The study objective was to evaluate the retinal response to deficiencies of zinc and taurine present throughout the period of postnatal retinal development. At parturition, Sprague-Dawley dams were ...assigned to one of four treatments in a 2 × 2 factorial design with two levels of zinc (4.5 and 50 μg/g) and two levels of taurine (0 and 2 μmol/g). Guanidinoethyl sulfonate, a taurine transport inhibitor, was added to the drinking water of the rats receiving 0 μmol/g taurine. Male pups (n = 10) were weaned on to their respective diets at postnatal day 22. Dark adapted electroretinograms and oscillatory potentials (OP) were recorded in the pups at 48-57 days of age. At maximal light intensity, the amplitudes of the a- and b-waves were depressed by deficiency of either nutrient, but the influence of combining these treatments was less than additive; the same pattern was evident for V
max
, the maximum amplitude obtained when the b-wave was plotted as a function of light intensity. This type of interaction was also evident for the amplitudes of OP
1
, OP
3
and OP
4
. Zinc deficiency independently decreased the amplitude and increased the latency of OP
5
, and increased the latencies of OP
3
and OP
4
. Light and transmitting electron microscopic examination revealed the most pronounced retinal degeneration in the rats deficient in both zinc and taurine. Tibia zinc and liver taurine concentrations provide evidence that these nutrients also interact in other tissues. The findings of this study demonstrate retinal damage with deficiencies of zinc and taurine during postnatal life. These nutrients interact in at least some of their functions in the retina through an as yet unidentified mechanism.
Although zinc is essential for normal fetal growth and development, little is known about factors that influence its transfer across the placenta. The in situ perfused guinea pig placenta model was ...used to study the influence of zinc-binding ligands in fetal circulation on maternofetal placental zinc transfer. A placenta of each anesthetized sow was perfused (on the fetal side) with a physiological perfusate via the umbilical vessels, with the fetus excluded. The sow was infused intravenously with 65Zn as a tracer of placental zinc clearance and with antipyrine as an indirect indicator of maternal placental blood flow. Maternal plasma and placental effluent samples collected at intervals were counted for 65Zn with a gamma counter, and the absorbance of nitrosated antipyrine was measured at 350 nm. The addition of physiological levels of zinc-binding ligands (albumin, L-histidine and L-cysteine) to the perfusate increased the relative maternofetal clearance of zinc across the placenta calculated as zinc clearance/antipyrine clearance mean +/- SEM; 0.113 +/- 0.016 vs. 0.062 +/- 0.012; ligands vs. no ligands; n = 8; P less than 0.05. The results suggest that the availability of zinc-binding ligands in fetal circulation is one determinant factor of placental zinc transfer.
The influence of zinc (Zn) deficiency on erythrocyte deformability was investigated in the rat. Weanling, male Wistar rats were fed a diet containing <1 mg/kg Zn ad libitum for 3 weeks (-Zn). ...Controls were fed ad libitum (+ ZnAL) or pair-fed (+ ZnPF) the same diet containing 100 mg/kg Zn. Weanling rats were included as experimental time zero controls. Erythrocyte deformability was measured at standard shear stress with increasing osmolality in the ektacytometer. Elongation index (the ratio of length to width of the diffraction pattern of the deformed cells) was plotted against osmolality to generate an osmotic deformability profile. Characteristics of this profile were analyzed by a one-factor analysis of variance followed by Tukey's test. Maximum cell deformability (Elmax) and minimum deformability (Elmin) were significantly depressed in samples from the + ZnPF group as compared with those from the + ZnAL group (P <0.05). Elmax and Omax (the osmolality at which Elmax occurs) were increased in the + ZnAL group as compared with the experimental time zero group. There were no differences between the -Zn group and the + ZnPF group when assessed by, Tukey's test, but a paired t test indicated that Elmax was significantly lower in the Zn group (P = 0.049). In summary, zinc depletion itself causes a minor depression in whole cell deformability, while the accompanying decrease in feed intake results in a more pronounced decrease due to diminished membrane flexibility. Erythrocyte deformability is increased in the normal 6-week-old rat compared with that of the 3-week-old weanling rat; this is due to increased membrane deformability.
