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Biomedical subjects

R L Mueller

Publications and source records attributed to R L Mueller.

At least 19 recordsLinked to original sources
PubMed1991

[Biocompatibility studies of periodontal dressings].

Periodontal packs have to be considered medications due to their direct contact to the gums and wound surfaces. For this reason a high cell biological compatibility has to be considered as one of their most important properties. For this reason, the cytotoxicity of all periodontal packs commonly used in Germany was examined, using the "Erlangen Ciliate Test". This method, which is commonly used to determine the cytotoxic and cytostatic properties of a wide variety of different materials and substances, is based on liquid cultures of the eucaryotic organism "Tetrahymena piriformis", using an excellent correlation with mammalian or human tissue cultures as well as the LD50. A significant toxicity of up to 50% could be shown in all but one periodontal pack. In addition, the antibacterial properties of the same materials were examined, using liquid cultures of Staphylococcus aureus and hemolyzing streptococci group A. However, using this method, no significant antibacterial effects could be shown.

Animals↗
PubMed1989

[The problem of carcinogenic N-nitroso compounds--30 years old].

For 30 years a correlation between N-nitroso compounds and cancer in man has been suspected. Investigations of nitrate and nitrite in food and human gastric cancer were performed all over the world. Literature on nitrosamines and nitrosamides is abundant, but it is impossible to make a realistic assessment of the danger of N-nitroso compounds and their precursors for man. Restriction of unnecessary intake of nitrate through drinking water and food is in any case an important task of hygiene.

Animals↗
PubMed1989

[Bismuth--an environmental pollutant of the future].

Campylobacter pylori had become an interesting object in the discussion of the etiology of gastritis and peptic ulcer. Marshall was the first to describe antrum gastritis and duodenal ulcers as infectious diseases. Consequently new forms of therapy like antibiotics and bismuth salts were studied. In time the most favoured method of treatment is the administration of inorganic bismuth salts. There is a lack of recognition about the behaviour of this heavy metal in environment. 0.5 to 1 gram pure Bismuth per day and person leaves the patients naturally by faeces. The number of patients with gastric disorder is very large. Becomes bismuth a environmental problem in future?

Bismuth↗
PubMed1987

Evidence that epichlorohydrin is not a toxic metabolite of 1,2-dibromo-3-chloropropane.

The major urinary metabolite of 14C-epichlorohydrin, after oral administration to rats, was identified previously (Gingell et al. 1985) to be N-acetyl-S-(3-chloro-2-hydroxypropyl)-L-cysteine (ACPC) at 36% of the administered dose. In a similar study reported here, 1,2-dibromo-3-chloropropane (DBCP) was metabolized to at least 20 radioactive urinary metabolites. ACPC was only a minor metabolite (4%) of DBCP. Epichlorohydrin was metabolized in vitro by rat liver microsomes to alpha-chlorohydrin, but DBCP was not metabolized to epichlorohydrin or alpha-chlorohydrin under similar conditions. Covalent binding of radioactivity to liver microsomal proteins occurred for both substrates, but was less for 14C-epichlorohydrin than for 14C-DBCP. Addition of 3,3,3-trichloropropylene oxide, an inhibitor of epoxide hydrolase, increased the extent of protein binding of epichlorohydrin, but decreased the amount of 14C-DBCP which was bound. The data indicate the epichlorohydrin is not a significant in vivo nor in vitro metabolite of DBCP in the rat, and is unlikely to be responsible for the toxicity of DBCP.

Animals↗
PubMed1987

[Dynamics of endogenous bacterial nitrite formation in the stomach. 2. Follow-up observations with standardized secretion from the porcine stomach].

The bacterial nitrite synthesis in gastric juice from porcine stomach mucin and the decrease of nitrite after adding acid, which has often been described in literature-results of an examination with a standardizable biomodel. A decrease of nitrite concentration was only seen after adding a small volume acid of high concentration. Simulating the acid secretion by a large volume of low concentrated acid mixed with pepsin-solution (artificial gastric secrete, DAB 8) a considerable increase of nitrite concentration can be observed. An explanation can be the structure of stomach mucous gel can be solubilized in water and thus the ions are liberized inside of the stomach mucin. In the discussion of the endogenous synthesis of cancerogenic N-Nitroso-compounds it must be considered if this phenomena also can be observed in human secretes.

