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Biomedical subjects

R L Sutherland

Publications and source records attributed to R L Sutherland.

175 records · Page 10Linked to original sources
PubMed1976

Quantitative estimates of cytoplasmic and nuclear oestrogen receptors in chick oviduct. Effect of oestrogen on receptor concentration and subcellular distribution.

(3H)Oestradiol exchange techniques were developed for the determination of specific oestrogen receptor site concentrations in the cytoplasm and nuclei of chick oviduct cells. Non-labelled, receptor-bound oestrogens were exchanged with (3H)oestradiol during a 24-h incubation at 20 degrees C, 2 h at 30 degrees C or 45 min at 3 degrees C. Both "soluble" and "insoluble" nuclear receptors were stable for at least 6 h at 30 degrees C and 3 degrees C but a proportion (approx. 30%) of cytoplasmic sites from withdrawn chickens were inactivated after 2 h at 20 degrees C. The magnum of 4-week-old immature chickens (weight = 15 mg) contained 0.20 pmol of oestrogen receptor which corresponds to 4275 receptor sites/cell, when it is assumed that all magnum cells have equal concentrations of receptor. In primarily stimulated chickens of similar age which had received 10x1 mg of oestradiol benzoate/day, the magnum weighed approximately 800 mg and contained 8.65 pmol of oestrogen receptor (4610 sites/cell). Withdrawal from primary oestrogenic stimulation for 3-6 weeks resulted in a 110 mg magnum which contained 1.20 pmol of receptor (2225 sites/cell). Oviducts from immature and withdrawn chickens had the majority (73-77%) of their oestrogen receptors sites in the receptor sites in the cytoplasmic fraction, while in primary stimulated chicken oviducts the majority (82%) of receptor sites were located in the nucleus. A single secondary injection of oestradiol, to oestrogen-withdrawn chickens, resulted in apparent translocation of cytoplasmic receptors to the nucleus during the first hour after injection. The magnitude of the decline in cytoplasmic receptor, and the concurrent increase in nuclear receptor concentration, was dose-dependent between 2 and 100 mug oestradiol/kg body weight. Larger doses of oestradiol up to 1 mg/kg did not increase the concentration of nuclear receptor above the maximum level seen at 100 mug oestradiol/kg. The initial rapid accumulation of nuclear receptor sites was followed by a period of progressive decline. The initial rapid accumulation of nuclear receptor sites was followed by a period of progressive decline. By 15 h after an injection of 100 mug oestradiol/kg, the concentration of nuclear sites had reached pre-injection levels. During the same time period, the depleted cytoplasmic receptor levels were replenished such that they reached control values by 12 h and were about 150% of the pre-injection level at 24 h.

Animals↗
PubMed1976

The transcapillary exchange of thyroid hormones and thyroxine-binding proteins between blood and tissue fluids.

A study has been made of the relative importance of potien bound and unbound hormone in the exchange of thyroid hormones between blood and interstitial fluid. 2. When [I] tyroxine (or thriiodothyronine) and [I] human serum albumin were injected simultaneously into the circulation of sheep with chronic lymphatic fistulae, the thyroid hormones were removed from the circulation and apperaed in all lymph samples at a greater fractional rate than human serum albumin. 3. The steady-state lymph/plasma concentrations ratios of the two specific thyroxine binding proteins were similar to each other and to those of albmin and total thyroxine. 4. Gel filtration studies indicated that the two specific thyroxine binding proteins, ovine serum albumin and human serum albumin, were all of similar molecular size. 5. Concentrations of unbound thyroxine in plasma and various samples of lymph from the one animal were similar. 6. Increasing the proportion of thyroid hormone that was unbound resulted in an increase rate of equilibration of labelled hormone between blood plasma and lymph. 7. Perfusion of the popliteal lymph node demonstrated that thyroid hormones were removed from lymph during its passage through the node. The amount removed was related to the proportion of hormone in the unbound state.

Animals↗
PubMed1976

The thyroxine-binding properties of rat and rabbit serum proteins.

