Computational Study of Fluid Mechanical Disturbance Induced by Endovascular Stents

Arterial restenosis following stent deployment may be influenced by the local flow environment within and around the stent. We have used computational fluid dynamics to investigate the flow field in the vicinity of model stents positioned within straight and curved vessels. Our simulations have revealed the presence of flow separation and recirculation immediately downstream of stents. In steady flow within straight vessels, the extent of flow disturbance downstream of the stent increases with both Reynolds number and stent wire thickness but is relatively insensitive to stent interwire spacing. In curved vessels, flow disturbance downstream of the stent occurs along both the inner and outer vessel walls with the extent of disturbance dependent on the angle of vessel curvature. In pulsatile flow, the regions of flow disturbance periodically increase and decrease in size. Non-Newtonian fluid properties lead to a modest reduction in flow disturbance downstream of the stent. In more realistic stent geometries such as stents modeled as spirals or as intertwined rings, the nature of stent-induced flow disturbance is exquisitely sensitive to stent design. These results provide an understanding of the flow physics in the vicinity of stents and suggest strategies for stent design optimization to minimize flow disturbance.     

Focal nodular hyperplasia in a child with Beckwith–Wiedemann syndrome

Beckwith–Wiedemann Syndrome (BWS) is associated with somatic overgrowth and a high risk for embryonal tumors, including hepatoblastoma, a highly malignant liver tumor of childhood. Focal nodular hyperplasia (FNH), on the other hand, is a benign tumor of the liver that is uncommon in childhood. Herein we describe a case of FNH in a child with BWS, the first such report in the literature.     

Luteinized cystic ovarian hyperplasia associated with placentomegaly due to chorangiomatosis

Luteinized cystic ovarian hyperplasia (LCOH) is a rare benign condition characterized by bilateral ovarian enlargement during pregnancy secondary to high maternal human chorionic gonadotropin serum levels referred to occur under several conditions. We report the case of a 29-year-old obese woman with LCOH incidentally discovered during cesarean section of a single pregnancy at 35 weeks of gestation for fetal intrauterine demise. The fetus showed external ambiguous genitalia, imperforate anus, bilateral dysplastic kidneys, and hydrometrocolpos secondary to atresia of the vagina. The placental weight was 1,450 g (normal for gestational age: 415 g). The placenta showed diffuse chorangiomatosis (CM) characterized by multifocal stem villi enlargement containing increased number of small vessels with alpha-smooth muscle actin positive cells in the walls in a dense reticulin fibers-rich stroma. The combination of LCOH and placentomegaly due to CM appears to be unique.     

Characterization of the tetanus toxin model of refractory focal neocortical epilepsy in the rat

PURPOSE: To characterize in detail a model of focal neocortical epilepsy. METHODS: Chronic focal epilepsy was induced by injecting 25-50 ng of tetanus toxin or vehicle alone (controls) into the motor neocortex of rats. EEG activity was recorded from electrodes implanted at the injection site, along with facial muscle electromyographic (EMG) activity and behavioral monitoring intermittently for up to 5 months in some animals. Drug responsiveness was assessed by using the antiepileptic drugs (AEDs) diazepam (DZP) and phenytoin (PHT) delivered systemically, while 1,2,3,4-tetrahydro-6-nitro-2,3-dioxo-benzo[f]quinoxaline-7-sulfonamide (NBQX), a competitive antagonist at AMPA receptors, was administered directly to the brain to investigate the potential benefits of focal drug delivery. RESULTS: Tetanus toxin induced mild behavioral seizures that persisted indefinitely in all animals. EEG spiking activity, occurring up to 80% of the time, correlated with clinical seizures consisting of interrupted behavioral activity, rhythmic bilateral facial twitching, and periods of abrupt motor arrest. Seizures were refractory to systemic administration of DZP and PHT. However, focal delivery of NBQX to the seizure site reversibly reduced EEG and behavioral seizure activity without detectable side effects. CONCLUSIONS: This study provides a long-term detailed characterisation of the tetanus toxin model. Spontaneous, almost continuous, well-tolerated seizures occur and persist, resembling those seen in neocortical epilepsy, including cortical myoclonus and epilepsia partialis continua. The seizures appear to be similarly resistant to conventional AEDs. The consistency, frequency, and clinical similarity of the seizures to refractory epilepsy in humans make this an ideal model for investigation of both mechanisms of seizure activity and new therapeutic approaches.     

