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Biomedical subjects

J Polster

Publications and source records attributed to J Polster.

At least 19 recordsLinked to original sources
PubMed2005

Flavanols in somatic cell division and male meiosis of tea (Camellia sinensis) anthers.

Young anthers excised from closed tea flower buds ( Camellia sinensis L.) were stained as fresh tissues with p-dimethylaminocinnamaldehyde reagent to localize flavanols associated with nuclei and chromosomes, apart from those flavanols stored in vacuoles. This staining reagent yields a blue colour for flavanols. In the nonsporogenic somatic cells of developing anthers, flavanols were found to be attached to chromosomes at all mitotic stages. Male meiosis started at a bud size of about 3.5 mm in diameter in pollen mother cells which displayed generally more or less pronounced blue nuclei and cytoplasm. The meiotic divisions from prophase I to telophase II were characterized by blue stained nuclei and chromosomes, but within the cytoplasm there was, if any, a random and very poor reaction for flavanols. Metaphase and telophase of meiotic divisions showed maximally condensed chromosomes staining dark blue. Early in telophase II, the cytoplasm was again stained blue; this faded at late tetrad stage. Flavanols of young mitotic and older non-mitotic anthers were determined using high pressure liquid chromatography--chemical reaction detection (HPLC-CRD). Catechin, epicatechin, B2, and epigallocatechin were minor compounds, whereas epicatechin gallate and epigallocatechin gallate were found in higher amounts. The major flavanol compound of the anthers, epicatechin gallate, exhibited a significant affinity to histone sulphate, as shown by UV-VIS spectroscopic titration.

Camellia sinensis↗
PubMed2004

Nuclei of tea flowers as targets for flavanols.

The tea plant (Camellia sinensis L.) is famous for its flavanol-based constituents being valuable for human health. These flavanols associate with the nuclei of tea flowers, which is demonstrated histochemically by blue colouration using the selective staining reagent p-dimethylaminocinnamaldehyde (DMACA). Sepals, petals, stamens, pollen tubes, ovaries and ovules were studied. All these organs were shown to contain flavanols in vacuolar compartments, in nuclei and, exceptionally, also in the cytoplasm of pollen tubes. In all cells, even in those lacking vacuoles, the nuclei stained blue for flavanols. The extremely divergent development, shape and function of the diverse flower organs did not basically influence the nuclear flavanol association. Nevertheless, within the limits of this study, a few tissue-dependent differences in staining intensity were obvious. Interactions between epicatechin and nuclear histone proteins (histone sulphate) were studied by UV-VIS spectroscopic titration and by means of Mauser diagrams. The results show that the observed association equilibria are strongly dependent on pH (8.0 and 7.4) and on the buffer used (Tris, phosphate).

Cell Nucleus↗
PubMed2003

Flavanol binding of nuclei from tree species.

Light microscopy was used to examine the nuclei of five tree species with respect to the presence of flavanols. Flavanols develop a blue colouration in the presence of a special p-dimethylaminocinnamaldehyde (DMACA) reagent that enables those nuclei loaded with flavanols to be recognized. Staining of the nuclei was most pronounced in both Tsuga canadensis and Taxus baccata, variable in Metasequoia glyptostroboides, faint in Coffea arabica and minimal in Prunus avium. HPLC analysis showed that the five species contained substantial amounts of different flavanols such as catechin, epicatechin and proanthocyanidins. Quantitatively, total flavanols were quite different among the species. The nuclei themselves, as studied in Tsuga seed wings, were found to contain mainly catechin, much lower amounts of epicatechin and traces of proanthocyanidins. Blue-coloured nuclei located centrally in small cells were often found to maximally occupy up to 90% of a cell's radius, and the surrounding small rim of cytoplasm was visibly free of flavanols. A survey of 34 gymnosperm and angiosperm species indicated that the first group has much higher nuclear binding capacities for flavanols than the second group.

Binding Sites↗
PubMed1999

Evaluation of data produced by optode arrays under flow injection analysis (FIA) conditions using a partial least squares method (PLS2).

