ABSTRACT
BACKGROUND AND PURPOSE: To determine the effect of curative radiation therapy (46-50 Gy) on the sex hormone levels in male rectal cancer patients. MATERIALS AND METHODS: Twenty-five male rectal cancer patients (mean age 65 years), receiving pelvic radiation therapy (2 Gyx23-25 fractions in 5 weeks) were included. Serum testosterone, FSH and LH were determined before start of treatment, at the 10th and 25th fractions, and 4-6 weeks after completed radiotherapy. The testicular dose was determined by thermoluminescent dosimetry. RESULTS: Five weeks of radiation therapy (46-50 Gy) resulted in a 100% increase in serum FSH, a 70% increase in LH, and a 25% reduction in testosterone levels. After treatment, 35% of the patients had serum testosterone levels below lower limit of reference. The mean radiation dose to the testicles was 8.4 Gy. A reduction in testosterone values was observed already after a mean dose of 3.3 Gy (10th fraction). CONCLUSION: Radiation therapy (46-50 Gy) for rectal cancer resulted in a significant increase in serum FSH and LH and a significant decrease in testosterone levels, indicating that sex hormone production is sensitive to radiation exposure in patients with a mean age of 65 years.
Subject(s)
Follicle Stimulating Hormone, Human/blood , Follicle Stimulating Hormone, Human/radiation effects , Luteinizing Hormone/blood , Luteinizing Hormone/radiation effects , Rectal Neoplasms/radiotherapy , Testosterone/blood , Testosterone/radiation effects , Aged , Dose Fractionation, Radiation , Estradiol/blood , Estradiol/radiation effects , Humans , Male , Middle Aged , Rectal Neoplasms/blood , Sex Hormone-Binding Globulin/metabolism , Sex Hormone-Binding Globulin/radiation effects , Thermoluminescent Dosimetry , Time FactorsABSTRACT
Purified rabbit and sheep sex hormone-binding globulins (SHBGs) were photolabeled by Delta 6-testosterone. The maximal levels of specific incorporation were respectively 0.33 and 0.30 mol of label/mol of homodimer. Tryptic cleavage of photolabeled SHBGs gave a single radioactive peptide for rabbit SHBG and two major radioactive peptides S1 and S2 for sheep SHBG. Edman sequencing of the photolabeled peptide of rabbit SHBG revealed a single sequence corresponding to peptidic fragment Leu-118-Lys-134. Subcleavage of this peptide with elastase led to a single radioactive peptidic fragment corresponding to dipeptide Met-133-Lys-134, identified by mass spectrometry, while deletion of the C-terminal residue with carboxypeptidase B showed that all the radioactivity remained on peptide Leu-118-Met-133, thus demonstrating that photolabeling occurred exclusively on Met-133, the only residue common to the two radioactive subcleaved peptides. Edman sequencing of peptides S1 and S2 of sheep SHBG showed a same single sequence corresponding to residues Gln-126-Arg-140 which contained no identifiable phenylthiohydantoin derivative at cycle 14, thus indicating that in both cases the corresponding Met-139 residue is the main site of photolabeling, as confirmed for peptide S1 by the presence at this cycle of a major peak of radioactivity while in peptide S2 the photoattachment of Delta 6-testosterone was found labile in the conditions of sequencing. The photolabeled peptide S1 was characterized by mass spectrometry which showed the covalent fixation of one mole of Delta 6-testosterone and the presence of a biantennary oligosaccharide attached at Asn-133, which suggests that the steroid-binding site is probably not deeply buried in the SHBG homodimer.
Subject(s)
Methionine/metabolism , Photoaffinity Labels/metabolism , Sequence Homology, Amino Acid , Sex Hormone-Binding Globulin/metabolism , Testosterone/analogs & derivatives , Amino Acid Sequence , Animals , Electrophoresis, Polyacrylamide Gel , Gamma Rays , Hydrolysis , Kinetics , Molecular Sequence Data , Peptide Fragments/chemistry , Peptide Fragments/isolation & purification , Peptide Fragments/metabolism , Photoaffinity Labels/pharmacology , Rabbits , Sex Hormone-Binding Globulin/chemistry , Sex Hormone-Binding Globulin/isolation & purification , Sex Hormone-Binding Globulin/radiation effects , Sheep , Testosterone/metabolism , Testosterone/pharmacology , Trypsin/metabolismABSTRACT
The purpose of "Vitamin" experiment is to study the efficiency of protective substances on three biological acellular systems aqueous solutions exposed to cosmic radiation in space. The first system "LDL" is a low density lipoprotein. The second is "E2-TeBG complexe" in which estradiol (E2) is bound to its plasmatic carrier protein, testosterone-estradiol binding globulin (TeBG). The third is "pBR 322", a plasmid. "Vitamin" experiment was accommodated in the Biopan which had been mounted on the outer surface of a Foton retrievable satellite. The experiment was exposed to space environment during 15 days. A stable temperature of about 2O degrees C was maintained throughout the flight. "Vitamin" experiment preliminary results are presented and discussed.
