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Biomedical subjects

D Sklan

Publications and source records attributed to D Sklan.

At least 163 records · Page 9Linked to original sources
PubMed1978

Lipogenesis in the brain of thiamine-deficient rat pups.

(1) The effect of thiamine deficiency during pregnancy and lactation on lipogenesis in the brain of rat pups was determined. (2) Acetate incorporation to brain lipids in thiamine-deficient rats in vivo was no less than in pair fed control rats, apart from slightly reduced fatty acid synthesis in the cerebrum. (3) Glucose incorporation to brain lipids in vivo was considerably reduced in thiamine-deficient pups. (4) The inducible NADP dependent malic enzyme activity was increased in thiamine-deficient pup brains. (5) The synthesis of acetyl-CoA appears to be the rate limiting step in lipogenesis in thiamine-deficient pup brains.

Acetates↗
PubMed1978

New formal approaches to the determination of energy and amino acid requirements of chicks.

Body weight and the intake of metabolizable energy of chicks as function of age, were resolved into a linear equation from which the energy requirements for maintenance and growth were extracted. The metabolizable energy requirement for maintenance was calculated to be 1.91 and 1.62 Cal./g. 2/3, and that for weight gain was 2.05 and 2.19 Cal./g. for male White Rock and female 2--8-week old Leghorn chicks, respectively. The amino acid requirements of growing broiler chicks were calculated from the maintenance requirements, body weight gain and body weight, the proportions of feather protein in total body protein, and the amino acid composition of carcass and feathers. The requirements thus calculated, correlated well with various values in the literature. Diets formulated on the basis of the present model, were lower in protein and amino acid contents than those formulated on the basis of NRC allowances. These differences were pronounced in diets designed for 6--8 week old chicks. The weight gains obtained were similar for both types of diets. Feed conversion were slightly poorer and abdominal fat higher in chicks fed the model diets. It is concluded that the present model can serve, at least as an initial approach, to calculate the protein and amino acid requirements.

Amino Acids↗
PubMed1978

1alpha-hydroxycholecalciferol: a promising therapeutic approach for renal osteodystrophy.

The effectiveness of 1alpha-hydroxycholecalciferol [1alpha-OH)D3] in healing uremic bone disease was investigated in 10 uremic patients on maintenance dialysis. Seven patients received 1alpha-(OH)D3, 2 microgram/day, for six months, and three patients served as a control group. Bone density was determined from X-rays of the second phalanx of the second digit. The apparent intestinal calcium absorption improved on treatment with 1alpha-(OH)D3, serum calcium levels and bone density significantly increased, and a significant decrease in serum alkaline phosphatase activity was observed. In one patient, reversal of uremic myopathy occurred after 17 days of 1alpha-(OH)D3 therapy.

Absorptiometry, Photon↗
PubMed1977

The effect of lipids on taurocholate absorption from intestinal loops in the rat.

The rates of uptake and serosal transfer of [14C]-labelled taurocholate (7.77 mM in bicarbonate buffer, pH 6.5) were determined in situ in ligated segments of rat intestine in the presence of lipids. Oleic acid, monoolein, lecithin, and lysolecithin enhanced taurocholate uptake and transfer in the jejunum, each lipid exhibiting an optimal concentration at which the bile acid fluxes were maximal. The maximal rates of bile acid uptake observed with the various lipids were close to four times the uptake rates found with the lipid-free taurocholate medium, whereas serosal transfer rates under optimal conditions were enhanced about six-fold. The optimal concentrations differed widely among the various lipids, being inversely related to the lipids' polarity. Simultaneous measurement of taurocholate and [3H]-labelled oleic acid showed that under optimal conditions, when the molar concentration of oleic acid was about equal to that of the bile acid, the fatty acid and bile acid also exhibited closely similar rates of absorption. At other fatty acid concentrations, the fractional rate of absorption of the bile acid was much lower than that of the fatty acid. The rates of uptake and serosal transfer of pure taurocholate by the ileum exceeded those of the jejunum by factors of about 7 and 15, respectively, but in the presence of lipids this difference in absorptive capacity for bile acid between the distal and proximal segment largely disappeared.

Animals↗
PubMed1977

Effect of caffeine on increasing the motility of frozen human sperm.

A preliminary report on the effect of the addition of caffeine to 45 frozen sperm samples, in order to restore the effectiveness and motility of frozen stored human sperm, is presented. The addition of 7.2 mM caffeine proved optimal and resulted in 40% to 80% increased sperm motility after 30 days of frozen storage. The use of rapid-rate freezing to produce frozen sperm pellets and the addition of one frozen pellet of buffered caffeine (7.2 mM) to five sperm pellets before thawing are recommonded. For slow-rate freezing in paillettes, the addition of a caffeine solution (final concentration, 7.2 mM) to the sperm and protective medium is recommended. With these methods, frozen storage of hypomotile sperm, which previously could not be preserved by freezing, is now practical.

Caffeine↗
PubMed1977

Milk composition and thiamine transfer in thiamine deficient rats.

Milk composition was determined in rats maintained on a thiamine deficient diet from the 10th day of pregnancy. Percentage of thiamine transfer was reduced after the 14th postpartum day. Milk composition of thiamine deficient dams 18 days postpartum revealed similar protein and amino acid levels in both thiamine deficient and control rats, whereas milk protein fractions showed some differences. Milk lactose levels were depressed in thiamine deficient rats. Fatty acid content was higher in milk of thiamine deficient than in pair fed and adlibitum controls. The supply of a larger proportion of calories from lipids rather than carbohydrates may have clinical significance.

