamics. The polymorphisms in genes encoding receptors relevant to treatment cause variation in sensitivity to many drugs. beta2 Adrenoceptor genetic variation contributes to regulation of blood pressure and hemodynamic changes by mediating peripheral vasodilatation. Laryngoscopy and tracheal intubation associated with hemodynamic changes. Although there are four nonsynomic single-nucleotide polymorphisms (SNPs) of beta2 adrenoceptor gene, codon 16 (Arg16Gly) and codon 27 (Gln27Glu) SNPs are both common and functionally important. In this paper, the authors investigated the beta2 adrenoceptor Gly16 and Glu27 SNPs in response to drugs relevant to anesthesia and how these SNPs impacted upon the cardiovascular phenotypes. The authors measured arterial systolic and diastolic blood pressure, heart rate, and rate-pressure product before induction of anesthesia and 1 min following laryngoscopy and tracheal intubation. Genomic DNA was amplified and genotyped using allele-specific polymerase chain reaction (ASPCR) and restriction fragment length polymorphism (RFLP) assays, respectively. When the authors compared hemodynamic results according to genotypes, the patients with Gln homozygote allele at codon 27 exhibited significant increase of heart rate than patients with Glu allele after laryngoscope and tracheal intubation.     

A rare cause of intestinal perforation: ingestion of magnet

Background  

Ingestion of foreign objects is a common problem in children. Ingestion of one more magnets may require surgical intervention because of risk of perforation.     

Adiponectin levels and cardiovascular risk factors in hypothyroidism and hyperthyroidism

OBJECTIVE: Adiponectin, an adipose tissue-derived hormone, has been reported to have anti-inflammatory and anti-atherogenic effects. The physiological effect of adiponectin on the metabolic changes and its relation with cardiovascular risk factors in thyroid dysfunction states is still not clear. The aim of the study was to evaluate plasma adiponectin level and its relation to cardiovascular risk factors in patients with thyroid dysfunction. PATIENTS AND MEASUREMENTS: Sixty-seven patients with hypothyroidism, 56 patients with hyperthyroidism and 52 age- and sex-matched euthyroid subjects were enrolled in the study. Adiponectin, C-reactive protein (CRP), homocysteine (Hcy), lipid parameters, Lipoprotein(a) [Lp (a)], Apolipoprotein (Apo) A, Apo B and fibrinogen levels were measured in all subjects. Insulin sensitivity was determined using the Homeostasis Model Assessment (HOMA-IR). RESULTS: Circulating adiponectin levels were not different between the groups (16.2 +/- 5.0, 15.1 +/- 3.7, 15.9 +/- 4.8 ng/ml; hypothyroid, hyperthyroid, euthyroid group, respectively). Plasma adiponectin levels correlated negatively with body mass index (BMI) and HOMA-IR index and positively with high-density lipoprotein cholesterol (HDL-C) in all groups. There was a significant correlation between adiponectin and CRP levels in both hypothyroid and hyperthyroid groups. In all groups, adiponectin levels did not correlate with age, systolic blood pressure, diastolic blood pressure and thyroid hormones. Multiple regression analysis revealed BMI and HDL-C levels to be the most important predictors of circulating adiponectin levels. CONCLUSIONS: Plasma adiponectin levels are associated with BMI and HDL-C levels in patients with hypothyroidism and hyperthyroidism. But there is not a direct relation of adiponectin with thyroid hormones in these patients.     

Influence of Heavy Cigarette Smoking on Heart Rate Variability and Heart Rate Turbulence Parameters

