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Martin Ludwig

Publications and source records attributed to Martin Ludwig.

16 recordsLinked to original sources
PubMed2005

Deep UV laser-induced fluorescence detection of unlabeled drugs and proteins in microchip electrophoresis.

Deep UV fluorescence detection at 266-nm excitation wavelength has been realized for sensitive detection in microchip electrophoresis. For this purpose, an epifluorescence setup was developed enabling the coupling of a deep UV laser into a commercial fluorescence microscope. Deep UV laser excitation utilizing a frequency quadrupled pulsed laser operating at 266 nm shows an impressive performance for native fluorescence detection of various compounds in fused-silica microfluidic devices. Aromatic low molecular weight compounds such as serotonin, propranolol, a diol, and tryptophan could be detected at low-micromolar concentrations. Deep UV fluorescence detection was also successfully employed for the detection of unlabeled basic proteins. For this purpose, fused-silica chips dynamically coated with hydroxypropylmethyl cellulose were employed to suppress analyte adsorption. Utilizing fused-silica chips permanently coated with poly(vinyl alcohol), it was also possible to separate and detect egg white chicken proteins. These data show that deep UV fluorescence detection significantly widens the application range of fluorescence detection in chip-based analysis techniques.

Chymotrypsinogen↗
PubMed2005

INSL3 in the benign hyperplastic and neoplastic human prostate gland.

The human prostate gland is a well known source of H1 and H2 relaxin but information is lacking on the expression and potential role of the INSL3 peptide hormone within the prostate gland. In the present study we have investigated the expression of human INSL3 in patients with benign prostate hyperplasia (BPH), prostate intraepithelial neoplasia (PIN) and prostate carcinoma tissues. Of the prostate epithelial cells, strongest INSL3 expression was detected in the basal epithelial cell compartment. Weaker INSL3 mRNA expression and immunoreactive INSL3 production were observed in secretory epithelial cells and in interstitial smooth muscle cells. Prostate epithelial cells were also a source for transcripts encoding the INSL3 receptor LGR8 suggesting the presence of an autocrine/paracrine INSL3-LGR8 ligand-receptor system within the human prostate. Three human prostate carcinoma cell lines displayed differential gene activity for INSL3 and LGR8. While LNCaP was devoid of INSL3, the androgen-insensitive PC-3 and the stromal prostate cell line hPCP co-expressed INSL3 and LGR8 transcripts. In addition to expressing INSL3 mRNA, the LGR8-negative DU-145 also expressed an INSL3 splice form formerly demonstrated in thyroid carcinoma cells. When incubated with recombinant INSL3, PC-3 cells showed significantly increased intracellular cAMP levels indicating functional LGR8 receptors. INSL3 did not alter the proliferative or metabolic activity of PC-3 carcinoma cells. Instead, PC-3 responded to INSL3 with significantly enhanced tumor cell motility and a transcriptional down-regulation of ErbB receptors and EGF. All-trans-retinoic acid was demonstrated in PC-3 to up-regulate LGR8 gene activity in a dose- and time-dependent manner while having no effect on INSL3 gene activity. In conclusion, we have identified a functional INSL3-LGR8 ligand-receptor system in human prostate carcinoma cells.

Cell Line, Tumor↗
PubMed2004

Separation of fluorescein isothiocyanate-labeled amines by microchip electrophoresis in uncoated and polyvinyl alcohol-coated glass chips using water and dimethyl sulfoxide as solvents of background electrolyte.

On-chip capillary electrophoresis with uncoated and polyvinyl alcohol-coated glass channels in aqueous and nonaqueous dimethyl sulfoxide (DMSO) background electrolyte (BGE) solutions was applied in the separation of five amines derivatized with fluorescein-5-isothiocyanate. In aqueous BGE at pH 9.2, baseline separation of the analytes was not achieved on uncoated glass chips, but the separation was clearly improved when the chip channels were coated with polyvinyl alcohol (PVA). Separation was successful in nonaqueous DMSO electrolyte solution containing ammonium acetate and sodium methoxide, on both uncoated and PVA-coated glass microchips. The differences in the pK(a) values of analytes were probably amplified in DMSO, and all five analytes were at least partly dissociated and were separated. Because the viscosity of DMSO is higher than that of water, the migration times were longer in DMSO.

