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Biomedical subjects

I Ebels

Publications and source records attributed to I Ebels.

At least 55 records · Page 3Linked to original sources
PubMed1979

Preliminary characterization of bovine pineal prolactin releasing (PPRF) and release-inhibiting factors (PPIF) activity.

Bovine pineal glands were subjected to extraction with dilute acetic acid, gel filtration on Sephadex G-25 and subsequent ultrafiltration through Diaflo membranes PM10, UM2 and UM05. Various fractions derived at each step were tested for the presence of substances which stimulate or inhibit prolactin secretion in vitro and in vivo. Both prolactin releasing (PPRF) and release-inhibiting (PPIF) activities were observed. PPRF activity was present in certain fractions derived from Sephadex G-25 and in the PM10 residue (MW congruent to less than 10,000). Whereas both the UM2 residue (MW greater than 1000) and UM05 filtrates (MW less than 500) was seen to inhibit pituitary prolactin release in vitro, the UM05 residue (MW greater than 500 and less than 1000) inhibited prolactin release in vivo, possibly by stimulating the secretion of the hypothalamic prolactin inhibiting factor. On the basis of its inactivation by trypsin it was concluded that PPIF may be a peptide or contain a peptide moiety indispensible for its biological activity. Experiments are in progress to characterize pineal prolactin-regulating activities and to elucidate further the physiological role of the pineal gland in the regulation of prolactin secretion.

Animals↗
PubMed1979

A survey of some active sheep pineal fractions and a discussion on the possible significance of pteridines in those fractions in in vitro and in vivo assays.

Aqueous extracts of sheep pineals are separated on Sephadex G-25 fraction with antigonadotropic activity are ultrafiltered through the membrane UM 2. The UM 2 filtrate is subsequently filtered through the membrane UM 05. The actions of the different fractions on the anterior hypophysis and hypothalamus are discussed. The fractions which show an activity are further separated on Sephadex G-10. The active Sephadex G-10 fractions of the UM 05 filtrate acting on the anterior hypophysis in vitro are purified by electrophoresis and paper chromatography. After elution of different fluorescence bands the main inhibitory activity is found in a region, with the same Rf value as synthetic 6-biopterin. Gas liquid chromatography and mass spectrometry studies of the isolated fractions are carried out. The mass spectrum of an isolated compound from that fraction is identical with that of synthetic 6-biopterin. Thinlayer chromatography and the results of the Crithidia fasciculata test reveal that the isolated compound is probably identical with 6-L-erythrobiopterin. The activity of the active paper chromatography fraction (C4) is compared with the activity of three synthetic biopterin-preparations in vitro and in vivo.

Animals↗
PubMed1978

Location by paper chromatography of compensatory ovarian hypertrophy (COH) inhibiting activity in acetic acid extracts from bovine pineals.

Acetic acid extracts of bovine pineals and cerebral cortex were separated on Sephadex G-25 columns. Subsequently two low molecular weight fractions, F2 and F3, were ultrafiltered through the membranes UM2 and UM05. The UM05 residues were gel filtered on Sephadex G-15 columns or chromatographed on Dowex W50-X4 columns. Fractions from these columns were tested and those which showed COH-inhibiting activity were separated by preparative paper chromatography in different solvents. The absorption spectra of those fractions were recorded and tested for COH-inhibiting activity were separated by preparative paper chromatography in different solvents. The absorption spectra of those fractions were recorded and tested for COH-inhibition. By these methods, a COH-inhibitor was localized in three different solvents. Some active paper chromatography fractions were studied in high pressure, reverse phase, liquid chromatography. This latter method showed that the active fractions obtained by paper chromatography contain several orthophthlaldehyde (OPT) positive compounds. Key words: acetic acid, bovine pineal extracts, compensatory ovarian hypertrophy (COH), paper chromatography, high pressure, reverse phase, liquid chromatography.

Acetates↗
PubMed1978

Pineal peptides.

In pineal extracts several activities have been observed which cannot be explained on the basis of their content of melatonin or other pineal indoles to which an antigonadotropic activity is ascribed. The significance of structurally identified and unidentified substances is not fully understood. The list includes a neurohypophysial peptide, vasotocin (AVT), hypothalamic releasing factors and certain unidentified substances including the antigonadotropin under investigation in our laboratory. Our initial experiments demonstrated the presence of a non-melatonin antigonadotropin (PAG) in partially purified extracts of bovine, ovine, rat and human pineals. Purification by ion exchange chromatography and amino acid analyses have shown that this substance is not AVT. Recent purification studies include paper chromatography and high performance chromatography as final steps. It is concluded that if the active principle in a peptide, or contains a peptide moiety important for the biological activity, it may be present only in minute amounts in the puriest fractions derived and the quantities of recoverable material may be similar to those amounts of releasing factors recoverable from hypothalamic tissue. It is anticipated that large scale preparative methods will be required for structural determination. High performance chromatography may prove to be extremely useful in future studies.

