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Biomedical subjects

I Richter

Publications and source records attributed to I Richter.

At least 37 records · Page 2Linked to original sources
PubMed1987

[Resorption and metabolic utilization of D-[alpha-15N]lysine and L-[alpha-15N]lysine after oral administration, with special reference to the metabolism of intestinal bacteria].

Absorption of D-[alpha-15N]lysine and L-[alpha-15N]lysine following an oral single pulse labelling at a dosage of 5 mg 15N'/kg body weight was compared in four subjects aged 4 to 14 months. The wastages of 15N' in the faeces ranged from 0.3 to 5% of the input implying comparably high absorption rates of both the lysine enantiomers. Only about 7.6% of the 15N from the alpha-amino groups were found in the urine after loading with L-[alpha-15N]lysine. In contrast, about 80.2% of the 15N' dose from D-[alpha-15N]lysine were eliminated renally. However, 18.5% of the 15N' dose on an average were retained after D-[alpha-15N]lysine administration. This is certainly due to a partial desamination of D-lysine. The faecal bacteria isolated from the faeces contained no or only small amounts of 15N' after D-[alpha-15N]lysine loading. Following L-[alpha-15N]lysine administration a measurable 15N enrichment of the faecal bacteria of up to 0.09 at % excess was achieved in almost all cases.

Administration, Oral↗
PubMed1986

Blood level, distribution, excretion, and metabolite pattern of [14C]-brotizolam in the rat, dog, and rhesus monkey.

Following oral and intravenous administration the absorption, distribution, metabolite pattern and excretion of 14C-labeled brotizolam (2-bromo-4-(2-chlorophenyl)-9-methyl-6H-thieno[3,2-f]-1,2,4-triazolo [4,3-a]-1,4-diazepine, We 941, Lendormin), a new hypnotic, was studied in rats, dogs, and rhesus monkeys. Given orally to these species, [14C]-brotizolam was rapidly and extensively absorbed. The distribution of the radiolabeled drug was very fast indicated by blood level curves as well as by rat whole body autoradiography. [14C]-Brotizolam and its metabolites crossed the placenta; they also occurred in the milk of rats. In all species studied radioactivity was eliminated from blood with very similar half-lives ranging from 14.8 to 20.8 h. The renal portion of the total radioactivity elimination increased from 5.5% of the dose given to rats to 33.5% in rhesus monkeys and to 51.4% in dogs. Total excretion was complete 3 to 4 days after [14C]-brotizolam administration. Biliary excretion also occurred. In the species studied thin layer chromatographic separation of the biliarily and renally excreted radioactivity indicated a similar but not the same pattern of 2 to 3 major metabolites which were mostly totally conjugated. Unchanged [14C]-brotizolam was only excreted in minor quantities, if at all.

Animals↗
PubMed1985

[Biochemical studies with oxitropium bromide. 1. Pharmacokinetics and metabolism in the rat and dog].

The bronchospasmolytic drug (8r)-6 beta, 7 beta-epoxy-8-ethyl-3 alpha-[(-)-tropoyloxy]-1 alpha H, 5 alpha H-tropanium bromide (oxitropium bromide, Ba 253 BR, Ventilat) was tested pharmacokinetically as a 14C labelled substance in rats and dogs. Following oral administration low concentrations of radioactivity persisting over several hours were measured in the blood of dogs and rats. The active ingredient which can be separated from the metabolites by thin layer chromatography and quantified via the radioactivity reaches a maximum in the rat plasma after 1 to 2 h; it is then eliminated from the blood with a half-life of approx. 4 h. Following intravenous administration the radioactivity measured directly (active ingredient + metabolites) is distributed rapidly into the tissue of the rat and the dog. The distribution phase is followed by a relatively fast elimination phase ending in the terminal elimination phase approx. 1 h after administration. Rats and dogs eliminate the radioactivity mainly with the feces after oral administration, whereas following intravenous administration the rat eliminates about half with the feces and half via the kidneys. Biliary excretion of the rat is 12% after oral and 14% after intravenous administration. The rat absorbs 14% and the dog 28% of dose. Five metabolites have been demonstrated in the urine of the rat and the dog. Metabolism takes place exclusively in the tropaic acid part of the molecule and by hydrolysis of the compound.

Animals↗
PubMed1985

15N-tracer-kinetic studies on the nitrogen metabolism of very small preterm infants on a diet of mother's milk.

