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Perikles Simon

Publications and source records attributed to Perikles Simon.

17 recordsLinked to original sources
PubMed2006

Albumin in immunohistochemistry: Foe and friend.

Immunohistochemical procedures constitute a high methodological value in both pathologic diagnostics and research. Staining quality depends on a large variety of interference factors. Primarily, background staining reduces the quality of evaluation by reducing the chromatic discrimination. For the identification of important interference factors, various incubation steps and composition of solutions recommended in routine protocols were altered or omitted in our study. Surprisingly, the most important effect concerning background staining reduction could be significantly attributed to the omission of albumin which usually is recommended as a reducer of background stainings. However, in contrast to this negative effect, albumin could also increase specific staining intensity. These findings lead to the recommendation of a careful use of albumin in immunohistochemistry because of the dichotomous effects mentioned above. Furthermore, these results imply that in case of a good specific staining pattern, the use of albumin in immunohistochemical solutions merely exerts significant negative background staining effects.

Central Nervous System↗
PubMed2006

Doping in fitness sports: estimated number of unreported cases and individual probability of doping.

AIMS: Recent studies have suggested that the use of doping substances and particularly of anabolic androgenic steroids (AAS) is often practised by fitness centre visitors. These studies employed direct interview techniques and questionnaires to assess the estimated number of unreported cases of doping. Because people hesitate to provide compromising information about themselves, these techniques are subject to response errors. In this study we applied an alternative interview technique to assess more accurately unreported cases of doping in fitness centres. DESIGN AND PARTICIPANTS: The present investigation employed the randomized response technique (RRT) to reduce response errors. A cohort of 500 people from 49 fitness centres participated in this study. FINDING: The RRT revealed a high prevalence of doping (12.5%). In addition, and most importantly, the present RRT study revealed an alarmingly high prevalence of illicit drug use, specifically of cocaine use, that has been severely underestimated by previous studies. CONCLUSIONS: The RRT confirmed previously estimated rates of AAS use assessed by direct interview techniques and voluntary questionnaires, but uncovered a much higher usage rate of illicit drugs among fitness centre visitors. This outcome enabled us to construct a 'probability' rating for the use of doping substances in fitness centre visitors. Given its high prevalence and the predominant use of AAS, doping among fitness centre visitors is an issue of extreme relevance for the health care system. Our study may help to characterize further doping substance users and to develop and apply prevention and intervention programmes specifically to individuals at high risk.

Adult↗
PubMed2006

Activation of the PKB/Akt pathway in histological benign prostatic tissue adjacent to the primary malignant lesions.

In order to evaluate the molecular heterogeneity of prostate cancer, this study examined the expression of Akt-pathway related parameters within the cancerous prostate gland. PTEN, p-Akt and p27kip1 are known to be altered in prostate cancer. Tissue samples from malignant, tumor adjacent benign and benign areas of 25 whole mounted prostate cancer specimens were processed to 583 tissue microarray cores. Immunohistochemically determined biomarker expression was correlated to the different localizations. p-Akt and p27kip1 showed increased staining in malignant tissue compared to the respective benign tissue (p < 0.01 and p < 0.05). The adjacent but histologically benign tissue had increased levels (p < 0.05 and p < 0.01), whereas no significant difference was found between the adjacent and malignant regions. A highly significant correlation of p-Akt and p27kip1 in benign tissue (p < 0.001) was lost in the adjacent areas and in the malignant tissue (p = 0.054 and p = 0.12). In tendency, PTEN expression was decreased in the malignant regions and revealed the highest staining in the adjacent zone. According to the results obtained, the expression of p-Akt and p27kip1 was increased in both the adjacent microscopically benign tissue as well as the primary tumors when compared with the histologically benign tissue specimens that served as biological control. The increased expression of PTEN indicates its regulatory function in the initial steps of a deteriorated cell cycle control as well as uncontrolled cellular proliferation, for example, which seem to be present in the normal prostatic tissue surrounding the primary malignant lesion. The addition of molecular markers to a 'classical' histopathological approach might contribute to an enhanced sensitivity of analytical approaches aimed at the detection of malignant or premalignant lesions within prostatic biopsies.

