Effect of artificial photoperiods on plasma thyroxine-binding prealbumin and retinol-binding protein in Japanese quail

Variations in thyroxine-binding prealbumin (TBPA) and retinol-binding protein (RBP) concentrations in plasma were determined in Japanese quail subjected to a shortened solar lighting cycle lasting 4 months of real time. The concentration of TBPA varied inversely with the length of daily photoperiod up to 15 h (correlation coefficient r = −0·99) when a minimum level was reached of about 50% of that obtained under short days consisting of 8 h light: 16 h darkness (8L : 16D). A slight reversal in the concentration of TBPA occurred with photoperiods in excess of 16 h. The time-lag in response of the cyclic change in TBPA after the change in the lighting cycle was 8 days. The concentration of holoRBP, on the other hand, showed little change with photoperiods <15 h, but between 15 and 17·5 h it passed through peak values which were 24% and approximately 10% higher than the initial concentrations in female and male birds respectively. Total immunoreactive RBP concentrations in plasma peaked similarly in females but in males the apparent changes were not significant. The molar ratio of the two proteins (TBPA: RBP) which form a 1:1 complex in plasma also changed inversely with photoperiod from 1·6 on short (8L : 16D) to 0·6 on long (16L : 8D) days. When the ratio declined below 1·0 it was noted that rapid growth of the gonads took place and when this ratio returned to > 1·0 regression set in. The changes in plasma TBPA concentration were examined in Japanese quail subjected to sudden changes in photoperiod from short (8L : 16D) to long (20L : 4D) days and vice versa. In the group of birds transferred from short to long days the plasma level declined significantly (P<0·05) within 3 days, whereas birds changed from long to short days were more refractory in that a significant increase was seen only after 30 days. The synthesis of TBPA in liver is closely controlled by photoperiod and it seems that this protein plays an important role in the peripheral distribution of thyroxine and perhaps also influences the cyclical supply of retinol to the gonads.

Changes in plasma concentrations of thyroxine binding prealbumin and retinol binding protein in Japanese quail after hatching

1. Male and female Japanese quail (Coturnix coturnix japonica) were reared under short daily photo-periods (8 h light-16 h dark) to inhibit sexual development with free access to food and water. Blood was sampled at frequent intervals for 13 weeks from hatching in order to monitor the developmental changes in plasma concentrations of the two proteins which are important in the transport of retinol, retinol-binding protein (RBP) and thyroxine-binding prealbumin (TBPA). 2. Measurements of body-weight, blood packed cell volume and plasma total protein concentration showed that the birds had a normal pattern of growth and haematological development. Plasma concentrations of TBPA, total immunoreactive RBP (IRBP) and holoRBP were 220, 60 and 45 micrograms/ml respectively in 1-d-old quail and rose to 430, 165 and 140 micrograms/ml at 14 d of age, which was 10 d after the corresponding change in total protein. Neither RBP nor TBPA concentrations were significantly different between the sexes during the 13 weeks, but there were minor fluctuations in concentration within relatively narrow limits.

The effects of crimping on the healing of prosthetic arterial grafts

The purpose of this study was to determine whether the crimping of arterial prostheses affected their healing. In ten dogs, 6 mm knitted Dacron grafts were implanted in the infrarenal aortas; 6 grafts were crimped, 4 uncrimped. Each was seeded with venous endothelium to produce a cellular lining. The grafts were removed a month after implantation and compared by light microscopy as to the (1) thickness of the inner lining, (2) completeness of endothelial healing, and (3) patterns of vasa vasorum. (1) and (3) were assessed using H & E sections and (2) by AgNO3 Häutchen preparations. The lining in uncrimped grafts was thinner and more uniform than in crimped grafts: 50.1 +/- 45.7 vs 263 +/- 183 mu, p < 0.001. While the completeness of healing was similar for both groups, 4 crimped grafts had unhealed areas in the centers of the crimps, corresponding to the thicker areas of the linings. In both kinds of grafts, vasa vasorum communicated with vascular channels parallel to the axis of flow and near the perigraft fat. In the uncrimped grafts, the smaller secondary vasa also were directed along the axis of flow, in contrast to crimped grafts in which they were circumferential to the graft and parallel to the crimps. In all instances vasa penetrated within 500 mu of the lumen. We conclude that crimping causes a change in the pattern of development of vasa vasorum in healing fabric grafts and a thicker inner lining associated with areas of delayed healing which may increase the risk of thrombosis.

