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Biomedical subjects

J Ruzicka

Publications and source records attributed to J Ruzicka.

At least 37 records · Page 2Linked to original sources
PubMed1995

Flow injection fluorescence microscopy applied to a rapid cell surface immunoassay.

A perfusion system for fluorescence microscopy that utilized a flow injection system was developed and used to study cell surface antibody binding on viable cells grown in monolayer cultures on coverslips. A polyclonal cell-specific antiserum used to probe the cell surface was monitored by indirect immunofluorescence. The flow injection system was completely automatic and allowed controlled perfusion of cell surfaces with the desired sequence of antibodies. The individual steps of the indirect assay were studied to determine the binding behavior of the primary cell surface antibody, the labeled second antibody, and control of nonspecific binding. Under stopped flow conditions, the second antibody was maximally bound within 10 min, while constant mixing of the second antibody solution over the cells resulted in maximal binding within as little as 6 min. A primary antibody contact time of 2 min followed by a wash and then exposure to the second antibody for 2 min showed that this fast automated procedure could distinguish specific from nonspecific binding of cell surface antibodies to the same set of cells for several repeated exposures. The flow injection fluorescence microscopy system can be automated to allow screening for cell surface antibodies and to study their interaction with specific cell surface antigens.

Animals↗
PubMed1994

Fast kinetic measurements and on-line dilution by flow injection cytometry.

An improved flow injection cytometry (FIC) system suitable for fast cellular kinetic measurements and on-line dilution is described. The instrument allows for measurements from 1.2 s (+/- 0.05 s) after the initiation of mixing, up to any time thereafter. Crucial factors in determining fast kinetic measurements, such as the displacement volume for sample introduction, rate of transport to cytometric interrogation point, and the mixing speed are evaluated and discussed. By varying the volume aspirated, this instrument can facilitate the dilution of cells and/or reagent over a range of one order of magnitude. The fast kinetic and on-line dilution capabilities were demonstrated by on-line staining of DNA in trout erythrocytes with 4',6-diamidino-2-phenylindole (DAPI). The utility of the instrument for measurement of enzyme kinetics was illustrated using human lymphocytes, measuring the glutathione S-transferase (GST) catalyzed reaction between monochlorobimane (MCB) and glutathione (GSH).

Animals↗
PubMed1994

Flow injection renewable surface immunoassay: a new approach to immunoanalysis with fluorescence detection.

This paper introduces a new methodology of carrying out heterogeneous immunoassays automatically, using a flow injection technique on a renewable surface. Flow injection renewable surface immunoassay (FIRSI) relies on the use of a minute amount of beads to form a reactive surface, which is interrogated by fluorescence spectrometry. Following the assay, on-line regeneration normally used in flow based immunoassays is avoided by fluidically removing the spent reactive surface and replacing it with a new layer of beads. This allows the monitoring of antibody-antigen binding at its early stages, dramatically increases the sampling frequency of a serial assay, and eliminates the problems associated with a decrease in surface reactivity caused by repetitive use. A model system utilizing anti-mouse IgG1-coated beads and mouse IgG1 protein is used to characterize the method with respect to reproducibility, flow rate, contact time, and amount of beads.

Animals↗
PubMed1993

Jet ring cell: a tool for flow injection spectroscopy and microscopy on a renewable solid support.

A new flow cell design for spectroscopic measurements of suspensions, the jet ring cell, is introduced. This cell exploits radial flow through a narrow ring-shaped gap to retain suspended particles within the detection region. This ring constitutes a detection volume of well-defined area from which the trapped particles can be instantaneously removed at will. The bed of particles thus forms a renewable surface, which can be probed by reflectance, fluorescence, or chemiluminescence using a microscope or optical fiber. This device should prove useful for microscopic study of cells, for automated immunoassays, and for preconcentration of analytes on sorbents with in situ spectroscopic detection. In conjunction with a fiber optic detection system, the jet ring cell becomes a component of a renewable chemical sensor system.

Animals↗
PubMed1993

Flow injection cytometry: a new approach for sample and solution handling in flow cytometry.

