Studies of the effect of variation of blend ratio on permselectivity and heterogeneity of ion-exchange membranes.

Heterogeneous ion-exchange membranes (both cationic and anionic types) have been synthesized by solution casting techniques using polyvinyl chloride (PVC) as binder and ion-exchange resin (-300+400 mesh). The binder:resin ratio varied from 60:40 to 30:70. The transport behavior of the membranes has been evaluated chronopotentiometrically in sodium chloride (NaCl) solutions of different concentrations. The different parameters E(0) (potential drop across the membrane at the instant of application of current I), E(max) (maximum potential drop across the membrane after the application of current I), DeltaE (magnitude of the potential jump across the membrane at transition time tau), Itau(1/2), tau, etc., have been evaluated. The isoconductance points were determined and based on the microheterogeneous model proposed by Zabolotsky and Nikonenko (J. Membrane Sci. 79 (1993) 181) the distribution factors beta has been evaluated for both types of ion exchange membranes. The electroconductivity of the joint gel (kappa ) and pure gel phases (kappa ' ) has been determined. At any particular solution concentration the transport number as well as the permselectivity of membranes increases with increased resin content of the membrane. The microheterogeneity factor beta exhibits synchronization among the each set of four different membranes for both the cationic and anionic type.

Double-blind, placebo-controlled study of amantadine hydrochloride in the treatment of children with autistic disorder.

OBJECTIVE: To test the hypothesis that amantadine hydrochloride is a safe and effective treatment for behavioral disturbances--for example, hyperactivity and irritability--in children with autism. METHOD: Thirty-nine subjects (intent to treat; 5-19 years old; IQ > 35) had autism diagnosed according to DSM-IV and ICD-10 criteria using the Autism Diagnostic Interview-Revised and the Autism Diagnostic Observation Schedule-Generic. The Aberrant Behavior Checklist-Community Version (ABC-CV) and Clinical Global Impressions (CGI) scale were used as outcome variables. After a 1-week, single-blind placebo run-in, patients received a single daily dose of amantadine (2.5 mg/kg per day) or placebo for the next week, and then bid dosing (5.0 mg/kg per day) for the subsequent 3 weeks. RESULTS: When assessed on the basis of parent-rated ABC-CV ratings of irritability and hyperactivity, the mean placebo response rate was 37% versus amantadine at 47% (not significant). However, in the amantadine-treated group there were statistically significant improvements in absolute changes in clinician-rated ABC-CVs for hyperactivity (amantadine -6.4 versus placebo -2.1; p = .046) and inappropriate speech (-1.9 versus 0.4; p = .008). CGI scale ratings were higher in the amantadine group: 53% improved versus 25% (p = .076). Amantadine was well tolerated. CONCLUSIONS: Parents did not report statistically significant behavioral change with amantadine. However, clinician-rated improvements in behavioral ratings following treatment with amantadine suggest that further studies with this or other drugs acting on the glutamatergic system are warranted. The design of these and similar drug trials in children with autistic disorder must take into account the possibility of a large placebo response.

Effects of dietary calcium on the metabolism of trace elements in male and female rats.

The effect of dietary calcium on the metabolism of iron, zinc, copper, and manganese in male and female rats was investigated. For 3 or 6 weeks the rats were fed three diets containing: (1) 0.26, (2) 0.52, or (3) 2.08% Ca. The apparent absorption of iron was depressed by the high calcium diet, and manganese absorption was highest in the low calcium groups. Generally there was a decrease in the absorption of minerals from 3 to 6 weeks. With an increase in the dietary calcium the absorption of Ca and P decreased. The liver iron concentration in the females fed diet 3 decreased from about 600 to 200 microg/g dry weight. The high calcium intake also caused a slight increase in the heart calcium levels in both sexes. However, diet 3 prevented kidney calcification in the female rats at 6 weeks and this was attributed to a dramatic decrease in the urinary phosphorus, although the calcium had increased about 40 times. In males, on the other hand, the high calcium diet caused some kidney calcification.

The effect of dietary copper and zinc on cholesterol metabolism.

