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Biomedical subjects

P Jandik

Publications and source records attributed to P Jandik.

14 recordsLinked to original sources
PubMed2002

Initial study of using a laminar fluid diffusion interface for sample preparation in high-performance liquid chromatography.

This report describes a new microfluidic device called the H Filter for sample preparation prior to HPLC. The H Filters make possible a diffusional transfer of an analyte from a sample stream into a stream of a "receiver" fluid. Existing mathematical models can be used for optimizing experimental conditions. The authors have selected the extraction of the antibiotic cephradine from blood to demonstrate the utility of the new device. The extracts of blood samples spiked with cephradine levels between 0.2 and 100 microg/ml were analyzed using a C8 reversed-phase column and UV detection at 260 nm. The HPLC results were in good agreement with theory. The recovery of 32.2+/-2.8% was uniform over the entire range of cephradine concentrations. The new method completely avoids the use of centrifuges, that is otherwise typical for most current methodologies for the preparation of blood samples prior to HPLC analysis.

Cephradine↗
PubMed2001

Kirsten ras mutations in patients with colorectal cancer: the 'RASCAL II' study.

Researchers worldwide with information about the Kirsten ras (Ki-ras) tumour genotype and outcome of patients with colorectal cancer were invited to provide that data in a schematized format for inclusion in a collaborative database called RASCAL (The Kirsten ras in-colorectal-cancer collaborative group). Our results from 2721 such patients have been presented previously and for the first time in any common cancer, showed conclusively that different gene mutations have different impacts on outcome, even when the mutations occur at the same site on the genome. To explore the effect of Ki-ras mutations at different stages of colorectal cancer, more patients were recruited to the database, which was reanalysed when information on 4268 patients from 42 centres in 21 countries had been entered. After predetermined exclusion criteria were applied, data on 3439 patients were entered into a multivariate analysis. This found that of the 12 possible mutations on codons 12 and 13 of Kirsten ras, only one mutation on codon 12, glycine to valine, found in 8.6% of all patients, had a statistically significant impact on failure-free survival (P = 0.004, HR 1.3) and overall survival (P = 0.008, HR 1.29). This mutation appeared to have a greater impact on outcome in Dukes' C cancers (failure-free survival, P = 0.008, HR 1.5; overall survival P = 0.02, HR 1.45) than in Dukes' B tumours (failure-free survival, P = 0.46, HR 1.12; overall survival P = 0.36, HR 1.15). Ki-ras mutations may occur early in the development of pre-cancerous adenomas in the colon and rectum. However, this collaborative study suggests that not only is the presence of a codon 12 glycine to valine mutation important for cancer progression but also that it may predispose to more aggressive biological behaviour in patients with advanced colorectal cancer.

Adolescent↗
PubMed2001

Simultaneous analysis of homocysteine and methionine in plasma.

The new isocratic cation exchange method separates up to eight different amino thiols. The separated sample components are detected electrochemically using a gold electrode and the integrated pulsed amperometry. The eluent composition is, for example, 0.15 M sodium perchlorate, 0.02 M perchloric acid and 5% acetonitrile. The report describes the optimization of chromatographic parameters such as column diameter and eluent composition. Quantitative performance is discussed for eight different amino thiols using standards. Also presented is a long term quantitative study for homocysteine and methionine in plasma samples. The preparation of plasma samples is simpler than with the previously reported version of the method. Only a reduction step is required, and neither column switching nor derivatization are necessary.

Cation Exchange Resins↗
PubMed2001

Simplified in-line sample preparation for amino acid analysis in carbohydrate containing samples.

This report describes a new, automated chromatographic procedure eliminating carbohydrates from amino acid samples prior to their analysis by anion-exchange chromatography and integrated amperometric detection. In the first step, a sample is brought onto a short cation-exchange column (trap column) in hydrogen form. Carbohydrates are passing through this column, while only amino acids are retained. Subsequently, the cation-exchange column, holding the amino acid fraction, is switched in-line with the gradient pump and separator column. The mobile phase used at the beginning of the separation (NaOH; pH 12.7) transfers amino acids from the trap column onto the anion-exchange column and the amino acid separation is completed without any interference by carbohydrates. All common amino acids are recovered following the carbohydrate removal step. The average value of their recovery is 88.1%. The calibration plots were tested between 12.5 and 500 pmol (amounts injected). The mean value of correlation coefficients of calibration plots was calculated as 0.99. The mean value of relative standard deviations from five replicates was 3.9%. The usefulness of the method is illustrated with two chromatograms of a carrot juice sample obtained before and after the in-line removal of carbohydrates.