Amines↗
PubMed2004

Subsecond chiral separations on a microchip.

Fast chiral separation of DNS-amino acids could be realized using microchip electrophoresis with fluorescence detection. For this purpose, highly sulfated cyclodextrins (HS-gamma-CD) were used as chiral selectors enabling high selectivity. Even subsecond separation of DNS-tryptophan, DNS-norleucine, DNS-phenylalanine, DNS-methionine, and DNS-aspartic acid could be achieved. Baseline separation could be accomplished within 720 ms, which is the fastest separation of enantiomers reported to date. A more complex mixture consisting of three chiral DNS-amino acids could be separated within 3.3 s utilizing a separation length of only 7 mm and an electrical field strength of 2012 V/cm.

Amino Acids↗
PubMed2004

Two-year experience with the german-translated version of the NIH-CPSI in patients with CP/CPPS.

OBJECTIVES: To examine, after psychometric evaluation and validation of the translated National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI), the practical value of this questionnaire in a routine diagnostic prostatitis setup for patients with chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS). The NIH-CPSI is a well-accepted tool for the symptomatic evaluation of patients with CP/CPPS. The recently translated German version has not yet been validated in detail. METHODS: A total of 137 consecutive patients attending a prostatitis outpatient department were classified according to the internationally accepted NIH consensus classification into CP/CPPS NIH type IIIA (n = 53; mean age 43.2 years) and IIIB (n = 84; mean age 43.4 years). For psychometric analysis, the overall type III group was evaluated for reliability and validity of the German NIH-CPSI. The psychometric properties of the translated NIH-CPSI were compared with those of the original English version. In addition, the total scores of all men and separately for CP/CPPS NIH types IIIA and IIIB were evaluated. RESULTS: The German NIH-CPSI was reliable, with an alpha coefficient for the overall index and its subscales of between 0.60 and 0.74. However, the internal consistency of the pain subdomain was lower in our translated version (alpha 0.60) compared with the original English version (alpha 0.86). In this cohort, men with NIH type IIIB CP/CPPS were significantly (P = 0.03) more symptomatic in the total index compared with men with NIH type IIIA CP/CPPS. CONCLUSIONS: The German version of the NIH-CPSI has a relatively high reliability and face and construct validity overall. A validated translated NIH-CPSI is suggested as a standardized tool to quantify chronic pelvic pain symptoms for different countries and languages.

Adult↗
PubMed2003

Experience with different questionnaires in the management of patients with CP/CPPS: GPSS, IPSS and NIH-CPSI.

A number of different self assessment questionnaires have been developed in order to evaluate specific symptoms of chronic prostatitis. The most popular indices in Germany are the Giessen Prostatitis Symptom Score(GPSS), the International Prostate Symptom Score (IPSS) and the Chronic Prostatitis Symptom Index of the National Institutes of Health (NIH-CPSI). The major aim of our study was the evaluation of these questionnaires in patients with chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS). In addition, we analysed questionable differences in symptomatology between the subgroups NIH III A and B. A total of 203 native speaking German men with symptoms of CP/CPPS attending the Giessen prostatitis outpatient department were included in our protocol. According to the strict criteria of the Giessen examination protocol, 84 men were classified as CP/CPPS type NIH III B and 54 men as NIH III A. The psychometric and descriptive results were analysed with SPSS software. The Cronbach alpha, as a parameter for the internal consistency for each index, showed acceptable values. The correlation coefficient for each index was also sufficient. The median total scores of the GPSS and NIH-CPSI were significantly higher in patients with CP/CPPS type NIH III B. The IPSS results were the same. All symptom indices demonstrated acceptable to good values for psychometric validation. Similar symptomatic findings were available using GPSS and NIH-CPSI.