Protein synthesis and breakdown, nitrogen flux and other parameters of nitrogen metabolism were measured in five male preterm infants with a mean gestational age of 30.4 +/- 1.95 complete weeks of gestation and a mean body weight of 1592 +/- 517 g. The infants were fed on mothers' milk; the measurements were made at a post-conceptional age of 31.6 +/- 1.9 weeks of gestation (Ia) and were repeated at 34.4 +/- 1.9 weeks of gestation (Ib). [15N]-glycine (95 atom per cent) was used as a tracer, administered as a single enteral dose of 20 mg/kg. Whole-body protein parameters were calculated from an assumed three-pool model. The results were compared with data from moderately small preterm (II) and full-term (III) infants measured at post-conceptional ages of 36.1 +/- 1.4 and 48.0 +/- 2.8 weeks respectively. Protein synthesis rates tended to decrease with increasing post-conceptional age: 14.3 +/- 4.5 g/kg/d (Ia); 11.8 +/- 2.9 g/kg/d (Ib); 7.9 +/- 2.7 g/kg/d (II); and 7.7 +/- 1.4 g/kg/d (III). Protein breakdown and nitrogen flux showed the same trends. Possible consequences for the appropriate nutrition of very small preterm infants are discussed.

Birth Weight↗
PubMed1983

Evaluation of different 15N-tracer substances for calculation of whole body protein parameters in infants.

The validity of using different 15N-tracer substances to measure whole body protein parameters, i.e., protein synthesis, protein breakdown, net protein gain, protein turnover, metabolic pool, and reutilization, was assessed by comparing the results obtained with: [15N]glycine, a mixture of 10 15N-labeled amino acids, and a 15N-labeled chicken egg protein in two infants, 9 and 12 weeks old, who were fed human milk. The tracer substances were fed orally as a single dose corresponding to a 15N-excess quantity of 0.2 mmol X kg-1 body weight. 15N Excretion in the urine was measured cumulatively by emission spectrometry, and the data on the protein metabolism were calculated by means of a three-pool model. All three tests yielded consistent net protein gains. The protein synthesis, protein breakdown, protein turnover, and nitrogen reutilization values produced by the [15N]glycine tracer study were higher than those produced by application of the 15N-amino acid mixture and the 15N-labeled egg protein. However, in our opinion, this discrepancy does not justify the replacement of [15N]glycine by expensive 15N-amino acid mixtures as tracer substances.

Amino Acids↗
PubMed1983

15N-tracer investigations into the nitrogen metabolism of preterm infants fed mother's milk and a formula diet.

Protein synthesis, protein breakdown, protein-N turnover, and other parameters describing the nitrogen metabolism were measured in five male preterm infants. The weight of the subjects at birth was 2,064 +/- 107 g and the measurements were performed at age 16.0 +/- 4.5 days in the case of the mother's milk diet and 27.4 +/- 6.8 days in the case of the formula diet containing 1.8% protein. The parameters were measured by means of the 15N-tracer technique using [15N]glycine (95 atom %) applied in a single oral dose of 20 mg/kg as a tracer. The three-pool model proposed by Winkler and Faust was used to calculate the whole body protein parameters. No difference in net protein gain, protein synthesis, protein breakdown, or the other protein metabolism parameters were recorded despite the different protein inputs. Renal nitrogen excretion and the rate of endogenous urea N excretion were significantly higher for the formula diet than for the mother's milk diet. The protein synthesis rate of 7.9 g X kg-1 X day-1 was, as has previously been observed, higher than in other age groups. The protein metabolism of the preterm infant older than 33 weeks of gestational age does not benefit from a formula diet based on cow's milk that is richer in protein than mother's milk.

Glycine↗
PubMed1983

15N-labelled yeast protein--a valid tracer for calculating whole-body protein parameters in infants: a comparison between [15N]-yeast protein and [15N]-glycine.

The validity of [15N]-glycine and 15N-labelled yeast protein as tracers for investigating the parameters of nitrogen metabolism in man was studied by comparisons of each tracer in three infants on different diets. Both tracers were administered with the food as a single oral dose of 0.2 mmol 15N-excess nitrogen per kg body weight. Cumulative 15N-excess excretion in the urine was measured by emission spectrometry and a three-compartment model was used to calculate the pool sizes by computer. In all three comparisons the values calculated for protein synthesis, protein breakdown, protein turnover and reutilization after administration of 15N-labelled yeast protein were slightly lower than those calculated after administration of [15N]-glycine. The particular advantage of applying a highly enriched, completely labelled [15N]-protein instead of [15N]-glycine as a tracer is that the protein, containing some 20 amino acids, doubtless gives a more accurate picture of protein metabolism than the use of a single amino acid labelled with heavy nitrogen. However, the small differences between the whole-body parameters calculated from 15N-labelled yeast protein and [15N]-glycine do not justify the general replacement of [15N]-glycine by 15N-labelled protein.

