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Biomedical subjects

R Maier

Publications and source records attributed to R Maier.

At least 127 records · Page 7Linked to original sources
PubMed1982

Identity of calcitonin extracted from normal human thyroid glands with synthetic human calcitonin-(1-32).

Calcitonin in human thyroid glands obtained at autopsy from normal subjects were extracted with 2 M acetic acid. The extracts were additionally purified by adsorption to Sep-Pak C18 cartridges, and calcitonin was identified after gel filtration analysis, reverse-phase high-performance liquid chromatography (HPLC), thin-layer chromatography and isoelectric focusing. The purification steps were monitored by radioimmunoassay, and partially purified calcitonin was used for biological and physicochemical comparison with synthetic human calcitonin-(1-32) and its Met8-sulfoxide form. On gel filtration analysis a predominant peak coeluted with the synthetic hormone, and on HPLC two discrete peaks with the retention times of monomeric and dimeric human calcitonin were found. Thin-layer chromatography allowed the detection of two peaks with the Rf of human calcitonin-(1-32) and of its sulfoxide, respectively. The pI (7.9) of the predominant peaks of synthetic calcitonin were identical. Our findings provide strong evidence that the predominant forms of human calcitonin extracted from normal thyroid glands correspond to synthetic calcitonin-(1-32) and to dimeric calcitonin.

Calcitonin↗
PubMed1981

Modification of spectinomycin. 2. Derivatives of 4-dihydro-4-deoxy-4(R)-aminospectinomycin.

Acyl derivatives 5a approximately j and alkyl derivatives 7a approximately r of 4-dihydro-4-deoxy-4(R)-aminospectinomycin (1a) were prepared and tested for antibacterial activity. Only acyl compounds derived from long chain aliphatic acids showed activity in vitro, but were inactive when tested in vivo. All alkyl derivatives were active in vitro. In vivo however only the short chain derivatives 7a approximately c were active. Compound 7b showed higher activity than spectinomycin.

Bacteria↗
PubMed1981

[Postnatal developmental changes in the posterior cranial fossa area. I. Facies posterior partis petrosae (porus et meatus acusticus internus, fossa subarcuata, apertura externa aqueductus vestibuli, apertura externa canaliculi cochleae)].

1. In the newborn the lateral edge of the internal acoustic pore is located about 13.3 mm, in the 2-year-old about 22.5 mm and in the adults about 28.5 (22 to 34) mm from the paramedian plane of the skull. Also the mean distance from the lateral wall of the skull increases from about 13 to 30 mm in the postnatal period. 2. Without the postnatal development of height and width of the internal acoustic pore the postnatal extension (from a mean value of 5 mm in the newborn to about 10 mm in the 15- to 17-year-old) also the postnatal development of height and width of the internal acoustic meatus were measured. 3. Size, width and position of the subarcuata fossa, the external aperture of the aqueduct of the vestibulum just as the external aperture of the cochlear canaliculus were determined. The results were discussed in detail with the datas of former investigators.

Adolescent↗
PubMed1980

[Treatment with thyroid hormones with special reference to coronary disease].

Since thyroid hormones in a particular degree increase the need of oxygen of the heart, in a present coronary heart disease must be differentiated between the advantages of a treatment with thyroid hormones and the disadvantages of a deterioration of the angina pectoris and the dangers of a myocardial infarction, respectively, which are to be expected by this. In general one will be reserved with a thyroxine therapy in patients with a bland struma and coronary heart disease. In hypothyreotic patients one has to find out the individual optimum dosis, in which cases all the cardiological measures for the treatment of the coronary heart disease must be used. This optimum dose is a compromise between the inconveniences of the hypothyreosis and the danger of the coronary heart disease. Often a slightly hypothyreotic metabolic condition must be kept, in order not to endanger the patient.

Animals↗
PubMed1979

The pharmacology of diclofenac sodium (Voltarol).