Adolescent↗
PubMed2003

Chronic prostatitis/chronic pelvic pain pyndrome): seminal markers of inflammation.

The new prostatitis classification proposes the inclusion of seminal leukocytes in the diagnosis of inflammatory chronic pelvic pain syndrome (CPPS). The present study has been performed to clarify the role of seminal leukocytes and inflammatory seminal plasma parameters in order to contribute to the differential diagnosis between inflammatory (category IIIA) and non-inflammatory (category IIIB) CPPS. A total of 112 consecutive symptomatic patients (mean age 37.3 years; range 21-64) attending our prostatitis outpatient clinic were investigated. Men with evidence for bacterial infection were excluded by prior standardized lower urinary tract localization studies. Men were categorized into inflammatory and non-inflammatory CPPS according to the leukocyte analysis in expressed prostatic secretions (EPS) and urine after prostatic massage (VB 3). Ejaculate analysis was performed after lower urinary tract localization studies. Inflammatory markers included peroxidase positive leukocytes (PPL) and PMN-elastase. Receiver operating characteristic curves were constructed to analyze cutpoints provided that the differences were significant. Increased leukocyte counts in EPS/VB 3 were found in 64 men, while in 48 this was not the case. No differences could be detected in relation to patients' age ( P>0.05). In men with category IIIA prostatitis, PPL and elastase in the seminal fluid were significantly increased ( P<0.001). For PPL and elastase, a cutpoint of 0.113 x 10(6)/ml and 280 ng/ml, respectively, were suggested. Increased PPL (>0.113 x 10(6)/ml) and elastase (>280 ng/ml) in the seminal fluid indicate inflammatory disease provided that the ejaculate analysis is performed on the same day after lower urinary tract localization studies.

Adult↗
PubMed2003

High-speed chiral separations on a microchip with UV detection.

Fast chiral separations of a variety of basic and acidic compounds could be realized on microfluidic quartz chips. A microchip electrophoresis instrument equipped with a linear imaging UV-detector was used. The usually applied but troublesome fluorescence tagging in order to enable fluorescence detection could be omitted. Using sulfated cyclodextrins as chiral selectors baseline separation of 19 compounds could be achieved in less than 1 min with high reproducibility. The relative standard deviation of migration time was below 7%. The fastest separation could be performed in 2.5 s which is to date the fastest separation of enantiomers reported. It was possible to apply microchip electrophoresis (MCE) for the determination of high enantiomeric excess (ee) values, as exemplarily shown for pseudoephedrin where 2% of the minor enantiomer could reliably be determined beside high amount of the other isomer. Successful separation of a mixture of 3 chiral drugs could be performed in a single run in less than 11 s utilizing a separation length of only 12 mm. These results show that MCE has great potential for fast chiral analysis and high-throughput screening.

Buffers↗
PubMed2003

Microchip electrophoresis for chiral separations.

Microchip electrophoresis (MCE) is a promising new technique for the separation of enantiomers. This recently introduced technique enables chiral separations to be performed in seconds on tiny micromachined devices. This review is intended to give a brief introduction into the principles of chiral separations with MCE with regard to methodology and instrumentation. Different approaches to realize chiral separations in microfluidic devices are described and discussed. This review gives an overview of original work done in this field with emphasis on approaches to improve detection and resolution in chiral MCE.

Electrophoresis, Capillary↗
PubMed2003

Coated microfluidic devices for improved chiral separations in microchip electrophoresis.

