Prognosis of sentinel node staged patients with primary cutaneous melanoma

Background

This study investigated survival probabilities and prognostic factors in sentinel lymph node biopsy (SLNB) staged patients with cutaneous melanoma (CM) with the aim of defining subgroups of patients who are at higher risk for recurrences and who should be considered for adjuvant clinical trials.

Methods

Patients with primary CM who underwent SLNB in the Department of Dermatology, University of Tuebingen, Germany, between 1996 and 2009 were included into this study. Survival probabilities and prognostic factors were evaluated by Kaplan-Meier and multivariate Cox proportional hazard models.

Results

1909 SLNB staged patients were evaluated. Median follow-up time was 44 months. Median tumor thickness was 1.8 mm, ulceration was present in 31.8% of cases. The 5-year Overall Survival (OS) was 90.3% in SLNB negative patients (IB 96.2%, IIA 87.0%, IIB 78.1%, IIC 72.6%). Patients with micrometastases (stage IIIA/B) had a 5-year OS rate of 70.9% which was clearly less favorable than for stages I–II. Multivariate analysis revealed tumor thickness, ulceration, body site, histopathologic subtype and SLNB status as independent significant prognostic factors.

Conclusion

Survival rates of patients with primary CM in stages I–II were shown to be much more favorable than previously reported from non sentinel node staged collectives. For future clinical trials, sample size calculations should be adapted using survival probabilities based on sentinel node staging.     

Experimental Actinobacillus pleuropneumoniae challenge in swine: Comparison of computed tomographic and radiographic findings during disease

ABSTRACT: BACKGROUND: In pigs, diseases of the respiratory tract like pleuropneumonia due to Actinobacillus pleuropneumoniae (App) infection have led to high economic losses for decades. Further research on disease pathogenesis, pathogen-host-interactions and new prophylactic and therapeutic approaches are needed. In most studies, a large number of experimental animals are required to assess lung alterations at different stages of the disease. In order to reduce the required number of animals but nevertheless gather information on the nature and extent of lung alterations in living pigs, a computed tomographic scoring system for quantifying gross pathological findings was developed. In this study, five healthy pigs served as control animals while 24 pigs were infected with App, the causative agent of pleuropneumonia in pigs, in an established model for respiratory tract disease. RESULTS: Computed tomographic (CT) findings during the course of App challenge were verified by radiological imaging, clinical, serological, gross pathology and histological examinations. Findings from clinical examinations and both CT and radiological imaging, were recorded on day 7 and day 21 after challenge. Clinical signs after experimental App challenge were indicative of acute to chronic disease. Lung CT findings of infected pigs comprised ground-glass opacities and consolidation. On day 7 and 21 the clinical scores significantly correlated with the scores of both imaging techniques. At day 21, significant correlations were found between clinical scores, CT scores and lung lesion scores. In 19 out of 22 challenged pigs the determined disease grades (not affected, slightly affected, moderately affected, severely affected) from CT and gross pathological examination were in accordance. Disease classification by radiography and gross pathology agreed in 11 out of 24 pigs. CONCLUSIONS: High-resolution, high-contrast CT examination with no overlapping of organs is superior to radiography in the assessment of pneumonic lung lesions after App challenge. The new CT scoring system allows for quantification of gross pathological lung alterations in living pigs. However, computed tomographic findings are not informative of the etiology of respiratory disease.     

Affinity purification of fibrinogen using a ligand from a peptide library.

An affinity resin containing the peptide ligand Phe-Leu-Leu-Val-Pro-Leu (FLLVPL) has been developed for the purification of fibrinogen. The ligand was identified by screening a solid-phase combinatorial peptide library using an immunostaining technique. The specific binding of fibrinogen to the ligand has been characterized by isothermal calorimetry and adsorption isotherms and is dominated by both hydrophobic interactions and ionic interactions with the N-terminal free amino group. The effective association constant of fibrinogen was substantially higher when the peptide was immobilized on the resin than in solution; moreover, it increased with increasing peptide density, suggesting a cooperative binding effect. A low ionic strength buffer at pH 4 was used successfully to elute adsorbed fibrinogen from the column with high purity, retention of factor XIII crosslinking activity, and minimal, if any, loss of biological function. This general approach to ligand selection and characterization can be used to develop peptide ligands for the affinity purification of diverse proteins on a large scale.     

Dihydrofluorescein diacetate is superior for detecting intracellular oxidants: comparison with 2',7'-dichlorodihydrofluorescein diacetate, 5(and 6)-carboxy-2',7'-dichlorodihydrofluorescein diacetate, and dihydrorhodamine 123.

To detect intracellular oxidant formation during reoxygenation of anoxic endothelium, the oxidant-sensing fluorescent probes, 2',7'-dichlorodihydrofluorescein diacetate, dihydrorhodamine 123, or 5(and 6)-carboxy-2',7'-dichlorodihydrofluorescein diacetate were added to human umbilical vein endothelial cells during reoxygenation. None of these fluorescent probes were able to differentiate the controls from the reoxygenated cells in the confocal microscope. However, dihydrofluorescein diacetate demonstrated fluorescence of linear structures, consistent with mitochondria, in reoxygenated endothelium. This work tests the hypothesis that dihydrofluorescein diacetate is a better fluorescent probe for detecting intracellular oxidants because it is more reactive toward specific oxidizing species. To investigate this, dihydrofluorescein diacetate was exposed to various oxidizing species (hydrogen peroxide, superoxide [KO2], peroxynitrite, nitric oxide, horseradish peroxidase, ferric iron, xanthine oxidase, cytochrome c, and lipoxygenase) and compared with the three other popular probes. Though oxidized dihydrofluorescein has higher molar fluorescence, comparison of the reactions of dihydrofluorescein with these other three probes in a cell-free system indicates that dihydrofluorescein is sometimes less fluorescent than the other probes. In addition, we find that the reactivity of all of the probes is very complex. Based on the results reported here, it is no longer appropriate to think of these probes as detecting a specific oxidizing species in cells, such as H2O2, but rather as detectors of a broad range of oxidizing reactions that may be increased during intracellular oxidant stress. Cell-loading studies indicate that dihydrofluorescein achieves higher intracellular concentrations than the second brightest intracellular probe, 2',7'-dichlorodihydrofluorescein. This fact and its higher molar fluorescence may account for the superior brightness of dihydrofluorescein diacetate. Dihydrofluorescein diacetate may be a superior fluorescent probe for many cell-based studies.     

