Plasma vitamin A composition and retinol-binding protein concentration during egg formation in laying hens

Blood plasma vitamin A composition (retinol, retinyl ester) and retinol-binding protein (RBP) were determined in three phases (empty; soft- and hard egg) of the egg formation period in laying hens. The retinyl ester level remained in the range of 6 to 11% of the total plasma vitamin A concentration during egg formation. The retinol and RBP increased significantly during the time of soft period. The molar ratio between retinol and RBP ranged between 0.72-0.77. The increase of retinol and RBP may be caused by the sexual steroid effect for satisfying the retinoid needs of the ovarium and shell gland (avian uterus).     

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.     

Serum zinc, retinol and retinol-binding protein levels in cirrhotics with hypogonadism

Levels of serum zinc, retinol and retinol-binding protein (RBP) were measured in 16 male hypogonadal cirrhotics and compared with 13 male cirrhotic patients without evidence of hypogonadism. Their ages ranged from 20 years to 76 years with a mean of 40.06 +/- 15.6 years (+/- s.e.m.) while non-hypogonadal patients had an age range of 30-55 years with a mean of 41.23 +/- 7.2 years. Mean testicular volume for hypogonadal patients was 6.69 +/- 3.5 cm3 (+/- s.e.m.) while for non-hypogonadal ones it was 12.15 +/- 6.0 cm3. Mean serum zinc level in hypogonadal patients was 4.43 +/- 0.05 mumol/l which was significantly lower than for those without hypogonadism (6.8 +/- 0.09 mumol/l). Similarly serum retinol was lower in hypogonadal patients (0.40 +/- 0.07 mumol/l) than in patients without hypogonadism (0.53 +/- 0.12), although this difference was not statistically significant. RBP was also lower in the hypogonadal patients (0.79 +/- 0.49 mumol/l) than in those without (1.36 +/- 0.74 mumol/l, P less than 0.05). It is concluded that hypogonadal cirrhotics have lower levels of serum zinc and RBP than those without hypogonadism. These deficiencies may contribute to the genesis of hypogonadism in cirrhosis of the liver and supplementation of zinc alone or with vitamin A early in the disease may retard the development of this feature of the disease.     

Serum retinol and retinol-binding protein levels do not predict subsequent lung cancer

Retinol and retinol-binding protein levels were measured in sera previously obtained, and stored in the frozen state, at multiphasic health checkups from 151 persons subsequently found to have lung cancer (cases) and 302 persons who remained free of cancer (controls). Two controls were matched to each case for sex, skin color, age, date of multiphasic health checkup, and aspects of the smoking habit. Mean levels in cases and controls were, respectively, retinol: 82.17 and 82.37 micrograms/dl (p = 0.93), and retinol-binding protein: 6.04 and 6.00 mg/dl (p = 0.81). Mean differences between cases and controls were, retinol: 0.195 micrograms/dl with 95% confidence limits, -3.91 and 4.30 micrograms/dl; retinol-binding protein: -0.033 mg/dl with 95% confidence limits, -0.31 and 0.24 mg/dl. No significant trend in relative risk of lung cancer was observed when the retinol or retinol-binding protein distribution was divided into quintiles. No significant associations were observed in subgroups based on age, sex, histologic type of cancer, cigarette consumption, or interval between blood drawing and cancer diagnosis. In this large study, retinol and retinol-binding protein levels were not useful in predicting the subsequent development of lung cancer.     

Significance of postprandial blood concentrations of retinol, retinol-binding protein, and carotenoids when assessing the vitamin A status of children

The effect of ingesting a breakfast rich in vitamin A on postprandial blood serum concentration of retinol, retinol-binding protein, and carotenoids has been investigated in children between 5 and 8 yr of age. They were divided by age in two groups (5 to 6 and 7 to 8 yr) and then randomly assigned in three groups to be studied cross-sectionally immediately before and at 2 and 4 h after the ingestion of a meal containing 337 micrograms of retinol equivalents (48% as retinol and 52% as carotenoids). The ingestion of breakfast did not alter significantly (p greater than 0.05) the postprandial serum concentrations of retinol, retinol-binding protein; or carotenoids in any of the age groups. These results indicate that up to 4 h the postprandial blood serum concentrations of these parameters are representative of their corresponding basal concentrations. Therefore, in practice and particularly under field survey conditions, the blood samples required to assess the vitamin A status of children can be obtained either fasting or within 4 h after breakfast without altering the results.     