Chiral separations of fluorescein isothiocyanate-labeled amines have been performed in poly(vinyl alcohol) (PVA)-coated microfluidic glass chips. Baseline separation of enantiomers could be realized in coated devices while they could not be resolved in uncoated chips. The electroosmotic flow (EOF) in PVA-coated channels is suppressed over a wide pH range which leads to a considerable improved reproducibility of migration times in repetitive analysis. Due to the high resolution obtained in such devices, it was possible to reliable determine the enantiomeric purity with high accuracy. One percent of the minor enantiomer could be determined in the presence of large excess of the other enantiomer. As the EOF was suppressed, the anionic compounds were detected at the anode whereas the dominant EOF in uncoated devices resulted in an effective mobility to the cathode. Applying PVA-coated channels considerable improved precision of migration times was found. The relative standard deviation of migration times was below 1% in PVA-coated devices. Accordingly, excessive rinsing or etching steps in order to stabilize the EOF could be omitted while this was necessary for a reliable operation of uncoated devices.

Electrophoresis, Capillary↗
PubMed2003

Surface modification in microchip electrophoresis.

Different approaches and techniques for surface modification of microfluidic devices applied for microchip electrophoresis are reviewed. The main focus is on the improved electrophoretic separation by reducing analyte-wall interactions and manipulation of electroosmosis. Approaches and methods for permanent and dynamic surface modification of microfluidic devices, manufactured from glass, quartz and also different polymeric substrates, are described.

Acrylic Resins↗
PubMed2003

Measuring single-kidney glomerular filtration rate on single-detector helical CT using a two-point Patlak plot technique in patients with increased interstitial space.

OBJECTIVE: We measured the single-kidney glomerular filtration rate (GFR) with a two-point Patlak plot technique based on multiphasic CT in patients with hydronephrosis or pyelonephritis or both. The question we sought to answer in our study was, Does increased interstitial space as measured with the Patlak plot technique cause overestimation of GFR? SUBJECTS AND METHODS: Twenty adult patients treated with percutaneous nephrostomy were studied. The CT protocol consisted of an unenhanced scan and three subsequent scans obtained 38, 71, and 102 sec after the initiation of the contrast medium injection. Plasma clearance of the contrast medium was determined and used as the reference. Additionally, single-kidney excretory clearance was determined by separate urine collections from the left and right kidneys. A three-compartment model calculation was made using all data available to estimate volume and transfer rate constant of the interstitial space. RESULTS: The GFR determined using plasma clearance correlated well with the GFR determined using excretory clearance, with a correlation coefficient of r = 0.94 and a regression line of y = -6 + 0.97 x x. GFR of both kidneys as measured using CT was overestimated according to the GFR determined using plasma clearance, with a correlation coefficient of r = 0.80, and a regression line of y = 35 + 0.79 x x. Single-kidney excretory clearance GFR was similarly overestimated using single-kidney CT GFR, with a correlation coefficient of r = 0.81 and a regression line of y = 20 + 0.84 x x. Single-kidney parenchymal volume was used as an indicator of interstitial space enlargement. The overestimation of excretory clearance GFR using CT correlated significantly with the parenchymal volume of the individual kidneys. A high correlation was also found between overestimation of total GFR determined with CT and interstitial space estimated using a three-compartment model calculation. Relative interstitial space was estimated to be 25% (range, 9-46%) of total kidney volume. CONCLUSION: Using the interstitial space as a third compartment may introduce an error into the measurement of GFR with the Patlak plot technique. We found that the CT protocol in our study resulted in considerable overestimation of GFR as determined with the Patlak plot in patients with increased interstitial space.

Contrast Media↗
PubMed2002

Design and performance of a microchip electrophoresis instrument with sensitive variable-wavelength fluorescence detection.