Amino Acids↗
PubMed2001

Proteome study of colorectal carcinogenesis.

Development of cancer is a complex process involving multiple changes in gene expression. To unravel these alterations, a proteome approach aimed at the identification of qualitative and quantitative changes in protein composition, including their post-translational modifications, attracts great attention. Our study was focused on the identification of proteins whose amount is altered in the course of malignant transformation of colon mucosa. Proteins extracted from tissue specimens or cell lysates were separated by two-dimensional gel electrophoresis (2-DE). Comparative analyses of 2-DE protein patterns were done using computerized image analysis. Selected proteins exhibiting statistically significant abundance alterations comparing healthy and diseased tissues were identified by mass spectrometry. Globally, we have found 57 proteins that exhibited either a significant decrease or increase in amount in pathological tissues, and 18 of these were annotated by mass spectrometry. The alterations in the expression of nine proteins were common for both precancerous and neoplastic tissues suggesting their role in colon tumorigenesis. The epithelial origin of all identified spots was checked in two cell lines Caco-2 and DLD-1 originating from well-differentiated and poorly differentiated colon carcinoma, respectively.

Adenocarcinoma↗
PubMed2000

New technique for increasing retention of arginine on an anion-exchange column.

A method is described for enhancing retention of arginine on a pellicular anion-exchange column. Arginine exhibits adjustable increases of retention time that are dependent on the acidity of standard or sample matrix. This effect is based on interactions of the protonated form of arginine with the residual cation-exchange groups on the core beads of pellicular particles. The relative magnitude of retention time shift of arginine is evaluated for identical concentrations of hydrochloric, sulfuric, and perchloric acids. Although the direct addition of acid is very effective in influencing the retention of arginine, it affects peak shapes and retention of other peaks in the chromatographic separation. The new technique-acid coinjection-achieves a similar retention enhancement for arginine with only a minimal effect on the rest of the separation. Detection limits, reproducibility results, and calibration data are presented for the chromatography of amino acids with acid coinjection. Improved resolution of arginine is demonstrated with chromatograms of soybean hydrolysate and cell culture samples.

Arginine↗
PubMed2000

Irinotecan combined with fluorouracil compared with fluorouracil alone as first-line treatment for metastatic colorectal cancer: a multicentre randomised trial.

BACKGROUND: Irinotecan is active against colorectal cancer in patients whose disease is refractory to fluorouracil. We investigated the efficacy of these two agents combined for first-line treatment of metastatic colorectal cancer. METHODS: 387 patients previously untreated with chemotherapy (other than adjuvant) for advanced colorectal cancer were randomly assigned open-label irinotecan plus fluorouracil and calcium folinate (irinotecan group, n=199) or fluorouracil and calcium folinate alone (no-irinotecan group, n=188). Infusion schedules were once weekly or every 2 weeks, and were chosen by each centre. We assessed response rates and time to progression, and also response duration, survival, and quality of life. Analyses were done on the intention-to-treat population and on evaluable patients. FINDINGS: The response rate was significantly higher in patients in the irinotecan group than in those in the no-irinotecan group (49 vs 31%, p<0.001 for evaluable patients, 35 vs 22%, p<0.005 by intention to treat). Time to progression was significantly longer in the irinotecan group than in the no-irinotecan group (median 6.7 vs 4.4 months, p<0.001), and overall survival was higher (median 17.4 vs 14.1 months, p=0.031). Some grade 3 and 4 toxic effects were significantly more frequent in the irinotecan group than in the no-irinotecan group, but effects were predictible, reversible, non-cumulative, and manageable. INTERPRETATION: Irinotecan combined with fluorouracil and calcium folinate was well-tolerated and increased response rate, time to progression, and survival, with a later deterioration in quality of life. This combination should be considered as a reference first-line treatment for metastatic colorectal cancer.

Adenocarcinoma↗
PubMed2000

The association between specific nutritional antioxidants and manifestation of colorectal cancer.

Determination of specific antioxidants for examination of oxidative balance and immune responses may be of value in the early diagnosis of colorectal cancer. In the present report, we investigated urinary excretion of zinc, copper, and neopterin and serum levels of vitamins A, C, and E in 30 patients (age = 64 +/- 12 y) with colorectal cancer at the time of diagnosis and in 30 control subjects (age = 61 +/- 11 y) with benign disorders not associated with a systemic inflammatory response. Urinary excretion of zinc, copper, and neopterin was significantly elevated, and serum concentration of vitamin A was decreased in patients with colorectal cancer; these changes are characteristics of systemic immune activation. These phenomena may be of use for the detection of tumor progression and immune response to neoplasm.

