Empyema as a complication of retropharyngeal and neck abscesses in children

Empyema developing from retropharyngeal abscess is a rare complication. Two infants with clinical symptomatology and inital chest radiographic findings of pleural fluid which suggested the possibility of retrophoryngeal abscess are described. A child with submandibular and cervical abscesses is also reported; pleural fluid and mediastinal abscess developed less than 24 hours after admission. Pathological processes in the neck can spread into the chest or conversely, either by direct continuity or by dissection through the fascial planes enveloping the cervical compartments. The middle or visceral space which is in direct continuity with the mediastinum is generally the area in which cervicothoracic disease inter-relates.     

Sonography in the diagnosis and management of pancreatic pseudocysts and effusions in childhood

Blunt trauma to the abdomen is the main cause of pancreatic injury in childhood. One of the most common causes of injury is child abuse. Pancreatitis, pancreatic pseudocyst, and loculated peripancreatic effusion are sequellae of this trauma. The diagnosis of these lesions is aided by ultrasound. Pancreatic injury in children may require different methods of management than it does in adults. Persistently elevated serum amylase levels and increasing cyst size are indications for surgical intervention. However, the natural history of a pseudocyst in an otherwise normal child may lead to spontaneous resolution. In this report, three cases of pancreatic pseudocyst caused by child abuse are presented. In two of the patients, the cysts underwent spontaneous resolution.     

Prosthetic arterial graft occlusion: a complication of tourniquet use during arteriography

Tourniquet-induced reactive hyperemia, generally considered a safe procedure for enhancing visualization of the arteries in the distal lower extremity, caused acute occlusion of a Dacron arterial graft in one patient. This rare complication can be avoided through use of an alternative such as a chemical vasodilator in patients with susceptible synthetic vascular grafts.     

Topology and order of formation of interchain disulfide bonds in von Willebrand factor

Interchain disulfide bonds between the subunits in von Willebrand factor (vWf) dimers and in vWf multimers have been studied using some unique features of the cultured human umbilical vein endothelial cell system. Ammonium chloride inhibition of multimerization of vWf allowed selective examination of vWf dimeric molecules, and monoclonal antibody against the vWf propolypeptide was used to separate pro-vWf dimers from mature dimers. After cleavage of dimers and multimers with Staphylococcus aureus V-8 protease, the location of interchain disulfide bonds in amino (N)-terminal or carboxyl (C)-terminal fragments was determined by gel electrophoresis under reduced and nonreduced conditions. The first interchain disulfide bonds formed during dimerization are in the C-terminal region of the subunits, whereas interdimer disulfide bonds are located in the N-terminal portion. These data confirm recent electron microscopic projections of disulfide bond locations and provide support to the hypothetical role of the propolypeptide in the multimerization process.     

Influence of ablation parameters on refractive changes after phototherapeutic keratectomy

PURPOSE: The aim of the current study was to control the hypothetical effects of decreased laser energy delivered to the peripheral cornea during phototherapeutic keratectomy (PTK) and provide quantitative calculation of induced low and high order aberrations. METHODS: We employed a model eye to simulate the refractive effect of homogeneous laser corneal irradiation, as in PTK, for different laser fluences (range 125 to 225 mJ/cm2) and treatment depths up to 200 microm. RESULTS: The hyperopic shift induced by the relatively lower energy delivered at the peripheral ablation zone during PTK was proportional to the treatment depth and inversely proportional to the energy fluence. The hyperopic shift calculated using the above ablation parameters was lower compared to previously reported clinical results. Higher order wavefront aberration (total root mean square) changes were of minimal significance for treatment depths up to 200 microm. CONCLUSIONS: After PTK, a hyperopic shift cannot be attributed to the energy delivery method alone. Modification of laser energy delivery algorithms may only minimize PTK-induced hyperopia.