The growth of the second underpotentially deposited silver layer on Pt(100)

The electrodeposition of Ag on Pt(100)-(1 × 1) in perchlorate electrolyte was studied by means of time-resolved in situ scanning tunnelling microscopy (STM) and cyclic voltammetry. One monolayer of Ag is deposited underpotentially (upd) ca. 500 mV positive of the Ag⁺/Ag equilibrium potential. Several millivolts positive of the equilibrium potential, a second well defined upd layer forms. Its growth was observed to proceed via island formation and coalescence. This process occurs in two separate stages that manifest themselves in voltammetric peaks as well as in the STM images.     

Brain Death Further Promotes Ischemic Reperfusion Injury of the Rabbit Myocardium

Background. Little is known about preload-dependent cardiac function after brain death (BD) and subsequent graft preservation.

Methods. A validated model of BD in rabbits was developed and myocardial performance was studied after BD induction and 1 hour of subsequent global hypothermic ischemia using a validated rabbit model and an isolated work-performing heart preparation.

Results. Significant decreases in stroke work, left ventricular contractility, and left ventricular relaxation were observed 2 hours after BD. After global hypothermic ischemia, significant decreases in stroke work, left ventricular contractility, and left ventricular relaxation were observed in the BD group compared with controls. Cardiac output and coronary flow were also significantly decreased in BD hearts compared with controls. Creatine kinase release was increased by 32.5% in BD hearts compared with controls.

Conclusions. In a rabbit model, BD combined with global hypothermic ischemia causes a significant decrease in left ventricular function compared with global hypothermic ischemia. This dysfunction may be attributed to a significant decrease in coronary flows in BD hearts.     

Quantification of oxidative DNA modifications in mitochondria

Specific repair endonucleases were used to quantify oxidativemodifications in mitochondrial DNA (mtDNA) from rat liver andfrom porcine liver and kidney by means of a relaxation assay.In rat liver mitochondria the number of modifications sensitiveto formamidopyrimidine-DNA glycosylase (FPG protein), whichinclude 8-hydroxyguanine (8-oxo-7, 8-dihydro-guanine) residues,was only 0.8±0.2 per 10⁵ base pairs (bp). Even lowervalues were observed in porcine kidney (0.5±0.3 per 10⁵bp) and liver (0.4±0.2 per 10⁵ bp). The numbers of sitesof base loss (AP sites) sensitive to T4 endonuclease V and of5,6-dihydropyrimidines sensitive to endonuclease III were lessthan 0.2 per 10⁵ bp in all cases. The data provide evidencethat the steady-state levels of oxidative mtDNA modificationsare low under physiological conditions, either because reactiveoxygen species generated in the mitochondria are instantly inactivatedor because of efficient DNA repair processes inside mitochondria.     

Solitary bronchioloalveolar carcinoma: CT criteria

The computed tomographic (CT) scans of 30 patients with solitary bronchioloalveolar carcinoma were reviewed. Common features at CT included the peripheral or subpleural location of a pulmonary mass (25 cases), pseudocavitation (18 cases), heterogeneous attenuation (17 cases), irregular margins forming a star pattern (22 cases), and pleural tags (21 cases). Using these CT criteria, four independent observers attempted to identify cases of bronchioloalveolar carcinoma from a larger sample of lung cancers and benign lesions by categorizing a series of test cases into four probability categories. Although the bronchioloalveolar carcinomas were correctly ranked in the two highest probability categories 75% of the time (in 45 of 60 cases), there was considerable overlap with other lung lesions, particularly with adenocarcinoma and large cell undifferentiated carcinoma. However, even though the typical features of bronchioloalveolar carcinoma are not invariable or highly specific, they are characteristic enough to suggest the diagnosis.     

Maintenance and synthesis of proteins for an anucleate axon

The anucleate (distal) segment of a crayfish medial giant axon (MGA) remains intact for months in vivo after severing the axon from its cell body, a phenomenon referred to as long-term survival (LTS). We collected axoplasm from chronic anucleate MGAs by perfusing 2-cm lengths of axons with an intracellular saline. This axoperfusate was analyzed by SDS-PAGE and silver stained. Axoperfusate proteins from intact MGAs and from chronic anucleate MGAs exhibiting LTS for up to 6 months were the same. Furthermore, immunoreactive levels of actin and β-tubulin were similar in axoperfusates from intact and chronic anucleate MGAs. This maintenance of proteins in chronic anucleate MGAs must be due to a lack of protein degradation and/or to local protein synthesis by a source other than the cell body. To investigate local protein synthesis in vitro, we added [³⁵S]-methionine to the extracellular saline surrounding intact and chronic anucleate MGAs. After 4- to 6-h incubations, radiolabelled proteins were detected in axoperfusates analyzed by SDS-PAGE and fluorography. The similarity between radiolabelled proteins in axoperfusates and MGA glial sheaths indicated a glial origin for the radiolabelled axoperfusate proteins. Various observations and control experiments suggested that glial-axonal protein transfer occurred by a physiological process. Glial-axonal protein transfer may contribute to the maintenance of proteins during LTS of chronic anucleate MGAs.