Vitamin A status of preterm infants: correlation between plasma retinol concentration and retinol dose response

Retinol dose response tests were performed on 83 preterm infants shortly before discharge by giving orally 5000 IU of an aqueous dispersion of retinol. Predose plasma retinol concentrations were 2.5-20.5 micrograms/dL (0.087-0.72 mumol/L) and the retinol dose responses were 0-59.8%. The regression of retinol dose response on predose retinol was -0.58. There was a parallel increase in both retinol and retinol-binding protein and an increase in the molar ratio of retinol-binding protein to prealbumin. Prealbumin did not increase. These findings suggest that preterm infants have reduced liver stores of vitamin A.     

Seasonal variations in plasma retinol and carotenoid levels in rural Gambian women

Plasma carotenoid levels exhibited a major seasonal variation in pregnant and lactating women in Keneba, a rural Gambian village. This is probably due mainly to the seasonally related contribution of mangoes, which are a major dietary component during May and June, but are essentially unavailable for the remainder of the year. Plasma retinol levels, on the other hand, exhibited much less seasonal variation, although a trend towards higher levels in May and June was just discernible. Plasma retinol levels were significantly lower than those observed in a group of pregnant and lactating women living in the UK.     

Vitamin A intake and plasma retinol levels in healthy elderly men and women

We examined intakes of vitamin A (diet plus supplement) and plasma retinol levels in a select group of elderly men (n = 90) and women (n = 110) on three separate occasions over a 4-y period. Median dietary levels remained at approximately 1400 retinol equivalents (RE) in men and 1250 RE in women. There were no time trends or gender differences noted in plasma retinol concentrations. Approximately 44% of the elderly men and women consumed an average of 2000 RE of a vitamin A supplement daily. Those taking supplement had a greater mean plasma retinol concentration than those not taking a supplement. This effect was greater in men than in women. A review of previous studies revealed that plasma retinol increases from a mean of approximately 35 micrograms/dL (1.22 mumol/L) at preschool age to a plateau of approximately 60 micrograms/dL (2.09 mumol/L) by age 40 y in men and 60 y in women.     

Plasma concentrations of carotenoids, retinol, and tocopherols in preeclamptic and normotensive pregnant women

This case-control study was conducted in Lima, Peru, from June 1997 through January 1998 to assess whether plasma concentrations of carotenoids (alpha-carotene, beta-carotene, lycopene, lutein, zeaxanthin, beta-cryptoxanthin), retinol, and tocopherols (alpha-tocopherol and gamma-tocopherol) are decreased in women with preeclampsia. A total of 125 pregnant women with preeclampsia and 179 normotensive pregnant women were included. Plasma concentrations of antioxidants were determined using high performance liquid chromatography. After adjusting for maternal demographic, behavioral, and reproductive characteristics and total plasma lipid concentrations, the authors found a linear increase in risk of preeclampsia with increasing concentrations of alpha-tocopherol (odds ratio of the highest quartile = 3.13; 95% confidence interval: 1.06, 9.23, with the lowest quartile as the reference group; p value of the test of linear trend = 0.040). The risk of preeclampsia decreased across increasing quartiles of concentrations for retinol (odds ratio of the highest quartile = 0.32; 95% confidence interval: 0.15, 0.69, with the lowest quartile as the reference group; p value of the test of linear trend = 0.001). Some of these results are inconsistent with the prevailing hypothesis that preeclampsia is an antioxidant-deficient state. Preliminary findings confirm an earlier observation of increased plasma concentrations of alpha-tocopherol among women with preeclampsia as compared with normotensive pregnant women.     

Plasma vitamin A, retinol-binding protein, and prealbumin in postoperative breast cancer patients

Plasma vitamin A and its circulatory transport proteins, retinol-binding protein (RBP) and prealbumin, were measured in nine postoperative female breast cancer patients, who were apparently disease-free at the time of blood collection. The plasma concentrations of these parameters were found to be similar to that of the age- and sex-matched healthy controls with the exception of two patients, who subsequently had cancer recurrence. The values of vitamin A, RBP, and prealbumin were all very low in these two patients.     