Adult↗
PubMed1999

Analyzing mixtures of amino acids and carbohydrates using bi-modal integrated amperometric detection.

Described in this work is a new detection methodology - bi-modal integrated amperometric detection - for identifying peaks and as a tool for solving difficult separation problems. Bi-modal integrated amperometry makes it possible to selectively detect amino acids, amino sugars, and carbohydrates following their separation by anion-exchange. Selectivity is gained by two different methods of integrating anodic current on an otherwise identical waveform. As with the single-mode integrated amperometry reported previously, the limits of detection are in the femtomole range and linear calibration plots are possible over three orders of magnitude. This new detection method does not require analyte derivatization. The practical utility of this new technique is demonstrated in the analysis of amino acids and sugars in a recombinant mammalian cell culture medium.

Amino Acids↗
PubMed1994

Urinary zinc excretion and acute phase response in cancer patients.

We investigated urinary zinc and serum levels of C-reactive protein, alpha-1 acid glycoprotein, haptoglobin, transferrin and prealbumin in 55 patients with solid tumors and 20 controls. Urinary zinc, serum C-reactive protein, alpha-1 acid glycoprotein and haptoglobin were significantly higher, and serum prealbumin was significantly lower in cancer patients. A significant positive correlation between urinary zinc and C-reactive protein, alpha-1 acid glycoprotein and haptoglobin, as well as a negative correlation with transferrin and prealbumin were observed. Hyperzincuria in cancer patients appears to be linked to the acute phase response. Our data provide further evidence implicating systemic inflammatory response in increased urinary zinc excretion.

Acute-Phase Reaction↗
PubMed1992

New approach to the analysis of low levels of anions in water.

Optimized electromigrative sample introduction improves detection limits for anions in capillary electrophoresis. Reproducible results are achieved for micromolar and nanomolar levels of concentration. The new method offers shorter runtimes, improved resolution and greater simplicity in comparison with ion chromatography. The technique was applied to water samples from the power industry. Trace levels of anions are monitored routinely in water for steam generation in conventional and nuclear power plants. Reproducible and accurate results are presented for pure water samples containing typical concentrations of anions as well as for more specific types of samples, such as water compositions in the primary and secondary circuits of a nuclear power plant.

Anions↗
PubMed1987

Effect of pretreating samples with boric acid before liquid-chromatographic determination of urinary catecholamines.

Isolation of catecholamines on prepacked gravity-fed ion-exchange columns in conjunction with liquid-chromatographic separation is occasionally subject to disturbances of unknown origin, especially after injection of H3BO3 eluates from the ion-exchange columns onto the chromatography column. Peak spreading, sometimes even peak splitting, has been observed in many laboratories--effects easily confused with those sometimes caused by voided columns or by impurities. To elucidate the origins of these interferences, we performed a combined voltammetric and chromatographic investigation. We show that complexation of the catechol group by borate ions and dissociation of those pH-labile complexes in the course of the chromatographic separation is the cause of those peak distortions. Addition of a small volume of diluted HCI to the borate eluates eliminates such interference and leads to reproducible, easily interpretable chromatographic separations.

Boric Acids↗
PubMedDate not supplied

Mitogen-induced lymphocyte proliferation and systemic immune activation in cancer patients.

AIMS AND BACKGROUND: Proliferative response of lymphocytes to mitogens is known to be decreased in cancer patients. Depressed proliferation of lymphocytes in other disorders has been linked to systemic inflammatory response. METHODS: Lymphocyte proliferation in response to phytohemagglutinin (PHA) and concanavalin A, as well as urinary neopterin, plasma interferon-gamma and interleukin-4, were investigated in 41 patients with solid tumors. RESULTS: The proliferative response to PHA was significantly depressed in cancer patients at most of the concentrations examined. Urinary neopterin and plasma interferon-gamma were significantly elevated in cancer patients, whereas interleukin-4 was undetectable in all the subjects. A negative correlation was observed between urine neopterin and lymphocyte proliferative response to mitogens. CONCLUSIONS: Lymphocyte proliferative response to PHA is significantly diminished in cancer patients, and this depression appears to be partly linked to systemic inflammatory response. Plasma interferon-gamma was significantly increased in cancer patients, whereas interleukin-4 was undetectable.

Adult↗