The thyroxine (T4) binding properties of rat and rabbit serum proteins were studied using a gel equilibration technique, gel filtration and polyacrylamide gel electrophoresis. In both species two different T4 binding molecules were identified in whole serum and in Cohn fraction V preparations. Only one of these binding species demonstrated the characteristics of specific binding, i.e., high affinity for the hormone and binding site saturability. The mean (+/- SD) apparent association constants (ka) at 37 C for the specific binding proteins in whole rat and rabbit serum were 3.5 +/- 0.5 x 10(8)M-1 and 2.8 +/- 0.5 x 10(8)M-1, respectively. The mean T4 binding capacities of these proteins were 4.3 +/- 1.2 x 10(-6)M and 7.4 +/- 1.0 x 10(-6)M for rat and rabbit serum, respectively. Non-specific binding was due to serum albumin. Rat albumin (ka = 6.1 +/- 1.6 x 10(5)M-1, at 37 C) bound T4 significantly more strongly than did rabbit albumin (ka = 2.3 +/- 0.4 x 10(5)M-1, at 37 C) when it was assumed that there was only one T4 binding site/molecule of albumin. The ability of rat albumin to bind more T4 could also be explained by a greater number of T4 binding sites/molecule. Partial separation of the two T4 binding species was attained by gel filtration on Sephadex G200 columns. The specific binding protein of both rat and rabbit serum was eluted slightly later than the corresponding serum albumin. Polyacrylamide gel electrophoresis resulted in the separation of two distinct T4 binding peaks in the rat, but with rabbit serum clear separation of the two T4 binding molecules was not attained. In both species the specific binding protein migrated anodal to serum albumin.

Alpha-Globulins↗
PubMed1975

The thyroxine-binding properties of serum proteins. A competitive binding technique employing sephadex G-25.

A competitive binding technique is described for the estimation of the thyroxine (T4)-binding properties of serum proteins in dilute blood serum and lymph. When used in conjunction with an assay for total T4 the following parameters can be estimated: the number of functionally different T4 binding proteins, their individual association constants and binding capacities for T4, the amount of T4 which is bound to each binding species, and the concentration of unbound (free) T4. Both human and sheep serum have three functionally different T4-binding proteins. The association constants for the three human proteins were 9.5x10(9), 1.6x10(8) and 3.1x10(5) 1/mol for T4-binding globulin (TBG), T4-binding prealbumin (TBPA) and serum albumin, respectively. The corresponding sheep proteins, TBG, TBP-2 and albumin, had association constants of 8.9x10(9), 1-4 X 10(8) and 3.5x10(5) 1/mol. Human TBG had a mean binding capacity of 21.3 mug/100 ml and that of ovie TBG was 12.8 mug/100 ml. The other specific binding proteins (TBPA in man and TBP-2 in sheep) had mean binding capacities of 307 and 359 mug/100 ml respectively. Two functionally different T4-binding proteins were identified in rat serum.

Animals↗
PubMed1975

Effect of ionic strength and ionic composition of assay buffers on the interaction of thyroxine with plasma proteins.

When plasma proteins are diluted with buffer the ionic strength and ionic composition of that buffer affects the interactions between thyroxine (T4) and its plasma protein-binding sites. Increases in phosphate, chloride or barbiturate ion concentration from 50 to 200 mmol/l caused a significant decrease in the affinity of plasma proteins for T4, and a concurrent increase in the concentration of unbound T4. These results cannot be completely accounted for by changes in ionic strength since at the same ionic strength different anions caused quantitatively different effects on unbound T4 concentration. The degree of depression of T4 binding by the three anions studied was in the order barbiturate greater than chloride greater than phosphate. The results of a systematic study on the composition of diluent buffer systems indicated that when a 50 mM-sodium phosphate-100 mM-NaCl buffer (pH 7-4) was used as a plasma diluent, there were unlikely to be gross changes in the T4-binding properties of plasma proteins with dilution.

Barbiturates↗
PubMed1972

Soft contact lenses.

A series of 55 patients were fitted with a new type of hydrophilic soft contact lens. These were found more comfortable than hard contact lenses and they had a protective and pain-relieving action in cases of chronic corneal disease. Vision was not as good as with hard contact lenses and a greater potential danger of infection was found. They are preferred by many patients despite the noticeable thick edge and the difficulty of obtaining an identical replacement.

Adolescent↗