A modular instrument for high-speed microchip electrophoresis (MCE) equipped with a sensitive variable-wavelength fluorescence detection system was developed and evaluated. The experimental setup consists mainly of a lamp-based epifluorescence microscope for variable-wavelength fluorescence detection and imaging and a programmable four-channel bipolar high-voltage source capable of delivering up to +/- 10 kV per channel. The optical unit was equipped with a high-sensitivity photomultiplier tube and an adjustable aperture. The system was applied to MCE separations of flurescein isothiocyanate (FITC)-labelled amines utilizing blue light (450-480 nm) for excitation as well as for the separation of rhodamines utilizing excitation light in the green spectral region (531-560 nm). At optimized conditions baseline separation of four FITC-labelled amines could be obtained in less than 50 s at a detection limit of 460 ppt (1 nM) with a signal-to-noise ratio of 3:1. Three rhodamines could be baseline-separated in less than 6 s at a detection limit of 240 ppt (500 pM). The relative standard deviations of absolute migration times determined in repetitive MCE separations of FITC-labelled amines were below 2.5% (n= 25). By the application of cyclodextrin-modified electrolytes, chiral separation of FITC-labelled amines could be performed in seconds demonstrating the potential of microchip electrophoresis for chiral high-throughput screening.

Cyclodextrins↗
PubMed2002

Poly(vinyl alcohol)-coated microfluidic devices for high-performance microchip electrophoresis.

The channels of microfluidic glass chips have been coated with poly(vinyl alcohol) (PVA). Applied for microchip electrophoresis, the coated devices exhibited a suppressed electroosmotic flow and improved separation performance. The superior performance of PVA-coated channels could be demonstrated by electrophoretic separations of labeled amines and by video microscopy. While a distorted sample zone is injected using uncoated channels the application of PVA-coated channels results in an improved shape of the sample zone with less band broadening. Applying PVA-coated microchips for the separation of amines labeled with Alexa Fluor 350 even sub-second separations, utilizing a separation length of only 650 microm, could be obtained, while this was not possible using uncoated devices. By using PVA-coated devices rather than an uncoated chip a threefold increase in separation efficiencies could be observed. As the electroosmotic flow (EOF) was suppressed, the anionic compounds were detected at the anode whereas the dominant EOF in uncoated devices resulted in an effective mobility to the cathode. Besides improved separation performance another important feature of the PVA-coated channels was the suppressed adsorption of fluorescent compounds in repetitive runs which results in an improved robustness and detection sensitivity. Applying PVA-coated channels, rinsing or etching steps could be omitted while this was necessary for a reliable operation of uncoated devices.

Amines↗
PubMed2002

Seminal secretory capacity of the male accessory sex glands in chronic pelvic pain syndrome (CPPS)/chronic prostatitis with special focus on the new prostatitis classification.

OBJECTIVE: The aim of the study was to evaluate the secretory dysfunction of the male accessory glands in men with inflammatory versus non-inflammatory chronic pelvic pain syndrome (CPPS). METHODS: One hundred and twelve consecutive patients symptomatic for chronic pelvic pain were included into the study. All underwent a combined granulocyte analysis in expressed prostatic secretions (EPS) and a four-glass-test followed by ejaculate analysis. Patients were subgrouped according to elevated granulocyte counts in prostatic secretions, leukocytes in semen, or any of both. The content/total enzyme activity of the secretory seminal plasma parameters gamma-glutamyl-transferase (gamma-GT), fructose, and alpha-glucosidase representing the secretory capacity of the prostate gland, the seminal vesicles, and the epididymes, respectively, were investigated. RESULTS: The only significant findings were a reduced total enzyme activity of gamma-GT in men stratified according to elevated granulocyte counts in prostatic secretions (p=0.022; cutpoint 9.85U per ejaculate; sensitivity 61.1%, specificity 58.8%, AUC 0.6347) and in men with any inflammatory sign (p=0.033; cutpoint 9.9U per ejaculate, sensitivity 63%, specificity 58.33%, AUC 0.6404). CONCLUSIONS: Secretory damage of the prostate gland in men with inflammatory CPPS is demonstrable provided that increased granulocytes in prostatic secretions are part of the diagnostic criteria. However, because of the low sensitivity and specificity of gamma-GT it cannot be recommended as diagnostic tool to detect inflammatory disease on the basis of reduced secretory capacity.

Adult↗