Alexander Novotny

In vitro and in vivo porphyrin accumulation by C6 glioma cells after exposure to 5-aminolevulinic acid

Several malignant tissues synthesize endogenous porphyrins after exposure to 5-aminolevulinic acid (5-ALA). The present experiments have been designed to elucidate whether the C6 glioma cell, a model cell for human malignant glioma, similarly synthesizes porphyrins when exposed to 5-ALA, and whether specific synthesis occurs when C6 cells are inoculated into rat brains to form a tumor. In this situation the blood-brain barrier may interfere with 5-ALA availability, and spreading of porphyrins with edema outside the tumor may occur. Flow cytometry is used to determine the course of cell volume and porphyrin fluorescence intensities in cultured C6 cells which are incubated in 1 mM 5-ALA. For the induction of experimental brain tumors, 10(4) untreated C6 cells are inoculated into the brains of rats. After 9 days animals receive 100 mg 5-ALA/kg body weight. Brains are removed after 3, 6, or 9 h and frozen coronal sections obtained for H/E staining or fluorescence spectography. Cultured C6 cells show a linear increase of protoporphyrin IX fluorescence after exposure to 5-ALA, which begins to plateau after 85 min. Marked fluorescence is also observed in solid and infiltrating experimental tumor. However, faint fluorescence also occurs in normal tissue, basal pia, choroid plexus, and, more obviously, in white-matter tracts bordering the tumor (maximal distance: 1.5 +/- 0.7 mm). The observations demonstrate that C6 cells synthesize protoporphyrin IX after exposure to 5-ALA in vitro and in vivo. However, when utilizing 5-ALA for fluorescence detection or photodynamic therapy of brain tumors, attention should be paid to the possibility of protoporphyrin IX occurring outside the tumor.

Significance of histopathological tumor regression after neoadjuvant chemotherapy in gastric adenocarcinomas: a summary of 480 cases

Objective: An increasing number of patients with locally advanced gastric carcinomas (GC) are being treated with preoperative chemotherapy before surgery. Background: Histopathological tumor regression may have an important prognostic impact in addition to the UICC-TNM classification system. Methods: We evaluated the histopathological tumor regression in 480 surgical resection specimens of GC after neoadjuvant cisplatin-based chemotherapy, using an established system encompassing three tumor regression grades based on the estimation of the percentage of residual tumor tissue at the primary tumor site in relation to the macroscopically identifiable former tumor bed. Tumor regression was correlated to clinicopathological characteristics and patient survival. Results: Of the patients in this study, 102 (21.2%) had complete or subtotal tumor regression (<10% residual tumor), 121 (25.2%) had partial tumor regression (10–50% residual tumor), and 257 (53.5%) had minimal or no regression (>50% residual tumor). Tumor regression was significantly associated with posttreatment tumor category (pT), lymph node status (pN), lymphatic invasion status (pL), and resection status (P < 0.001). Major histopathological regression was less frequent in tumors of the distal stomach and tumors of nonintestinal type (P = 0.003). Tumor regression (P = 0.009) and postoperative Lymph node status (P < 0.001) were independent prognostic factors for survival in a multivariate analysis of tumor regression, ypT/N/L category, resection status, grading and Lauren´s classification. Conclusions: Assessment of histological tumor regression after preoperative chemotherapy in GC provides objective and highly valuable prognostic information in addition to posttherapeutic lymph node status. A standardized tumor regression grading system should be implemented in pathological reports of these tumors.

MALDI Imaging Identifies Prognostic Seven-Protein Signature of Novel Tissue Markers in Intestinal-Type Gastric Cancer

Proteomics-based approaches allow us to investigate the biology of cancer beyond genomic initiatives. We used histology-based matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry to identify proteins that predict disease outcome in gastric cancer after surgical resection. A total of 181 intestinal-type primary resected gastric cancer tissues from two independent patient cohorts were analyzed. Protein profiles of the discovery cohort (n = 63) were directly obtained from tumor tissue sections by MALDI imaging. A seven-protein signature was associated with an unfavorable overall survival independent of major clinical covariates. The prognostic significance of three individual proteins identified (CRIP1, HNP-1, and S100-A6) was validated immunohistochemically on tissue microarrays of an independent validation cohort (n = 118). Whereas HNP-1 and S100-A6 were found to further subdivide early-stage (Union Internationale Contre le Cancer [UICC]-I) and late-stage (UICC II and III) cancer patients into different prognostic groups, CRIP1, a protein previously unknown in gastric cancer, was confirmed as a novel and independent prognostic factor for all patients in the validation cohort. The protein pattern described here serves as a new independent indicator of patient survival complementing the previously known clinical parameters in terms of prognostic relevance. These results show that this tissue-based proteomic approach may provide clinically relevant information that might be beneficial in improving risk stratification for gastric cancer patients.