Background: Cigarette smoking increases the risk of cardiovascular events related with several mechanisms. The most suggested mechanism is increased activity of sympathetic nervous system. Heart rate variability (HRV) and heart rate turbulence (HRT) has been shown to be independent and powerful predictors of mortality in a specific group of cardiac patients. The goal of this study was to assess the effect of heavy cigarette smoking on cardiac autonomic function using HRV and HRT analyses. Methods: Heavy cigarette smoking was defined as more than 20 cigarettes smoked per day. Heavy cigarette smokers, 69 subjects and nonsmokers 74 subjects (control group) were enrolled in this study. HRV and HRT analyses [turbulence onset (TO) and turbulence slope (TS)] were assessed from 24‐hour Holter recordings. Results: The values of TO were significantly higher in heavy cigarette smokers than control group (?1.150 ± 4.007 vs ?2.454 ± 2.796, P = 0.025, respectively), but values of TS were not statistically different between two groups (10.352 ± 7.670 vs 9.613 ± 7.245, P = 0.555, respectively). Also, the number of patients who had abnormal TO was significantly higher in heavy cigarette smokers than control group (23 vs 10, P = 0.006). TO was correlated with the number of cigarettes smoked per day (r = 0.235, P = 0.004). While LF and LF/HF ratio were significantly higher, standard deviation of all NN intervals (SDNN), standard deviation of the 5‐minute mean RR intervals (SDANN), root mean square of successive differences (RMSSD), and high‐frequency (HF) values were significantly lower in heavy smokers. While, there was significant correlation between TO and SDNN, SDANN, RMSSD, LF, and high frequency (HF), only HF was correlated with TS. Conclusion: Heavy cigarette smoking has negative effect on autonomic function. HRT is an appropriate noninvasive method to evaluate the effect of cigarette on autonomic function. Simultaneous abnormal HRT and HRV values may explain increased cardiovascular event risk in heavy cigarette smokers.     

Repaglinide plus single-dose insulin glargine: a safe regimen for low-risk type 2 diabetic patients who insist on fasting in Ramadan

Aim of this prospective study is to evaluate the effect of repaglinide t.i.d. (three times a day) plus single-dose insulin glargine regimen in low-risk type 2 diabetic patients during Ramadan fasting. Participants had been taking the regimen for at least 3 months. Patients with a history of diabetic coma, severe hypoglycemic crisis or repeating attacks of hypoglycemia were excluded. Hypoglycemic unawareness, kidney or liver disease or HbA1c over 8% were also accepted as exclusion criteria. Eleven patients who insisted on this worship and eight non-fasting cases were involved. All were told to make home-glucose-monitorisation weekly and report any hypoglycemic event throughout Ramadan. Fasting blood glucose (FBG), post-prandial blood glucose (PBG) and fructosamine levels, body weights and blood pressures were recorded just before and after Ramadan. Seven patients in each group concluded the follow-up. Any significant change was detected in the parameters in either groups (P>0.05). Glucose control remained unchanged; fructosamine 318.14+/-65.38 versus 317.28+/-52.80 mmol/L in fasting group, 290.71+/-38.48 versus 290+/-38.56 mmol/L in non-fasting group. None of them exhibited either a major or a minor hypoglycemic event. The results of this pilot study indicated that repaglinide t.i.d. plus single-dose insulin glargine regimen was safe for low-risk type 2 diabetic patients who insisted on fasting during Ramadan.     

Racial differences in adiponectin in youth: relationship to visceral fat and insulin sensitivity

OBJECTIVE: The purpose of this study was to investigate 1) whether adiponectin is associated with insulin sensitivity independent of visceral adipose tissue in African-American and Caucasian youth and 2) whether adiponectin is associated with racial differences in insulin sensitivity. RESEARCH DESIGN AND METHODS: Total body fat was measured by dual-energy X-ray absorptiometry and abdominal adipose tissue with computed tomography. Insulin sensitivity was measured by a 3-h hyperinsulinemic-euglycemic clamp. RESULTS: Adiponectin was inversely associated (P < 0.01) with visceral adipose tissue, fasting insulin, and proinsulin and was positively related (P < 0.01) to insulin sensitivity after controlling for Tanner stage and sex independent of race. Stepwise multiple regression revealed that adiponectin was a strong independent predictor of insulin sensitivity, explaining 27% of the variance in insulin sensitivity. When subjects were categorized into tertiles of visceral adipose tissue and further low (< or = 50th) and high (>50th) adiponectin groups, insulin sensitivity was significantly different across the visceral adipose tissue groups (main effect, P < 0.01) in both races. However, within each visceral adipose tissue group, subjects with high adiponectin had higher insulin sensitivity (main effect, P < 0.05) than subjects with low adiponectin, independent of race. Racial differences in insulin sensitivity remained significant (P < 0.01) after controlling for leptin and visceral adipose tissue but not (P > 0.05) after additional adjustment for adiponectin. CONCLUSIONS: Adiponectin is associated with insulin sensitivity independent of visceral adipose tissue in both African-American and Caucasian youth. Low adiponectin in African-American youth may be a biological marker that predisposes them to a greater risk of insulin resistance.