Aged↗
PubMed2006

Regulation of immediate early gene expression by exercise: short cuts for the adaptation of immune function.

Onset of physical activity induces a wide variety of rapid biophysical and biochemical responses that act on cells and lead to a wide range of phenotypic adaptations. Here we elucidate the role of immediate early gene (IEG) expression as a first line of transcriptional response that mediates protein neosynthesis and leads to adaptation of immune function. New posttranscriptional mechanisms have been described that speed up transcriptional responses. These include RNA-RNA interactions such as those exploited by miRNAs and stimulus-dependent cytoplasmic polyadenylation. We describe these shortcuts that modulate expression and discuss the challenges of accurately measuring them using various transcriptomic screening and quantification approaches. Although there is high complexity of the upstream as well as the downstream pathways that lead to IEG expression, IEG expression itself may only show a limited number of response patterns. Focusing transcriptomic approaches in exercise immunology at the IEG-level may facilitate the discovery of exercise-specific transcriptional signatures.

Adaptation, Physiological↗
PubMed2005

cDNA microarray analysis reveals novel candidate genes expressed in human peripheral blood following exhaustive exercise.

It is generally accepted that exhausting endurance exercise exhibits strong effects on the immune system. Such effects have been attributed to changes in the cellular composition of peripheral blood as well as to changes in the expression of plausible candidate genes. The list of candidate genes is far from being complete, since this issue has not yet been investigated in a systematic way. In this study, we used a custom-made cDNA microarray focused on inflammation as a screening approach to study gene expression in eight one-half marathon runners before, immediately after, and 24 h after exercise. Significant differential gene expression was verified by quantitative real-time PCR. Linear regression analysis showed that microarray expression analysis of cell type-specific surface molecules reflects the observed individual cellular shifts in peripheral blood cells with high statistical significance. In line with the results of former studies, we observed an upregulation of mitogen-activated protein kinase-activated protein kinase-2 (MAPKAP-K2), L-selectin, and IL-1 receptor antagonist (IL-1ra) after exhaustive exercise. The main results of this study report, for the first time, the downregulation of CD81; the upregulation of thioredoxin, which may play an important part in anti-oxidative defense; and, surprisingly, the downregulation of the anti-carcinogenic gene glutathione-S-transferase-3 (GSTM3) in peripheral blood. The study shows cDNA microarray expression analysis as a reliable systematic instrument to complete the list of candidate genes that may play a role in exhaustive exercise-induced modulation of the immune response.

Adult↗
PubMed2005

Anabolic ergogenic substance users in fitness-sports: a distinct group supported by the health care system.

BACKGROUND: Anabolic ergogenic substance use, in particular the use of anabolic androgenic steroids, is a serious problem in general. Nevertheless, it is subject to debate whether ergogenic substance users exhibit similar features as multiple substance users or whether they constitute a discrete group. METHODS: One thousand eight hundred and two standardized, anonymous questionnaires were distributed among visitors of 113 fitness centers. Questions were asked concerning biometric parameters, social indicators, physical fitness, use of natural stimulants, general illicit drugs and ergogenic substances. With logistic regression analysis, multivariate odds ratios were estimated to investigate the association of anabolic ergogenic substance or general illicit drug use with other parameters. RESULTS: 13.5% of all participants confessed to having used anabolic ergogenic substances at some point in time. Anabolic ergogenic substance use was positively related with cocaine use, training years, training frequency, negatively related to the level of education, alcohol intake and less frequently used by Germans than by non-Germans. General illicit drug use, however, was positively related with alcohol intake, smoking and a university degree and negatively with having children. In addition, anabolic ergogenic substance use was significantly related with the use of general illicit drugs based on the strong relation with the use of cocaine, which is an ergogenic substance itself. The health care system supplies 48.1% of the anaolic ergogenic substance users with their substances and 32.1% are even monitored by a physician. CONCLUSIONS: The results of this study strengthen the notion that anabolic ergogenic substance users constitute a specific body-oriented substance user group. Uncommon for general illicit drug use, the health care system is a major sponsor of anabolic ergogenic substance users. These findings suggest the need for alternative approaches for successful prevention and intervention programs.

