Biomedical subjects

W Augustin

Publications and source records attributed to W Augustin.

At least 55 records · Page 3Linked to original sources

PubMed1988

Impairment of the respiratory chain in the b-c1 region as early functional event during Fe2+/ascorbate induced peroxidation in rat liver mitochondria.

An attack at the level of the respiratory chain was established as the reason for the early inhibition of oxygen uptake during Fe2+/ascorbate induced peroxidation by following the activities of complexes I-IV separately. The close correlation between the decline of mitochondrial respiration and the activity of complex III strongly suggests that an impairment of the respiratory chain in the b-c1 region represents one of the first functional events in the causal sequence of peroxidative reactions preceding the phase of massive malondialdehyde production.

Animals↗

PubMed1987

Relations between enzyme activities connected with energy metabolism and parameters of food energy utilization in young and adult rats. Part 1. Studies on dietary effects on weight, body composition and energy gain.

Weaned male Wistar rats were fed ad libitum besides standard pellets a normal-protein (NP), a low-protein (LP) and a high-fat (HF) diet for different periods of time. In comparison to rats on the NP diet the body weight of the LP group was significantly lower after seven weeks feeding, not after a duration of about forty weeks. No remarkable diet-related differences were detected by determination of the mean body composition and of the relative gross energy content of the body neither after seven nor forty weeks. Total gross energy intake was practically identical both for the NP and LP rats irrespective on the duration of the feeding period. A significantly lower quotient of body energy gain/total gross energy intake under the protein-restrictive LP diet after seven weeks suggests the expression of an energy dissipation obviously no longer visible after a long time feeding period.

Animals↗

PubMed1987

Relations between enzyme activities connected with energy metabolism and parameters of food energy utilization in young and adult rats. Part 2. Enzyme activities related to alpha-glycerophosphate shuttle in various tissues.

The possible significance of food composition connected with the alpha-glycerophosphate (alpha GP) shuttle, a putative metabolic pathway of energy dissipation, was investigated at the level of enzyme activities. Liver, adipose tissue, slow-twitch and fast-twitch muscle of weaned male Wistar rats fed ad libitum for seven and for forty weeks a normal-protein (NP), a low-protein (LP), and a high-fat (HF) diet were examined. No striking dietary influences on cytosalic (NAD-linked glycerophosphate dehydrogenase, glyceraldehyde-phosphate dehydrogenase) and mitochondrial (succinate dehydrogenase, cytochrome c oxidase) enzyme activities could be detected, but mitochondrial alpha-glycerophosphate dehydrogenase (m-GPDH) showed an about twofold increase of its activity in the liver of LP-fed animals after seven weeks. A relationship between the "gross efficiency of food energy utilization" and tissue m-GPDH levels could not be established in general. The proposed inducing effect of a LP diet on the magnitude of the GP shuttle observed in the liver of young and adult rats seems to be interconnected reciprocally with the degree of metabolic energy dissipation only under the conditions of growth. The calculated capacities of the alpha GP shuttle are compatible with the assumption of its function as an energy dissipating pathway which is restricted in its magnitude.

Adipose Tissue↗

PubMed1987

Metabolism of intact reticulocytes and mitochondria under lowered energy load induced by cycloheximide.

Cycloheximide was used to decrease the energy load by inhibitors of hemoglobin synthesis as the major ATP-consumer in intact rabbit reticulocytes. Inhibitor concentrations up to 2.5 X 10(-5) M led to decreased ATP-production at simultaneously elevated ATP/ADP ratios. Higher inhibitor levels resulted in further decreasing ATP-production but now in the reverse parallel to declining ATP/ADP ratios. Studies with intact reticulocyte mitochondria revealed almost no influence on respiration rates at the low range of concentrations but increasing inhibitions of state 3, state 4 and uncoupled respiration as well, with a 50% inhibition around 3 mM. Thus the dual action of the inhibitor is obviously due to the specific suppression of protein synthesis on the one hand and the unspecific inhibition of mitochondrial respiration on the other. Similar conclusions have been drawn by using ouabain to suppress the ATP-consumption by Na-K-ATPase. A preliminary load characteristic for rabbit reticulocytes with glucose as substrate is presented.

Adenosine Diphosphate↗

PubMed1987

[6-keto-prostaglandin F1 alpha and thromboxane B2 in the amniotic fluid and peripheral venous blood in healthy pregnant patients and in pregnant patients with pre-eclampsia].

