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Biomedical subjects

B Günther

Publications and source records attributed to B Günther.

At least 19 recordsLinked to original sources
PubMed2005

Influence of hospital volume on local recurrence and survival in a population sample of rectal cancer patients.

AIMS: To investigate the role of hospital volume and individual hospitals on long term outcomes (local recurrence and survival) of rectal cancer patients. METHODS: One thousand thirty-eight patients with rectal cancer were diagnosed between 1996 and 1998. From these, we analysed 884 patients with a resected invasive primary rectal cancer. Median follow-up was 5.7 years. The impact of hospital volume (<10, 10-30 and >30 rectal cancer patients annually) on local recurrence and survival was examined in a Cox model. Differences between the four largest clinics in the high volume group were also investigated. RESULTS: In the multivariate model predicting survival the following variables were significant: UICC stage, grade, age, local recurrence, and (neo-) adjuvant therapy treatment. In the multivariate model predicting local recurrence UICC stage, tumour localisation, and neoadjuvant therapy treatment were significant variables. Hospital volume was not a significant factor for survival or local recurrence. Within the high volume category one hospital showed significantly worse local recurrence rates than all other hospitals, but no survival difference could be seen between the four largest hospitals of the high volume group. CONCLUSIONS: This analysis of a rectal cancer population found that hospital volume did not determine survival or local recurrence. Detailed clinical data with long term follow-up from cancer registries are vital to demonstrate the quality of routine care.

Aged↗
PubMed2005

[Substances for staining biological tissues: use of dyes in ophthalmology].

The azo dye trypan blue and the cyanine dye indocyanine green have been used in ophthalmology since the 1980 s to dye the anterior capsule in cataract operations and to stain epiretinal membranes in order to remove the membrana limitans interna (ILM). By means of a standardized in vitro test in accordance with DIN EN ISO 10993, it has now been shown that both dyes and the theoretically possible alternatives - the anthrachinone alizarincyanine green and the trityl dyes fast green and lissamine green - are cytotoxic in the normal concentrations of maximum 1.5 g/l. On the other hand, the new product Blueron(R) with the trityl dye patent blue, which has been developed to dye the anterior capsule, is completely biocompatible, even at a high dosage of up to 2.8 g/l.

Anthraquinones↗
PubMed2001

Carbon nanotube bags: catalytic formation, physical properties, two-dimensional alignment and geometric structuring of densely filled carbon tubes.

The catalytic CVD synthesis, using propyne as carbon precursor and Fe(NO3)3 as catalyst precursor inside porous alumina, gives carbon nanotube (CNT) bags in a well-arranged two-dimensional order. The tubes have the morphology of bags or fibers, since they are completely filled with smaller helicoidal CNTs. This morphology has so far not been reported for CNTs. Owing to the dense filling of the outer mother CNTs with small helicoidal CNTs, the resulting CNT fibers appear to be stiff and show no sign of inflation, as sometimes observed with hollow CNTs. The fiber morphology was observed by raster electron microscopy (REM), transmission electron microscopy (TEM), and atomic force microscopy (AFM). The carbon material is graphitic as deduced from spectroscopic studies (X-ray diffraction, Raman and electron energy-loss spectroscopy (EELS)). From Mössbauer studies, the presence of two different oxidation states (Fe0 and FeIII) of the catalyst is proven. Geometric structuring of the template by two different methods has been studied. Inkjet catalyst printing shows that the tubes can be arranged in defined areas by a simple and easily applied technique. Laser-structuring creates grooves of nanotube fibers embedded in the alumina host. This allows the formation of defined architectures in the microm range. Results on hydrogen absorption and field emission properties of the CNT fibers are reported.

Journal Article↗
PubMed2001

Negative regulation of Ros receptor tyrosine kinase signaling. An epithelial function of the SH2 domain protein tyrosine phosphatase SHP-1.