Transient diffuse reflectance spectra in the visible wavelength region from an enzyme optode were evaluated to determine artificial mixtures consisting of penicillin and ampicillin simultaneously. In order to achieve a discrimination of the samples the optode operated at two different working pH values. Using an appropriate FIA modus a linear range in the increase and decrease of the time-dependent signal was registered which could be easily fitted by means of ordinary linear regression. In this way characteristic static and dynamic features of the enzyme catalyzed reaction could be extracted for the evaluation by partial least-squares (PLS). The pre-processed raw data were differently weighted and the optimal number of primary factors was each selected by full cross validation. The interpretation of the spectral loadings and the correlation matrix identifies redundant variables resulting in a model with an optimal number of variables. The results obtained with this model show that the straightforward linear regression can be a sufficient approach to avoid the introduction of systematic errors in on-line pre-processing of data.

Ampicillin↗
PubMed1999

Primary biomechanical influence of different sterilization methods on a freeze-dried bone-ligament transplant.

The transmission of bacteria and viruses in ligament transplants should be prevented by sterilization. In this study, the influence of two different methods on the mechanical properties of a freeze-dried medial collateral ligament was analyzed in sheep. Group I (n = 10) was treated with irradiation (26 kGy) and group II (n = 10) with ethyleneoxide. The mechanical properties changed in respect of the maximal load: group I (-29.9%; P < 0.05), group II (-7.7%), elongation: group I (-6.6%), group II (-0.3%), stress: group I (-20.1%), group II (-6.8%), strain: group I (-0.64%), group II (-0.3%), stiffness: group I (-10.2%), group II (-10.5%), energy: group I (-31.4%), group II (-6.9%) and elastic modulus: group I (-1.3%), group II (-5.0%). The irradiation dose significantly reduced the maximal load, whereas ethyleneoxide sterilization resulted only in minor changes. Because of the potential cancerogenity of ethyleneoxide, a close monitoring of aeration times and its residuals are very essential. Further studies with lower irradiation doses of between 15 and 26 kGy seem to be justified.

Animals↗
PubMed1998

High incidence of pathogenic microorganisms in bone allografts explanted in the morgue.

We analyzed the influence of the environment on bacterial contamination in 431 bone allografts from 97 donors (68 multiorgan, grafts taken in the operation theater; 29 morgue donors). From each bone transplant we cultured two aerobic and two anaerobic tissue specimens. The overall contamination rate was 49% (theater 51%, morgue 40%). In grafts explanted in the morgue, we noted more pathogenic microorganisms (60%) than in multiorgan donors, explanted under aseptic surgical conditions (33%). We conclude that the harvesting environment constitutes the major source of pathogenic microorganisms.

Bacteria, Aerobic↗
PubMed1997

Application of fuzzy logic in multicomponent analysis by optodes.

Fuzzy logic can be a useful tool for the determination of substrate concentrations applying optode arrays in combination with flow injection analysis, UV-VIS spectroscopy and kinetics. The transient diffuse reflectance spectra in the visible wavelength region from four optodes were evaluated to carry out the simultaneous determination of artificial mixtures of ampicillin and penicillin. The discrimination of the samples was achieved by changing the composition of the receptor gel and working pH. Different algorithms of pre-processing were applied on the data to reduce the spectral information to a few analytic-specific variables. These variables were used to develop the fuzzy model. After calibration the model was validated by an independent test data set.

Ampicillin↗
PubMed1995

Long term results of uncemented Judet hip endoprostheses.

We reviewed 94 patients in whom 113 Judet uncemented total hip endoprostheses had been inserted; 83 had a mean follow up of 10.8 years (range 6 to 13 years). The Merle dAubigne and Harris hip scores were used for clinical evaluation. In the long term follow up, severe or moderate pain was present in 38.6% of hips. Radiographs were studied and radiolucent lines, and other evidence of loosening, were recorded. Twenty hips (24.1%) showed radiological signs of loosening of the acetabular cup and a displacement of more than 5 mm in 37.3%. The loosening rate of femoral stems was 32.5%, but only 8.4% showed subsidence. The cumulative survival rate at 6 years was 84.1%, decreasing to 55.1% after the eleventh year. Complications and other aspects of the outcome are discussed. Our results were on the whole not satisfactory and we cannot recommend this type of uncemented endoprosthesis for routine total hip replacement.

