Catheter drainage of symptomatic postoperative mediastinal effusion guided by computed tomography. A nonoperative approach

Postoperative mediastinal effusion after cardiac operations is a common phenomenon and has a potential for serious complications, such as tamponade necessitating urgent drainage. Computed tomography of the chest provides excellent postoperative visualization of the mediastinum. Catheter insertion or paracentesis guided by computed tomography has been used to accomplish nonoperative drainage of symptomatic postoperative mediastinal effusion in six cases. This technique offers simplicity, safety, and cost effectiveness.     

Normally unused positional cues guide ectopic afferents in the leech CNS.

Central projections from peripheral sensory neurons segregate into distinct, ventrally positioned longitudinal tracts within the segmental ganglia of the leech Hirudo medicinalis. As documented here, there is an additional tract in the neuropils of the fifth and sixth body ganglia, located at the lateral margin and formed by afferent axons (the "sex afferents") originating from sensory neurons located in the male and female genitalia. Ablation of the genitalia results in the complete absence of this additional tract. We asked (1) whether segmental differences exist in the distribution of pathway cues available to the sex afferents, and (2) whether central pathway selection by these axons is specific. We transplanted the primordia of the male genitalia to several ectopic positions posterior to the sixth body segment and labeled the ectopic sex afferents in order to examine their paths in the CNS. In about 50% of the experimental animals, afferent axons originating in the transplanted tissue segregated into a distinct lateral fiber bundle within the neuropil of a nearby ganglion, in a position corresponding to their normal one in the sex ganglia. The sex afferents therefore find their normal pathways even in the ganglia of inappropriate segments, although these pathways are not used by any other afferents in these ganglia. We propose, therefore, that the positional cues employed by afferent axons to select appropriate pathways in the ganglionic neuropil are expressed in all segments of the leech CNS, regardless of whether such cues are normally used by afferent axons in each segment.     

Office Systems and Their Influence on Mammography Use in Rural and Urban Primary Care

CONTEXT: Breast cancer screening rates are lower in rural communities. Although studies have addressed barriers to mammography for rural residents, physician practice barriers have received less attention. PURPOSE: Controlled clinical trials have shown that the use of office reminder systems in primary care practices is related to increased clinical care rates. Therefore, we compared office systems use in primary care practices located in rural and urban communities and assessed the impact of these systems on rural-urban differences in mammography utilization. METHODS: We identified female Kansas Medicare beneficiaries aged 65 to 79 from Medicare claims data (N = 24,030) and determined which beneficiaries received a mammogram between April 1, 1999, and March 31, 2001. We linked beneficiaries to their primary care providers and obtained surveys from 180 primary care practices on their use of office reminder systems. FINDINGS: Mammography rates ranged from 20% to 92% (mean = 65%) among the 180 practices. Flowsheets with a mammography prompt were used by 33% of the practices, 38% utilized nonphysician staff to identify women due for mammograms, and 15% used computerized reminder systems. Urban practices used flowsheets more often than rural practices (44% versus 16%, P < 0.001). A multivariable regression model demonstrated higher mammography rates in urban practices, group practices, and practices using mammography flowsheets. CONCLUSIONS: Despite success in randomized controlled trials, reminder systems are not used often by primary care providers and are used even less often in rural compared to urban practices. Consistent implementation may be a major barrier to the successful adaptation of flowsheets by primary care offices.     

Specificity in transmembrane helix–helix interactions can define a hierarchy of stability for sequence variants

The folding, stability, and oligomerization of helical membrane proteins depend in part on a precise set of packing interactions between transmembrane helices. To understand the energetic principles of these helix-helix interactions, we have used alanine-scanning mutagenesis and sedimentation equilibrium analytical ultracentrifugation to quantitatively examine the sequence dependence of the glycophorin A transmembrane helix dimerization. In all cases, we found that mutations to alanine at interface positions cost free energy of association. In contrast, mutations to alanine away from the dimer interface showed free energies of association that are insignificantly different from wild-type or are slightly stabilizing. Our study further revealed that the energy of association is not evenly distributed across the interface, but that there are several "hot spots" for interaction including both glycines participating in a GxxxG motif. Inspection of the NMR structure indicates that simple principles of protein-protein interactions can explain the changes in energy that are observed. A comparison of the dimer stability between different hydrophobic environments suggested that the hierarchy of stability for sequence variants is conserved. Together, these findings imply that the protein-protein interaction portion of the overall association energy may be separable from the contributions arising from protein-lipid and lipid-lipid energy terms. This idea is a conceptual simplification of the membrane protein folding problem and has implications for prediction and design.     

Loss of nuclear p21(Cip1/WAF1) during neoplastic progression to metastasis in gamma-irradiated p21 hemizygous mice

p21(Cip1/WAF1) localizes to the nucleus in response to gamma-irradiation induced DNA damage and mediates a G(1) checkpoint arrest. Although gamma-irradiated p21(+/-) mice develop a broad spectrum of tumors, gamma-irradiated p21(-/-) mice develop significantly more metastatic cancers. To evaluate the expression of p21 in tissues prone or resistant to tumorigenesis as a function of gamma-irradiation, and to determine whether phenotypic loss of p21 heterozygosity occurs during tumor progression in p21(+/-) mice, tissues and tumors from gamma-irradiated mice were evaluated immunohistochemically. The percentage of tumors in p21(+/-) mice that were nuclear p21-positive declined with progression to metastasis (p<0.0001). Benign tumors were more often p21-positive and comprised of larger subsets of nuclear p21-positive cells than were malignant tumors of the same histopathological type, while metastatic cancers were nuclear p21-negative (p=0.0003). Even when a primary cancer was comprised of a subset of nuclear p21-positive cells, the metastatic foci of that same cancer were nuclear p21-negative. Mesenchymal tumors, though rare, were more likely metastatic than were epithelial tumors (p=0.0004), and these were invariably nuclear p21-negative. Prepubescent epithelial tissues from which most tumors later originated in mice with reduced p21 gene dosage (i.e., harderian gland, ovary, small intestine, and lung) were p21 expressive within 4 h of gamma-irradiation (p=0.0625), so that p21/Ki67 ratios increased post-gamma-irradiation (p=0.03). In contrast, p21 did not localize to nuclei of cortical thymocytes, a tissue where tumorigenesis was not augmented by reduced p21 gene dosage. Cellular subclones of malignant tumors, especially those of mesenchymal cell origin, which lack nuclear p21 may more readily acquire the genetic alterations of the metastatic phenotype.     

Effect of Preoperative Single-Dose Corticosteroid Administration on Postoperative Morbidity Following Esophagectomy

Background  

Eight clinical trials involving the administration of preoperative i.v. methylprednisolone have been undertaken in order to decrease the considerable inflammatory response to esophageal resection, in an effort to decrease the supposedly associated morbidity and mortality