In order to characterize the prostacyclin and thromboxane system during gestosis the stable degradation products 6-keto-prostaglandin F1 alpha (6-keto-PG F1 alpha) and thromboxane B2 (TX B2) have been determined by radioimmunoassay in amniotic fluid and maternal venous plasma from 16 normotensive pregnant women and 14 patients with preeclampsia. At preeclampsia as well in amniotic fluid as in plasma a tendency towards lowered levels of 6-keto-PG F1 alpha and at the same time increased levels of TX B2 may be visualized. In the plasma generally significant higher levels of both 6-keto-PG F1 alpha and TX B2 than in amniotic fluid have been established. The imbalance between anti-aggregatory and vasodilatatory prostacyclin and proaggregatory and vasoconstrictory thromboxane in preeclampsia is indicated by an increase of the ratio TX B2/6-keto-PG F1 alpha from 1.38 to 2.44 in amniotic fluid and from 1.88 to 2.81 in plasma.

6-Ketoprostaglandin F1 alpha↗

PubMed1986

Prostaglandin E and F profiles in human fallopian tubes during different phases of the menstrual cycle.

Prostaglandin (PG)E and F equivalents have been determined in fallopian tubes from 26 women by radioimmunoassays following appropriate extraction and separation procedures. Both PGE and F equivalents at ranges between 5 and 100 ng/g wet weight exhibit profiles of increasing concentrations along the oviduct with low contents at the uterotubal junction and maximal levels in the fimbrial region. During the luteal phase of the cycle about 2-fold higher levels of PGE and F equivalents were detected than during the follicular phase in both the ampullary and isthmic portion of the oviduct. A general decline of PG levels was observed in tissues from patients at the perimenopause. The distribution of PGs within the oviduct is compatible with a preferential localization in its mucosal part, which may represent the main target for a progesterone-mediated stimulation of PG production during the luteal phase.

Adult↗

PubMed1986

[Prostaglandin E and F content of the amniotic fluid in various stages of beginning labor].

Levels of prostaglandin (PG) E- and F-equivalents determined radio-immunologically in amniotic fluid from women with uncomplicated pregnancies at term were related to the cervical state and the onset of regular labour. The lowest levels of both PG E- and F-equivalents with about 400 pg/ml were measured in the group with an immature cervix. An about twofold increase of both PG's appears characteristic for the cervical ripening, whereas the readiness for the initiation of regular uterine contractions is apparently indicated by further raises of PG F2 alpha. At the beginning of parturition distinct elevations can be registered for both PG's with a dominance of PG F. From their dynamics in amniotic fluid conclusions about different functions of PG's during the period preceding labour can be drawn.

Amniotic Fluid↗

PubMed1985

Dissipation of electrochemical ion gradients induced by carbonyl cyanide p-trifluoromethoxyphenylhydrazone and valinomycin in rabbit reticulocytes as loads of energy metabolism.

The protonophor FCCP and the K+-ionophor valinomycin stimulated the respiration of highly enriched intact rabbit reticulocytes to stationary rates of 200 and 130% of the control at optimal concentrations of about 5 and 50 nmoles/ml cells, respectively. Further increased inhibitor concentrations result in the stepwise decline of respiration rates down to control values. Parallel determinations of adenine nucleotides revealed increasingly lowered ATP/ADP ratios from about 10 to about 5 with valinomycin and 3 with FCCP. The impaired mitochondrial ATP formation was presumably not fully stoichiometrically compensated by elevated glycolytic ATP production as estimated from the rates of lactate production. It can be concluded that both ionophors act mainly at the level of the mitochondrial membrane, although minor effects exerted at the plasma membrane cannot be excluded. Apparently FCCP induces more effective loads than valinomycin on the energy balance of reticulocytes as reflected in phosphorylation levels of adenine nucleotides.

Adenosine Diphosphate↗

PubMed1985

Phospholipid patterns and phospholipase A2 activities in gastric mucosa of rats developing carcinomas after surgically induced enterogastric reflux.