The early changes in retinol-binding protein and prealbumin concentrations in plasma of protein-energy malnourished children after treatment with retinol and an improved diet

1. Changes in total retinol-binding protein (RBP), the holoprotein (holoRBP) and prealbumin (PA) concentrations have been monitored in plasma of thirty protein- and vitamin A-deficient preschool children from within a few hours up to 7 weeks after treatment with retinol and a good-quality protein diet. 2. The children were classified into groups according to nutritional status as having either kwashiorkor, marasmus-kwashiorkor or marasmus, and given formula diets whose protein and energy contents increased stepwise from 1 g and 105 kJ/kg body-weight respectively up to 4 g and 733 kJ/kg body-weight after 4 weeks. Retinol was administered in the forms of retinyl palmitate either orally or intramuscularly. 3. PA and total RBP were determined by electroimmunoassay procedures and the holoRBP by its fluorescence after separation from other plasma proteins. 4. RBP in plasma of the vitamin A-deficient child is largely denatured and incapable of binding administered retinol, which must first be taken up by the liver before native holoRBP is released. An increased pool of native apoprotein accumulates in the liver during vitamin A deficiency which is released into plasma quickly after retinol uptake to form peak concentrations of total and holoRBP approximately 3 h after dosing intramuscularly and 6 h orally. 5. The accumulated pool of RBP was highest in livers from the marasmus group and lowest in those from the kwashiorkor group, reflecting their relative capacities to synthesize plasma proteins. 6. The mean plasma concentrations of total and holoRBP for the various groups were minimal 24-48 h after dosing with retinol and then improved almost linearly over the following week. 7. Mean plasma PA concentrations of the various groups on admission were also in order of the severity of their malnutrition. There was little or no change in this protein concentration over the first 24 h after dosing with retinol, but thereafter the mean values rose almost linearly over 2 weeks. Albumin on the other hand changed little during the first week. The results show that PA is the more sensitive measurement of protein nutritional status.

Oral versus intramuscular vitamin A in the treatment of xerophthalmia

In a controlled trial 69 children with corneal xerophthalmia were given 200 000 IU oil-miscible vitamin A by mouth and a matched group of 45 children were given 100 000 IU water-miscible vitamin A intramuscularly. Both groups received an additional oral dose the next day. There was no detectable difference in the clinical response to the two regimes, even when analysis was limited to patients with concomitant diarrhoea or protein-energy malnutrition. Although serum-vitamin-A levels were significantly higher after parenteral than oral therapy, holoretinol-binding-protein levels were not. Oral administration of vitamin A is not only more practical but appears to be just as effective as parenteral administration in the treatment of severe xerophthalmia.

Seasonal changes in plasma retinol-binding holoprotein concentration in Japanese quail (Coturnix coturnix japonica)

1. Seasonal changes in retinol-binding holoprotein (holoRBP) concentration in plasma of groups of male and female Japanese quail (Coturnix coturnix japonica) were examined over 18 months. 2. In Expts 1 and 2 the birds were maintained under natural lighting conditions and in Expt 3 under artificial-light photoperiods corresponding to the changing daylength at 56 degrees N latitude. All groups were at 18-20 degrees and received Superlayers' (Rank Hovis McDougall) pellet diet. 3. The mean plasma holoRBP concentration in all groups changed in an annual cycle with minimal values in September-October and maximal values in February-April, when daylength or light photoperiod increased to more than 10 h. 4. The group mean values in the female cycle change 2-3-fold from 50-100 microgram/ml in late summer to 220-280 microgram/ml in the spring, whereas in the male the range is only 1.3-1.5 times, from 140-170 to 180-250 microgram/ml. 5. In the female the rate of egg laying was maximal in April-May and lowest in November-December. 6. The spring increase in plasma holoRBP reflects the increased vitamin A requirement of birds for reproduction and it is presumably under hormonal control. The wider amplitude in the female cycle compared with the male probably arises from the additional demand for the transfer of vitamin A into the eggs and hence the need for a higher initial secretion rate from the female liver to meet it.