Male "viable motheaten" (me(v)) mice, with a naturally occurring mutation in the gene of the SH2 domain protein tyrosine phosphatase SHP-1, are sterile. Known defects in sperm maturation in these mice correlate with an impaired differentiation of the epididymis, which has similarities to the phenotype of mice with a targeted inactivation of the Ros receptor tyrosine kinase. Ros and SHP-1 are coexpressed in epididymal epithelium, and elevated phosphorylation of Ros in the epididymis of me(v) mice suggests that Ros signaling is under control of SHP-1 in vivo. Phosphorylated Ros strongly and directly associates with SHP-1 in yeast two-hybrid, glutathione S-transferase pull-down, and coimmunoprecipitation experiments. Strong binding of SHP-1 to Ros is selective compared to six other receptor tyrosine kinases. The interaction is mediated by the SHP-1 NH(2)-terminal SH2 domain and Ros phosphotyrosine 2267. Overexpression of SHP-1 results in Ros dephosphorylation and effectively downregulates Ros-dependent proliferation and transformation. We propose that SHP-1 is an important downstream regulator of Ros signaling.

3T3 Cells↗
PubMed2001

Sensorineural hearing loss and the incidence of Cx26 mutations in Austria.

A clinical evaluation and Cx26 mutation analysis was performed in 92 consecutive patients with sensorineural hearing loss in order to delineate the spectrum of genetically caused hearing loss. Among patients of Austrian origin, 53% were classified with hereditary hearing loss. Cx26 mutations were found in 26% of NSHL patients (40% of familial vs 18% of sporadic cases). The mutation 35delG accounted for 52.8% of all presumed GJB2 disease alleles. The second most frequent mutation was L90P (16.7%) having been reported with a prevalence of 0.7-3.5% in other populations. Three novel mutations were found. The novel mutation, R143Q, was associated with dominant high-frequency hearing loss. Pseudodominant transmission of NSHL was seen in four families with Cx26 mutations. A mutation 35delG carrier rate of 0.9% was observed among 672 controls from West-Austria. Cx26 mutations were found associated with mild to profound, and with asymmetric hearing impairment.

Austria↗
PubMed2001

"Electro-fishing" in the lab: a new method to detect acute effects of heavy metals and organic pollutants in invertebrate indicator organisms.

Acute toxicity of heavy metals and organic pollutants was examined using Rhabditis oxycerca (Nematoda) and Paramecium spec. (Protozoa, Ciliata) as indicator organisms. The substances tested were based on the composition found in the river Odra. They were used in graduated dilution series (1000-fold, 500-, 250-, 167-, 125-, 100-, and 83-fold of the Odra concentration). In a special apparatus with an electric field the animals were induced to migrate from the anode to the cathode. Their migration activity (distance) and the number of migrating animals were influenced by the substances tested. To assess the extent of damage, results were compared with controls (tap water) and reference substances (aldicarb and chloracetamide). The investigations showed that heavy metal concentrations > 100-fold of the Odra concentration led to behavioural changes of both test organisms. The organic pollutants, in contrast, did not cause detectable changes in ciliates and only led to slight reductions in the migration activity of nematodes, without concentration-dependent gradations.

Animals↗
PubMed2001

Time-frequency analysis of arterial pressure oscillations in anesthetized dogs: effects of standardized hemorrhages.

The purpose of this preliminary study was to investigate the advantages of the time-frequency analysis through the Continuous Wavelet Transform (CWT) compared to classical Fourier analysis using the Fast Fourier Transform (FFT) in arterial pressure signals from anesthetized mongrel dogs before and during standardized hemorrhages. Systemic arterial pressure pulsations were recorded using catheter-tip manometers. CWT and FFT were applied to arterial pressure pulsations to obtain module coefficients of this transformation and its associated contours during the evolution of progressive hemorrhages, in amounts of 15, 34, and 66% of the estimated total blood volume. This mathematical analysis enabled us to identify the evolution of the frequency components of aortic valve functions, heart dynamics, respiratory influences, and vasomotor activities. Furthermore, we isolated the modulating signal of amplitude modulation phenomenon present in the arterial pressure records, as described in previous papers, being the heart rate carrier frequency. The CWT is a very sensitive and reliable procedure to analyze (time-frequency) the oscillatory phenomena in two dimensions, and to provide more information than the FFT. This new analytical procedure may provide new insights in the study of shock pathophysiology.

