Reconstruction of a tracheobronchial tree disruption with bovine pericardium

Iatrogenic tracheobronchial disruption is a rare, life-threatening condition. Depending upon the extent of the injury, its location, and the condition of the patient, repair/reconstruction options may be limited. The natural history of bovine pericardium used to repair one such tracheal injury has been documented.     

Hippocampal formation is required for geometric navigation in pigeons

The geometric properties of bounded space have attracted considerable attention as a source of spatial information that can guide goal navigation. Although the use of geometric information to navigate has been observed in every species studied to date, the neural mechanisms that support the representation of geometric information are still debated. With the purpose of investigating this topic, we trained pigeons with lesion to the hippocampal formation to search for food in a rectangular-shaped arena containing one wall of a different color that served as the only distinctive environmental feature. Although lesioned pigeons learned the task even faster than control animals, probe trials showed that they were insensitive to geometric information. Control animals could encode and use both geometric and feature information to locate the goal. By contrast, lesioned pigeons relied exclusively on the feature information provided by the wall of a different color. The results indicate that the avian hippocampal formation is critical for learning the geometric properties of space in homing pigeons.     

The trauma of first episode psychosis: the role of cognitive mediation

OBJECTIVE: First episode psychosis can be a distressing and traumatic event which has been linked to comorbid symptomatology, including anxiety, depression and PTSD symptoms (intrusions, avoidance, etc.). However, the link between events surrounding a first episode psychosis (i.e. police involvement, admission, use of Mental Health Act, etc.) and PTSD symptoms remains unproven. In the PTSD literature, attention has now turned to the patient's appraisal of the traumatic event as a key mediator. In this study we aim to evaluate the diagnostic status of first episode psychosis as a PTSD-triggering event and to determine the extent to which cognitive factors such as appraisals and coping mechanisms can mediate the expression of PTSD (traumatic) symptomatology. METHOD: Approximately 1.5 years after their first episode of psychosis, patients were assessed for traumatic symptoms, conformity to DSM-IV criteria for posttraumatic stress disorder (PTSD), and their appraisals of the traumatic events and coping strategies. Psychotic symptomatology was also measured. RESULTS: 31% of the sample of 35 patients who agreed to participate reported symptoms consistent with a diagnosis of PTSD. Although no relationship was found between PTSD (traumatic) symptoms and potentially traumatic aspects of the first episode (including place of treatment, detention under the MHA etc.), intrusions and avoidance were positively related to retrospective appraisals of stressfulness of the ward (i.e. the more stressful they rated it the greater the number of PTSD symptoms) and the patient's coping style (sealers were less likely to report intrusive re-experiencing but more likely to report avoidance). CONCLUSIONS: The results call into question whether it is possible to make claims for a simple causal link between psychosis and PTSD. Instead patients' appraisals of potentially traumatic events and their coping styles may mediate the traumatic impact of a first episode of psychosis.     

Role of imaging in the diagnosis of acute appendicitis in children

The aim of the study was to investigate the place of imaging in the diagnosis and treatment of acute appendicitis. The files of 2,427 children with suspected acute appendicitis were reviewed for clinical management and operative findings. The sample was divided into 3 groups at time of admission: (1) before diagnostic imaging was available in our department (1991-1994); (2) after the introduction of imaging studies on a random basis in equivocal cases (1995-1998); and (3) after a policy was formulated for ultrasound use in all equivocal cases followed by computed tomography if necessary (1999-2000). Results showed that the rate of misdiagnosis decreased from 13.2% in group 1 to 6.5% in group 2 and 6.1% in group 3. False-positive findings (normal appendix with positive scan) were noted in 16.7% of group 2 and 25% of group 3; false-negative findings (appendicitis at surgery with negative scan) in 23.8% and 9.5%, respectively. Computed tomography was performed in 8 children and prevented unnecessary surgery in 4 of them. We conclude that in equivocal cases of acute appendicitis, imaging studies performed by skilled operators can improve the accuracy of diagnosis, saving patients unnecessary surgery, and identifying other conditions that mimic appendicitis.     