Animals↗
PubMed1987

[Dynamics of endogenous bacterial nitrite formation in the stomach. 3. Dependence of nitrate and nitrite concentration on secretion volume].

The nitrate and nitrite concentration of 96 fasting gastric juice samples of young healthy volunteers were analysed. Two different methods have been used to take the gastric juice: 54 secrete samples were taken directly from the stomach, 42 secrete samples were taken after instillation of 500 ml sterile nitrite and nitrate free NaCl solution ("gastric-washing"). It could be shown that the expected high dilution of nitrite and nitrate concentration after gastric washing does not occur. A possible explanation might be that the solubilisation we could formerly observe in a biological pattern leads to a release of ions. This fact is very important for the question of endogen synthesis of cancerogenic N-nitroso compounds, because high nitrite and nitrate concentrations are subjects of interests as precursors of these compounds.

Bacteria↗
PubMed1987

[Dynamics of endogenous bacterial nitrite formation in the stomach. 4. Localization and reciprocal action of nitrate and nitrite in the healthy human stomach].

The nitrate and nitrite concentrations of 42 fasting gastric juice samples of young healthy human volunteers were analysed. It could be shown by separate determination of the concentration in the real secrete and the mucous gel that the amount of nitrate in the gel is about ten times higher than in the real secrete. The former conception, after which nitrate only gets by swallowed saliva into the stomach, has to be completed. It is obvious that the mucigenous glands of the stomach, like the saliva glands, are also able of nitrate enrichment and secretion. These results are very important for the evaluation of nitrate as a precursor of cancerogenic N-nitroso compounds.

Bacteria↗
PubMed1987

[Dynamics of endogenous bacterial nitrite formation in the stomach. 5. Dependence of the nitrate concentration on the pH value of the stomach secretion].

The content of nitrate and nitrite was examined in the fasting gastric juice samples of 54 anamnestically healthy, young voluntary test-persons after at least 12 h of food abstinence. The analysis was made separately each time for the proper watery gastric juice as well as for the gastric mucus. It could be shown that significant differences exist between the concentration of nitrate and nitrite in the juice and the gastric mucus, that there is a pH-dependence in the concentration of nitrate in the juice and that the already earlier described gastric source of nitrate by the enrichment of nitrate ions in the juice producing glands of the gastric lining can be confirmed here too.

Bacteria↗
PubMed1987

[Dynamics of endogenous bacterial nitrite formation in the stomach. 6. Redox potential and nitrite formation in stomach secretions].

The redox potential depending on the pH-value and the concentration of nitrite was examined in the fasting gastric juice samples of 132 anamnestically healthy, young, voluntary test-persons. It turned out that small pH-values (acid) are associated with high redox potentials and big pH-values (neutral) with smaller redox potentials. Therefore the hydrogen ion pressure (rH-value) resulting from these two quantities generally is situated in the indifferent range. Reducing properties of the whole juice can only occasionally be found, and apparently only then, if a neutral juice is acidified. Oxidizing properties have to be classified as exceptional cases. It cannot absolutely be traced on behalf of the findings, that can be raised with natural juices, if and when answered affirmatively, which effects the redox potential has on the formation of bacterial nitrite.

Bacteria↗
PubMed1986

[Campylobacter-like bacteria (C. pylori) in the healthy stomach?].

UNLABELLED: Some authors recently published reports on the findings of unidentified S-shaped spiral bacteria, so called "Campylobacter pylori", in the gastric epithelium and the significant connection between these strains and gastric diseases. 24 fasting gastric juice samples of young healthy volunteers were now analysed bacteriologically using the campylobacter isolation techniques. RESULTS: It was not possible to find the so called "C. pylori" in the healthy stomach.

Bacteriological Techniques↗
PubMed1986

Nitrate and nitrite in normal gastric juice. Precursors of the endogenous N-nitroso compound synthesis.