A prototype instrument for sample and solution handling in flow cytometry has been constructed. The system is modular and allows the control of any combination of up to 4 pumps, 2 selection valves, and 2 injection valves. These devices are controlled by a computer using TTL-logic. The flow injection instrument is interfaced to the flow cytometer via a 6-port injection valve, thereby facilitating virtually any flow pattern to be implemented without affecting the fluidics of the cytometer. Salient features of the instrument are accurate control of the volume of injected sample and reagent, reproducible timing, and controlled mixing conditions. Results from model experiments of on-line staining of trout erythrocytes with different concentrations of 4',6-diamidino-2-phenylindole (DAPI) and propidium iodide (PI) are shown. Possible ways to improve the performance and utility of the instrument are also discussed.

Animals↗
PubMed1993

Flow injection fluorescence microscopy: a novel tool for the study of cells through controlled perfusion.

Current methods of microscope stage perfusion do not take full advantage of existing technology for precise fluid control. The concept of flow injection, used extensively by analytical chemists, is described and its application to the fluorescence microscopic study of cultured cells is proposed. Using this technique, cells may be exposed to single or multiple reagent zones of almost any profile, sequence, and duration, with computer-controlled precision. A flow injection system is employed in conjunction with a novel perfusion chamber--the fountain cell. The ability of the flow injection system to perfuse cells with a reagent with a reproducibility of 1% RSD is demonstrated. The system was used to monitor changes in calcium levels in baby hamster kidney cells loaded with FURA-2 as a result of stimulation with a precisely timed concentration of ionomycin. The unique feature of the technique is that it allows a series of responses of a given cell to be directly compared to each other.

Animals↗
PubMed1993

Epidemiologic pathology of ovarian cancer from the Vaud Cancer Registry, Switzerland.

OBJECTIVE: To provide further information on the descriptive epidemiology and survival of ovarian cancer patients by specific histologic types. STUDY DESIGN: Descriptive epidemiological study. Cases of ovarian cancer registered between 1974 and 1988 in the Vaud Cancer Registry, Switzerland (based on a population of approximately 530,000 inhabitants), were analysed. RESULTS: A total of 649 cases were registered, corresponding to an overall age-standardized (world population) incidence of 9.6/100,000. The most common histotype was serous carcinoma (41%, incidence rate 4.0/100,000), followed by endometrioid (13%), mucinous (12%), clear cell (5%), and undifferentiated carcinomas (3%); 20% of the cases were classified as 'epithelial, unspecified', and 6% were non-epithelial cancers. There was a tendency for the incidence of all epithelial types to rise up to the seventh decade of age, and to level off thereafter. The increases between the ages of 45 and 65 were, however, mostly in serous carcinomas whose proportion of total ovarian epithelial cancer peaked in middle age. Overall, 5-year relative survival was 32%. Survival rate was 32% for serous carcinomas, but was significantly higher for endometrioid (51%) and, among nonepithelial neoplasms, for germ-cell cancers (68%). Survival rates were poor for undifferentiated and 'epithelial, unspecified' carcinomas (16%). Relative survival was systematically higher below age 60 than at age 60 or over. In the two subsequent calendar periods examined (divided according to the approximate time when the use of platinum-based chemotherapy began to spread, i.e., 1982), 5-year relative survival rates were 28% and 36%, respectively (chi 1(2) = 6.1, p = 0.02). CONCLUSION: The present report is a population-based description of the epidemiologic pathology and prognosis of ovarian cancer, and provides evidence of a significant improvement of survival over the past decade. This may be due to changed diagnostic methods (e.g., ultrasonography), improved surgical approach, (platinum-based) chemotherapy, or a combination of all these factors.

Adult↗
PubMed1993

An ovarian tumor of probable Wolffian origin.

The clinico-pathological features of one rare case of an ovarian tumor of probable Wolffian origin are reported. This tumor arises within the rete ovarii and is predominantly cystic on gross examination. Microscopically these cysts are lined by flattened epithelial cells and are separated by solid areas formed by large tubular glands. It is difficult to recognize this type of tumor on frozen section and to distinguish it from adenocarcinoma of the ovary. Surgery can be limited to total hysterectomy and bilateral salpingo-oophorectomy. No adjuvant therapy is necessary.

Adenocarcinoma↗
PubMed1992

Sequential injection immunoassay utilizing immunomagnetic beads.

