Biomedical subjects

K Seferiadis

Publications and source records attributed to K Seferiadis.

45 records · Page 3Linked to original sources

PubMed1992

A sensitive and specific competition microELISA for the immunoactive polypeptide parathymosin and detection of this peptide in porcine tissues.

A sensitive and specific microELISA assay is described for the immunoactive polypeptide parathymosin. Antibodies against a synthetic peptide corresponding to the rat parathymosin sequence 5-30 were raised in rabbits immunised with this peptide conjugated to keyhole limpet hemocyanin (KLH). The useful range of the assay was 0.25-30 pmol (3-330 ng) of parathymosin and the assay was specific. The related immunoactive polypeptides prothymosin alpha or thymosin alpha 1 showed no cross-reactivity. In spiking experiments the recovery of the assay was found to be greater than 92% at all concentrations tested. The intra-assay variation was 17%, whereas the inter-assay variation was 26%. Using this assay the highest concentration of parathymosin was found in porcine liver, followed by kidney, lung, thymus and spleen. This assay compares favorably with one microELISA and two RIA methods already published, in that it is more sensitive by at least an order of magnitude, and it is simpler and quicker.

Animals↗

PubMed1992

Appearance of thymosin alpha 1 in supernatants of monocytes incubated with prothymosin alpha.

Prothymosin alpha, a polypeptide of 109 to 111 amino acid residues, contains the entire thymosin alpha 1 sequence (residues 1-28) at its amino terminal. Human peripheral blood monocytes incubated with prothymosin alpha release thymosin alpha 1 in the culture supernatants. In addition total RNA is found to increase. The production of thymosin alpha 1 involves de novo protein synthesis as shown by the kinetics of this release and its inhibition by actinomycin D and cycloheximide. Thymosin alpha 1 release, possibly in association with HLA-DR, stimulates the proliferation of the T cell population.

Animals↗

PubMed1992

Positive feedback effect of oestradiol in superovulated women.

To investigate the mechanism of blockage of the luteinizing hormone (LH) surge in superovulated women, six normally ovulating women were studied in three cycles: a spontaneous cycle treated with exogenous oestrogen (oestradiol benzoate cycle), a cycle treated with follicle stimulating hormone (FSH; 225 IU/day; FSH cycle) and a cycle treated with FSH plus exogenous oestrogen (FSH + oestradiol benzoate cycle). Oestradiol benzoate was injected i.m. on cycle days 4 (0800 and 2000 h), 5 (0800 h) and 6 (0800 h) at doses of 0.5, 1.0, 2.0 and 2.5 mg respectively to achieve supraphysiological levels of serum oestradiol. Exogenous oestrogen (supraphysiological oestradiol levels) induced an LH surge in all six women in the oestradiol benzoate cycles, but failed to stimulate an LH surge in three of the six patients during treatment with FSH. In three patients treated with FSH, an LH surge was stimulated both by supraphysiological (FSH + oestradiol benzoate cycles) and 'high normal' oestradiol levels (FSH cycles), while in three patients treated with FSH only, the LH surge was blocked, although the threshold level for the positive feedback effect had been exceeded by cycle day 9. We conclude that in women, supraphysiological concentrations of oestradiol exert a positive feedback effect on LH secretion. It is suggested that the occurrence of an LH surge in cycles superovulated with FSH is not dependent on serum oestradiol concentrations, but mainly on the strength of ovarian inhibitory substances.

Estradiol↗

PubMed1991

Isolation and partial sequence of goat spleen prothymosin alpha.

Goat prothymosin alpha, a highly acidic polypeptide of pI3.5, 109 amino acid residues, has been isolated from lymphoid and non-lymphoid tissues of young female goats. Unlike rat, murine and porcine prothymosins alpha, goat prothymosin alpha appears at a higher concentration in the spleen compared with the thymus. The sequence of segments of the polypeptide involving known mutations has been determined, by automatic sequencing of its tryptic peptide fragments. The acidic amino acid-rich segment in the middle of the molecule, including residues 49-83, has not been sequenced. Goat prothymosin alpha closely resembles bovine prothymosin alpha, with only one substitution, proline for alanine at position 85. It also resembles human prothymosin alpha, with only three substitutions. It differs more significantly from rat and murine prothymosins alpha, by two deletions and three substitutions. The results show the highly conserved nature of the molecule, with substitutions at given positions only.

