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Biomedical subjects

R Jung

Publications and source records attributed to R Jung.

At least 109 records · Page 6Linked to original sources
PubMed1987

[Synthesis of tetracontapeptide--a hypothetical evolutionary precursor of calcium-binding proteins. I. Synthesis of (1-9), (10-14), (15-20), (21-26), (29-33), (34-40) fragments].

Fragments (1-9), (10-14), (15-20), (21-26), (29-33) and (34-40) of a tetracontapeptide hypothetical ancestor of calcium-binding proteins were synthesised with the use of pentafluorophenyl esters. Formation of a succinimide derivative was detected during synthesis of fragment (15-20) containing Asp(OBzl)-Gly sequence. To avoid this side process, tert-butylprotecting group was used instead of benzyl group. alpha-Carboxyls of C-terminal amino acids were protected by phenacyl group.

Biological Evolution↗
PubMed1987

[Synthesis of tetracontapeptide--a hypothetical evolutionary precursor of calcium-binding proteins. II. Condensation of fragments].

A tetracontapeptide was obtained by condensation of synthetic fragments (see the preceding paper) with the use of pentafluorophenyl esters as well as with carbodiimide and hydroxybenzotriazole. Racemization during fragment condensation was 1-2 per cent. Deblocking of the protected tetracontapeptide was carried out by treatment with trifluoroacetic acid and hydrogen fluoride with thioanisole. The obtained peptide was purified by gel-chromatography and HPLC.

Biological Evolution↗
PubMed1986

Optimized conditions for solid-phase sequencing: simultaneous chemical cleavage of a series of long DNA fragments immobilized on CCS anion-exchange paper.

A solid-phase method for simultaneous sequencing of ten or more long DNA fragments has been developed, using as support the cellulose matrix for chemical sequencing (CCS), anion-exchange paper [Rosenthal et al., Nucl. Acids Res. 13 (1985) 1173-1184]. We optimized several of the seven steps which include: (i) immobilization; (ii) washing; (iii) modification; (iv) washing; (v) sorting of the paper segments; (vi) piperidine reaction and chemical elution, and (vii) lyophilization. During carrier-supported chemical cleavage with dimethylsulfate (DMS) (G), HCOOH (A + G), KMnO4 (T greater than Pu) and NH2OH (C), losses of immobilized DNA are very low. DNA fragments ranging in length from several hundred bp up to 6 kb can be effectively chemically eluted from CCS paper during the piperidine reaction with an efficiency of more than 90%. Because no DNA salt elution and ethanol precipitation steps are necessary the method is rapid, convenient and allows complete automation.

Anions↗
PubMed1985

Effects of using liver fractions from different mammals, including man, on results of mutagenicity assays in Salmonella typhimurium.

Twenty chemicals, including 16 aromatic amines, were studied in the Salmonella/mammalian-microsome mutagenicity test using the bacterial strains TA100 and TA98 to compare the activation potential of liver preparations from several mammalian species. The hepatic post-mitochondrial supernatants (S-9 fractions) of rat, mouse, hamster, dog, monkey and man were used for metabolic activation. Striking quantitative and even qualitative differences were apparent in the capacity of the different preparations to activate the compounds to mutagens. All compounds that gave positive results in the Ames test when activated with a liver preparation from Aroclor-pretreated rats were also identified as mutagens when tested in the presence of S-9 from one or more other species. Four substituted anilines, however, were converted to mutagenic metabolites only in the presence of a post-mitochondrial fraction of hamster liver. Three human carcinogens, 2-aminoanthracene, benzidine and cyclophosphamide were detected as mutagens under various experimental conditions, including metabolic activation by human or monkey liver S-9. There were no qualitative differences in the mutagenic responses obtained in assays with human and monkey liver S-9.

Amines↗
PubMed1985

Studies on the design of animal tests for the corrosiveness of industrial chemicals.

Using a defined method for the determination of irritant and corrosive effects, the effects of varying the exposure time and the extent of occlusion were investigated and compared in rabbit skin experiments (by occlusive and semi-occlusive methods, each at exposure times of 1 hr and 4 hr). The results for 23 substances demonstrate that exposure for 1 hr normally leads to a realistic assessment of corrosiveness, in agreement with those given in the EEC 'Dangerous Substances Directive' (67/548/EEC; Off. J. Europ. Commun. 1967, 196, 1). With several substances, the 4-hr exposure leads to corrosive effects that do not occur under practical conditions. Moreover, a 4-hr exposure does not lead to a realistic hazard assessment in every case; some substances exhibit a corrosive effect in this test but are not classified as "corrosive" in the EEC Guideline Annex I, no. 1.1. Results using the semi-occlusive method did not usually differ from those obtained with the occlusive method. In general, the semi-occlusive method can be used, and in the case of volatile substances it is strongly advocated.

Animals↗
PubMed1985

Mutagenicity studies of a carcinogenic nitrofuran and some analogues.