Mechanisms of 5-aminolevulinic acid uptake at the choroid plexus

Abstract : 5‐Aminolevulinic acid (5‐ALA) is a precursor of porphyrins and heme that has been implicated in the neuropsychiatric symptoms associated with porphyrias. It is also being used clinically to delineate malignant gliomas. The blood‐CSF barrier may be an important interface for 5‐ALA transport between blood and brain as in vivo studies have indicated 5‐ALA is taken up by the choroid plexuses whereas the normal blood‐brain barrier appears to be relatively impermeable. This study examines the mechanisms of 5‐[3H]ALA uptake into isolated rat lateral ventricle choroid plexuses. Results suggest that there are two uptake mechanisms. The first was a Na+‐independent uptake system that was pH dependent (being stimulated at low pH). Uptake was inhibited by the dipeptide Gly‐Gly and by cefadroxil, an α‐amino‐containing cephalosporin. These properties are the same as the proton‐dependent peptide transporters PEPT1 and PEPT2, which have recently been shown to transport 5‐ALA in frog oocyte expression experiments. Choroid plexus uptake was not inhibited by captopril, a PEPT1 inhibitor, suggesting PEPT2‐mediated uptake. The presence of PEPT2 and absence of PEPT1 in the choroid plexus were confirmed by western blotting. The second potential mechanism was both Na+ and HCO3‐ dependent and appears to be an organic anion transporter, although it is possible that removal of Na+ and HCO3‐ may indirectly affect PEPT2 by affecting intracellular pH. The presence of PEPT2 and a putative Na+/HCO3‐‐dependent organic anion transporter is important not only for an understanding of 5‐ALA movement between blood and brain but also because these transporters may affect the distribution of a number of drugs between blood and CSF.

Predicting Individual Survival After Gastric Cancer Resection: Validation of a U.S.-Derived Nomogram at a Single High-Volume Center in Europe

Objective:Validation of a U.S.-derived nomogram for individual prediction of disease-specific gastric cancer survival at a European institution. Summary Background Data:One major issue of modern cancer treatment is the individualization of therapy. For gastric cancer, Kattan et al, at Memorial Sloan-Kettering Cancer Center, New York, NY, developed a nomogram, allowing to predict individual patient risk of tumor-related death after R0 resection from basic patient-related variables. The validity of the nomogram has not yet been shown in patients from other institutions. The accuracy of the nomogram when applied to patients after having undergone R0 gastric cancer resection at a European high-volume center was investigated. Methods:Clinical data from patients who underwent R0 gastric cancer resection at Klinikum rechts der Isar, Technical University of Munich, Germany and fitted the respective derivation criteria were used for external validation (n = 862). Nomogram predictions for 60- and 108-month disease-specific survival were calculated for each patient and compared with actual survival. The concordance index was used as an accuracy measure. Results:The bootstrap-corrected concordance index was 0.77 and was superior when compared with the predictive ability of International Union Against Cancer tumor stage (P < 0.008). Nomogram calibration was excellent for 60-month disease-specific survival. Nomogram predictions showed the trend to underestimate survival in stage II/III disease of the MRI patients. Conclusions:The use of the nomogram created by Kattan et al is not only confined to the institution where it was created, but it can be adopted by other institutions with similar surgical strategies.

Fluorescence-guided resections of malignant gliomas — an overview

Radical resections of contrast-enhancing tumour in patients with malignant gliomas may be pertinent for survival but are often difficult to achieve due to uncertainties in distinguishing tumour margins intra-operatively. In this respect a number of novel methods are being examined which aim at enhancing resections. Among these methods, resections that exploit the accumulation of fluorescent porphyrins within malignant glioma tissue in response to exogenous administration of a metabolic percursor, 5-aminolevulinic acid, may offer particular advantages. This article summarises the clinical background and current status of 5-ALA drug development for fluorescence-guided resections of malignant gliomas and analyses the available literature with regard to possible mechanisms that govern the highly specific accumulation of fluorescent porphyrins in malignant glioma tissue in response to 5-ALA administration.

DNA methyltransferase 1 as a predictive biomarker and potential therapeutic target for chemotherapy in gastric cancer

PURPOSE DNA methylation contributes to carcinogenesis by mediating transcriptional regulation and chromatin remodelling, which may influence the effect of DNA-damaging drugs. We examined the prognostic and predictive impact of DNA methyltransferase (DNMT) 1 and 3b expression in gastric carcinomas (GC) treated by neoadjuvant chemotherapy. In vitro, DNMT1 expression and chemosensitivity were investigated for a functional relationship and the DNMT inhibitor decitabine (DAC) was tested as an alternative treatment option. PATIENTS AND METHODS DNMT1/3b expression was analysed immunohistochemically in 127 pretherapeutic biopsies of neoadjuvant (platinum/5-fluorouracil)-treated GC patients and correlated with response and overall survival (OS). Short hairpin RNA technology was used to knockdown DNMT1 in the GC cell line, AGS. The chemosensitivity of GC cell lines to DAC alone and to DAC in combination with cisplatin was analysed by XTT or colony formation assays. RESULTS High DNMT1 and DNMT3b expression was found in 105/127 (83%) and 79/127 (62%) carcinomas, respectively. Patients with low DNMT1 expression demonstrated a significantly better histopathological/clinical response (P=0.03/P=0.008) and OS (P(log-rank)=0.001). In vitro, knockdown of DNMT1 caused an increased chemosensitivity towards cisplatin. Combined treatment with cisplatin and DAC showed a synergistic effect leading to increased cytotoxicity in the cisplatin-resistant cell line AGS. CONCLUSION Low DNMT1 expression defines a subgroup of GC patients with better outcomes following platinum/5FU-based neoadjuvant chemotherapy. In vitro data support a functional relationship between DNMT1 and cisplatin sensitivity. Besides its potential use as a predictive biomarker, DNMT1 may represent a promising target for alternative therapeutic strategies for a subset of GC patients.