Plasma lycopene, other carotenoids, and retinol and the risk of cardiovascular disease in women

BACKGROUND: Growing evidence suggests that lycopene has significant in vitro antioxidant potential. Lycopene has rarely been tested in prospective studies for its role in cardiovascular disease (CVD) prevention. OBJECTIVE: We examined the association between plasma lycopene and the risk of CVD in middle-aged and elderly women. DESIGN: A prospective, nested, case-control study was conducted in 39 876 women initially free of CVD and cancer in the Women's Health Study. Baseline blood samples were collected from 28 345 (71%) of the women. During a mean of 4.8 y of follow-up, we identified 483 CVD cases and 483 control subjects matched by age, smoking status, and follow-up time. Plasma lycopene, other carotenoids, retinol, and total cholesterol were measured. RESULTS: In analyses matched for age and smoking, with adjustment for plasma cholesterol, the relative risks (RRs) and 95% CIs of CVD in increasing quartiles of plasma lycopene were 1.00 (referent), 0.78 (95% CI: 0.55, 1.11), 0.56 (0.39, 0.82), and 0.62 (0.43, 0.90). In multivariate models, the RRs were 1.00 (referent), 0.94 (0.60, 1.49), 0.62 (0.39, 1.00), and 0.67 (0.41, 1.11); those in the upper compared with the lower half of plasma lycopene had an RR of 0.66 (0.47, 0.95). For CVD, exclusive of angina, women in the upper 3 quartiles had a significant multivariate 50% risk reduction compared with those in the lowest quartile. The stepwise addition of individual plasma carotenoids did not affect the RRs. CONCLUSIONS: Higher plasma lycopene concentrations are associated with a lower risk of CVD in women. These findings require confirmation in other cohorts, and the determinants of plasma lycopene concentrations need to be better understood.     

Immunogenicity and effectiveness of Haemophilus influenzae type b conjugate vaccine in HIV infected and uninfected African children

The quantitative (anti-Hib capsular polysaccharide antibody concentrations; anti-HibPS) and qualitative (bactericidal activity and avidity) aspects in immune responses to Haemophilus influenzae type b polyribosyl ribitol phospshate-CRM(197) conjugate vaccine (HibCV; HibTiter) were evaluated in 66 HIV infected children not receiving anti-retroviral therapy and 127 HIV uninfected children. Surveillance was conducted for invasive Hib disease in a cohort of 39,865 (approximately 6.4% of whom were HIV infected) children from March 1998 to June 2004. HIV infected children had lower anti-HibPS geometric mean antibody concentrations 1 month post-immunisation than HIV uninfected children (P<0.00001) and were less likely to have anti-HibPS antibody concentrations of >or=1.0 microg/ml (RR 0.54; 95% CI 0.43-0.69). A lower proportion of HIV infected children than HIV uninfected children (RR 0.78; 95% CI 0.66-0.93) had measurable anti-Hib serum bactericidal activity (SBA) and the HibPS antibody concentration required for 50% killing of Hib bacteria was greater among HIV infected than HIV uninfected children (P=0.001). The estimated risk of HibCV failure was 35.1-fold greater (95% CI 14.6-84.6) amongst HIV infected than HIV uninfected children.     

Guinea pig ascorbate status predicts tetrahydrobiopterin plasma concentration and oxidation ratio in vivo

Tetrahydrobiopterin (BH₄) is an essential co-factor of nitric oxide synthases and is easily oxidized to dihydrobiopterin (BH₂) which promotes endothelial nitric oxide synthase uncoupling and deleterious superoxide production. Vitamin C has been shown to improve endothelial function by different mechanisms, some involving BH₄. The hypothesis of the present study was that vitamin C status, in particular low levels, influences biopterin redox status in vivo. Like humans, the guinea pig lacks the ability to synthesize vitamin C and was therefore used as model. Seven day old animals (n = 10/group) were given a diet containing 100, 250, 500, 750, 1000, or 1500 ppm vitamin C until euthanasia at age 60–64 days. Blood samples were drawn from the heart and analyzed for ascorbate, dehydroascorbic acid (DHA), BH₄ and BH₂ by high-performance liquid chromatography. Plasma BH₄ levels were found to be significantly lower in animals fed 100 ppm vitamin C compared to all other groups (P < .05 or less). BH₂ levels were not significantly different between groups but the BH₂-to-BH₄ ratio was higher in the group fed 100 ppm vitamin C (P < .001 all cases). Significant positive correlations between BH₄ and ascorbate and between BH₂-to-BH₄ ratio and DHA were observed (P < .0001 both cases). Likewise, BH₂-to-BH₄ ratio was negatively correlated with ascorbate (P < .0001) as was BH₄ and DHA (P < .005). In conclusion, the redox status of plasma biopterins, essentially involved in vasodilation, depends on the vitamin C status in vivo. Thus, ingestion of insufficient quantities of vitamin C not only leads to vitamin C deficiency but also to increased BH₄ oxidation which may promote endothelial dysfunction.     