Adult↗
PubMed1993

Software FIACRE: bioprocess monitoring on the basis of flow injection analysis using simultaneously a urea optode and a glucose luminescence sensor.

Various computer programs for large-scale bioprocess control and optimization have been developed as well as software for simple laboratory routine analysis. In comparison, software can hardly be found that works on laboratory scale and provides the control of complex flow injection analysis (FIA) systems, multisubstrate determination, data evaluation as well as minimal process control abilities. The sensors applied can be of different type (luminometric or other optical as well as electrochemical biosensors). The development of such a software may be very helpful for the transfer of FIA/biosensor systems from the state of development to industrial processes. Hence, each analysing system--even a well established biosensor--has to be individually adapted to the process, a task which is best done under laboratory conditions. Such a flexible, computer-controlled FIA system for research level based on the software FIACRE is presented. Five FIA/(bio)sensor system can be controlled simultaneously. Additionally, common temperature and pH recordings are possible. Determinations of substrate concentrations are performed by means of calibration curves which can be recorded at different times. This allows supervising the activities of the sensors during a cell cultivation and controlling the bioprocess, e.g. by adding substrate to a cell culture. The automated monitoring of the degradation of glucose and urea by two different optical sensing principles during a cell cultivation under the control of one microcomputer is presented for the first time. For this purpose, already well examined biosensors (a urease optode and a luminometric glucose sensor) were employed and their properties discussed under the aspect of working in real cultivation media. It will also be shown that substrates being of interest for bioprocess control can be detected by slight modifications of known reactions. For example, substrates of NADH-dependent enzymatic reactions can be detected by the luminol chemiluminescence system, and optodes can be employed for pH, penicillin and glucose determination.

Alcohol Dehydrogenase↗
PubMed1993

[HIV-screening in bone transplantation].

Tissue transplantation obviously always involves the risk of HIV transmission. Since 1980, the Orthopaedic University of Muenster has conducted careful anamnestic and laboratory screening in 62 donors. Epidemiological investigations show that 90.1% of HIV-positive people in Germany are between 20 and 50 years old. For 25 donors (40%) the results of the HIV antigen test performed in the recipients of the other organs guaranteed HIV negativity. A further 17 donors (28%) were outside the epidemiologic risk group aged between 20 and 50 years. Tissue from all 20 other donors (32%) was subjected to a secondary sterilization method, e.g. fumigation with ethylene oxide or irradiation with 25 kGy.

AIDS Serodiagnosis↗
PubMed1992

Inflammatory reactions in primary osteoarthritis of the hip and total hip prosthesis loosening.

In 14 patients [9 with loosened total hip arthroplasty (THA), 5 with primary osteoarthritis], the inflammatory cell infiltrate was characterized in cryostat tissue sections using antibodies against subsets of macrophages and lymphocytes. In all patients the abundance of a mature type macrophage (25F9+) was observed, whereas 27E10+ macrophages, characteristic of acute inflammatory reactions, were not seen in primary osteoarthritis but were found in 4 out of 9 patients with THA loosening. The RM3/1 + macrophage phenotype was seen in some of both sets of patients (osteoarthritis 4/5; THA loosening 4/9). The markers MRP8 and MRP14 typical of immature macrophages, were found in all patients with osteoarthritis and in some (4/9 and 8/9 respectively) of those with THA loosening. IOT4+ T-helper cells were only present in 1/5 5 patients with osteoarthritis and in 2/9 patients with THA loosening. IOT8+ T-suppressor lymphocytes were more frequently present (in 4/5 and 5/9 respectively). The data reveal remarkable differences between the two groups of patients. While the inflammatory infiltrate in patients with osteoarthritis lacks the characteristics of acute inflammation, in patients THA loosening the inflammatory process seems to be determined by periods of acute reactions. The occasional presence particularly of T-helper cells suggests that the inflammatory process is less T-cell but rather macrophage-driven.

CD4-CD8 Ratio↗
PubMed1990

[Biomechanics of the hip joint].

The load of the hip joint is related to the density of bone, thickness of cartilage and pattern of the cancellous bone. The X-rays of the hip joint must provide all information for the calculation of the individual strain and stress.

Biomechanical Phenomena↗
PubMed1987

Hemodynamic and neurohumoral response to hydralazine versus captopril: a controlled study in idiopathic dilated cardiomyopathy.

