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Biomedical subjects

F Richter

Publications and source records attributed to F Richter.

At least 91 records · Page 5Linked to original sources
PubMed1988

Systemic availability of propionate and acetate in liver cirrhosis.

In 15 patients with cirrhosis of the liver and 10 control subjects, 7.5 mmol sodium propionate and 7.5 mmol sodium acetate were instilled endoscopically into the duodenum. Venous concentrations of propionate and acetate were measured for 90 min after administration of the enteral dose by gas-liquid chromatography. In patients with liver cirrhosis, propionate rose from a basal value of 6.1 +/- 4.7 (SD) microM to a peak concentration of 50.1 +/- 25.6 microM, whereas, in controls, it rose only from 1.4 +/- 1.6 to 10.3 +/- 7.6 microM. The oral propionate clearance was significantly lower in patients with cirrhosis (4.51 +/- 1.63 L/min) than in controls (118.47 +/- 154.79 L/min). Acetate went up from 39.5 +/- 16.3 to 134.1 +/- 62.7 microM in patients with cirrhosis and from 60.9 +/- 19.0 to 102.0 +/- 44.0 microM in controls. The oral acetate clearance was lower in patients with liver cirrhosis (2.80 +/- 2.17 L/min) than in control persons (10.86 +2- 5.72 L/min). The differences between the groups were more striking for propionate than for acetate values. It is concluded that the systemic availability of propionate and acetate is higher in patients with liver cirrhosis than in controls. This may be due to portosystemic shunting and/or diminished hepatic and extrahepatic extraction of the acids.

Acetates↗
PubMed1987

Input-output functions of cochlear microphonics in chronic experiments on awake rabbits.

Chronically implanted electrodes were used to record cochlear microphonics (CM) in awake rabbits. Test stimuli were sine waves of 1,250, 2,500, 5,000 and 10,000 Hz, with intensities increased from 40 to 100 dB SPL. By using this long-term method for registering the CM, we have found that the form of the input-output functions recorded is in agreement with that from acute experiments as described in the literature. Our method proved to be valid for recording CM with constant amplitudes over a period of 8-10 weeks. Our present results form a basis for further investigations concerning noise overload.

Animals↗
PubMed1987

Time lapse effects of impulse noise on cochlear microphonics in rabbits observed in chronic experiments.

Cochlear microphonics (CM) were recorded from awake rabbits with chronically implanted electrodes. Test frequencies used were 1,250, 2,500, 5,000 and 10,000 Hz, with intensities increased from 40 to 100 dB SPL. The rabbits were exposed to ten noise impulses of 144 dB SPL, which were then followed by impulse intensities of 153 and 164 dB SPL for the same animal. Input-output functions before and after each noise exposure were recorded, and recovery processes of the CM were tracked. After 144 dB SPL impulses, complete recovery of CM occurred; the effects of 153 dB SPL impulses varied from restitution up to complete CM loss. Impulses of 164 dB SPL caused an irreversible CM loss in all cases. Despite inter-individual differences, the threshold for irreversible CM loss in rabbits may occur between impulse noise intensities of 153 and 164 dB SPL.

Animals↗
PubMed1987

Glycogen phosphorylase isozyme pattern in rat liver and isolated non-parenchymal liver cells.

The isozyme distribution of glycogen phosphorylase (EC 2.4.1.1) was studied in adult rat liver and isolated non-parenchymal liver cells by means of immuno-titration. In adult rat liver, the L-type of glycogen phosphorylase was found to dominate, whereas the heterogeneous non-parenchymal liver cell population apparently contains all three glycogen phosphorylase isozymes.

Animals↗
PubMed1984

The influence of passive smoking on the cardiovascular system.

Cardiovascular effects of tobacco smoke have been studied in passive smokers far less extensively than in active smokers. Under real-life conditions, passive smokers inhale approximately 0.02 to 0.01 of the amount of particulate matter taken up by active smokers. Their nicotine concentration in serum is within a range that is barely distinguishable from the background level. The increase in carboxyhemoglobin rarely exceeds 1%. In healthy subjects heavily exposed to tobacco smoke, no or only slightly acute effects on the cardiovascular system are found. Whether or not passive smoking is likely to aggravate symptoms in patients with advanced coronary heart disease has not yet been unequivocally established and requires further investigation. From a few studies on occupational groups exposed to carbon monoxide (CO) and from experiments with animals chronically treated with CO or nicotine, the conclusion can be drawn that neither CO nor nicotine is likely to play a role in the development and progression of coronary heart disease in those concentrations normally found in passive smokers.