Vitamin E deficiency and erythrocyte deformability in the rat Paterson, P.G. (University of Saskatchewan , Saskatoon, Saskatchewan, Canada); Gorecki, D.K.J; Card, R.T
The Journal of nutritional biochemistry,
06/1994, Letnik:
5, Številka:
6
Journal Article
Recenzirano
It has been suggested that erythrocyte deformability is decreased in vitamin E deficiency due to oxidative damage to the cell membrane. Male Wistar rats (66 to 88 g) were fed ad libitum an ...AlN76-based diet containing tocopherol-stripped corn oil without added vitamin E for 8 weeks (- E; n = 8). Control animals were fed ad libitum the same diet containing 50 IU/kg dl-alpha-tocopheryl acetate (+E; n = 7). Vitamin E deficiency was confirmed by depressed mean (+/- SEM) plasma alpha-tocopherol levels (micromole/L), as measured by high performance liquid chromatography -E: 0.5 +/- 0.1; +/- +E: 20.3 +/- 1.8 and elevated hydrogen peroxide-induced hemolysis (%) -E: 92.6 +/- 2.4; +E: 4.2 +/- 1.6; P 0.05 by Students t test. The only alteration in a complete blood count was a depression in reticulocyte number (X 10(12)/L) -E: 0.19 +/- 0.02; +E: 0.46 +/- 0.03; P 0.05. Erythrocyte deformability was measured at standard shear stress under conditions of increasing osmolality in the ektacytometer. Elongation index (the ratio of length to width of the diffraction pattern of the deformed cells) was plotted against osmolality to generate an osmotic deformability profile. EImax (the maximum elongation index) and O hyper (the osmolality at which the elongation index is half of EImax, on the hypertonic arm of the curve) were significantly increased in samples from the -E group (P 0.05 by Student's t test). In summary, erythrocyte deformability as measured by the ektacytometer was not decreased by a subclinical vitamin E deficiency in the rat. In fact, a small but significant increase in maximum deformability was observed in erythrocytes from vitamin E-deficient rats
The effect of dietary zinc deficiency on patterns of phosphorylation and dephosphorylation of rat erythrocyte membrane proteins and erythrocyte filterability was examined. Weanling male Wistar rats ...were fed an egg white—based diet containing less than 1.1 mg zinc/kg diet ad libitum for 3 wk. Control rats were either pair-fed or ad libitum—fed the basal diet supplemented with 100 mg zinc/kg diet. Net phosphorylation and dephosphorylation of erythrocyte membrane proteins were carried out by an in vitro assay utilizing γ-32PATP. The membrane proteins were subsequently separated by sodium dodecyl sulfate—polyacrylamide gel electrophoresis, and the 32P content of gel slices was counted by Cerenkov counting. Erythrocyte filterability was measured as the filtration time of suspensions of erythrocytes, both untreated and preincubated with diamide, under constant pressure. Erythrocyte ghosts from zinc-deficient rats demonstrated greater dephosphorylation of protein bands R1 plus R2 and R7 than pair-fed rats and greater net phosphorylation of band R2.2 than pair-fed or ad libitum—fed control rats (P < 0.05). Erythrocytes from ad libitum-fed control rats showed significantly longer filtration times than those from zinc-deficient or pair-fed control rats. In conclusion, dietary zinc deficiency alters in vitro patterns of erythrocyte membrane protein phosphorylation and dephosphorylation, whereas the depression in food intake associated with the zinc deficiency increases erythrocyte filterability.
Zinc levels of hospitalized elderly Paterson, Phyllis G; Lee, Eva; Christensen, David A ...
Journal of the American Dietetic Association
85, Številka:
2
Journal Article
Extract: Zinc status was evaluated in 99 elderly patients. Sixty-seven percent had plasma zinc levels and three patients erythrocyte zinc levels below the range reported for younger adults. Urinary ...zinc levels were within the range for younger adults. Serum alkaline phosphatase and lactic dehydrogenase were not specific indicators of zinc nutriture. The majority of subjects had an adequate supply of zinc-rich foods. Zinc status appears to be adequate in this population. (Author)