Animals↗
PubMed2001

Circadian coupling between pancreatic secretion and intestinal motility in humans.

Human interdigestive intestinal motility follows a circadian rhythm with reduced nocturnal activity, but circadian pancreatic exocrine secretion is unknown. To determine whether circadian changes in interdigestive pancreatic secretion occur and are associated with motor events, pancreatic enzyme outputs, proximal jejunal motility, and plasma pancreatic polypeptide concentrations were measured during consecutive daytime and nighttime periods (12 h each) in seven healthy volunteers using orojejunal multilumen intubation. Studies were randomly started in the morning or evening. Nocturnally, motility decreased (motor quiescence: 67 +/- 22 vs. 146 +/- 37 min; motility index: 3.59 +/- 0.33 vs. 2.78 +/- 0.40 mmHg/min; both P < 0.05) but amylase output increased (273 +/- 78 vs. 384 +/- 100 U/min; P < 0.05) and protease output remained unchanged (P > 0.05); consequently, enzyme/motility ratio increased. Amylase outputs were always lowest during phase I. Motor but not pancreatic circadian activities were associated with sleep. Pancreatic polypeptide plasma concentrations were unchanged. Consequently, intestinal motor and pancreatic exocrine functions may have different circadian rhythms, i.e., decreased motor and stable secretory activity during the night. However, the association between individual phases of interdigestive motor and secretory activity is preserved. The nocturnal increase in enzyme/motility ratio is probably not caused by increased cholinergic tone.

Amylases↗
PubMed1999

Pressure oscillations in anesthetized dogs and its conversion into quasi-periodic orbits.

Using a basic representation of dynamic systems, arterial blood pressure pulsation is converted into quasi-periodic orbits with the purpose of transforming a periodic phenomena into a cyclical one by plotting the pressure p(t) versus its first derivative dp/dt. This elementary mathematical procedure made it possible to evaluate the variability of the systemic arterial pressure pulsations, both systolic and diastolic, as well as the slope variability of the anachrotic and catachrotic phases. Two periods, which can be used to estimate different sources of variability, can be distinguished in the catachrotic phase. One corresponds to the open aortic valves, and the other is associated with the closed valves. Furthermore, through the first derivative of pressure oscillations we were able to identify small changes in arterial pressure, which appeared when the sampling rate was at least 150 samples per second. Since the time variable was converted into a parameter, the result was a synoptic or holistic approach, which is a considerable improvement for the visual analysis of cardiovascular phenomena. This simplified mathematical procedure can be easily implemented on a personal computer in real time and applied to all rhythmic phenomena in Physiology and Pathology.

Anesthesia↗
PubMed1998

Comparison of different anticalcification treatments for stentless bioprostheses.

BACKGROUND: New anticalcificant treatments have been developed because tissue calcification is a major contributing factor for bioprosthetic valve failure. METHODS: Aortic valve leaflet and aortic root tissue samples from stentless bioprostheses treated with No-React (Biocor, Belo Horizonte, Brazil), AOA (Medtronic freestyle, Minneapolis, MN), and BiLinx (St. Jude Medical, St. Paul, MN) were compared to a control group by subcutaneous implantation in 60 male weanling Sprague-Dawley rats. RESULTS: Calcium levels were in the range of 0.3 to 2.2 mg/g dry tissue at 3 and 12 weeks in all three treated aortic valve leaflet implants. The BiLinx treatment proved anticalcificant effectiveness on aortic root samples as well. There were statistically significant differences for valve leaflet tissue samples: No-React = AOA < BiLinx < < Control and for aortic root tissue samples: BiLinx < < AOA < Control = No-React. CONCLUSION: Calcification of aortic valve leaflets was significantly reduced by all new anticalcificant treatments. Inhibition of cellular calcification (BiLinx) resulted in additional reduction of aortic root calcification. Maximum anticalcificant properties upon both leaflet and aortic root is important as these are considered a functional unit in stentless bioprostheses.

