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Biomedical subjects

C H Irvine

Publications and source records attributed to C H Irvine.

At least 73 records · Page 4Linked to original sources
PubMed1975

Serum concentrations of FSH, LH and progesterone during the oestrous cycle and early pregnancy in the mare.

Heterologous radioimmunoassays were developed for equine FSH and LH. Serum concentrations were measured in twenty-three mares throughout the oestrous cycle and early pregnancy. FSH concentrations were raised fivefold by 'surges' rather than 'spiked', occurring at 10- to 11-day intervals during the oestrous cycle and early pregnancy. The late oestrous/early dioestrous surge of FSH appeared to initiate development of up to twenty follicles. The mid-dioestrous surge may be important for the further development of follicles destined to ovulate 10 to 13 days later. Levels of LH were increasing by the onset of oestrus and reached their maximum 1 to 2 days after ovulation. This rise in LH may stimuate maturation of the follicle throughout oestrus. An inverse relationship between progesterone and LH levels occurred, suggesting a negative feedback, but there was no such relationship between FSH and progesterone concentrations.

Animals↗
PubMed1975

Postnatal changes in total and free thyroxine and triiodothyronine in foal serum.

Total tyhroxine (TT4), free thyroxine (FT4), total triiodothyronine (TT3) and free triiodothyronine (FT3) concentrations in foal umbilical cord blood were respectively 14, 5 7 and 3 times the concentrations of these hormones in adult horse blood. The TT4 levels in foals declined rapidly to reach adult concentrations by Day 16 and FT4 levels declined steadily during the first 3 months of life. Foal TT3 levels rose during the first 10 hr after birth and thereafter declined, although they were still X2-5 higher than adult levels at 3 months of age. Levels of FT3 similarly increased after birth becoming X8 higher than adult levels at 3 days of age. They declined after this time but were still twice the normal adult levels at 3 months of age. Associated with these age changes were an increase in the free hormone percentage and a decrease in binding protein concentration. The very high levels of thyroid hormones in newborn foals may be responsible for their extremely high thermogenic capacity and rapid pre- and post-natal rates of growth, especially of the musculo-skeletal and nervous systems.

Age Factors↗
PubMed1974

Relative rates of transcapillary movement of free thyroxine, protein-bound thyroxine, thyroxine-binding proteins, and albumin.

The rate of appearance of labeled thyroxine (T4) and albumin in lymph from various areas after simultaneous i.v. injection of the labeled substances in conscious ambulatory sheep has been used to estimate the relative rates of transcapillary movement of stable T4 and albumin. Labeled T4 appeared in hepatic lymph at the same rate as albumin. In intestinal and leg lymph, labeled T4 appeared eight and four times as rapidly as albumin indicating that T4 crosses capillaries in these areas independently of and much more rapidly than albumin and other proteins having similar distribution kinetics. The lymph:plasma ratios for all the T4-binding proteins including albumin were very similar in any one area showing that the relative fractional rates of transcapillary movement of these proteins were very similar. Therefore in extrahepatic areas, transcapillary movement of T4 in the protein-bound form was quantitatively much less important than in the free form. The findings support earlier views, recently questioned, that free T4 is of considerable physiological significance.

Animals↗
PubMedDate not supplied

Structure of equine corticotropin releasing factor.

A 41 amino acid peptide, probably identical in structure to human corticotropin releasing factor, was isolated from 70 equine hypothalami by methanol extraction, immunoaffinity chromatography and single step of reverse phase HPLC. The amino acid sequence was determined by gas phase sequence analysis. Probable carboxyl terminal amidation was demonstrated by similar retention times for equine and human corticotropin releasing factor on reverse phase HPLC at pH 8. The likely structure of equine corticotropin releasing factor is: Ser-Glu-Glu-Pro-Pro- Ile-Ser-Leu-Asp-Leu-Thr-Phe-His-Leu-Leu-Arg-Glu-Val-Leu-Glu-Met-Ala-Arg- Ala-Glu - Gln-Leu-Ala-Gln-Gln-Ala-His-Ser-Asn-Arg-Lys-Leu-Met-Glu-Ile-Ile-NH2. The purified peptide is equipotent with human corticotropin releasing factor in an in vitro bioassay and in a human plasma binding protein assay.

Amino Acid Sequence↗