Variations of various plasma (albumin, prealbumin, retinol binding protein), and urinary parameters during measles in Senegalese children

In order to evaluate the effect of measles on proteins carrying vitamin A, we have examined 58 children with measles (24 have been seen again 2 weeks later) and 52 healthy controls of similar age and nutritional status. During the course of fever we have observed a high urinary excretion of urea and creatinine with proteinuria while the hydroxyproline index is significantly lower than in the controls. Irrespective of the nutritional status the plasma levels of albumin, prealbumin and R.B.P. are consistantly low. Two weeks later, while the albumin level has decreased, the other parameters are aiming towards normal values. The higher levels of prealbumin and R.B.P. suggest a reactivation of the hepatic protein synthesis. The urinary excretion of R.B.P. has not changed significantly during measles. We have observed rather high urinary losses of R.B.P. in the controls. The low levels of plasma prealbumin possibly do not allow the complete binding of the R.B.P.     

Selenium, retinol, retinol-binding protein, and uric acid. Associations with cancer mortality in a population-based prospective case-control study.

Using a prospective case-control study design, baseline levels of plasma selenium, retinol, and retinol-binding protein, and baseline blood uric acid levels were compared in 136 case patients who subsequently died from cancer and 238 matched control subjects. Subjects were followed for an average of 8 1/2 years. In matched analyses, selenium levels were lower in case patients with gastrointestinal or prostate cancer; retinol levels, lower in those with gastrointestinal or breast cancer; retinol-binding protein levels, lower in case patients with gastrointestinal cancer; and uric acid levels, lower in a group with "other" cancers. However, only the uric acid association with "other" cancers and the retinol-binding protein association with gastrointestinal cancer were statistically significant (P < or = .02) in conditional logistic regression analyses controlling for multiple potential covariates. Relationships for each of the substances varied by cancer site, and although some relationships were suggestive, our results point to the need for larger studies with adequate numbers for site-specific analyses.     

Plasma levels of retinol, carotenoids, and tocopherols in relation to dietary pattern among pregnant Tanzanian women

In Tanzania, as in other developing countries, dietary intake of nutrients in pregnant women is marginal or lower than the recommended intakes and therefore these women are at high risk for deficiencies. Our aim was to evaluate the relationship between diet and plasma levels of retinol, carotenoids, and alpha-tocopherol in the third trimester of pregnancy. Ninety pregnant women aged between 18 and 45 years were equally recruited from three villages. Seven-day food frequency data was collected by questionnaire. Plasma levels of retinol, carotenoids, and tocopherols were assessed by high-performance liquid chromatography (HPLC). Results indicated that cooked green leafy vegetables constituted the major source of provitamin A carotenoids, with low intake of yellow/orange fruits and preformed vitamin A. Lutein, lycopene, and beta-carotene were the predominant carotenoids in the plasma with mean values of 1.61, 0.84, and 0.63 mumol/L, respectively. There was no significant correlation between frequencies of vegetable consumption and either plasma retinol or carotenoids. However, increased consumption of green leafy vegetables with oil, which increases bioavailability, was correlated with high plasma retinol levels (p = 0.03). Low retinol levels (< or = 0.70 mumol/L) were present in 26% of women. The mean plasma retinol concentration was 0.89 mumol/L and 63% of the women had values below 1.05 mumol/L. The mean plasma alpha-tocopherol concentration was 15.4 mumol/L and women with plasma retinol concentration > 1.05 mumol/L had significantly higher mean alpha-tocopherol than women with plasma retinol concentration < or = 0.70 mumol/L (p < or = 0.01). Twenty-four percent of the women were anemic (hemoglobin: Hb < 110 g/L) and the mean Hb value was 116.3 g/L.