Diclofenac is a potent anti-inflammatory and analgesic compound with good antipyretic and uricosuric properties. It is one of the most potent inhibitors of prostaglandin synthetase known. It shows a favourable therapeutic ratio considering its efficacy, and proved superior to the reference drugs in terms of gastro-intestinal tolerability. All metabolites are clearly less potent than the parent compound.

Analgesics↗
PubMed1978

Epstein-Barr virus infections in the X-linked recessive lymphoproliferative syndrome.

Prospective studies demonstrated variable phenotypic expression of the X-linked recessive lymphoproliferative syndrome (X.L.R.L.S.) in three brothers: (1) hypogammaglobulinaemia and subclinical Epstein-Barr-virus (E.B.V.) infection with antibody response to E.B.V.; (2) E.B.V. infection with defective immune response to E.B.V., fatal infectious mononucleosis (I.M.), and immunoblastic lymphoma; and (3) histiocytic lymphoma. Hypogammaglobulinaemia and measles pneumonitis had preceded infection with E.B.V. The diverse phenotypic expressions probably resulted from the varied immune response to E.B.V. Recombination of X chromosomes was documented by Xg-blood-group studies in a survivor. E.B.V. can induce fatal I.M. and malignant lymphoma in X.L.R.L.S., but an immune response to E.B.V. can be protective.

Adolescent↗
PubMed1977

[Metabolism of the sulphated glycosamino-glycans of skin, cartilage and bone of rats with adjuvant arthritis (author's transl)].

The time course of the quantitative changes in connective tissue of non-inflamed dorsal skin and of inflamed hind limbs was investigated by means of radioactively-labelled sulphate. Whereas the rate of incorporation of 35SO4 into the skin is reduced, its turnover in the inflamed tissue is greatly accelerated. This increase is observed both in the soft (cartilage) and hard (bone) connective tissue on both hind legs. The citric acid content of affected bone is lower than in healthy animals.

Animals↗
PubMed1977

Biological activities of ACTH-analogues varied in the active site.

The steroidogenic and lipolytic activities of corticotrophin-(1-24)-tetracosapeptide and [Lys17,18]corticotrophin-(1-18)-octadecapeptide amide were compared with those of corresponding analogues substituted in position 8 with norarginine and homoarginine, and in position 9 with phenylalanine and pentamethylphenylalanine. The norarginine containing analogues demonstrated a rewarding activity, although they were generally somewhat less active than the homoarginine containing compounds. This confirms the previous conclusions concerning the indispensability of arginine as a guanidinium derivate. The analogues in which phenylalanine was a substitute for tryptophan, constituted partial agonists with a low activity in steroidogenesis and lipolysis but a rather high melanophore stimulating activity. Insertion of the permethylated derivative of phenylalanine in this position, which ensures the presence of an aminoacyl residue with the full electron donor properties of tryptophan, destroyed the low steroidogenic and lipolytic activity, but increased the MSH-activity about 2-fold.

Adrenal Glands↗
PubMed1977

Differences between in-vitro and in-vivo potencies of corticotrophins: an interpretation in terms of metabolic stability.

Relative activities of a series of corticotrophin analogues have been measured by means of five different bioassays using the rat. Similarities in the relative potencies of various ACTH analogues determined using lipolysis or steroidogenesis in vivo and for the lipolytic and steroidogenic responses of fat pads and adrenal slices in vitro emerged and support the concept of a close structural relationship between the ACTH receptors in adipose and adrenal tissues in the rat. Potencies based on the steroidogenic response of isolated adrenal cells, adrenal slices or in-vivo experiments differed markedly from each other. Inactivation of peptides did not occur in the isolated cell assay, so it is likely that this assay estimates potency at the receptor level. A number of arguments suggest that the difference between the isolated cell assay and the other steroidogenic assays lies solely in the effects of peptide inactivation in the latter, and this allows the relative metabolic stabilities for the peptide analogues in these assays to be calculated. In this way it can be shown that: (1) Replacement of L-Ser by D-Ser in amino acid position 1 markedly increases the metabolic stability of the peptide and has only a slight effect on receptor properties. (2) Shortening at the NH2-terminus reduces the activity of peptides at the receptor level by several orders of magnitude, but increases their relative metabolic stability. (3) Introduction of amide groups at the CO2H-terminus markedly increases receptor potency of (1-16), (1-17) and (1-18) ACTH without affecting their metabolic stability in vivo. However, amidation of the CO2H-terminus does have a large effect on metabolic stability in the adrenal slice assay. (4) Replacement of Arg by Lys in positions 17 and 18 of (1-18) ACTH increases potency at the receptor level (adrenal cells) but has little effect on metabolic stability. The comparison of potencies obtained in the various assays, therefore, throws light on the significance of each assay. In addition, the effects of structural modification of analogues can be separately evaluated with respect to the metabolic stability of a peptide and its potency at the receptor level.