To study the hemodynamic and neurohumoral effects of hydralazine versus captopril after the first dose, 15 patients with idiopathic dilated cardiomyopathy (NYHA Class II and III) were included in a crossover trial with a washout period of three days. Hemodynamic parameters were measured by using a Swan-Ganz thermodilution catheter, and venous blood was sampled during supine rest and standardized upright exercise before (control) and 60 min after drug administration. Compared to the control phase, hydralazine induced an increase in heart rate and cardiac index (p less than 0.01), and a decrease in mean arterial pressure and pulmonary wedge pressure (p less than 0.01, p less than 0.05, respectively). The hemodynamic effects were associated with increased norepinephrine plasma concentration during upright exercise (p less than 0.05) and increased plasma renin activity (p less than 0.01). After administration of captopril, heart rate at rest (p less than 0.05), mean arterial pressure, and pulmonary wedge pressure decreased significantly (p less than 0.01). Cardiac index remained unchanged. Norepinephrine plasma concentrations were not significantly influenced despite a tendency to lower levels during upright exercise. Plasma renin activity increased (p less than 0.01) and aldosterone at rest decreased significantly (p less than 0.05). These differences in neurohumoral response between both drugs may be important for their long-term effects.

Adult↗
PubMed1983

[Value of echocardiography in the preoperative diagnosis of acute bacterial endocarditis].

Open-heart surgery was performed in 26 of 56 patients with acute bacterial endocarditis seen in three years. Non-controllable infection, cardiac failure or embolism were the indications for operation. In all instances pre-operative invasive angiographic diagnosis was dispensed with, indications being based entirely upon clinical findings plus the results of M-mode or cross-sectional echocardiography. In 22 of the 26 patients the pre-operative echocardiographic diagnosis coincided with the intra-operative one. In the other four patients the pre-operative echocardiographic findings were incomplete, but no surgically important information had been missed.

Adult↗
PubMed1983

An investigation into the frequency of mitral valve prolapse in von Willebrand disease.

The reported extremely high incidence of mitral valve prolapse in von Willebrand patients (60%) in combination with multiple signs of mesenchymal dysplasia points to a hitherto unknown pleiotropic effect of the von Willebrand gene and needs further confirmation. Therefore, we looked for the presence of mitral valve prolapse in 19 patients with classical von Willebrand disease. While 58% of these patients had one or more physical findings which could be interpreted as symptoms of mesenchymal dysplasia, we found only one patient with a mitral valve prolapse (5.3%), comparable to the 6% incidence in the normal population. Therefore, we must conclude that there is no association between mitral valve prolapse and von Willebrand disease.

Adolescent↗
PubMed1983

Detection of ostium secundum atrial septal defects by transoesophageal cross-sectional echocardiography.

Transoesophageal cross-sectional echocardiography has special advantages when investigating the interatrial septum which is imaged perpendicularly without echo dropouts from an oesophageal transducer position. The technique was successfully used in 19 out of 20 patients (95%) with an ostium secundum atrial septal defect and in 30 control subjects. In all of the latter the interatrial septum was visualised as a continuous echo structure separating the atria, whereas a distinct discontinuity representing the septal defect was apparent in all patients with atrial septal defect. Echocardiographic measurement of the defect size correlated well with surgical findings in 11 patients who underwent open heart surgery in the course of this study. In a comparative transthoracic examination, adequate recordings were obtained in 18 of the 20 patients and in 26 of the 30 control subjects. Direct subcostal visualisation of the defect was reliable in 10 of 18 patients. Peripheral venous contrast studies were also performed with the transoesophageal as well as the transthoracic technique. Echo contrast remained confined to the right heart in the control subjects. Left sided contrast appearance diagnostic of an interatrial communication was shown in the patients using the transoesophageal technique (100% sensitivity), with an additional right atrial negative contrast apparent in seven patients. The transthoracic approach, on the other hand, showed left sided echo contrast in 14 of 18 patients and an additional negative contrast effect in two of the 14. It is concluded that transoesophageal is superior to transthoracic cross-sectional echocardiography as a highly sensitive method for the detection and evaluation of ostium secundum atrial septal defects.

Adolescent↗