Monoaminergic activity in subregions of raphé nuclei elicited by prior stress and the neuropeptide corticotropin-releasing factor

Corticotropin-releasing factor (CRF) coordinates neuroendocrine responses to stressful stimuli; one mechanism through which CRF may modulate hypothalamic-pituitary-adrenal axis activity is via actions on neuromodulatory systems such as serotonergic systems. Recent electrophysiological studies and the distribution of CRF receptors within midbrain and pontine raphé nuclei suggest that stress and CRF may have actions on topographically organized subpopulations of serotonergic neurones. We compared the effects of vehicle or intracerebroventricular r/hCRF injections (0, 0.1, 1 or 10 micro g) in rats previously maintained in home cages or restrained for 1 h, 24 h before injection, on monoamine and monoamine metabolite tissue concentrations in the dorsal (lateral wings, rostral midline, caudal midline), median (rostral, caudal) and interfascicular raphé subdivisions of the midbrain and pontine raphé nuclei, using brain microdissection and high-performance liquid chromatography with electrochemical detection. At the lowest dose studied (0.1 micro g), CRF infusions in previously stressed rats decreased 5-hydroxytryptophan (5-HTP) and 5-hydroxyindoleacetic acid (5-HIAA) concentrations only within the rostral median raphé nucleus. At higher doses, CRF infusions in previously stressed rats increased tissue concentrations of 5-HTP, serotonin (5-HT), or the serotonin metabolite, 5-HIAA, within rostral (but not caudal) regions of the median and dorsal raphé nuclei. By contrast, restraint stress alone had no effect on tissue concentrations of 5-HTP, 5-HT or 5-HIAA measured 24 h later in any subdivision, while CRF injections in rats not previously exposed to restraint stress, with few exceptions, also had no effect. These results suggest that the effects of CRF on serotonergic function are context-dependent, dose-dependent, and regionally specific within subdivisions of the brainstem raphé nuclei.     

Multiple neural network classification scheme for detection of colonic polyps in CT colonography data sets

RATIONALE AND OBJECTIVES: A new classification system for colonic polyp detection, designed to increase sensitivity and reduce the number of false-positive findings with computed tomographic colonography, was developed and tested in this study. MATERIALS AND METHODS: The system involves classification by a committee of neural networks (NNs), each using largely distinct subsets of features selected from a general set. Back-propagation NNs trained with the Levenberg-Marquardt algorithm were used as primary classifiers (committee members). The set of features included region density, Gaussian and mean curvature and sphericity, lesion size, colon wall thickness, and the means and standard deviations of all of these values. Subsets of variables were initially selected because of their effectiveness according to training and test sample misclassification rates. The final decision for each case is based on the majority vote across the networks and reflects the weighted votes of all networks. The authors also introduce a smoothed cross-validation method designed to improve estimation of the true misclassification rates by reducing bias and variance. RESULTS: This committee method reduced the false-positive rate by 36%, a clinically meaningful reduction, and improved sensitivity by an average of 6.9% compared with decisions made by any single NN. The overall sensitivity and specificity were 82.9% and 95.3%, respectively, when sensitivity was estimated by means of smoothed cross-validation. CONCLUSION: The proposed method of using multiple classifiers and majority voting is recommended for classification tasks with large sets of input features, particularly when selected feature subsets may not be equally effective and do not provide satisfactory true- and false-positive rates. This approach reduces variance in estimates of misclassification rates.     

Policies on screening female athletes for iron deficiency in NCAA division I-A institutions

Iron deficiency is the most prevalent nutritional deficiency in the United States. This condition has been reported to affect 60% of female athletes. The Centers for Disease Control and Prevention emphasize screening for anemia in women of childbearing age. The purpose of this study was to determine the number of National Collegiate Athletic Association (NCAA) Division I-A schools that implement screening for iron deficiency in female athletes as well as the screening policies for those who do. A link to an online survey was sent to 94 NCAA Division I-A schools to determine current practices concerning screening and treating female athletes for iron deficiency. There was a 58% response rate. Frequencies for each response were computed. Forty-three percent of responding institutions report screening female athletes for iron deficiency. This study suggests that screening for iron deficiency in female athletes at NCAA Division I-A schools is not a routine procedure and, for those who do screen, variability exists in the criteria for diagnosis, as well as in treatment protocols. Standard protocols for assessment and treatment of iron deficiency in female athletes need to be developed and implemented.     

Excessive bleeding and transfusion in a prior cardiac surgery is associated with excessive bleeding and transfusion in the next surgery

If there is a genetic predisposition to excessive bleeding, there should be an association in excessive blood loss between multiple cardiac surgeries. We retrospectively determined in 174 patients the association of excessive bleeding between 2 cardiac surgeries with cardiopulmonary bypass between January 19, 1990 and June 25, 2002. Excessive bleeding was defined by 2 criteria: (a) postoperating room chest tube blood loss over 24 h more than or equal to 750 mL (chest tube drainage [CTD] > or = 750) and (b) transfusion of any non-red blood cell (RBC) blood products. Logistic regression was used to estimate the association between excessive bleeding at the first and second cardiac procedures. The logistic regression models for CTD > or = 750 in the second surgery determined that CTD > or = 750 in the first surgery compared to CTD < 750 had an unadjusted odds ratio of 2.18 (P = 0.03) and an odds ratio of 2.42 (P = 0.03) when adjusted for age, sex, body surface area, preoperative anticoagulant use, cardiopulmonary bypass duration, and procedure type at second surgery. The logistic regression model for any non-RBC use in the second surgery determined that any non-RBC use in the first surgery compared with no non-RBC use had an unadjusted odds ratio of 2.32 (P = 0.02) and an odds ratio of 2.55 (P = 0.02) when adjusted for age, sex, body surface area, preoperative anticoagulant use, cardiopulmonary bypass duration, and procedure type at second surgery. We conclude that a history of excessive bleeding during the first operation is associated with more than two times increased risk for excessive bleeding in the second surgery.     

Status of Borrelia burgdorferi infection after antibiotic treatment and the effects of corticosteroids: An experimental study

Sixteen specific-pathogen-free beagles were infected with Borrelia burgdorferi. Three groups of 4 dogs were treated with antibiotics for 30 consecutive days starting 120 days after tick exposure; 4 dogs were untreated controls. At day 420 after tick exposure and again before euthanasia, 2 dogs of each group were treated with prednisone for 14 days. All dogs contracted infection and 11 developed acute arthritis 50-120 days after exposure. After day 120, one of 12 antibiotic-treated dogs and 2 of 4 untreated dogs became lame. Antibiotic therapy reduced the frequency of Borrelia-positivity in subsequent skin biopsy samples. After prednisone treatment, both control dogs developed severe polyarthritis. At euthanasia, single tissues of the antibiotic-treated dogs and multiple tissues of all control dogs were Borrelia-positive by polymerase chain reaction. Viable spirochetes were not recovered from antibiotic-treated dogs. Two antibiotic-treated dogs showed histologic evidence of minimal lesions, whereas all control dogs had mild polyarthritis with periarteritis.