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Biomedical subjects

F Bergmann

Publications and source records attributed to F Bergmann.

At least 91 records · Page 5Linked to original sources
PubMed1984

Effects of chronically elevated intake of different concentrations of saccharin on morphine tolerance in genetically selected rats.

Sixty-four LC2-Hi and LC2-Lo female rats were chronically supplied with either water or a solution of 1, 3 or 30 mM of sodium-saccharin. Pain sensitivity, as well as its reduction by a 2.5 mg/kg morphine injection, were measured in a hot-plate test. High saccharin consuming LC2-Hi rats did not exhibit significant morphine-induced analgesia (MIA) compared to baseline, after 38 days of drinking of saccharin, irrespective of concentration. MIA of those rats were maintained on water was significant. In contrast, the low consuming LC2-Lo animals maintained either on water or on 1 and 30 mM saccharin showed significant MIA compared to baseline, following the same exposure period. The findings demonstrate that chronically elevated saccharin intake, activates an endogenous opiate system leading ultimately to cross-tolerance to the analgetic effects of morphine.

Animals↗
PubMed1983

Dose effects of morphine on the spontaneous unit activity recorded from the thalamus, hypothalamus, septum, hippocampus, reticular formation, central gray, and caudate nucleus.

Spontaneous activity was recorded from 652 units in 8 subcortical structures of unanesthetized rats. Recordings were obtained in central gray, mesencephalic reticular formation, parafasciculus thalami, caudate nucleus, anterior and ventromedial hypothalamus, lateral septum, and dorsal hippocampus. Eighty recordings were obtained from untreated animals and 80 from saline-injected controls, none of which showed any significant changes of unit activity during the 4- 5-hr observation period. The effect of morphine, given in 5 incremental doses from 0.5 to 30.0 mg/kg ip, was followed in 492 units. Morphine enhanced or depressed spontaneous discharge rates, or caused biphasic effects, ie enhancement alternating with depression and vice versa. Naloxone induced increase in firing after either effect of morphine, or reduced spontaneous activity after morphine-induced increases. However, when morphine reduced neuronal discharges, naloxone never caused further depression. In 86 units, morphine at any dosage failed to alter neuronal activity, but in 54 of these units naloxone nevertheless induced alterations in firing rates. The pattern of responses to morphine differed between all 8 brain regions examined and was characteristic for each individual structure. This is the first systematic study describing the dose-response characteristics of morphine in 8 brain sites recorded simultaneously. Furthermore, it utilized freely behaving animals without the interference of anesthetics, which are themselves known to interact with opiates. The variety of response patterns seen supports the neuropharmacological evidence for multiple opiate receptors or multiple sites of opiate action.

Animals↗
PubMed1983

Improvement of skin flap survival by local injections of Regitine and propranolol. An experimental study in the rat.

An increase in the surviving area of skin flaps was achieved by local injections of alpha-adrenergic and beta-adrenergic blocking agents. Dorsal skin flaps of albino rats were injected postoperatively at their bases with Regitine (Ciba-Geigy, Switzerland), propranolol and a combination of these two drugs, two or three times daily for 6 days. All the pharmacologically treated animals showed a significantly better flap survival rate than did the control group (P less than 0.001). More frequent injections gave increasing flap survival areas. However, a combination of the above-mentioned drugs did not improve the results when compared with propranolol administered alone, and was less effective than Regitine administered alone.

Animals↗
PubMed1982

Stereotyped responses of rats to two 2-halogenoergolines: 2-bromo-alpha-ergocryptine and lergotrile.

Stereotyped responses to apomorphine, 2-bromo-alpha-ergocryptine (BEC) and lergotrile were compared in naive animals and after various pretreatments. Lergotrile was about half as effective as apomorphine in naive rats, while BEC produced intense stereotyped reactions only after pretreatment with p-chlorophenylalanine. Inhibitors of catecholamine biosynthesis (alpha-methyltyrosine and alpha-methyldopa) only impaired the response to BEC. Haloperidol, a dopamine antagonist, blocked the lergotrile-induced stereotypy within a few minutes, but had a rather slow effect on the response to BEC. It is concluded that lergotrile mainly activates dopamine receptors directly, similar to apomorphine. BEC, however, has a predominantly indirect effect, stimulating the formation and subsequent release of both dopamine and 5-hydroxytryptamine. The relationship of this difference in mechanism to the differences in structure is discussed.

Animals↗
PubMed1980

Growth disturbance following fracture of the tibia in children.

Orthoradiographs were produced from 13 to 36 months after tibial fractures in 85 children. Fifty-nine were complete i.e. tranverse or longitudinal, and 28 fractures were incomplete i.e. infractions or fissures. The difference in the length of the tibia from growth disturbance caused by the fracture was found to be related to the age of the child at the time of fracture and the sex. An overgrowth was found to occur in the age group from 3 to 10 years in girls and from 3 to 12 years in boys, whereas in the older children a growth retardation was demonstrated. No correlation with the type of fracture, or with the residual angulation after reduction, could be established. The growth disturbance appeared to last for 1 to 2 years. We conclude that a more concerned attitude towards residual shortening at the time of reduction should be adopted in girls from the age of 10 and boys from the age of 12 years in order to compensate for the growth retardation induced by the fracture.

Adolescent↗
PubMed1980

On the mechanism of action of 2-amino-4-methylpyridine, a morphine-like analgesic.