Phospholipid patterns of the gastric mucosa from rats after operations inducing enterogastric reflux showed characteristic differences in relation to control rats: diminution of parent phospholipids phosphatidylethanolamine and phosphatidylcholine concomitant with increases of the corresponding lysophospholipids, increase of the sphingomyelin portion, indications for lipid peroxidations possibly connected with small drops of acidic phospholipids, and an elevated phospholipase A2 activity. The observed phospholipid changes support the assumption of disturbed membrane functions caused by activation of lipolytic activities as one factor involved in progressive mucosal alterations mostly manifested as carcinomas of the stomach.

Adenocarcinoma↗

PubMed1985

Association of creatine kinase with rat heart mitochondria: high and low affinity binding sites and the involvement of phospholipids.

Cleavage of mitochondrial phosphatidylethanolamine (PE), phosphatidylcholine (PC) and cardiolipin (CL) by phospholipase A2 but not selective degradation of PE and PC by phospholipase C dissociates creatine kinase from rat heart mitochondria. Creatine kinase exhibits a high resistance against Triton X-100 solubilization up to concentrations of 0.05-0.1%. Scatchard plot of rebinding experiments using mitoplasts revealed the presence of both low and high affinity binding sites; the latter may account for the originally bound creatine kinase activity. It is suggested that creatine kinase is specifically bound to a CL containing domain of the inner mitochondrial membrane.

Animals↗

PubMed1983

Increase of prostaglandin E and F equivalents in amniotic fluid during late pregnancy and rapid PG F elevation after cervical dilatation.

Prostaglandin E and F equivalents in amniotic fluid from 163 women were determined after amniocentesis using chromatographic group separation and radioimmunoassay. Both PG E and F equivalents remained unchanged at levels below 100 pg/ml until week 34 of gestation and increased exponentially thereafter reaching levels of 745 and 821 pg/ml at weeks 41/42. Cervical dilatation at weeks 9 - 12 and 37 - 42 of pregnancy resulted in rapid elevations of PG F equivalents, but not of PG E, by factors of about 3 and 13, respectively. It is assumed that the slowly increasing production of both PG E and F demonstrated during the last weeks of pregnancy is connected with maturation processes within the feto-placental unit preceding birth, whereas the rapid formation of high PG levels channeled to the PG F pool in response to mechanical stimuli resembles the processes closely related to the trigger mechanisms for the onset and progress of spontaneous labour at term.

Amniocentesis↗

PubMed1983

An improved modification of the biuret method for the determination of protein in turbid materials with high lipid and hemoglobin content.

The quantitative determination of protein by means of the biuret method frequently yields erroneous values, especially when applied to turbid, lipid- and hemoglobin-containing materials. These errors can only partially be abolished either by the addition of detergents or by destroying the Cu-protein complex by KCN addition. It was found that most disturbances were almost completely eliminated after prior precipitation of protein by the addition of Triton X-100 to the solubilizing biuret reagent and absorbance measurements being performed at a wavelength of 572 nm before and after the addition of KCN. Values of protein determinations according to the proposed assay and protein concentrations calculated from Kjeldahl nitrogen determinations have been shown to agree fairly satisfactory. The proposed assay represents a relatively simple and versatile approach for the evaluation of protein concentrations in a variety of materials containing lipids, hemoglobin and of some other turbidities as well.

Adipose Tissue↗

PubMed1983

[Behavior of primary prostaglandins in the amniotic fluid, maternal venous blood and umbilical cord blood during spontaneous delivery at term].

Levels of prostaglandin (PG) A/B, E and F equivalents have been determined in amniotic fluid, maternal venous blood and cord blood in the course of normal deliveries at term using radioimmunoassay after proper extraction and group separation of PG's by chromatography. With progress of cervical dilatation amniotic fluid levels increased from initial values of 0.34 to 0.52 ng/ml for PG A/B up to pressing period, while PG E rised from 2.3 to 5.5 ng/ml and PG F from 4.9 to 60.4 ng/ml, respectively. Comparatively lower increases of maternal plasma levels, essentially unchanged within the last trimester, were observed from 133, 100 and 102 pg/ml for PG A/B, E and F at the early first stage of labour to levels of 231, 209 and 357 pg/ml after the second stage. Higher levels of PG's in cord blood after spontaneous deliveries, not exhibiting significant arterio-venous differences, further strengthen the limited value of PG determinations in maternal plasma for the elucidation of the role of PG's in the physiology of gestation and parturition, but support a prevailing uterine not fetal localisation of PG production. The excessive PG F increase during birth, obviously caused by selective stimulation of PG F-synthesis, validitates the hypothesis, that this PG seems to be causally responsible for initiation and maintenance of uterine contractions in normal delivery.