A novel sequential injection immunoassay (SIIA) method is described which utilizes immunomagnetic beads to investigate short-time antibody binding. The method is versatile and flexible and may therefore be adapted to many different applications. Initial results for a competitive assay are also presented. The immunomagnetic bead reactor is created within the flowing stream by retaining immunomagnetic beads with an electromagnet to form an open tube reactor. Thus, the spent beads may be discharged after each analysis. This eliminates the problems of instability of reaction surfaces and eliminates the need for additional time traditionally required for regeneration of the solid-reacting phase in order to not only save time and increase sampling frequency but also to provide each individual sampling cycle with a fresh, uniform portion of beads. The spent beads are collected off line and may be regenerated later. Short-time binding kinetic studies demonstrate linear initial binding under 1 min, which then begins to reach saturation in approximately 10 min. Competitive binding assays of monoclonal mouse IgG (MRC OX-19) to polyclonal sheep anti-mouse IgG immobilized to the immunomagnetic beads show reproducible linear displacement in 30-120-s reactions. Fluorescence detection is utilized with a detection limit of 155 ng/mL, and since the reaction time is typically 2 min or shorter, the sampling frequency is 30 samples/h.

Animals↗
PubMed1991

Fundamentals of sinusoidal flow sequential injection spectrophotometry.

A rational design of the sequential injection analyzer is based on description of the mutual penetration of sample and reagent zones, which are sequentially stacked into a tubular conduit and then injected into a reactor and transported toward the detector by means of a carrier stream, flowing at a preprogrammed rate. Variables governing zone penetration have been identified by a series of dispersion experiments, for sequential injection of two and three zones, thus outlining the conditions for performing single- and double-reagent-based assays. A parallel is drawn between conventional flow injection and corresponding sequential injection colorimetric determinations of chloride and phosphate, with the aim of suggesting guidelines for the development of spectrophotometric- and fluorescence-based sequential injection methods.

Flow Injection Analysis↗
PubMed1991

Principles of stopped-flow sequential injection analysis and its application to the kinetic determination of traces of a proteolytic enzyme.

The concept of sequential injection analysis is described, and an application of this novel technique to an assay of traces of a proteolytic enzyme is demonstrated. The automated method is based on a stopped-flow procedure with fluorescence detection. Instead of using the conventional constant flow rate, a sinusoldal flow pattern, as generated by a robust cam-driven piston pump, has been applied. The validation of the novel flow injection system using a nonreactive fluorescent compound yielded highly reproducible results over a concentration range of 3 order of magnitude. The calibration graph for the enzyme activities in the range 5-75 micron mL-1 could be fitted a second-order polynomial. The detection limit is 2.5 micron mL-1, which corresponds to 7.2 ng mL-1 pure active enzyme.

Endopeptidases↗
PubMed1986

[Early diagnosis of premalignant and malignant lesions of the endometrium. Evaluation of a device for collecting intrauterine samples (the Inocurette) compared with exploratory curettage].

Screening methods for detecting more accurately carcinoma of the endometrium is becoming increasingly important because of the rising incidence of the condition. Inocurette has recently been invented to combine a scraping action with suction. This study investigates 385 patients who were admitted for diagnostic curettage or hysterectomy to which were added a series of 120 patients who were examined as out patients. Inocurette has a sensitivity of 86% and a specificity of 99%. It therefore can be considered as a reliable method of screening for the limits within which fractional diagnostic curettage should be used. Marked pain and great difficulty in introducing the apparatus made its use limited in respectively 15% and 14.5% of cases. So, the method is acceptable and useful within these limits. The results could be improved if on the one hand a thinner apparatus could be designed and on the other hand a substance could be found to soften the cervix so that it became easier to introduce the apparatus.

Adenocarcinoma↗
PubMed1984

[A case of Whipple disease with a pseudotumorous presentation: differential diagnosis with mesenteric panniculitis].

A case of Whipple's disease initially presenting as an inflammatory, granulomatous and pseudotumorous infiltration of the mesenterium is discussed. The initial diagnosis of mesenteric panniculitis was invalidated by the typical histological findings of Whipple's disease in a duodenal biopsy performed 18 months later for malabsorption syndrome. This case illustrates the difficulties besetting differential diagnosis of inflammatory and granulomatous lesions of the mesenterium.

Diagnosis, Differential↗