Adult↗
PubMed2005

Cathepsin D expression in renal cell cancer-clinical implications.

BACKGROUND: Whereas the expression of Cathepsin D (Cath D) is suggested to enhance the biological aggressiveness of human malignancies, its role in renal cell carcinoma (RCC), however, has not been investigated. METHODS: By tissue microarray analysis, tumor and benign tissue samples from 176 RCC patients were investigated for Cath D expression by immunohistochemistry and Western blots. Expression levels were correlated to clinical variables and to the postoperative outcome. RESULTS: High Cath D expression levels were detected in 29%/9% of tumor and benign tissue samples, respectively (p < 0.0001). In case of a high vs. low Cath D expression level, development of distant metastases was observed in 12% vs. 88% of cases (p < 0.05). With a median follow-up of 50 (2-146) months, high level Cath D expression was correlated with an improved long-term survival when compared with patients presenting with decreased expression [median long-term survival: 82 vs. 53 months in case of a high vs. low expression level] (p < 0.05). CONCLUSIONS: The Cath D staining pattern predicted a reduced risk for metastatic spread and tumor dependent death, hereby indicating its role as a biological variable revealing additional prognostic information for renal cell cancer patients. Increased expression of Cath D in tumor vs. benign tissue samples might indicate a role for the development and progression of RCC.

Biomarkers, Tumor↗
PubMed2005

Decline of immune responsiveness: a pathogenetic factor in Alzheimer's disease?

The involvement of immunological alterations in the pathogenesis of Alzheimer's disease (AD) is widely discussed. Hitherto, findings on systemic immunological alterations are inconsistent. We measured the concentrations of the pro-inflammatory cytokines IL-1beta, IL-2, IL-6, and TNF-alpha, and of the soluble receptors sIL-2r, sIL-6r, and sTNF-alphar, in cerebrospinal fluid (CSF) and serum of 20 Alzheimer patients and 21 controls. Moreover, we studied levels of the pro-inflammatory IL-6, Il-12, IFN-gamma, and TNF-alpha, and of the anti-inflammatory IL-5 and IL-13 in stimulated blood cell cultures from 27 AD patients and 25 controls. The levels in CSF and serum were diminished in AD or under detection limit. In mitogen-stimulated blood cultures we found a significant decrease of pro- and anti-inflammatory cytokines in the AD group. Our data suggest a general decline of immune responsiveness in AD. Based on the recent research, an impaired immune response may be considered as a pathogenetically relevant factor in AD. With respect to the putative role of ageing in AD, we assume a premature immunosenescence contributing to the Alzheimer's pathology.

Aged↗
PubMed2005

Thrombospondin 1 as possible key factor in the hemocompatibility of endocoronary prostheses.

Intracoronary stenting has markedly improved the patency of native coronary arteries after percutaneous transluminal coronary angioplasty (PTCA). Advances in stent technology and design, including drug releasing stents, have contributed to reduce the long-term restenosis rate. However, stenosis caused by neointimal hyperplasia, vascular remodeling and thrombosis is still a major problem after endocoronary stent procedures. This study focuses on differential gene expression of circulating peripheral blood cells after 90 min exposure to stents to search for initially activated cellular pathways, which may foster restenosis. Fresh human whole blood (1 IU heparin/ml), taken from non-medicated healthy volunteers, was incubated under flow conditions in an in vitro closed-loop stent-testing model (modified Chandler-Loop). Differential gene expression compared to resting conditions and to the experimental controls was investigated by a DNA-microarray technique encoding for over 17,000 genes simultaneously. As expected, a large variety of genes showed differential gene expression. Interestingly, Thrombospondin 1 (TSP-1), which plays a key role in initial immune defense, was found to be the most markedly up-regulated gene. We propose TSP-1 expression as an early indicator for the activation of immune responses following intracoronary stenting. After clarifying the participation of TSP-1 in vivo, future studies will therefore focus on TSP-1 as a potential prognostic factor, which may also help to develop and control new surface materials with an improved biocompatibility.