The effects of different amounts of dietary zinc and copper on cholesterol metabolism in the rat were investigated. The levels of the minerals used were comparable to those likely to occur in a normal mixed North American diet. Although the different levels affected the serum, liver, and femur concentrations of the minerals, they had no effect on the levels of serum and liver, total, esterified or free cholesterol, or on high density lipoprotein cholesterol. It was concluded that dietary copper and zinc, at levels likely to occur in a normal mixed diet, are not significant factors in cholesterol metabolism.

Beneficial effect of zinc supplementation on reproduction in rats fed rapeseed protein concentrate.

Three groups of 33 90-day-old female Sprague-Dawley rats were fed, ad libitum, the following diets for 2 weeks before breeding. Diet 1 (D1) contained 20% protein from casein, diet 2 (D2) had the same level of protein from Tower rapeseed (Brassica napus) protein concontrate (RPC) and diet 3 (D3) was the same as D2 with a zinc supplement (70 mg/l) in the drinking water. From each group 6 animals were killed before breeding and 5-9 animals were killed at 1 and 2 weeks of gestation and post-partum. From each rat, blood, thyroids, liver and femur were collected for the determination of zinc, copper, iron, manganese, calcium and magnesium. As a measure of the reproductive performance, body weight, number of pups in the uterus or delivered live or dead, and gestations days before parturition were recorded. The pups were examined for obvious deformities and also analysed for the above mineral elements by atomic absorption spectroscopy. In group D2, levels of zinc in maternal serum, liver, femur and in the pups were significantly lower than the comparable levels in the other two groups. The zinc supplemented RPC-fed group did not show the anorexia experienced by the unsupplemented group and there was neither a significant difference between reproductive performances of groups D1 and D3 nor was there any significant difference between the zinc levels determined. It was concluded that the toxic symptoms caused by RPC feeding was attributable to zinc deficiency probably caused by the high phytate level in the RPC.

Beneficial effect of zinc supplementation on reproduction in rats red rapeseed protein concentrate.

Three groups of 33 90-day-old female Sprague-Dawley rats were fed, ad libitum, the following diets for 2 weeks before breeding. Diet 1 (D1) contained 20% protein from casein, diet 2 (D2) had the same level of protein from Tower rapeseed (Brassica napus) protein concontrate (RPC) and diet 3 (D3) was the same as D2 with a zinc supplement (70 mg/l) in the drinking water. From each group 6 animals were killed before breeding and 5--9 animals were killed at 1 and 2 weeks of gestation and post-partum. From each rat, blood, thyroids, liver and femur were collected for the determination of zinc, copper, iron, manganese, calcium and magnesium. As a measure of the reproductive performance, body weight, number of pups in the uterus or delivered live or dead, and gestation days before parturition were recorded. The pups were examined for obvious deformities and also analyzed for the above mineral elements by atomic absorption spectroscopy. In group D2, levels of zinc in maternal serum, liver, femur and in the pups were significantly lower than the comparable levels in the other two groups. The zinc supplemented RPC-fed group did not show the anorexia experienced by the unsupplemented group and there was neither a significant difference between reproductive performances of groups D1 and D3 nor was there any significant difference between the zinc levels determined. It was concluded that the toxic symptoms caused by RPC feeding were attributable to zinc deficiency probably caused by the high phytate level in the RPC.

Bioavailability of zinc in infant cereals.

The bioabailability of zinc in three cereals was determined by a rat assay, using total femur zinc as the indicator. The basal diet contained 25% egg white solids and 0.6 microgram zinc per gram. The infant cereals were included in the diets at three graded levels to supply 3--12 microgram zinc per gram. Zinc sulphate was used as a standard source, with and without supplemental iron (185, 370, 555 microgram/g, respectively) at 3, 6 and 9 microgram zinc per gram with a view to determine the effect of excess iron on zinc availability. Added iron from sodium iron pyrophosphate was not found to have any effect on the bioavailability of zinc from zinc sulphate. The responses for the three cereals were linear but the regression lines representing them and the standard source did not have a common intercept. However, the ratio of the slope of the regression line for the test source to that of the standard indicated that the cereal containing soy protein was a better source of zinc (ratio = 0.49) than the barley cereal (9.10) or the rice cereal (0.32). These ratios did not show any correlation with the actual iron-precipitable phytate phosphorus content or the reported crude fibre content.