2-Amino-4-methylpyridine (2-AMP), when implanted into the ventral lateral thalamus of rats, does not cause stereotyped behavior. On the other hand, when compulsive biting and gnawing was evoked by thalamic implants of morphine (via stimulation of type 1 opiate receptors, which activate a dopaminergic mechanism) or of apomorphine, systemic application of 2-AMP suppressed this response. The anti-gnawing effect of 2-AMP was abolished by naloxone, indicating that the inhibitory action of 2-AMP involves activation of another, viz. type 2 receptor. The antagonistic influence of 2-AMP could also be suppressed by pretreatment of the rats with p-chlorophenylalanine. It is concluded that 2-AMP has only a weak effect on type 1 opiate receptors, linked to a dopaminergic mechanism, but it possesses high affinity to type 2 opiate receptors, which are connected with serotonergic pathways.

Analgesics↗
PubMed1979

Behavior of N-methylated allopurinols and related 4-thioxopyrazolo [3,4-d]pyrimidines towards bovine milk xanthine oxidase.

1. All available N-mono- and N,N'-dimethylallopurinols and the corresponding 4-thioxo derivatives have been tested as substrates or inhibitors of bovine milk xanthine oxidase (xanthine: oxygen oxidoreductase, EC 1.2.3.2). 2. None of the compounds tested revealed any inhibitory activity towards the enzyme. 3. All compounds were resistant to enzymic oxidation, with the exception of 7-methylallopurinol and its 4-thioxo analog. Both these compounds were attacked at position 6. 7-Methylallopurinol was oxidised nearly ten times faster than the isomeric 3-methylhypoxanthine. 4. These observations can be explained by assuming that for attack at C-6, the enzyme must bind both to N-1 and N-2 in the pyrazole ring and causes tautomerisation, which places a double bond at position 5,6 in the pyrimidine ring. This activation process resembles the activation of hypoxanthine.

Allopurinol↗
PubMed1978

Effects of propylbenzilylcholine mustard on injection into the liquor space of cats.

In unanaesthetized cats the effects were examined of propylbenzilylcholine mustard (PrBCM) on injection into the cannulated cerebral ventricles and cisterna magna. Extreme motor excitation, vocalization, shivering leading to fever, tachypnoea, panting, piloerection and salivation were produced on ventricular, vigorous scratching bouts on cisternal, injections. The sites of these actions are discussed. None of the effects was produced by atropine similarly injected. All effects were suppressed by anaesthetizing doses of pentobarbitone sodium injected intraperitoneally.

Animals↗
PubMed1977

Oxidation of hypoxanthines, bearing 8-aryl or 8-pyridyl substituents, by bovine milk xanthine oxidase.

1. Hypoxanthines, bearing at position 8 aryl or pyridyl substituents, are converted by bovine milk xanthine oxidase (xanthine: oxygen oxidoreductase, EC 1.2.3.2) into the corresponding xanthines at low rates. Oxidation is accelerated considerably when the 8-pyridyl substituents are quaternised. 2. In the enzymic oxidation of quaternary 8-pyridylhypoxanthines a lag phase precedes the attainment of a constant, maximal reaction rate. It is assumed that the delay is due to a relatively slow conformational change in the active enzymic center. 3. In 8-(3'-N-methylpyridinio)xanthine betaine, also the pyridinium moiety is attacked at high pH (9-11) to yield an N-methyl-2-pyridone. The analogous pyridone is the only oxidation product of 1-methyl-8-(3'-N-methylpyridinio)-hypoxanthine betaine, which is not attacked in the pyrimidine ring. 4. The cationic substrates are attracted to the enzyme by an anionic group, which probably forms an ion pair with a protonated amino group in or near the active center.

Animals↗
PubMed1977

Enzymic oxidation of 3-hydroxyxanthine to 3-hydroxyuric acid.

1. Bovine milk xanthine oxidase (xanthine:oxygen oxidoreductase, EC 1.2.3.2) oxidises 3-hydroxyxanthine slowly to 3-hydroxyuric acid; the 1-methyl derivative of 3-hydroxyxanthine is attacked about twice as fast. 2. The pH optimum for the reaction of 2-hydroxyxanthine is near 5, i.e. the neutral form of this substrate is attacked much faster than the anion. Probably in the "active" form of the latter, the negative charge is located mainly in the imidazole ring, thus inhibiting nucleophilic attack at C-8.

Animals↗
PubMed1977

Oxidation of methyl derivatives of pteridin-4-one, lumazine and related pteridines by bovine milk xanthine oxidase.

1. Pteridin-4-ones, methylated at nitrogen or carbon, N-methylated lumazines and related oxopteridines were studied as substrates of a highly purified bovine milk xanthine oxidase (xanthine : oxygen oxidoreductase, EC 1.2.3.2). 2. The enzyme can oxidise at high rates both uncharged and anionic substrates. Variation of enzymic activity with pH is mainly due to pH-dependent changes in the active enzymic center. 3. Milk xanthine oxidases at different stages of purification convert pteridin-4-one into the 4,7-dione (compound 13 in this article). 4. Methylation at C-6 in the pyrazine moiety enhances enzymic attack at C-2 in the pyrimidine ring. N-Methylation may increase or reduce rates of oxidation. 5. For oxidation at C-2, the most favorable form of the substrate bears a double bond at C(2) = N(3). Attack at C-7 is enhanced strongly in structures bearing a double bond at C(6) = C(7). 6. In general, pteridines react with xanthine oxidase as non-hydrated molecules. However, oxidation of 8-methyllumazine at C-7 may take place by dehydrogenation of the 7-CHOH group of the covalently hydrated molecule.

Animals↗