Amino Acid Sequence↗

PubMed1990

Enhancement of human T lymphocyte function by prothymosin alpha: increased production of interleukin-2 and expression of interleukin-2 receptors in normal human peripheral blood T lymphocytes.

The in vitro incubation of phytohemagglutinin (PHA)- or alloantigen-stimulated peripheral blood T cells with prothymosin alpha (ProT alpha) resulted in a marked and reproducible increase in the production of interleukin-2 (IL-2). Incubation of T cells with ProT alpha, in the absence of PHA or alloantigen, failed to induce any production of IL-2. ProT alpha by itself did not exert any IL-2 activity. Finally, ProT alpha was shown to increase the expression of IL-2 receptors on phytohemagglutinin- or alloantigen-activated T cells. These data provide the basis for understanding the in vitro immunoenhancing effects of ProT alpha in cellular immune systems.

Adult↗

PubMed1989

Circulating antibodies to prothymosin alpha in systemic lupus erythematosus.

Autoantibodies to prothymosin alpha, an immunoactive protein that exists in a large variety of mammalian tissues, were found to be present in patients with systemic lupus erythematosus (SLE) by a new, sensitive, and specific anti-prothymosin alpha ELISA. The antigen was prothymosin alpha, purified by high-pressure liquid chromatography from goat spleen extracts. Sera from 44 SLE patients and 276 healthy individuals were screened for the presence of anti-prothymosin alpha activity; 18% of SLE sera were found to be positive, compared with 1.8% of control sera. This anti-prothymosin alpha activity appears to be idiotypically distinct from either anti-thymosin alpha 1 activity or anti-dsDNA activity, as demonstrated by inhibition experiments. Significant positive correlation exists between anti-prothymosin alpha and anti-dsDNA activities of SLE sera (r = +0.596, n = 36, P less than 0.001), while no correlation was observed with the clinical activity (X2 = 1.239, 0.1 less than P less than 0.5) or with complement levels C3 and C4.

Antibodies, Antinuclear↗

PubMed1988

Isolation and partial characterization of prothymosin alpha from porcine tissues.

Prothymosin alpha, an immunoactive polypeptide of 12 kDa, has been isolated from porcine thymus, spleen, lung and kidney. It lacks aromatic and sulfur-containing amino acids and has a high content of glutamic and aspartic acids. Tryptic digestion of porcine thymus prothymosin alpha yielded peptides which on separation, amino acid analysis and alignment with the known sequence of prothymosin alpha from rat and man showed that the amino terminal portion of the molecule is conserved and the few differences present are confined to the carboxy terminal.

Amino Acid Sequence↗

PubMed1985

Selenium and haemodialysis: serum selenium levels in healthy persons, non-cancer and cancer patients with chronic renal failure.

In 40 healthy persons, 11 nondialyzed uremic patients and 27 dialyzed uremic patients, of whom 4 also had cancer, the selenium concentration in serum was determined. The mean serum selenium concentration in healthy persons was 13.6 +/- 0.8 micrograms/dl, in nondialyzed patients 11.9 +/- 1.9 micrograms/dl and in dialyzed uremic patients 11.3 +/- 1.0 micrograms/dl. There was a significant statistical difference between healthy persons and uremic patients (p less than 0.001), but not between dialyzed and nondialyzed uremic patients. The subgroup of cancer patients on hemodialysis also had low serum selenium concentrations. The possible role of low selenium levels as one of the factors responsible for the increased incidence of malignancy in patients with chronic renal failure is supported by several facts such as: low serum selenium levels detected in patients with malignant diseases; the higher cancer incidence in inhabitants of low-selenium areas, and the known ability of selenium to inhibit many types of experimental carcinogenesis.

Adolescent↗

PubMedDate not supplied

Quantitation of HBF gamma-chain types by HPLC in patients with myelodysplastic syndrome.

High levels of HbF were found in patients with myelodysplastic syndrome (MDS), as well as a possible switching of the ratio of the gamma chains from the adult to the newborn type in 25% of our patients. These abnormalities in general were not present in the parents. The possibility of having thalassemia or other hemoglobinopathies was excluded. The fetal hemoglobin percentage was quantitated by alkali denaturation of the hemolysate, and the gamma chain content was determined in blood hemolysate by HPLC following HbF isolation. A 7/3 ratio of fetal Gy/Ay was found in three patients. Since the survival of MDS patients with high HbF levels was longer than that of patients with low levels of HbF, this finding may be used as a potential prognostic factor.

Adult↗