Negative Regulation of TLR Responses by the Neuropeptide CGRP Is Mediated by the Transcriptional Repressor ICER

Communication between the nervous and immune systems involves the release of neuropeptides, such as calcitonin gene-related peptide (CGRP), from sensory nerves during inflammation. CGRP may inhibit the activities of both innate and adaptive immune cells, but the molecular pathways underlying this function are largely unknown. In this study, we identify CGRP as a potent inhibitor of TLR-stimulated production of inflammatory mediators, such as TNF-α and CCL4, by murine dendritic cells. Inhibition of TLR responses was independent of IL-10 and did not involve perturbation of canonical TLR signaling, including activation of MAPK and NF-κB. Instead, the inhibitory activity of CGRP was mediated by the cAMP/protein kinase A pathway leading to rapid up-regulation of the transcriptional repressor, inducible cAMP early repressor (ICER). Ectopically expressed ICER directly repressed the LPS-stimulated activity of a synthetic Tnf promoter, as well as TNF-α protein production driven by the endogenous promoter. Inhibition of dendritic cell gene expression by CGRP was associated with the presence of a composite cAMP response element/κB promoter element. In a murine model of endotoxemia, CGRP markedly attenuated serum TNF-α levels, and this effect was associated with the up-regulation of ICER. Together, these results establish a novel pathway for the negative regulation of TLR responses through the nervous system that critically involves induction of the transcriptional repressor ICER by the neuropeptide CGRP.

Procalcitonin ratio indicates successful surgical treatment of abdominal sepsis.

BACKGROUND On-demand relaparotomy has been associated with a slightly decreased mortality compared to planned relaparotomy in the surgical treatment of secondary peritonitis. On-demand relaparotomy must be performed without delay to detect progressing sepsis early, before the onset of multiorgan failure. The aim of the study was to evaluate procalcitonin (PCT) as a parameter for early detection of progressing sepsis after operative treatment of the infective source. METHODS In 104 consecutive patients with secondary peritonitis, PCT serum levels were monitored on postoperative days 1 and 2 after initial operative elimination of the septic focus. The PCT ratio between postoperative days 1 and 2 was calculated and correlated to the success of the initial intervention. The latter was considered inadequate if relaparotomies were necessary to eliminate the intraabdominal infection. RESULTS Using classification and regression tree analysis, a cutoff could be calculated at 1.03 for the PCT ratio of postoperative day 1 to day 2. Lesser values indicated unsuccessful elimination of the septic source, whereas values above 1.03 represented successful operative treatment of the septic focus. Unsuccessful treatment of the septic process could be detected with a specificity of 63% and a sensitivity of 95%. CONCLUSION The PCT ratio appears to be a valuable aid in deciding if further relaparotomies are necessary after initial operative treatment of an intraabdominal septic focus.

Prognostic Implications of the Seventh Edition of the International Union Against Cancer Classification for Patients With Gastric Cancer: The Western Experience of Patients Treated in a Single-Center European Institution

PURPOSE Validity of the seventh edition of the American Joint Committee on Cancer/International Union Against Cancer (AJCC/UICC) staging systems for gastric cancer has been evaluated in several studies, mostly in Asian patient populations. Only few data are available on the prognostic implications of the new classification system on a Western population. Therefore, we investigated its prognostic ability based on a German patient cohort. PATIENTS AND METHODS Data from a single-center cohort of 1,767 consecutive patients surgically treated for gastric cancer were classified according to the seventh edition and were compared using the previous TNM/UICC classification. Kaplan-Meier analyses were performed for all TNM stages and UICC stages in a comparative manner. Additional survival receiver operating characteristic analyses and bootstrap-based goodness-of-fit comparisons via Bayesian information criterion (BIC) were performed to assess and compare prognostic performance of the competing classification systems. RESULTS We identified the UICC pT/pN stages according to the seventh edition of the AJCC/UICC guidelines as well as resection status, age, Lauren histotype, lymph-node ratio, and tumor grade as independent prognostic factors in gastric cancer, which is consistent with data from previous Asian studies. Overall survival rates according to the new edition were significantly different for each individuals pT, pN, and UICC stage. However, BIC analysis revealed that, owing to higher complexity, the new staging system might not significantly alter predictability for overall survival compared with the old system within the analyzed cohort from a statistical point of view. CONCLUSION The seventh edition of the AJCC/UICC classification was found to be valid with distinctive prognosis for each stage. However, the AJCC/UICC classification has become more complex without improving predictability for overall survival in a Western population. Therefore, simplification with better predictability of overall survival of patients with gastric cancer should be considered when revising the seventh edition.