Amino Acids↗
PubMed1977

Site and extent of thiamin absorption in the rat.

The site and extent of absorption of thiamin hydrochloride was determined in rats using 51Cr-EDTA as a non-absorbed reference substance. The main site of absorption of thiamin was found to be the proximal 22 cm of the small intestine with relatively little absorption occurring distally, particularly at low dietary thiamine levels. Concentration of thiamin in the intestinal contents increased along the intestine reaching maximum levels in the distal small intestine. The results are compatible with two concurrent mechanisms of thiamin absorption with the active absorptive process being saturated at 0.5 to 1.0 muM.

Animals↗
PubMed1977

The effect of indomethacin on plasma levels of prostaglandin F2alpha in women in labour.

Prostaglandin F2alpha was measured by means of radiommunoassay in the serum of women in the active phase of term labour before and after rectal indomethacin administration. Samples of blood were collected every 20 or 30 seconds, between and during contractions. There was a significant decrease of the level of PGF2alpha in plasma 30 to 30 minutes after indomethacin administration, but the pattern of rapid short-term fluctuations in prostaglandin levels was unaltered.

Female↗
PubMed1977

Effect of thiamine deficiency in pregnant and lactating rats on the brain of their offspring.

In an attempt to create a model of human infantile beriberi, pregnant rats were fed, from the 10th day of pregnancy through lactation, a low-thiamine diet. Controls were either pair-fed or offered a nutritionally complete diet ad libitum. Dams exhibited symptoms of thiamine deficiency after 30 days on the experimental diet, whereas the their pups displayed signs of thiamine deficiency from the 14th postnatal day. Brain transketolase activity was depressed in day-old thiamine-deficient pups, and brain pyruvic acid levels were elevated after the 7th postnatal day. From the 14th postnatal day, brains of thiamine-deficient pups contained less phospholipids, cerebrosides and cholesterol than those of both controls. On the 21st day, weight and lipid content of brains of thiamine-deficient and of pair-fed pups were lower than those of normal controls. In some rats rehabilitation with thiamine was begun on the 19th day, and after 23 days, brain cerebroside content was still lower in the experimental group than in both controls. Since cerebrosides are an essential component of myelin, this finding may suggest damage of the myelin sheath.

Animals↗
PubMed1977

Utilization of choline from crude soybean lecithin by chicks. 2. Absorption measurements.

Absorption of choline was investigated in 30-day-old chicks fed a casein-glucose diet supplemented with either choline chloride or crude soybean lecithin and containing 91YCl3 as a nonabsorbable reference substance. The choline concentration, expressed as choline chloride, was 0.101% in both experimental diets. Net rates of absorption or secretion were computed from the amounts of 91Y and choline assayed in the contents of different segments of the small intestine. Net secretion of total choline into the duodenum was over twice the daily choline intake in both treatments. Most of the choline was absorbed in the upper small intestine. Of the small amounts remaining in the lower jejunum, significantly more choline was absorbed by the choline-fed chicks than by the lecithin-treated birds, but the rates of secretion into the duodenum, the rates of absorption from the upper small intestine and the overall apparent absorbability were not significantly different in the two treatments. Absorption measurements thus indicate that crude soybean lecithin may replace choline chloride as a source of choline.

Animals↗
PubMed1976

Site of bile acid absorption in the rat.

Bile acid absorption was measured in the small intestine of the rat using 91Y as a nonabsorbed reference substance. Some 50% of the secreted bile acids were absorbed in the proximal half of the small intestine. In situ incubations of ligated intestinal segments into which tauro(14C-carbonyl)cholic acid was introduced confirmed the considerable uptake of bile acids in the jejunum. The situ experiments indicated that serosal transport is the limiting stage of bile acid absorption in the jejunum but not in the ileum. Increasing bile acid concentrations in the in situ experiments did not affect the percentage disappearance of dose from the jejunum but reduced the percentage mucosal uptake in the ileum. It is concluded that, in the rat, the proximal small intestine is as important in the absorption of bile acids as the distal small intestine.

Animals↗
PubMed1975

51Cr-EDTA, 91Y and 141Ce as nonabsorbed reference substances in the gastrointestinal tract of the chicken.

The use of 91Y, 51Cr-EDTA, and 141Cr as nonabosrbed reference substances in the gastrointestinal tract of the chick was examined. In single oral dose experiments, more than 95% of the isotopes administered was recovered from the gastrointestinal tract 3 hours after dosing. 51Cr was higher in blood than the other isotopes tested. When the isotopes were fed continuously, the ratio of 91Y to 141Cr changed little throughout the gastrointestinal tract. However, the ratio of 91Y to 51Cr was higher in the crop and gizzard and lower in the duodenum than in the feed. Thus, passage time was shorter for 51Cr in the crop and gizzard and longer in the duodenum than that of 91Y. On the basis of distribution between solid and liquid phases in the intestinal contents, 91Y or 141Ce appears to be a suitable reference substance for studying the absorption of nitrogen and fatty acids, wheras 51Cr-EDTA would be preferable for bile acid absorption studies.

Animals↗