Animals↗
PubMed1984

[Analytic and diagnostic validity of the determination of carboxyhemoglobin in blood and carbon monoxide in the breath of smokers and non-smokers].

The analytic and diagnostic validity of the determination of carboxyhaemoglobin and carbon monoxide in smokers and non-smokers was investigated. Both methods are of high analytic and diagnostic validity. Precision and accuracy fullfil the essential requirements. Comparison of the methods shows good correlation (= 0.97) and linear regression (y = 51.5 X 10(-3)x + 6.26 X 10(-6] within the investigated range. Values for the conditional probabilities of sensitivity, specificity, predictive values, and efficiency are higher 0.80. Taking into account the standardized sample collection for the CO determination, the two methods are of comparable validity when used in clinical and epidemiological investigations on smokers and non-smokers.

Breath Tests↗
PubMed1983

Developmental changes of glycogen phosphorylase b isozymes in rat tissues.

The isozyme distribution of glycogen phosphorylase b was studied in various fetal, neonatal, and adult rat tissues by means of discontinuous polyacrylamide gel electrophoresis in the presence of glycogen in the separating gel. The brain-type isozyme BB being the predominant form in fetal rat tissues is replaced during maturation either partially (brain and kidney) or completely (skeletal muscle and liver) by the isozymes MM or LL, respectively. In the various organs, the developmental formation of the adult phosphorylase isozyme pattern does not proceed simultaneously. The definitive isozyme pattern is expressed in heart muscle at the 19th day of gestation. The isozyme transitions in liver and skeletal muscle are finished about two days after birth, while at this time in the brain just the muscle-type subunit M appears and forms the hybrid MB. The isozyme distribution of the maturated rat brain (BB, MB, MM) is not expressed before the 9th day of postnatal life.

Aging↗
PubMed1982

[Effect of normoxic and anoxic liver perfusion as well as ischemic liver storage on parameters of mitochondrial respiration and swelling].

Using the model of Hb-free perfused rat liver, the influence of normoxic or anoxic perfusion, as well as ischemic storage of the liver on parameters of respiration and on swelling has been studied comparatively. The system used for Hb-free perfusion ensures at normoxic perfusion of the liver the functional integrity of isolated mitochondria for a period of investigation of 180 min. Normothermal ischemia of the liver leads, already after 20 min, to a significant decline of the ADP/O quotient and of the respiration control coefficient of the isolated mitochondria, as well as to mitochondrial swelling. Hypothermal ischemia of the liver (25 degrees C) clearly diminishes the mitochondrial functional loss. As far as the liver disposes of an endogenous glycogen store, the integrity of the mitochondria isolated after anoxic liver perfusion (25 degrees C) is retained and longer than after hypothermal ischemia of the liver. Mitochondria isolated after anoxic perfusion from glycogen-deprived liver swell and uncouple as fast as mitochondria prepared after ischemic storage of the glycogen-containing liver. Normoxic reperfusion of the ischemically pre-damaged liver leads to partial recovery of the mitochondria, if reoxygenation of the liver is started no later than after 80 min of ischemic storagel.

Animals↗
PubMedDate not supplied

Role of short-chain fatty acids in the prevention of colorectal cancer.

Short-chain fatty acids (SCFAs: acetate, propionate, n-butyrate) arising in the large bowel during bacterial fermentation of dietary fibre and starch have paradoxical effects on colonic epithelial proliferation. While the three major SCFAs stimulate proliferation of normal crypt cells, n-butyrate and, to a lesser degree, propionate inhibit growth of colon cancer cell lines. At the molecular level, n-butyrate causes histone acetylation, favours differentiation, induces apoptosis and regulates the expression of various oncogenes. To understand the complex effects of SCFAs on carcinogenesis, it is important to study the intermediate stages of the adenoma-carcinoma sequence where a "switch" from stimulation to suppression of cell proliferation must occur.

Animals↗