Unusual findings in brain biopsies of two patients with acute magnetic resonance imaging lesions associated with focal seizures

PURPOSE: Patients with focal seizures often have magnetic resonance imaging (MRI) abnormalities in the brain region of their presumed seizure focus. Neoplasms, ischemic infarctions, inflammatory processes, and other specific pathologic entities have been diagnosed by biopsies of such MRI abnormalities. Two patients with this presentation had brain lesion biopsies with a leading presumptive diagnosis of glial neoplasm but were found to have indistinct histopathology. METHODS: Each patient was initially seen with focal seizures (right parietal region, right hippocampus) corresponding with focally increased T2 signal on MRI. In both patients, the preoperative clinical suspicion was for neoplastic or inflammatory processes. RESULTS: Several weeks after seizure onset, craniotomy in patient 1 and stereotactic needle biopsy in patient 2 revealed mild gliosis with reactive vascular changes and perivascular hemosiderin deposition, not diagnostic of but compatible with venous congestion (or possibly venous thrombosis). Postoperatively, patient 1 had brief sensory seizures that stopped 5 months after surgery, whereas subsequent seizures did not develop in patient 2. Both patients had normalization of their MRI (except for postoperative changes) and have remained seizure free. CONCLUSIONS: We describe two patients who had brain biopsies of striking focal increased T2 signal MRI abnormalities associated with seizures. Pathologic findings contradicted our preoperative suspicions (neoplasm or inflammatory process), compatible with (but not conclusive for) subacute venous congestion/thrombosis. These findings indicate that patients with seizures may have an associated discrete intraaxial MRI lesion that is not neoplastic. To our knowledge, this is the first report of focal seizure-associated MRI lesions with biopsy findings compatible with venous congestion/thrombosis.     

A case of angiolymphoid hyperplasia with eosinophilia (ALHE) of the upper lip

Angiolymphoid hyperplasia with eosinophilia (ALHE) is clinically characterized by intradermal or subcutaneous papules and/or nodules usually occurring in young adults. Lesions in the oral mucosa are extremely rare. We report a case and review the literature of ALHE cases involving the oral mucosa. A 40-year-old man presented with a painless, 20 x 20 mm, submucosal nodule on the upper lip. Histological examination of lip biopsy specimens revealed an increase in many small vessels. The vascular walls consisted of prominent endothelial cells with a histiocytoid appearance, which protruded into the lumen. Many eosinophils and lymphocytes were also seen around the vessels. The diagnosis of ALHE was made from the above findings.     

Drug induced hepatic focal nodular hyperplasia

Focal nodular hyperplasia, an uncommon benign hepatic tumor, has been reported following ingestion of various drugs and chemical agents. The authors report a case of a young girl who developed such lesion following ingestion of antituberculosis drugs for the treatment of her abdominal tuberculosis.     

Psychological adjustment in children and adults with congenital adrenal hyperplasia

OBJECTIVE: To determine psychological health in individuals with one form of intersexuality, congenital adrenal hyperplasia (CAH), and its relation to characteristics of the disease and treatment. STUDY DESIGN: Participants (ages 3-31 years) included 72 females and 42 males with CAH, and unaffected relatives (44 females and 69 males). Psychological adjustment was assessed with parent-reports on the Child Behavior Checklist (CBCL) and subject self-reports on the Self-Image Questionnaire for Young Adolescents (SIQYA) or the Multidimensional Personality Questionnaire (MPQ). Information about disease characteristics and genital surgery was obtained from medical records. RESULTS: There were no significant differences between females with CAH and unaffected females on any measure. Psychological adjustment was not significantly associated with genital virilization or age at genital surgery. Males with CAH were not significantly different from unaffected males in childhood, but they showed more negative affect at older ages. CONCLUSIONS: Psychological adjustment is not compromised in females with virilized genitalia who are treated early in life and reared as females. Adjustment does not appear to depend on the characteristics of the disease or its treatment, but sample size and restricted range limit generalizability about adjustment-disease associations.     

Sigmoidoscopy in children with chronic lower gastrointestinal bleeding

Objective: This study was done to assess the role of rigid sigmoidoscopy in diagnosis and prognosis of children with chronic and minor lower gastrointestinal bleeding. Methods: Retrospective review of the clinical notes of children under 15 years of age with minor and chronic lower gastrointestinal bleeding who had rigid sigmoidoscopy and biopsy between October 1998 and April 2002 at Liaquat Medical College Hospital, Hyderabad, Pakistan. Demographic data, clinical presentation, morbidity, sigmoidoscopic and histopathological findings were analysed to determine the role of rigid sigmoidoscopy in the management of rectal bleeding in children. Results: A total of 229 sigmoidoscopic examinations were carried out in 207 children with a mean age of 6 years. Seventy-seven per cent (160) of children were symptomatic for a year or more. Causes of bleeding were juvenile colorectal polyps (155 cases; 75%), non-specific proctitis (38 cases; 18%), solitary rectal ulcer (seven cases; 3.5%), lymphoid nodular hyperplasia (six cases, 3%) and foreign body (betel nuts) impaction (one case; 0.5%). Polyps were mostly in the rectosigmoid region and solitary in 136 (88%) children. All polyps were removed by rigid sigmoidoscopy. Histological examination of 137 polyps revealed juvenile type in 136 (99%) cases and low-grade dysplastic changes in one patient. Non-specific proctitis (n = 38) was confirmed histologically in 92% (n = 35) of cases and it was self-limiting in 86% of cases. Other findings include solitary rectal ulcer in seven, lymphoid nodular hyperplasia in six and telangiectasic (pyogenic) granuloma in one patient. Conclusion: Rigid sigmoidoscopy was useful in diagnosis, treatment and prognostic evaluation of children with chronic and minor lower gastrointestinal bleeding. Final diagnosis was confirmed by histopathology.