Relationship between damage accumulation and mechanical property degradation in cortical bone: microcrack orientation is important

The accumulation of damage and the associated degradation of the mechanical properties of cortical bone are postulated to contribute to age-, disease-, overuse-, and disuse-related skeletal fragilities. Therefore, gaining insight into the relationship between damage and degradation processes is essential in understanding the etiology of skeletal fractures. In investigating this relationship, the damage measure ideally needs to account for the size, the distribution density, and the orientation of microcracks. Existing measures of damage address the size and distribution density of microcracks; however, the orientation of cracks has not been well-investigated. Because the overall orientation of microcracks determines the material axis along which the greatest degradation will be experienced, we hypothesized that the incorporation of the relative orientation between microcracks and loading direction will improve the significance of the relationship between damage accumulation and material property degradation. A three-cycle damage protocol was used to induce tensile damage and to quantify the degradation of the elastic modulus of specimens from human donor femoral cortical bone (a 24-year-old and a 72-year-old man). Microcracks were evaluated by en bloc basic fuchsin staining of specimens after testing. The length (L(i)) and the orientation with respect to the loading direction (beta(i)) of each crack were quantified by a video microscopy system. Three damage measures were quantified for each specimen: the number of linear microcracks (Cr #), the sum of the crack lengths (SigmaL(i)) accounting for the microcrack size alone, and the sum of the projected crack length [SigmaL(Pi) = SigmaL(i)cos(beta(i))] accounting for both crack size and orientation. Inclusion of the orientation parameter improved the coefficient of determination between damage accumulation and the degradation of the elastic modulus: the coefficient of determination of the sum of the projected crack length (R(2) = 0.239) was 60% greater than that of the sum the projected crack length (R(2) = 0.149) and 33% greater than that of the number of linear microcracks (R(2) = 0.180). We conclude that microcrack orientation is an essential physical variable in the relationship between damage accumulation and degradation of mechanical properties of cortical bone tissue.     

Localization of postresection EGF receptor expression using laser capture microdissection

Background/Purpose: Epidermal growth factor (EGF) and its receptor (EGFR) are key components in the genesis of adaptation after small bowel resection (SBR). Within intestinal homogenates, EGFR expression is increased after SBR; however, the exact cells responsible for altered EGFR expression are unknown. In this study, laser capture microdissection (LCM) microscopy was used to elucidate the specific cellular compartment(s) responsible for postresection changes in EGFR expression. Methods: Male ICR mice underwent a 50% proximal SBR or sham operation. After 3 days, frozen sections were taken from the remnant ileum. Individual cells from villi, crypt, muscularis, and mesenchymal compartments were isolated by LCM. EGFR mRNA expression for each cell compartment was quantified using real-time polymerase chain reaction (PCR). Results: EGFR expression was increased after SBR within the crypt (2-fold) and muscularis compartments (3-fold). There were no changes detected after SBR in the villus tips or mesenchymal compartments. Conclusions: Increased expression of EGFR in crypts directly correlates with the zone of cell proliferation and supports the hypothesis that EGFR signaling is crucial for the mitogenic stimulus for adaptation. The finding of increased EGFR expression in the muscular compartment is novel and may implicate a role for EGFR as a mediator of the muscular hyperplasia seen after massive SBR. J Pediatr Surg 38:440-445.     