Animals↗
PubMed1977

Separation of pineal extracts by gelfiltration. VI. Isolation and identification from sheep pineals of biopterin; comparison of the isolated compound with some synthetic pteridines and the biological activity in in vitro and in vivo bioassays.

Aqueous extracts of sheep pineal bodies were separated on Sephadex G-25. Two low molecular weight Sephadex G-25 fractions, F2 and F3, were ultrafiltrated through the Amicon membrane UM-2. The UM-2 filtrate was subsequently filtrated through the ultramembrane UM-05 and the UM-05 filtrate was separated on Sephadex G-10 columns. After paper electrophoresis, preparative paper chromatography was carried out. The fluorescent band showing a Rf value identical with synthetic 6-biopterin was eluted; gas liquid chromatography and mass spectrometry of the isolated compound were carried out. The mass spectra of the isolated compound were shown to be identical with synthetic 6-biopterin. The results of the Crithidia fasciculata test and thinlayer chromatography study revealed that the isolated compound is identical with 6-L-erythro-biopterin. The activities of the isolated compound and of synthetic biopterin in in vitro and in vivo bioassays are demonstrated.

Animals↗
PubMed1976

Separation of pineal extracts by gelfiltration. V. Location by paper chromatography of a sheep pineal principle inhibiting hypophyseal gonadotropic activity.

Previously we were able to isolate by simple and mild methods from an aqueous sheep pineal extract an inhibiting principle action on the anterior hypophysis of male rats in vitro. This substance could be located by paper electrophoresis. In the present paper we describe the further purification of this active principle by paper chromatography in two different solvents. In two regions possessing a special fluorescence an inhibiting factor of the gonadotropic activity of the anterior pituitary was found in vitro.

Animals↗
PubMed1976

Separation of pineal extracts by gelfiltration. IV. Isolation, location and identification from sheep pineals of three indoles, identical with 5-hydroxytryptophol, 5-methoxytryptophol and melatonin.

Aqueous extracts of sheep pineal bodies were separated on Sephadex G-25. A low molecular Sephadex G-25 fraction F4 was filtrated on Sephadex G-10. Several distinct peaks could be detected showing excitation and fluorescence maxima resembling those of indoles. A thinlayer chromatography study revealed that one Sephadex G-10 peak contained a spot identical with that of synthetic 5-methoxytryptophol, another a spot with the same Rf-values in different solvents as synthetic 5-hydroxytryptophol, while from a third peak a substance was isolated identical with synthetic melatonin. Mass spectra of the isolated compounds were recorded. These results are compared with those of previous isolation studies.

Animals↗
PubMed1976

Effects of some low molecular weight sheep pineal fractions and melatonin on different tumors in rats and mice.

With these preliminary experiments attention is drawn to a possible relation between tumor development and the pineal. The influence of melatonin and some low molecular weight pineal fractions on the growth and incidence of different experimental tumors was compared. Some pineal fractions which have an effect on the activity of hypothalamus on anterior hypophyses of male rats and mice in vitro may be active in some of these tumor models.

Animals↗
PubMed1975

Separation of pineal extracts by gelfiltration. II. Identification and isolation of two indoles from sheep pineal glands.

After separation of aqueous extracts of sheep pineal bodies and sheep cerebral cortex on Sephadex G-25, a high fluorescence peak showing an excitation maximum at 305 leads to 310 nm and a fluorescence maximum at 350 leads to 355 nm was observed in pineal extracts, which could not be detected in cerebral cortex extracts. Separation of this pineal fluorescence peak on Sephadix G-10 with water elution, followed by gradient elution of water and NaOH, gave rise to several highly fluorescent peaks. From one of these it was possible to isolate a substance with Rf-values, using thinlayer chromatographic, fluorescence and mass spectra studies, identical with synthetic 5-hydroxyindole-3-acetic acid. From another peak a substance, idential with synthetic 5-methoxyindole-3-acetic acid, could be isolated. The results are compared with those obtained in previous studies.

Animals↗
PubMed1975

Separation of pineal extracts by gelfiltration. III. Sheep pineal factors acting either on the hypothalamus, or on the anterior hypophysis of mice and rats in in vitro experiments.

Some compounds, other than melatonin, can be detected in aqueous extracts of sheep pineals, using in vitro bioassays. Mild and simple separation methods are used such as gelfiltration on Sephadex G-25, ultrafiltration through Amicon ultramembranes UM-2and UM-05, followed by gelfiltration on Sephadex G-10 and paper electrophoresis. Some fractions are acting on the hypothalamus, others on the anterior hypophysis of mice and rats. The results are compared with those obtained previously with different extraction and separation methods. Key words: Pineal extract, pineal activities in vitro experiments, hypothalamus, anterior hypophysis, paper electrophoresis.

Animals↗