Lead concentration in the livers of Canadians.

Liver specimens were collected at 114 (83 males and 31 females) autopsies on accident victims and on 4 stillborn infants in seven Canadian Cities. The age of the individuals ranged from newborn to 89 years with about 70% being 19--65 years. The level of lead in the samples was determined by atomic absorption spectroscopy using a carbon rod atomizer. The concentration of lead in liver was low (microgram/g: Mean, 0.37, Median 0.28) at birth and during infancy. In the stillborn infants it ranged from 0.30 to 0.77 (Mean 0.51). 7ale adults had an average level of 1.78 (Median 1.41) whereas in adult females the corresponding values were 0.65 and 0.57. The liver lead concentration peaked at about the end of the fourth decard in adult males. There was no indication of any regional differences.

Nutrient levels of some foods of Eskimos from Artic Bay, N. W.T., Canada.

Native food samples of caribou, seal, and arctic char were collected from resident Eskimos in Arctic Bay, N.W. T., and analyzed for nutrients. Caribou and seal meats were similar in protein and fat content in comparison with beef. Arctic char was above the average in protein and fat content for fish. Ascorbic acid was present in significant amounts only in baby seal liver. Thiamin, riboflavin, vitamin B12, folacin, and pantothenic acid content ranged from average to high for seal and carbiou meat, respectively, in comparison to published values for pork and beef. The vitamin B6 content of caribou meat was comparable to average values reported for pork and beef but was lower in seal meat. Baby seal liver contained similar levels of thiamin, riboflavin, vitamin B12, folacin, and pantothenic acid and less vitamin B6 than those reported for pork, beef, calf, and lamb liver. Arctic char was not appreciably different in these vitamins from other fish. The iron content of the Eskimo foods was higher than the meat group of the mixed Canadian diet. The macro mineral nutrients in these foods were comparable to those in beef and fish. The amino acid composition of caribou and seal meat was similar to beef, except that seal meat had a lower content of sulfur-containing amino acids and a much higher content of histidine. The sample of seal and arctic char were relatively high in concentrations of long-chain unsaturated fatty acids.

Bioavailability of zinc in milk and soy protein-based infant formulas.

Total femur zinc of young rats was used to evaluate the biological availability of zinc in milk and soy protein-based infant formulas. A zinc deficient diet (0.8 mug Zn/g) containing egg white protein was supplemented with graded levels of zinc from zinc sulfate, milk and soy protein-based infant formulas. A plot of total femur zinc (log) after feeding the diet for 3 weeks versus the zinc added to the diet gave a linear relationship over the range of 0, 3, 6, 9 and 12 mug/g added zinc. By using a slope-ratio bioassay model, the relative biological availability of endogenous and added zinc in milk-based formula was estimated to be 0.86 and that of soy-based formula 0.67 (zinc sulphate = 1.00) with corresponding 95% fiducial limits being 0.82 to 0.91 and 0.62 to 0.71. Thus, to provide equivalent amounts of available zinc, the total zinc content of the soy protein-based formula would need to be at least 20% higher than that of the formula containing milk protein.

Effect of the matrix of the standard on results of atomic absorption spectrophotometry of zinc in serum.

Zinc in pooled human serum, diluted 10-fold with demineralized water, was determined by flame atomic absorption spectrophotometry. Recoveries of zinc added to the serum were calculated by use of standards prepared in water, physiological saline, synthetic serum, or dilute HNO3 (10 ml/liter). The flow rates were essentially the same (9.1 to 9.3 ml/min) for water, diluted synthetic serum or actual human serum, and diluted nitric acid. The mean apparent percentage recoveries (plus or minus SD) were the best (102.6 plus or minus 2.5) when the standards were prepared in nitric acid; the values obtained when standards in water were used were too high (111.5 plus or minus 3.9); those with standards prepared in physiological saline (92.0 plus or minus 3.2) or synthetic serum (92.3 plus or minus 2.5) were too low.