Adult↗
PubMed2004

Temporal changes of novel transcripts in the chicken retina following imposed defocus.

PURPOSE: Changes in retinal gene expression are one of the first steps in the signaling pathway underlying the visual control of eye growth. We tried to identify novel, yet unknown, genes, that alter their expression pattern following imposed defocus, wearing of diffusers, or during recovery from myopia. Sequences found earlier by differential display studies were applied to 5'-RACE and identified as 15 kDa selenoprotein P and prolidase. Moreover, we obtained more sequence information for a yet unidentified gene. We have studied the time course of expressions of these genes following lens or diffuser treatment. METHODS: Ten to 14 day old white leghorn chickens (4-7) were treated with a monocular +7 D or -7 D lenses for 2, 4, 6, or 24 h, or treated with monocular or binocular diffusers for 2, 4, or 6 h. Chickens of another group were allowed to recover from 4 days of diffuser wear for 4 h. Untreated chicks served as a control for contralateral eye effects. Following the extraction of retinal RNA, the relative expression of the three genes was determined by semi-quantitative real time PCR. RESULTS: We found a significant up regulation of selenoprotein P expression after 24 h of treatment with positive (+380%) or negative lenses (+387%) which was even more prominent in the contralateral untreated eyes (positive: +542%; negative: +786%). A rapid change in selenoprotein mRNA levels was induced by binocular diffuser wear for 2 h (+425%), whereas defocus blur in one eye led to an increase only after 6 h (+261%). There was a significant upregulation of prolidase mRNA after 24 h of treatment with positive (+75%) but not with negative lenses. Moreover, blur induced by diffusers resulted in a highly significant rise of prolidase mRNA levels after 4 h, both with monocular (142%) and binocular (106%) treatment. This is similar to what was found in the previous differential display (DD) screening of monocularly treated eyes. In contrast to the findings of the DD screening, the mRNA expression of the unknown gene remained unchanged both after hyperopic and myopic defocus. Again, blur induced by diffusers evoked the most prominent change after 6 h of binocular treatment. There were no significant alterations in the mRNA levels of the three investigated genes after 4 h of recovery from myopia that was induced by a 4 day period of diffuser treatment. CONCLUSIONS: The mRNA expression of selenoprotein P, prolidase, and of the not yet identified gene (sequence 3) is clearly altered by retinal image degradation imposed by diffuser wearing and, in part, by defocus imposed by spectacle lenses. However, none of the candidates are regulated by the sign of imposed defocus, suggesting a role in retinal contrast processing.

Animals↗
PubMed2004

Early transcriptional changes of retinal and choroidal TGFbeta-2, RALDH-2, and ZENK following imposed positive and negative defocus in chickens.

PURPOSE: Imposing defocus to the retina results in compensatory changes of axial eye growth. It is not clear which factors initially contribute to this process and whether they act on the post-translational, translational, or transcriptional level. We have measured early changes in mRNA levels, in response to imposed negative and positive defocus, of the transcription factor ZENK, the retinoic acid synthesis enzyme RALDH-2, and the growth factor TGFbeta-2. METHODS: Chickens 11 days of age were unilaterally treated with positive or negative spectacle lenses of 7 D power. After 0, 15, 30, and 120 min, mRNA was extracted from retina and choroid, and the concentration of the mRNAs of the three candidates was measured by quantitative real time PCR in both eyes. RESULTS: ZENK in the retina and RALDH-2 in the choroid displayed parallel signs of defocus dependent changes in mRNA levels after 15 or 30 min, respectively. ZENK mRNA levels were reduced in the retina after 15 min with both types of lenses but were then up regulated at 30 min with positive lenses and down regulated with negative lenses, similar to the previously observed changes in ZENK protein levels. Changes of RALDH-2 and TGFbeta-2 mRNA levels were confined to the choroid. Treatment with negative lenses resulted in a rapid (15 min) and persistent decrease in TGFbeta-2 mRNA concentration in the choroid. Negative lenses provoked parallel but less pronounced alterations in the open fellow eyes. CONCLUSIONS: Imposed defocus triggers extensive transcriptional changes of ZENK in the retina, and of TGFbeta-2 and RALHD-2 in the choroid. Changes in retina and choroid are rapid, show no phase delay with respect to each other, and can be considered, in the case of RALDH-2 and ZENK, as specific for the sign of imposed defocus. They occur prior to any morphological changes. This is consistent with a role in causing or controlling later changes in eye growth.