Adrenal Cortex Hormones↗
PubMed1977

Analogues of human calcitonin. V. Influence of basic amino acids in positions 11, 17 and 24 on hypocalcaemic activity in the rat.

The influence of positions 11 and 24 on hypocalcaemic potency and duration of action was examined. These positions are respectively occupied by threonine and glutamine in HCT, but by the basic amino acids lysine and arginine in SCT. Replacement of threonine by lysine trebled the hypocalcaemic potency of HCT and slightly prolonged its duration of action. Substitution of arginine for glutamine reduced the activity to about one tenth. The simultaneous introduction of both basic amino acids yielded an analogue intermediate in activity between those obtained by the single substitutions. The analogue [Bmp1, Va18, Lys11, Arg24]-HCT displayed the same effects as [Lys11]-HCT.

Amino Acid Sequence↗
PubMed1976

Influence of the assay conditions on the lipolytic potency in vitro of different adrenocorticotrophins.

The lipolytic activity of ACTH-(1-39) and ACTH-(1-24) in vitro has been compared on a molar basis in assays performed with both adipose-tissue slices and isolated fat cells. In the tissue-slice assay ACTH-(1-24) displayed 29% of the potency of ACTH-(1-39), whereas in the isolated-cell assay, ACTH-(1-24) was 3.9 times more potent than the longer peptide. This discrepancy seems to be due to the fact that ACTH-peptides are inactivated in the adipose-tissue-slice assay, but remain stable in the isolated-fat-cell assay. ACTH-(1-24) is inactivated more rapidly than ACTH-(1-39). Pre-incubation and washing of the tissue slices removes the inactivating principle, which most likely consists of peptidases, and their responsiveness is increased, so that both ACTH-peptides display similar lipolytic activity to that seen in the isolated-cell system. Comparison of the responsiveness of isolated fat cells and isolated adrenal cells indicates that the affinity of ACTH for the receptor of adrenal cells is approximately 100 times greater than its affinity for the fat-cell receptor.

Adipose Tissue↗
PubMed1976

Analogues of human calcitonin. IV. Influence of leucine substitutions in positions 12, 16 and 19 on hypocalcaemic activity in the rat.

The replacement of the three aromatic amino acids in positions 12, 16 and 19 of human calcitonin (HCT) by leucine residues, which occupy the corresponding positions, in ultimobranchial, e.g. salmon and eel, calcitonins, increased the hypocalcaemic potency of the peptide, as determined by bioassay on the rat, about 10-fold. The individual substitutions were not all equally augmentative: leucine (12) enhanced the activity of HCT about 4--5 times, but leucine (16) and (19) afforded no increase at all. Combination of leucine (12) with a deamino cysteine at the N-terminus yielded an analogue 10 times more potent than HCT. Another analogue containing valine in position 8 in place of methionine as well as the three leucine substituents in position 12, 16 and 19 proved more active than the tri-leucine analogue, but the additional introduction of tyrosine (22) nearly doubled the hypocalcaemic potency of the latter. The duration of the hypocalcaemic effects of the substituted peptides closely followed the changes in potency.

Amino Acid Sequence↗