Nitric oxide decreases the stability of DMPO spin adducts.

The effect nitric oxide (NO*) on the stability of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) adducts has been investigated using EPR spectroscopy. We report that the DMPO/HO* adduct, generated by porcine pulmonary artery endothelial cells in the presence of H2O2 and DMPO, or by a Fenton system (Fe(II)+H2O2) is degraded in the presence of the NO*-donor, 2-(N,N-diethylamino)-diazenolate-2-oxide (DEANO) or by bolus addition of an aqueous solution of NO*. A similar effect of DEANO was observed on other DMPO adducts, such as DMPO/*CH3 and DMPO/*CH(CH3)OH, generated in cell-free systems. Measurements of the loss of DMPO/HO* in the presence of DEANO in aerated and oxygen-free buffers showed that in both of these settings the process obeys first-order kinetics and proceeds with similar efficacy. This indicates that direct interaction of the nitroxide with NO*, rather than with NO2* (formed from NO* and O2 in aerated media), is responsible for destruction of the spin adduct. These results suggest that the presence of NO* may substantially affect the quantitative determination of DMPO adducts. We also show that NO2* radicals, generated by a myeloperoxidase/H2O2/nitrite system, also degrade DMPO/HO*. Because DMPO is frequently used to study generation of superoxide and hydroxyl radicals in biological systems, these observations indicate that extra caution is required when studying generation of these species in the presence of NO* or NO2* radicals.     

Cyclic Adenosine 3′,5′-Monophosphate in Escherichia coli

The concentration of cyclic adenosine 3',5'-monophosphate (c-AMP) in Escherichia coli growing on different sources of carbon was studied. Cultures utilizing a source of carbon that supported growth relatively poorly had consistently higher concentrations of c-AMP than did cultures utilizing sugars that supported rapid growth. This relationship was also observed in strains defective in c-AMP phosphodiesterase and simultaneously resistant to catabolite repression; in such strains the c-AMP concentration was slightly higher for several sources of carbon tested. Cultures continued to synthesize c-AMP and secreted it into the medium, under conditions that brought about an inhibition of the intracellular accumulation of the cyclic nucleotide. Transient repression of the synthesis of beta-galactosidase was not associated with an abrupt decrease in the cellular concentration of c-AMP.     

Efficient analysis of hepatic glucose output and insulin action using a liver slice culture system.

BACKGROUND: Liver slices have been reported to retain histological integrity and metabolic capacity for over 24 hours in flask culture systems, and they have been used for pharmacological and toxicological studies before. However, whether this method is suitable to measure hepatic glucose output is unknown. METHODS: Precision-cut liver slices were prepared from fresh male rat liver. After high-glucose pre-incubation (11.2 mmol/l), medium was changed to low-glucose conditions (0.5 mmol/l). Glucose and lactate levels as well as aspartate aminotransferase activity were monitored for 50 minutes with or without addition of insulin (600 pmol/l) and/or epinephrine (0.5 micromol/l). Slice potassium content and histology were examined to prove liver viability. RESULTS: We observed a stable glucose production from the liver slices of 0.3-0.4 micromol/g liver/min. Epinephrine increased (by 82+/-30%) and insulin decreased (by 80+/-8%) liver slice glucose output. Significant signs of ischemia were not detected. CONCLUSIONS: Hepatic glucose release can be reliably measured in a liver slice culture system, and it is regulated by major hormone systems. This method may be helpful for further characterization of direct insulin action and resistance in a complex tissue as the liver; however, pharmacological applications such as the analysis of drug effects on hepatic glucose metabolism can also be envisioned.     

Mutagenic and recombinagenic responses to defective DNA polymerase delta are facilitated by the Rev1 protein in pol3-t mutants of Saccharomyces cerevisiae

Defective DNA replication can result in substantial increases in the level of genome instability. In the yeast Saccharomyces cerevisiae, the pol3-t allele confers a defect in the catalytic subunit of replicative DNA polymerase delta that results in increased rates of mutagenesis, recombination, and chromosome loss, perhaps by increasing the rate of replicative polymerase failure. The translesion polymerases Pol eta, Pol zeta, and Rev1 are part of a suite of factors in yeast that can act at sites of replicative polymerase failure. While mutants defective in the translesion polymerases alone displayed few defects, loss of Rev1 was found to suppress the increased rates of spontaneous mutation, recombination, and chromosome loss observed in pol3-t mutants. These results suggest that Rev1 may be involved in facilitating mutagenic and recombinagenic responses to the failure of Pol delta. Genome stability, therefore, may reflect a dynamic relationship between primary and auxiliary DNA polymerases.