Aluminum↗
PubMed1997

Continuous wavelet transform of aortic pressure oscillations in anesthetized dogs: effects of 45 degrees tilting.

The time-frequency analysis of signals by means of continuous wavelet transform (CWT) was applied to blood pressure oscillations recorded from the aorta of anesthetized dogs. This method yielded two and three-dimensional representations of either the module or phase in function of time, in contrast with the fast Fourier transform (FFT) which gives the spectrum in the frequency domain. From the CWT of arterial pressure oscillations we obtained visual information on aortic valves closure, heart rate, respiratory rate and smooth muscle contractions in arterial and arteriolar walls (very low frequency component). The objective of this study was to analyze the frequency-time behavior in two and three-dimensional cardiovascular changes during 45 degrees head-up and head-down tilts, compared with zero degree supine position. In eight pentobarbitone anesthetized dogs, the postural changes were repeated for more than ten times in each one. Heart rate variability was derived by applying a new mathematical procedure. We utilized the pronounced changes of heart rate during each respiratory cycle (inspiratory tachycardia and expiratory bradycardia) to establish a correlation with the arterial pressure fluctuations during normal and tilting conditions. Significant differences in heart rate were observed between the 45 degrees head-up and head-down tilts, compared with the supine position. The results show that anesthetized dogs might constitute an appropriate model where to study orthostatic hypotension and microgravity blood shifts.

Anesthesia↗
PubMed1997

Allometry of ECG waves in mammals.

The present allometric study deals with the duration of three electrocardiographic intervals (PQ, QRS, QT) and their relationships with the corresponding cardiac cycle length (R-R interval) in mammals across a wide body mass range. The numerical values of the different ECG intervals were obtained from Grauwiler's (1965) monograph on the subject. Because the corresponding body masses were not given by this author, Heusner's (1991) data on basal metabolic rate as function of body mass were used to establish the most likely body mass figure for each case, based on the taxonomic identity between the corresponding specimens. On the other hand, in a recent study we established the "duality" of physiological times (Günther & Morgado, 1996) and, therefore, we adopted this novel approach to investigate the ECG intervals and their relationships with the R-R interval (heart rate reciprocal). Considering that the anatomy and physiology of auricles and ventricles are different (spheroids versus quasi-cylinders), and that excitation (sino-atrial node and His-Purkinje's system) and contraction processes can be described either by Euclidean or fractal geometries, only a quantitative analysis of the different ECG waves could resolve the dilemma. From the present preliminary study we can conclude that fractal geometry is prevalent with regard to ECG intervals.

Animals↗
PubMed1996

Detection and measurement of Staphylococcus epidermidis slime using an ELISA technique.

A polyclonal rabbit anti-serum against the strong slime-producing Staphylococcus epidermidis strain RP62A was absorbed with the slime-negative phase variant of this strain PV1 in order to remove not slime-specific antibodies. Using this antiserum we established an ELISA which enables detection of slime production in S. epidermidis extracts. The ELISA showed high absorbance when extracts from slime-positive strains (confirmed in the tissue culture tube test) were used as antigens. The high absorbance of slime-positive strains was greatly reduced by periodate oxidation of the extracts and was resistant to proteinase digestion suggesting that the detected antigen is composed of polysaccharides. In contrast to other rapid and simple laboratory detection methods for S. epidermidis slime, the slime-specific ELISA gave positive results in the presence of human serum.

