ascorbic-acid and Endocrine-System-Diseases

Topics: Adolescent; Arrhythmias, Cardiac; Ascorbic Acid; Blood Transfusion; Child; Cholelithiasis; Deferoxamine; Endocrine System Diseases; Female; Folic Acid; Growth Disorders; Heart Failure; Hematopoiesis; Humans; Iron; Leg Ulcer; Liver Diseases; Male; Pericarditis; Splenectomy; Thalassemia; Vitamin E

Topics: Animals; Ascorbic Acid; Bacteria; Bone Diseases; Chemical Phenomena; Chemistry; Collagen; Collagen Diseases; Endocrine System Diseases; Glycosides; Humans; Hydroxylation; Hydroxylysine; Hydroxyproline; Isomerism; Peptide Hydrolases; Plants; Polyribosomes; Procollagen-Proline Dioxygenase; Proline; Protein Precursors

Topics: Adrenal Cortex Hormones; Animals; Ascorbic Acid; Castration; Endocrine Glands; Endocrine System Diseases; Female; Gonadal Steroid Hormones; Ovary; Rats; Thyroid Hormones; Thyroidectomy

Topics: Ascorbic Acid; Carnitine; Endocrine System Diseases; Fatigue Syndrome, Chronic; Humans; Killer Cells, Natural; Virus Diseases

Peptidyl glycine alpha-amidation activity has been detected in human plasma and in several human tissues known to synthesize biologically active alpha-amidated peptides. Activity was monitored by measuring conversion of mono-[125I]-D-Tyr-Val-Gly into mono-[125I]-D-Tyr-Val-NH2. The plasma alpha-amidation activity is dependent on molecular oxygen, copper, and ascorbic acid and appears to recognize a variety of peptide substrates which contain carboxyl terminal glycine residues. Kinetic analyses demonstrated Michaelis-Menten kinetics with a Km of 14 mumol/L for D-Tyr-Val-Gly. Based on gel filtration, the apparent molecular weight of the peptidyl glycine alpha-amidation activity in human serum is 60,000. The level of peptidyl glycine alpha-amidation activity in adult plasma (N = 17) was 106 +/- 3 pmol/mL/h (Mean +/- SEM) with no difference between male and female subjects (range 84 to 126 pmol/mL/h). In subjects under 15 years old (N = 10), mean plasma activity was 128 +/- 10 pmol/mL/h, higher than values for adult control plasma (P less than .05). In serum from hypothyroid adults (N = 13), mean serum activity was 141 +/- 11 pmol/mL/hr, higher than euthyroid controls (P less than .025). The most striking elevations in alpha-amidation activity occurred in plasma from patients with peptide-secreting tumors. Patients with medullary thyroid carcinoma (N = 19) had a mean plasma peptidyl glycine alpha-amidation activity of 142 +/- 52 pmol/mL/h (range 84 to 435 pmol/mL/h). The level of plasma alpha-amidation activity in one patient with metastatic carcinoid tumor was 560 pmol/mL/h.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adolescent; Adult; Aged; Ascorbic Acid; Child; Copper; Endocrine System Diseases; Enzyme Activation; Female; Glycine; Humans; Kinetics; Male; Metals; Middle Aged; Mixed Function Oxygenases; Multienzyme Complexes; Oxidoreductases Acting on CH-NH Group Donors; Oxygen; Peptides

Topics: Animals; Ascorbic Acid; Biological Assay; Chorionic Gonadotropin; Endocrine System Diseases; Evaluation Studies as Topic; Female; Humans; Hyaluronoglucosaminidase; In Vitro Techniques; Male; Neutralization Tests; Ovary; Rats; Tissue Extracts; Urine