Earlier studies showed a strong carcinogenicity of the nitrofuran compound 1,2-dihydro-2-(5'nitro-2'furyl)-3-hydroxy-quinazoline-4-one since carcinomas of the urinary bladder in rats and dogs appeared already after six months of treatment. In order to compare possible mutagenic properties of the compound and to get some information on the genotoxic moiety of the molecule, the genotoxicity of four nitrofuran derivatives and of two chemical analogues without the nitrofuran residue was tested in the Ames Test, E. coli WP2 uvrA, and in the rec-assay with Bacillus subtilis. 2-Nitrofuran was also included in this study. Only 2-nitrofuran and the nitrofuran containing derivatives were active in these bacterial test systems. Metabolic activation by liver homogenate was not needed to demonstrate the genotoxic effects. 1,2-dihydro-2-(5'nitro-2'furyl)-3-hydroxy-quinazoline-4-one was more active in the mutagenicity tests in the presence of exogenous metabolic activation. Further studies revealed that this compound was able to induce unscheduled DNA synthesis but was not mutagenic in the micronucleus test.

Animals↗
PubMed1984

[Hemispheric dominance for speech and calculation: electrophysiologic correlates of left dominance in left handedness].

Slow brain potentials were recorded in left-handers and right-handers during: (i) processing of language and mental arithmetic tasks, without vocalization, and (ii) subsequent writing down of the answers with either the right or left hand. Left-sided laterality of negative potentials was taken as evidence of hemispheric dominance. It appeared during the processing of words and numbers in 26 of the 30 left-handers and was localized mainly in the left frontal and temporal parietal regions. Similar results were found with the right-handers. This electrophysiological evidence indicates that the left hemisphere is dominant for language and calculation in the vast majority of left-handers. Only when writing with either their left or right hand do left-handers show less left-sided laterality than right-handers.

Adolescent↗
PubMed1984

Endocrinological aspects of obesity.

Throughout this review I have emphasized the role that nutrition plays in determining the endocrine abnormalities often found in obesity. There appears to be no consistent thyroid abnormality. Increased cortisol production and metabolism is found in obesity but is reversible with loss of weight. Androgen production is increased in females and can also be reduced with dieting. On the other hand, total serum testosterone is reduced in males, although free serum testosterone is normal in all but those who are severely obese. Various pituitary abnormalities have also been reported; some are reversible but others apparently are not, although extensive follow-up studies are not available to allow a clear distinction to be made between reversible and non-reversible abnormalities. Insulin resistance, a common feature of obesity, is due to receptor and postreceptor defects but again is a reversible phenomenon. Thus there is little to indicate that obesity depends on some underlying endocrine abnormality but much evidence to suggest that the endocrine changes are secondary to the abnormal nutritional state of the patient. This should be remembered when investigating any obese patient for suspected endocrine pathology.

Adrenal Glands↗
PubMed1983

Bacterial mutagenicity investigation of epoxides: drugs, drug metabolites, steroids and pesticides.

Although it has been observed that many epoxides are ultimate mutagens, surprisingly little is known about epoxides to which man may be extensively exposed, e.g., physiological compounds, drugs, drug metabolites and pesticides. We have now investigated 35 such and related epoxides for mutagenicity, using reversion of his- Salmonella typhimurium TA98 and TA100 as biological end-point. None of the tested steroids (12 compounds), vitamin K epoxides (3 compounds) and pesticides (dieldrin, endrin, HEOM (1,2,3,4,9,9-hexachloro-6,7-epoxy-1,4,4a,5,6,7,8, 8a-octahydro-1,4-methanonaphthalene), heptachlor epoxide) showed any mutagenic activity. Negative results were also obtained with the antibiotics oleandomycin, anti-capsin and asperlin, the cardiotonic drug resibufogenin, the widely used parasympatholytic drugs butylscopolamine and scopolamine, the sedatives valtratum, didovaltratum and acevaltratum, the tranquilizer oxanamide as well as with the drug metabolites carbamazepine 10,11-oxide and diethylstilbestrol alpha,beta-oxide. Three barbiturate epoxides, formed by metabolism of allobarbital, alphenal and secobarbital, caused weak but reproducible mutagenic effects at high concentrations. The cytostatic agent ethoglucide was the only drug having substantial mutagenic activity. Its mutagenic potency was similar to those of the control epoxides styrene 7,8-oxide, p-bromostyrene 7,8-oxide and m-bromostyrene 7,8-oxide, but much lower than those of benzo[a]pyrene 4,5-oxide, benzo[e]pyrene 4,5-oxide and 7,12-dimethylbenz[a]anthracene 5,6-oxide. Some epoxides were also tested in other Salmonella typhimurium strains or in the presence of rat-liver S9 mix. Positive results were only obtained with compounds that had already been detected as mutagens in the direct test with strain TA100.

Animals↗
PubMed1982

[Slow brain potentials in writing: the correlation between writing hand and speech dominance in right-handed humans].