Aldehyde Oxidoreductases↗
PubMed2004

Posttranscriptional regulation of the immediate-early gene EGR1 by light in the mouse retina.

Synaptic plasticity is modulated by differential regulation of transcription factors such as EGR1 which binds to DNA via a zinc finger binding domain. Inactivation of EGR1 has implicated this gene as a key regulator of memory formation and learning. However, it remains puzzling how synaptic input can lead to an up-regulation of the EGR-1 protein within only a few minutes. Here, we show by immunohistochemical staining that the EGR-1 protein is localized in synapses throughout the mouse retina. We demonstrate for the first time that two variants of Egr-1 mRNA are produced in the retina by alternative polyadenylation, with the longer version having an additional 293 base pairs at the end of the 3'UTR. Remarkably, the use of the alternative polyadenylation site is controlled by light. The additional 3'UTR sequence of the longer variant displays an even higher level of phylogenetic conservation than the coding region of this highly conserved gene. Additionally, it harbours a cytoplasmic polyadenylation element which is known to respond to NMDA receptor activation. The longer version of the Egr-1 mRNA could therefore rapidly respond to excitatory stimuli such as light or glutamate release whereas the short variant, which is predominantly expressed and contains the full coding sequence, lacks the regulatory elements for cytoplasmic polyadenylation in its 3'UTR.

Animals↗
PubMed2004

Effects of positive and negative lens treatment on retinal and choroidal glucagon and glucagon receptor mRNA levels in the chicken.

PURPOSE: It has been found in the chicken that the amount of retinal glucagon mRNA increases during treatment with positive lenses. Pharmacological studies support the idea that glucagon may act as a stop signal for visually induced eye growth. To gain more insight into the functional role of glucagon, the changes of glucagon and glucagon receptor mRNA concentrations in retina and choroid over time were studied. Furthermore, the abundance of glucagon and the glucagon receptor was studied in different fundal layers (retina, retinal pigment epithelium[RPE], choroid) and the blood. METHODS: Semiquantitative real-time RT-PCR was used to measure glucagon and glucagon receptor mRNA levels in retina and choroid after positive and negative lens treatment for 2, 6, or 24 hours, by unilateral -7- or +7-D lenses. Contralateral eyes served as the control, and completely untreated animals provided further reference data. Intravitreal colchicine injections (which are known to reduce the number of glucagon cells sharply) were used to verify that the related decline in glucagon mRNA could be measured by real-time RT-PCR. RESULTS: In the retina, treatment with -7-D lenses induced an initial upregulation of glucagon mRNA in both eyes, followed by a significant downregulation. The treatment with +7-D lenses showed a significant but transient downregulation in the control eye superimposed on a trend toward upregulation in the treated eye. However, the changes in glucagon mRNA expression were not confined to the lens-treated eyes but were also found, although sometimes to a lesser extent, in the non-lens-covered fellow eyes. There was evidence of a transient increase in glucagon receptor mRNA levels in lens-treated eyes after either -7- or +7-D lens wear. In the choroid, no effect of imposed defocus was detected. The injection of colchicine led to the destruction of approximately 75% of the glucagon amacrine cells but the mRNA level of retinal glucagon decreased by only approximately 50%. Glucagon receptor expression was found to be higher in the RPE than the retina and choroid whereas, in the blood, glucagon and glucagon receptor mRNA expression was below detection level. CONCLUSIONS: The observed bidirectional regulation of glucagon mRNA in correlation with the sign of imposed defocus supports the idea that glucagon may act as a stop-and-go signal for eye growth. This is in line with a previous proposal based on studies of changes of the glucagon peptide content.