Animals↗
PubMed1996

[Surface law and allometric analysis of functions].

Since Rubner established in 1883 the "surface law", the basal metabolic rate (kcal/24 h) is expressed per square meter of body surface. This so-called biological law has been extrapolated to the standardization of several other functions as, for instance, to variables of the cardiovascular, respiratory and renal systems, which may lead to erroneous conclusions. The present paper is an attempt to establish, by means of the dimensional analysis and one of the theories of biological similarity, an allometric indexation procedure, which yields mass-independent numbers (MIN) for all functions which can be defined by means of the MLT-system of physics (M = mass; L = length; and T = time).

Animals↗
PubMed1996

Allometric algorithms.

The aim of the present study is to emphasize the applicability and versatility of the allometric equation in the biological sciences. This equation (Y = a x Mb) was introduced by Huxley (1932) for intra- and interspecific comparisons of morphological, physiological and ecological variables (Y), when they are expressed as functions of body mass (M). The regression analysis of the experimental data, plotted in a double logarithmic scale, yields a straight line, which is equivalent to the logarithmic form of the above mentioned allometric equation [log Y = log(a) + (b) x log(M)]. Only the exponent (b) can be calculated a priori for a given function, based firstly on the corresponding dimensional analysis in accordance with the MLT-system of physics, and secondly on one of the theories of biological similarity, while parameter (a) is of empirical nature. A relevant feature of the allometric equations is that they can be treated algebraically to obtain allometric ratios, mass independent numbers (MIN), and even dimensionless numbers (M0L0T0), which are valid for all organisms pertaining to the same taxonomic classification.

Algorithms↗
PubMed1996

In memoriam Professor Jaime Talesnik, MD.

In memoriam Jaime Talesnik. Born in Santiago, Chile, 18 May 1915; deceased Toronto, Canada, 7 April 1996. Medical studies at University of Chile, 1935-1940. MD, University of Chile, 1941. Assistant Professor of Physiology, Faculty of Biology and Medicine, University of Chile, 1940-45. Rockefeller Research Fellow, Banting-Best Institute, Department of Medical Research, University of Toronto, Canada, 1945-46. Associate Professor of Physiology, Faculty of Medicine, University of Chile, 1947-51. British Council Research Scholar in Pharmacology, National Institute for Medical Research, London, England, 1951-52. Associate Professor of Pathophysiology, Faculty of Medicine, University of Chile, 1952-63. Professor and Chairman, Department of Experimental Medicine, Faculty of Medicine, University of Chile, 1963-67. Visiting Professor, Department of Pharmacology, University of Toronto, Canada, 1967-69. Professor, Department of Pharmacology, University of Toronto, Canada, 1969-81. Professor Emeritus, University of Toronto, Canada, 1981. Member Emeritus, Medical Association of Chile, 1991. Honorary Member, Chilean Society of Physiological Sciences, 1995. Author of textbook of pathophysiology and many articles in scientific journals.

Canada↗
PubMed1996

Duality in physiological time: Euclidean and fractal.

The aim of the present study was to differentiate two modalities of intrinsic time scales: i- the geometric or Euclidean modality, which is based on the constant speed of mass transport or of wave transmission in cylindrical structures (arteries, veins, nerves), whose allometric exponent (TE = aMb) is b = 0.33, where M is body mass (kg) and a the mass coefficient; ii- the fractal time scale (TF), which is characteristic of organs with self-similar branching structures and with volume-specific flows, whose allometric exponent is b = 0.25. The proposed dichotomy could be confirmed by means of the statistical analysis of empirical allometric exponents (b). Our findings demonstrate the need to separate the chronology of bulk transport at long distances (inter-organic) which follows an Euclidean geometry (cylinders), from the fractal time scale, which operates at short distances (intra-organic) and is represented by a self-similar branching system which determines both the morphometric and physiometric characteristics within each organ.

Axons↗