Truncated WT1 mutants alter the subnuclear localization of the wild-type protein.

WT1 encodes a zinc-finger protein, expressed as distinct isoforms, that is inactivated in a subset of Wilms tumors. Both constitutional and somatic mutations disrupting the DNA-binding domain of WT1 result in a potentially dominant-negative phenotype. In generating inducible cell lines expressing wild-type isoforms of WT1 and WT1 mutants, we observed dramatic differences in the subnuclear localization of the induced proteins. The WT1 isoform that binds with high affinity to a defined DNA target, WT1(-KTS), was diffusely localized throughout the nucleus. In contrast, expression of an alternative splicing variant with reduced DNA binding affinity, WT1 (+KTS), or WT1 mutants with a disrupted zinc-finger domain resulted in a speckled pattern of expression within the nucleus. Although similar in appearance, the localization of WT1 variants to subnuclear clusters was clearly distinct from that of the essential splicing factor SC35, suggesting that WT1 is not directly involved in pre-mRNA splicing. Localization to subnuclear clusters required the N terminus of WT1, and coexpression of a truncated WT1 mutant and wild-type WT1(-KTS) resulted in their physical association, the redistribution of WT1(-KTS) from a diffuse to a speckled pattern, and the inhibition of its transactivational activity. These observations suggest that different WT1 isoforms and WT1 mutants have distinct subnuclear compartments. Dominant-negative WT1 proteins physically associate with wild-type WT1 in vivo and may result in its sequestration within subnuclear structures.     

Variations of normal sinus node function in relation to age: role of autonomic influence

An electrophysiological study of sinus node function, includingmeasurements of resting heart rate, maximal corrected sinusnode recovery time and sinoatrial conduction time, was performedin 30 patients, 12–79 years of age, without any clinical,electro car diographic or electrophy siological evidence ofsinus node disease. To analyse autonomic influences, variables were measured beforeand after sympathetic and parasympathetic blockade. No significantcorrelations were observed between age and electrophysiologicalmeasurements of sinus node function at the control study orafter sympathetic blockade. In contrast, the electrophysiologicalparameters of intrinisic sinus node activity were correlatedwith age and showed a progressive lengthening of mean sinuscycle length, of maximal corrected sinus node recovery timeand of sinoatrial conduction time. In addition, measurements after vagolysis suggest a progressivedecrease of parasympathetic activity with increasing age. These data also indicate that the respective role of the twocomponents of the autonomic nervous system vary with increasingage: parasympathetic activity predominates in younger subjects;sympathetic and parasympathetic tones are equilibrated in oldersubjects. The normal sinus node function represents an equilibrated system:in parallel with ageing of the intrinsic properties of the sinusnode, parasympathetic activity decreases so that basal propertiesremain stable throughout life.     

An automatic device for single-breath CO diffusing capacity in dogs

Summary We describe a very simply operated system by which single-breath CO diffusing capacity (D_LCO) can be measured in anesthetized dogs.All controls and the automatic system are operated pneumatically. Cams forming an integral part of the pistons of the inspiratory and experatory syringes activate push buttons which control the valves, enabling dead spaces to be flushed, a specific volume of air to be injected into the dog's lungs, and expiratory samples to be taken.Our results, due account being taken of the dogs' weight, are in the upper range of normal values published in earlier studies; the reproducibility of the method is good.     

Diaphragmatic hernia resulting in enterothorax following pediatric liver transplantation: a rare complication

Diaphragmatic hernia is a rare complication following solid organ transplantation. We here report three pediatric patients suffering from posttransplant enterothorax. One patient with biliary atresia presented with clinical signs of peritonitis without showing pulmonary symptoms four weeks following liver transplantation. The second patient was admitted with suspected pneumonia, whereas the third patient presented with recurrent abdominal pain over weeks and physical examination revealed the unexpected diagnosis of enterothorax. All patients received split liver transplants. Unspecific clinical signs mislead to suspected infectious complication under immunosuppression. No apparent risk factors for diaphragmatic hernia could be identified. Diaphragmatic hernia can present with a variety of atypical clinical symptoms. Severe or prolonged abdominal complains should lead to x-ray examination. We speculate that the split liver technique used in our center could lead to this rare complication due to the different anatomic position of the liver transplant in the abdomen.