Amniotic Fluid↗

PubMed1982

Involvement of periodic deacylation-acylation cycles of mitochondrial phospholipids during Sr2+-induced oscillatory ion transport in rat liver mitochondria.

Lysophosphatidylcholine and lysophosphatidylethanolamine levels were determined during Sr2+-induced oscillating ion fluxes in mitochondria prelabelled in vivo with 32Pi. Periodic fluctuations of both lyso compounds were established with an increase at the stage of simultaneously monitored K+ influx and a decrease at K+ efflux. The periodic activations and inactivations of phospholipase were found to be associated with periodic changes in the incorporation rates of labelled polyunsaturated fatty acids with an apparent phase difference of 180 degrees. Periodic deacylation-acylation cycles of phospholipids accompanying the periodic cycles of reversible ion accumulation and release are suggested to be involved in the trigger mechanism generating the permeability changes during oscillatory ion transport.

Animals↗

PubMed1982

[Obesity--a surgical problem?].

This a a survey or morbid obesity in man, its causes and possibilities of conservative and surgical treatment. The different aetiological types of obesity are dealt with. Special attention is focused on the mitochondrial oxidation-process.

Adult↗

PubMed1981

Evaluation of a rapid fractionation procedure of rabbit reticulocytes after digitonin or hypotonic hemolysis for the study of enzyme and metabolite distributions.

A rapid centrifugation procedure following cell lysis with either digitonin or short hypotonic shock in EDTA containing solutions was evaluated, applicable for investigations of enzyme and metabolite compartmentations in intact rabbit reticulocytes. The application of the digitonin disruption seems to be restricted to cell suspensions containing up to 40% reticulocytes only, whereas the hypotonic lysis can be used with practically pure reticulocytes, too. The distribution of markers revealed that an almost complete cell disruption, sufficient separation into pellet and supernatant fraction and satisfactory preservation of mitochondrial intactness could be achieved under appropriate conditions. The suitability of the proposed method in studies on reticulocyte energy metabolism is further supported by the almost insignificant ATP splitting during the entire procedure.

Adenosine Triphosphate↗

PubMed1981

Localization of hexokinase in mitochondria from rabbit reticulocytes and its relation to mitochondrial ATP-formation studied by measurement of 32P-fluxes.

The submitochondrial distribution of hexokinase was studied by repeated specific solubilizations and by tryptic digestion of isolated rabbit reticulocyte mitochondria. Whereas most of the enzyme is dissociably bound to the outer side of outer mitochondrial membrane, a small tightly bound portion is localized more internally. Electrophoretic separations did not reveal a specific isoenzyme pattern of the internal mitochondrial enzyme. Relationships between mitochondrial hexokinases and the intramitochondrial ATP pool, generated by oxidative phosphorylation, were studied by measuring 32P-fluxes following gamma-32P-ATP pulses on phosphorylating and non-phosphorylating mitochondria. Under both conditions, the specific activities in deoxyglucose-6-phosphate correspond closely to that of total gamma-ATP, thus not supporting a preferential use of intramitochondrial generated ATP by part of the mitochondrial hexokinases.

Adenosine Triphosphate↗

PubMed1981

[Prostaglandin levels in amniotic fluid during normal advanced pregnancy (author's transl)].

Radio-immuno assay was used, following extraction and fractionation, to measure primary prostaglandins in the amniotic fluid of 88 women in advanced pregnancy under normal conditions. No change was recordable from prostaglandin fraction B + A, whereas exponential rises were determined over the last four to six weeks of pregnancy for prostaglandins F and E. Prostaglandin E levels went up from 100 pg/ml amniotic fluid, between the 29th and 34th weeks of pregnancy, to 380 pg/ml, between the 39th and 40th weeks, whereafter they remained constant. Prostaglandin F levels were between 70 pg/ml and 100 pg/ml and went up to 422 pg/ml, with a mean value as high as 494 pg/ml being measured in the 41st and 42nd weeks of pregnancy. The prostaglandin E/F quotient decreased close to full term, between the 39th and 42nd weeks of pregnancy, on account of steeper rise of prostaglandin F. Prostaglandin approached nanogram values, more pronouncedly characteristic of childbirth, few hours before onset of regular pains.

Amniotic Fluid↗