The nitrate and nitrite levels of 75 gastric juice samples from young and healthy fasting volunteers were examined. For both parameters a dependence on the specific pH value of the secretion was detected. The rise of the nitrite level from normal 0.1 ppm in the acid to 1.4 ppm in the neutral range can be explained by the activity of the bacterial flora even in the healthy stomach, which has already been demonstrated earlier. The hitherto existing theory that nitrate originates exclusively from the salivary glands, and if not reduced to nitrite by bacteria in the mouth cavity, is brought into the stomach via swallowed saliva only, does not explain the observation that there is a rise in nitrate concentration in neutral juice, too. Further investigations have to be made to see whether there are other endogenous sources of nitrate except the salivary glands in the gastrointestinal tract. The environmental pollutant nitrate must be paid more attention to in future.

Adult↗
PubMed1985

[Bacterial colonization of the stomach caused by acid neutralization and inhibition of stomach emptying].

Gastric bacterial overgrowth was studied in 8 healthy volunteers. Total bacterial counts, nitrate-reducing bacteria and nitrite concentration were determined in fasting gastric juice before and after 4 weeks of treatment with a strong or with a mild antacid drug, a placebo preparation and the spasmolytic agent papaverine which is known to inhibit gastric evacuation. Placebo therapy and the mild antacid did not change any of the above parameters studied. The strong antacid caused a significant increase in the pH of gastric contents which was accompanied by an enormous increase in total bacterial counts, nitrate-reducing bacteria and nitrite concentration. Papaverine which did not cause a significant elevation of pH also definitely increased bacterial counts and nitrite concentration of gastric juice. Four weeks following termination of each treatment procedure, however, all changes outlined above had returned to pretreatment values. These results indicate that reversible gastric bacterial overgrowth under therapeutical conditions may occur when acidity of the stomach is reduced or gastric evacuation is retarded.

Adult↗
PubMed1977

Performance of swine chilled during artificial rearing.

There were more deaths among neonatal swine artificially reared for 21 days in individual cages at 27.9 C than among pigs reared under similar conditions at thermoneutrality (34.6 C). Furthermore, these deaths occurred at a younger age in the chilled animals. Chilled swine gained less body weight than did warm pigs for the first 15 days of life, although the survivors of the 27.9 C environment weighed the same as warm survivors at 22 days of age. Plasma glucose, liver, and skeletal muscle glycogen concentrations were significantly lower in neonatal swine exposed to 27.9 C from 1 to 4 days of age. Plasma nonesterified fatty acids, glycerol, cholesterol, and triglyceride concentrations were not altered by chilling. However, these lipid variables were significantly higher in 4-day-old nursig pigs than in animals reared artificially for the same period on artificial food. Adrenal gland weights and adrenal medullary catecholamine-synthetic enzyme activities were not altered by exposure to 27.9 C in pigs 1 to 4 days of age.

Animals↗
PubMed1976

Puerperal laparoscopic sterilization.

Two hundred and ninety-seven consecutive puerperal laparoscopic sterilization cases during a five-year period are reviewed. There were six failures to complete the laparoscopic sterilization. A single case of anesthetic cardiac arrest constituted the only major complication. There has been no mortality. Two subsequent pregnancies occurred in this series, and their follow-up operative findings are reviewed.

Adolescent↗
PubMed1976

Sympathoadrenal Neurochemistry and early weaning of swine.

Three litters of pigs were weaned at 21 days of age, and 3 others were left with the sow. Pigs were killed at 21, 23, 28, or 39 days of age. Weaned pigs exhibited anxiety, gastrointestinal dysfunction, and decreased rate of body weight gain. Plasma glucose or liver glycogen concentrations were not decreased by weaning. Adrenal gland weights and tyrosine hydroxylase (EC 1.14.3a), dopamine beta-hydroxylase (EC 1.14.2.1), phenethanolamine-N-methyl transferase (EC 2.1.1), and monoamine oxidase (EC 1.4.3.4) activities were increased after weaning. Adrenal catecholamine and cortisol levels and dopa decarboxylase (EC 4.1.1.26) and catechol-o-methyl transferase (EC 2.1.1.6) activities were not significantly altered, although some increases were indicated. Cranial cervical ganglionic choline acetyltransferase (EC 2.3.1.6) and tyrosine hydroxylase activities were increased after weaning. Weaning of swine at 21 days of age is a stressful experience, and many effects persist for at least 18 days; however, growth was no longer impaired 18 days after weaning.

Adrenal Glands↗