1. Slow cerebral potential shifts were recorded from the scalp over both cerebral hemispheres by retrograde summation while 23 right-handers were writing. Averaging included writing errors, but eliminated eye movements and other artifacts. Repeated writing of the same word or sentence was compared to writing different dictated words, to drawings, and to other control experiments. 2. Surface negative readiness potentials (Bereitschaftspotential) appeared about 1 s before writing, which was similar to those preceding other voluntary movements. 3. During writing, the writing potentials in different cortical regions began with a negative increase of the Bereitschaftspotential, usually followed by a plateau or positive waves. One or several biphasic potentials persisted for another 2 s after writing had ceased. 4. The writing potentials had rather constant forms in the same individual, but showed large interindividual variations of form and polarity. The largest initial negativity (with both ear lobes serving as reference) occurred at the vertex and the left motor region contralateral to the writing hand. 5. The left hemispheric preponderance of writing potentials, maximal at the precentral region contralateral to the writing hand, was less marked when writing with the left hand. An interaction of the writing hand and language dominance is assumed. 6. Writing the same word or short sentence repeatedly caused potentials of larger amplitude than the preceding readiness potentials. Writing dictated words or drawing figures after verbal stimuli that require language processing caused larger potentials in the left hemisphere than did repeated word writing. 7. The fact that negative potentials with larger left hemispheric amplitudes appear after verbal stimuli may indicate that language information is processed in the speech-dominant hemisphere before and during writing or drawing. 8. By variously combining bipolar leads, the lateral differences of the potential fields can be more clearly distinguished than by using only unipolar leads with ear reference.

Adult↗
PubMed1982

[The influence of buprenorphine and tramadol on the postoperative CO2 response after general anaesthesia (author's transl)].

The degree of respiratory depression caused by buprenorphine and tramadol were studied in two groups of 25 patients each by means of Read's re-breathing technique. The estimations were made during the immediate postoperative stage in order to include potential residual effects of the general anaesthesia. The slope of the CO2 curve as a measure of respiratory depression decreased by 27 per cent after administration of 0.3 mg of buprenorphine, a reduction which equals that produced by potent morphine-type analgesics. The response to 50 mg of tramadol was a non-significant decrease by 3 per cent. At doses mentioned buprenorphine produced reliable pain relief, whereas with tramadol the failure rate was 28 per cent. There was no difference between the two drugs in respect of circulatory reactions and side-effects. Despite its depressing effect on the respiration (an action it shares with all potent analgesics) buprenorphine is a very useful analgesic because it provides excellent pain relief, has no or only minimal addictive properties and is not subject to the Dangerous Drugs Act.

Analgesia↗
PubMed1982

Postural support of goal-directed movements: the preparation and guidance of voluntary action in man.

Goal-directed movements, such as punching and pointing, need preprogramming of postural support and visual control. These processes are recorded in man by EEG, EMG, oculogram, and a platform. The earliest cerebral correlate of voluntary action is the Bereitschaftspotential (readiness potential) or, after a trigger signal, the expectancy wave (CNV). These bilateral negative potential shifts increase to a Zielbewegungspotential (aiming potential) when a goal-directed movement is made, and end with a positive shift, when the goal is reached. During these cerebral potentials an attentive eye saccade is directed towards the target and an ordered sequence of bilateral muscle activations follows. This coordinated motor activity in trunk and leg muscles corresponds to a readiness innervation that prepares body posture and balance. It precedes the final aimed movement of the arm towards the target and postural adjustments such as the compensation of body and head rotation by the vestibular-ocular reflex. The temporal order of the cerebral, oculomotor and muscular events is schematized for punching and pointing movements in a figure. The limits of conscious control and the necessity of automatized learning for voluntary skilled movement under visual control are discussed. Some speculations are made about a possible origin of slow potential shifts by surface negative dipoles in columnar modules of the parasagittal cortex during the programming and monitoring of aimed motion.

Arm↗
PubMed1981

Mutagenicity of structurally related oxiranes: derivatives of benzene and its hydrogenated congeners.

The mutagenicities of 17 closely related oxiranes were determined in 4 tester strains (Salmonella typhimurium TA98, TA100, TA1535, TA1537). The test compounds comprised all possible oxides of benzene and its partially hydrogenated congeners. In TA100 and TA1535, 12 of the tested oxiranes were weak to moderate mutagens. 4 of these were also active in TA98. No mutagenicity was observed with the remaining 5 compounds in any of the 4 strains. The presence of a double bond in formal conjugation with the epoxide ring increased the mutagenicity relative to that of the saturated oxirane. Interestingly, additional epoxide rings within the same molecule did not markedly increase the mutagenic activity, and for the oxiranes that are not activated by a double bond, the relationship between mutagenic activity and the number of epoxide rings in the molecule was even inverse. The influence of bromo and hydroxyl substitution on oxirane mutagenicity is discussed. Most notably, a compound having a 4-hydroxyl group in syn position to a 1,2-epoxide ring fused to the cyclohexane ring, a structure which has been suggested to increase the electrophilic reactivity of dihydrodiol epoxides through hydrogen bonding, was almost inactive.

Benzene Derivatives↗