Diet↗
PubMed1982

[Indication for prophylactic and therapeutic thrombocyte substitution].

The substitution of thrombocytes is on principle indicated only when a disturbance of the formation is present. The prophylactic application, i.e. before the occurrence of a haemorrhage, which is sometimes life-limiting, is to be preferred, however, on account of the danger of sensitization it is bound to particular conditions: temporarily limited need of substitution, decreased immune reagibility of the recipient (basic disease, therapy), medico-therapeutically induced thrombocytopenia (cytostatic drugs); example: haemoblastoses. Prerequisites are subtile control of clinical effectiveness and formation of antibodies. In planned bone marrow transplantation only preparation of individual donors (not related!) with HLA-A/B match are to be used. The same is applied to already alloimmunized patients, in which case a negative lymphocytotox cross test must still be present. Patients without option to transplantation or without HLA-antibodies may receive also random preparations of individual donors or mixed preparations. AB0-minor-incompatibilities are without significance, AB0-major-incompatibilities are not permissible. The introduction of thrombocyte-specific testings is urgently to be aspired to.--Exclusively therapeutic substitution of thrombocytes, i.e. in manifest haemorrhage, is performed in a primarily not limited period of substitution, in a completely immune competent recipient with regularly low values of thrombocytes without cytoreductive therapy (example: aplastic anaemia). In these cases on account of high danger of sensitization only preparations of individual donors with HLA-A/B-match should be used. In cases of exception in thrombocytopenic, life-threatening haemorrhages on account of metabolic disturbances (immune thrombocytopenia, massive transfusions) the substitution with thrombocytic mixed concentrates is satisfied.--The substitution of thrombocytes is a common task of clinic and blood donation service, which opens new possibilities of therapy (e.g. transplantation of bone marrow).

Anemia, Aplastic↗
PubMed1982

Formation of ether lipids and wax esters in mammalian cells. Specificity of enzymes with regard to carbon chains of substrates.

The incorporation of radioactivity from individual constituents of an equimolar mixture of saturated straight-chain alcohols (14:0, 16:0, 18:0, 20:0) and of nearly uniform mixtures of isomeric cis- or trans-octadecenols (delta 8-delta 16) into alkyl, alk-1-enyl and acyl moieties of diradylglycerophosphocholines and diradylglycerophosphoethanolamines and into alkyl and acyl moieties of wax esters was studied in rat brain as well as in L 1210 and S 180 ascites cells. The pattern of incorporation of radioactivity from the substrates into alkyl and alk-1-enyl moieties of ether phospholipids and into alkyl moieties of wax esters reveals the following: (1) The enzymes catalyzing the biosynthesis of alkylacylglycerols, the common intermediates of cholinephospholipids and ethanolaminephospholipids, have no substrate specificity with regard to position of the double bond of either cis- or trans-octadecenols or of intermediate ether lipids derived therefrom. (2) CDPcholine:diradylglycerol cholinephosphotransferases exhibit a strong preference for alkylacylglycerols with cis-8, cis-9 and cis-10-octadecenyl moieties, but no preference for the double bond position in the trans-octadecenylacylglycerols. (3) CDPethanolamine:diredylglycerol ethanolaminephosphotransferases have no substrate specificity with regard to position of the double bond in cis- or trans-octadecenyl moieties of alkylacylglycerols. (4) THe enzyme systems catalyzing the biosynthesis of alkylacylglycerophosphocholines and alkylacylglycerophosphoethanolamines exhibit substrate specificity with regard to chain-length of saturated alcohols and intermediate ether lipids derived therefrom. (5) Alkylacylglycerophosphoethanolamine desaturase and (6) wax ester synthase are highly specific for alkylacylglycerophosphoethanolamines and long-chain alcohols, respectively, with regard to chain-length of saturated alkyl moieties, but not with regard to position of double bonds of cis- or trans-octadecenyl moieties.