Sensorineural hearing loss and Kawasaki disease: a prospective study

PURPOSE: Kawasaki disease (KD) is an acute, self-limited vasculitis of infants and children that is now the most common cause of acquired heart disease in the pediatric age group in the United States and Japan. Reports have documented the association of acute KD with sensorineural hearing loss. To assess the prevalence of hearing loss following acute KD in a geographically and ethnically diverse population, a prospective, multicenter study of hearing loss in patients with KD was conducted. MATERIALS AND METHODS: Patients with acute KD were enrolled in 7 clinical centers and underwent a primary audiologic evaluation within 30 days of the onset of fever. Patients were subsequently reevaluated after resolution of the acute phase of the disease. A questionnaire assessing risk factors for hearing loss was also administered. RESULTS: A total of 62 patients were evaluated during the 29-month study period. At the first audiologic evaluation, 19 patients (30.6%) had sensorineural hearing loss, 6 patients (9.7%) had conductive hearing loss, 17 patients (27.4%) had normal hearing, and 20 patients (32.3%) had inconclusive studies. Overall, 2 of 36 patients (5.5%) had sensorineural hearing loss documented on their second audiologic evaluation. No risk factors for hearing loss were identified by the questionnaire. CONCLUSIONS: Transient sensorineural hearing loss (20 to 35 dB) is a frequent complication of acute KD and may be related to salicylate toxicity in some patients. Persistent sensorineural hearing loss is uncommon. Parents and primary care providers should be made aware of the potential for persistent sensorineural hearing loss following resolution of KD, but routine audiologic screening of this patient population does not appear to be warranted.     

Quantitative EEG in schizophrenia and in response to acute and chronic clozapine treatment

Topographic quantitative electroencephalographic (EEG) power and frequency indices were collected in 17 treatment refractory, DSM-III diagnosed schizophrenic patients, before and after acute (single dose) and chronic (six weeks) clozapine treatment, as well as in 17 healthy volunteers. Prior to treatment, patients exhibited greater overall absolute theta power, slower mean alpha frequency and elevated absolute delta and total power in anterior regions. Acute dosing increased total spectrum power globally, slow wave power posteriorally, mean alpha frequency and beta power anteriorally and decreased alpha power posteriorally. Six weeks of clozapine treatment significantly reduced clinical ratings of positive and negative symptoms as well as symptoms of global psychopathology. Chronic treatment resulted in EEG slowing as shown by decreases in relative alpha power, mean beta/total spectrum frequency and by widespread increases in absolute total and delta/theta power. The preliminary findings suggest that brain electric profiling may be a promising tool for assessing and understanding the central impact of pharmacotherapeutic interventions in schizophrenia.     

Molecular effects of calcium binding mutations in Marfan syndrome depend on domain context

Mutations in the human fibrillin-1 (FBN-1) gene cause Marfan syndrome (MFS), an autosomal dominant disease of connective tissue. Fibrillin-1, a 350 kDa extracellular calcium binding protein, is a major structural component of 10-12 nm microfibrils and consists predominantly of two repeated module types: the calcium binding epidermal growth factor-like (cbEGF) domain and the transforming growth factor beta1 binding protein-like (TB) domain. A group of reported FBN-1 mutations is predicted to reduce calcium binding to cbEGF domains by removal of a side chain ligand for calcium. These mutations occur in two protein domain contexts, either in a cbEGF preceded by a TB domain or in a cbEGF preceded by another cbEGF domain. In this study we have used three proteases to probe structural changes caused by an N2144S MFS calcium binding mutation in a TB6-cbEGF32 and a cbEGF32-33 domain pair, and an N2183S mutation in the cbEGF32-33 pair. N-terminal sequence analysis of domain pairs digested in the presence and absence of calcium show that: (i) domain interactions between TB6 and cbEGF32 are calcium independent, despite the presence of a calcium binding site in cbEGF32; (ii) domain interactions between cbEGF32 and cbEGF33 are calcium dependent; and (iii) an N-->S mutation causes increased proteolytic susceptibility only when located in cbEGF33, consistent with a key role for interdomain calcium binding in rigidifying cbEGF domain linkages. These data demonstrate for the first time that the structural consequences of calcium binding mutations in fibrillin-1 cbEGF domains can be influenced by domain context.