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Biomedical subjects

L Duntas

Publications and source records attributed to L Duntas.

24 records · Page 2Linked to original sources
PubMed1990

Effects of TRH on pancreatic growth and secretion in rats.

Thyrotropin-releasing hormone (TRH) has been shown to be scattered throughout the gastrointestinal tract. High concentrations of TRH are reported in the pancreas of animals and humans. The present study was designed to investigate the pattern of pancreatic adaptation following chronic TRH administration in rats. Ten male Wistar rats were injected daily at 8.00 and 16.00 h with TRH (total dose of 6 mg/kg of body weight/day) via a chronic gastric fistula. Ten pair-fed control animals were injected with a saline solution. After 10 days, the rats were killed after an overnight fast; pancreatic wet weight, DNA, protein, amylase, trypsin, and lipase content were determined. Blood TRH levels were measured using a specific RIA (TRH antiserum K2B7, normal range of 30-80 fmol/ml). TRH increased pancreatic wet weight (+70%, p less than 0.01), DNA content (+83%, p less than 0.01), and protein content (+42%, p less than 0.05). Pancreatic enzyme concentrations (U/mg of DNA) were decreased (amylase, -81%; trypsin, -47%; lipase, -59%, p less than 0.01). Absolute rates of amylase discharge (U/mg of DNA) in vitro were reduced in TRH-treated rats (p less than 0.01) but the relative amount of basal and stimulated amylase discharge (% of total) was not influenced by TRH. Blood TRH levels were significantly increased (324 +/- 53 vs. 48 +/- 6 fmol/ml, p less than 0.01) 12 h after the last TRH administration. These data indicate that chronic TRH administration in rats induces pancreatic hyperplasia but decreases the pancreatic concentration of digestive enzymes.(ABSTRACT TRUNCATED AT 250 WORDS)

Amylases↗
PubMed1989

Method for rapid separation of 3,5,3'-triiodothyroacetic acid in human serum by fast protein liquid chromatography.

The 3,5,3'-triiodothyroacetic acid (TRIAC) has been approved as a valuable agent in the management of hyperthyroidism secondary to inappropriate secretion of thyrotropin. We have developed a fast protein liquid chromatography (FPLC) method for separation and quantification of TRIAC. Serum samples charged with TRIAC were extracted with methanol/ammonium acetate, the supernatants were evaporated to dryness, reconstituted in NaOH and injected on a reversed phase column for chromatography. For separation an isocratic elution method (methanol water; 0.1% trifluoroacetic acid) was used. The area under the curve (ml%) was compared with those of the calibration curves. Recoveries were 70 +/- 10.8%. TRIAC was eluted in 2.33 ml. Conclusively, the present method shows that TRIAC can be measured by FPLC and may be applied to the measurement of TRIAC in pharmacological studies.

Chromatography, High Pressure Liquid↗
PubMed1988

[Pharmacokinetics and pharmacodynamics of protirelin (TRH) in man].

Blood concentrations of thyrotropin-releasing hormone (TRH, Protirelin) were measured by a specific radioimmunoassay in 16 euthyroid subjects after intravenous (200 micrograms), nasal (2 mg) or oral (40 mg) administration of TRH. TRH blood levels peaked 2 min after i.v. administration (13,400 +/- 1,020 fmol/ml), 10 min after nasal (5,000 +/- 1,800 fmol/ml) and 150 min after oral (2,650 +/- 1,080 fmol/ml) administration. The degradation of TRH followed an exponential curve, giving a half-life of 6.5 min. The disappearance rate gave a "half-life" of 22 min in the nasal application group and of 31 min in the oral group. Maximal concentration of stimulated thyrotropin-stimulating hormone (TSH) always occurred 30 min after the peak TRH concentration without any correlation with the TRH concentration time integrals, suggesting that TSH secretion is dependent on a continually rising TRH blood level.

Administration, Intranasal↗
PubMed1986

[Acute factitious hyperthyroidism--moderate clinical symptoms in 3 cases under beta-blocker treatment].

The clinical and laboratory findings are described in three patients who ingested large amounts of L-thyroxine (two cases) and L-thyroxine together with L-triiodothyronine and who were treated with propranolol. Serum concentrations of thyroxine (maximum values 75 micrograms/dl, 64 micrograms/dl, and 20 micrograms/dl, respectively; normal range 4-12 micrograms/dl), triiodothyronine (maximum values 837 ng/dl, 453 ng/dl, and 566 ng/dl, resp.; normal range 80-180 ng/dl), reverse triiodothyronine (maximum values 235 ng/dl, 190 ng/dl, and 65 ng/dl, resp.; normal range 10-40 ng/dl) as well as free thyroxine equivalent and free triiodothyronine equivalent were monitored daily until they reached the normal range. Statistical analysis of the kinetics of these parameters indicated that the extreme thyroxine conversion was directed toward reverse triiodothyronine, partly due to the treatment with the beta-adrenergic blocker propranolol. The striking discrepancy between the high concentrations of the active hormones and the moderate clinical symptoms was most likely caused by peripheral effects of propranolol.

Adolescent↗