Animals↗
PubMed1981

[Occlusive adenoids causing cor pulmonale and pectus excavatum in a child (author's transl)].

In a Child respiration was impaired already during infancy by occlusive adenoids causing pectus excavatum, cardiomegaly with signs of right ventricular and right atrial hypertrophy, hepatomegaly and dystrophy. The child showed psychological injury as well. After adenectomy these symptoms gradually disappeared. The cardiorespiratory syndrome by obstruction of the upper airways demands active surgical therapy since it may lead to right ventricular failure and pulmonary edema.

Adenoidectomy↗
PubMed1981

Formation of ether lipids from isomeric cis-octadecen-1-ols in normal and neoplastic cells: substrate specificity of enzymes with regard to position of double bonds.

The pattern of incorporation of isomeric cis-[1-14C]octadecen-1-ols into alkyl moieties of glycerophospholipids of rat brain as well as of L 1210 and S 180 murine ascites cells revealed the following: 1) The enzymes involved in the biosynthesis of acylalkylglycerophospholamines have no substrate specificity with regard to position of the double bond of either cis-oectadecen-1-ols or of intermediate ether lipids derived therefrom. 2) CDPcholine: diradylglycerol cholinephosphotransferases exhibit a strong preference for acylalkylglycerols with cis-8, cis-9 and cis-10-octadecenyl moieties as substrates.

Animals↗
PubMed1981

[Kinetic tracer studies on protein synthesis during infancy using chemically defined diets containing 15N-lysine as a tracer (author's transl)].

A four-month-old infant with exocrine pancreas insufficiency was fed exclusively on a chemically defined diet. The amino acid formulation of this diet (a supplemented casein hydrolyzate) corresponds to that of breast milk. The 15N labeled lysine tracer (97.4 atom-%) was included in the diet without changing its chemical score. A trace dose of 2.22 mg/kg body weight was applied for 5 days after the infant had been maintained on a chemically defined diet for 11 weeks. Urine was collected over a period of 170 h. The compartment theory was used to calculate the following metabolic data. Cumulative renal 15N excretion showed that nitrogen retention was 90.8%. Protein synthesis amounted to 10.34 g kg-1 d-1 compared with a protein breakdown rate of 8.97 kg-1 d-1. Net protein gain in this infant was about 5.5 g d-1 corresponding to a rate of 1.38 kg-1 d-1 or 13.3% of the synthesis rate. The metabolic pool amounted to 4.96 g N kg-1 d-1. 75.99 mg N kg-1 h-1 was metabolized, mainly to protein, and only about 10% was excreted with the urine.

Amino Acids↗
PubMed1980

Ultrasound and barium study in the evaluation of upper abdominal masses.

Numerous radiological procedures are now available for investigation of upper abdominal masses of uncertain aetiology; however, certain limitations and pitfalls are associated with these procedures. It is suggested that the initial use of ultrasound and barium studies would frequently provide either a definite diagnosis or lead to the next appropriate line of investigation. The importance of not omitting the barium study is stressed.

Abdominal Neoplasms↗
PubMed1980

[Pharmakokinetic and clinical studies with azlocillin in paediatrics (author's transl)].

Azlocillin, an acylureido penicillin with bactericidal activity, is particularly effective against Pseudomonas, enterococci and Haemophilus influenzae. It is also very active against E. coli, various Proteus species and Bacteroides. Pharmacokinetic studies were carried out in 138 children of various ages (prematures, newborns, infants, schoolchildren) after administering 50-75-100 mg/kg/ body weight azlocillin via the i.v. or i.m. routes; The constant of elimination and the distribution volumes were calculated besides the serum levels. In prematures and newborns, therapeutically effective serum levels were obtained on administering 50 or 100 mg/kg body weight twice daily. Infants and older children required 100 or 75 mg/kg body weight t.i.d. Determination of azlocillin in the bronchial secretion after i.v. doses of 75 mg/kg body weight showed good elimination. Azlocillin was always identified up to the 5th hour post injectionem. Inspite of parenteral administration, azlocillin was identified in different concentrations in the meconium as well. 39 children were treated with azlocillin, 35 of whom had Pseudomonas infection. Very good results were obtained in infections of the urinary tract, wound infections, conjunctivitis, dacryocystitis and in one case of meningitis. Bronchopulmonary diseases did not take an equally good course, but in these cases the conditions had not been favourable. No serious side effects were revealed by testing several laboratory parameters.

Azlocillin↗