Animals↗
PubMed2003

Q-Gene: processing quantitative real-time RT-PCR data.

SUMMARY: Q-Gene is an application for the processing of quantitative real-time RT-PCR data. It offers the user the possibility to freely choose between two principally different procedures to calculate normalized gene expressions as either means of Normalized Expressions or Mean Normalized Expressions. In this contribution it will be shown that the calculation of Mean Normalized Expressions has to be used for processing simplex PCR data, while multiplex PCR data should preferably be processed by calculating Normalized Expressions. The two procedures, which are currently in widespread use and regarded as more or less equivalent alternatives, should therefore specifically be applied according to the quantification procedure used. AVAILABILITY: Web access to this program is provided at http://www.biotechniques.com/softlib/qgene.html

Algorithms↗
PubMed2003

Molecular biology of myopia.

Experiments in animal models of myopia have emphasised the importance of visual input in emmetropisation but it is also evident that the development of human myopia is influenced to some degree by genetic factors. Molecular genetic approaches can help to identify both the genes involved in the control of ocular development and the potential targets for pharmacological intervention. This review covers a variety of techniques that are being used to study the molecular biology of myopia. In the first part, we describe techniques used to analyse visually induced changes in gene expression: Northern Blot, polymerase chain reaction (PCR) and real-time PCR to obtain semi-quantitative and quantitative measures of changes in transcription level of a known gene, differential display reverse transcription PCR (DD-RT-PCR) to search for new genes that are controlled by visual input, rapid amplification of 5' cDNA (5'-RACE) to extend the 5' end of sequences that are regulated by visual input, in situ hybridisation to localise the expression of a given gene in a tissue and oligonucleotide microarray assays to simultaneously test visually induced changes in thousands of transcripts in single experiments. In the second part, we describe techniques that are used to localise regions in the genome that contain genes that are involved in the control of eye growth and refractive errors in mice and humans. These include quantitative trait loci (QTL) mapping, exploiting experimental test crosses of mice and transmission disequilibrium tests (TDT) in humans to find chromosomal intervals that harbour genes involved in myopia development. We review several successful applications of this battery of techniques in myopia research.

Animals↗
PubMedDate not supplied

Membranous expression and prognostic implications of epidermal growth factor receptor protein in human renal cell cancer.

BACKGROUND: It has been indicated that altered expression of the epidermal growth factor receptor (EGFR) promotes the invasive and metastatic potential of a variety of human malignancies. Therefore, the aim of the present study was to determine EGFR expression in clear cell renal cell carcinomas (RCC) to evaluate its prognostic relevance for the clinical course of the disease. MATERIALS AND METHODS: EGFR protein expression, detected by immunohistochemistry and tissue microarray analysis (TMA), was investigated in a cohort of 149 randomly selected patients subjected to tumor nephrectomy for RCC. RESULTS: The tumor cells preferably exhibited a homogeneous membrane-bound reactivity for EGFR; EGFR overexpression was detected in 70 (47%) of the primary tumor specimens, but in only 12 (9%) of the benign tissue samples (p<0.0001; Fisher's t-test). Tumor-associated EGFR staining was stratified into three groups: I: low staining score (n=75, 50%); II: intense expression (n=56, 38%); and III: strong overexpression (n = 18, 12%). Strong reactivity for EGFR was identified as predicting the patients' survival both during uni- and multivariate analysis (p=0.03). Interestingly, the overall survival of the intense expression group surpassed even the low expression group (p=0.023). CONCLUSION: The observation that primary RCC specimens exhibit EGFR at higher levels when compared with benign renal parenchyma indicates its role in tumor development and progression. The availability of more refined prognostic factors would assist decision making in terms of the value of more aggressive treatment options for prognostically defined subgroups of patients. Additionally, if overexpression of EGFR identifies RCC with a more aggressive biological behavior, the latter receptor might serve as a novel target for a more effective therapeutical approach to RCC.

Carcinoma, Renal Cell↗