Circannual changes in plasma concentrations of immunoreactive retinol-binding protein and luteinizing hormone in male and female Japanese quail

In a single experiment, lasting for 18 months, male and female quail were exposed to an annual cycle of artificial photoperiod synchronized with sunrise and sunset, and their plasma levels of immunoreactive retinol-binding protein (IRBP) and LH were monitored at frequent intervals. Plasma levels of both IRBP and LH showed a repeating annual cycle with maximal levels during the spring/summer, the period of reproductive activity and highest rate of egg-laying, and minimal levels during the autumn/winter. Plasma levels of IRBP and LH were significantly, but only weakly, correlated with each other. The possible role of LH in the regulation of plasma IRBP during reproduction is discussed. Evidence is presented that the proportion of IRBP which does not carry retinol (retinol-binding apoprotein; apoRBP) varies throughout the female breeding cycle and that the high apoRBP concentration noted in the spring/summer period may be related to the deposition of retinol in the egg.

Seeding arterial prostheses with vascular endothelium. The nature of the lining

Arterial prostheses seeded with autogenous vascular endothelium demonstrate a well-organized, cellular, inner lining. To determine the nature of the lining cells, six animals underwent replacement of the infrarenal aorta with Dacron prostheses. During the preparation of three such grafts, endothelium was scraped from the saphenous vein with a steel wool pledget, suspended in chilled Sack's solution, and mixed with blood used to preclot the graft. This suspension was omitted from the three control grafts. After six weeks, the grafts were removed, rinsed and examined. Fluorescent Factor VIII related antigen (F VIII-RA) strongly stained the lining cells. Silver nitrate Haütchen and electron microscopy preparations revealed a lining pattern characteristic of vascular endothelium. Endothelial cell-specific Weibel-Palade bodies were identified in the lining cell cytoplasm. Masson's trichrome staining revealed a relatively collagen-poor connective tissue within the seeded fabric. Transmission electron microscopy disclosed vascular smooth muscle cells between the seeded graft fabric and the lining cells. Vasa vasorum, arising from the outer capsule, penetrated the fabric to supply the inner capsules of the seeded grafts. It is concluded that the cells lining seeded canine arterial prostheses are true vascular endothelium supported by vascular smooth muscle cells, that the lining contains minimal connective tissue, and that vasa vasorum develop. Unseeded control grafts lacked these features.

Seeding endothelium onto canine arterial prostheses. The effects of graft design

To identify prosthetic characteristics that support the proliferation of an endothelial lining, 14 different graft designs were studied in dogs. The grafts were prepared by the use of a technique of endothelial seeding that we described previously. They were studied two and four weeks after their implantation. Weft-knit Dacron grafts (water porosity from 1,400 to 1,650 mL/min/sq cm) were the most successful. A velour index (velour stitch frequency times velour loop height) was computed. When the internal velour index (IVI) was greater than 60,000 loop-mu/sq cm, the percentage of clot-free surface was 17.2 +/- 14.5%, compared with 62.0 +/- 26.9% when the IVI less than 60,000 loop-mu/sq cm. Endothelium could be detected on 61.5% of the grafts when the IVI less than 60,00 loop-mu/sq cm, compared with 0% when the IVI greater than 60,000 loop-mu/sq cm. The cells that formed the outer capsule were better organized and more adherent to the graft when an external velour was present, but external velour did not affect the inner lining. We conclude that weft-knit Dacron grafts with water porosities from 1,400 to 1,650 mL/min/sq cm and with limited internal velour (IVI less than 60,000 loop-mu/sq cm) are suitable substrates for single-staged endothelial-cell seeding.

Seasonal changes in the plasma retinol-binding holoprotein concentration of sheep

1. Seasonal variations in plasma retinol-binding holoprotein concentration have been found in two groups of entire ewes and in a control group of wethers (castrated rams). 2. In each group retinol-binding holoprotein level was minimal in summer and increased to peak values in September just before the autumn breeding season.