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Biomedical subjects

J Sack

Publications and source records attributed to J Sack.

At least 127 records · Page 7Linked to original sources
PubMed1979

Breast milk thyroxine and not cow's milk may mitigate and delay the clinical picture of neonatal hypothyroidism.

Thyroxine concentration was measured in human milk and Cow's milk products by a specific radioimmunoassay. The mean (+/- S.E.M.) milk T4 concentration during the first 5 days postpartum was 0.7 +/- 0.3 microgram/dl (n = 11). The mean T4 concentration between 6-49 days postpartum rose to 3.1 +/- 0.2 microgram/dl (n = 108), falling after 50 days to a mean of 1.4 +/- 0.2 microgram/dl (n = 39). The mean (+/- S.E.M.) T3 concentration in breast milk in the first 50 days postpartum was 386 +/- 17 ng/dl (n = 56). T4 concentration in cow's milk products was less than 0.3 microgram/dl. Thyroxine concentration in 24 hours breast milk collection ranged from 0.7 to 7.7 microgram/dl and the total T4 in this milk ranged from 0.7 to 28 microgram/day. These data suggest that milk of human but not bovine origin may provide a significant exogenous source of T4 to the premature infant. This amount of exogenous T4 which is insufficient in preventing the proceeding of neonatal hypothyroidism, may delay the clinical recognition of this disorder. This once again emphasized the importance of early screening for neonatal hypothyroidism.

Animals↗
PubMed1979

Relationship between PAH transport and Na-K-ATPase activity in the rabbit kidney.

The relationship between Na-K-ATPase activity and p-aminohippurate (PAH) transport was examined in renal cortical slices of mixed-breed rabbits by using ouabain to vary the level of Na-K-ATPase activity. Ouabain increased passive PAH uptake, measured in the presence of probenecid. Slice homogenate Na-K-ATPase activity was inhibited by 50% with about 2 X 10(-6) M ouabain. When the concentration was 10(-5) M or above, active PAH uptake was inhibited. Lower concentrations (10(-7) and 10(-6) M) of ouabain stimulated active PAH uptake. Acetate stimulated PAH uptake when medium ouabain was less than 10(-4) M. Ouabain, 10(-5) M and higher, caused intracellular K+ to fall and Na+ to rise. The changes in active PAH uptake observed with ouabain correlated much better with changes in intracellular K+ or Na+ levels (P less than 0.01) than with changes in slice homogenate Na-K-ATPase activity. Vmax for active PAH uptake decreased with 5 X 10(-5) M ouabain, and tended to increase with 10(-7) M ouabain. Ouabain did not alter Km for active PAH uptake. The data support the hypothesis that there is a functional link between active PAH transport and Na-K-ATPase activity. This linkage may be an indirect one mediated by changes in intracellular cation concentrations.

Aminohippuric Acids↗
PubMed1979

Congenital hypoaldosteronism. Thirteen year follow-up in identical twins.

Identical male twins suffering from congenital hypoaldosteronism due to a rare adrenal enzyme deficiency between corticosterone and aldosterone were followed-upfrom birth till their present age of 13 years. The symptoms of salt loss disappeared and normal growth rate resumed following treatment with DOCA and salt supplementation. Discontinuation of mineralocorticoid administration at the age of 7 years resulted during a 5-year period in a marked decline in their growth rate. Labororatory data revealed a persistent, albeit less pronounced, metabolic impairment. Mineralocorticoid administration was resumed and the twins entered normal puberty and increased their growth rate, emphasizing their need for continued mineralocorticoid administration to maintain adequate growth rate and development.

Adrenal Cortex Hormones↗
PubMed1979

Serum 3,5,3'-triiodothyronine and 3,3',5'-triiodothyronine concentrations during acute heat load.

To determine the changes in thyroid hormone metabolism during short periods of exposure to heat, 30 euthyroid healthy male volunteers (aged 23--40 yr) were placed in a climatic chamber for 2 h (35 C, 50% relative humidity). The subjects were at complete rest during the first hour and performed light work (40 watts) during the second hour. Blood samples for T4, T3 and rT3 were drawn at 0, 60, and 120 min. Rectal temperature and heart rate were monitored continuously. No significant changes in T4, T3, rT3, rectal temperature, or heart rate were observed after the first hour (basal levels, 8.5 +/- 0.3 microgram/dl, 160 +/- 5 ng/dl, 14.5 +/- 2.5 ng/dl, 37.2 +/- 0.1 C, and 78 +/- 8 beats/min, respectively; mean +/- SEM). During the second hour, a significant rise in body temperature was recorded (38.5 +/- 0.1 C), accompanied by a significant decrease in mean serum T3 concentration and a rise in mean serum rT3 concentration, T4 concentration remained unchanged. Our findings suggest that, parallel to the elevation in body temperature, there is a shift in the conversion of T4 to the noncalorigenic rT3 metabolite rather than to T3.

Body Temperature↗
PubMed1979

Intra-amniotic thyroxine (T4) absorption by the premature human foetus.

We reported previously on the beneficial influence of intra-amniotic T4 injection in accelerating human foetal lung maturity. Twenty-four h after T4 (250 microgram) intra-amniotic injection, the mean cord serum T4 concentration in 13 premature newborns was 17 +/- 2.1 microgram/100 ml, while the T4 concentration in a matched group was only 11.6 +/- 0.9 microgram/100 ml: in 5 of the infants who received intra-amniotic thyroxine T4 was measured 12 h post-partum and rose from 16.1 +/- 1.8 to 24.3 +/- 2.6 microgram/100 ml. No change in maternal T4 concentration was observed. The mean cord serum T4 concentration in premature newborns delivered more than 3 days following T4 intra-amniotic injection, however, was not significantly different from that of the controls. These data suggest that T4 (250 microgram) injected intraamniotically is absorbed by the premature human foetus. Furthermore, the hyperthyroxinaemia is only transient, and does not prevent the post-natal T4 surge.

Absorption↗
PubMed1978

Enhancement of fetal lung maturity by intra-amniotic administration of thyroid hormone.

Following preliminary results in animal studies demonstrating that thyroxine (T4) injected directly into the fetus or the amniotic sac is capable of enhancing fetal lung maturity, a trial of thyroxine treatment in mean was carried out. Two hundred micrograms of T4 were injected intra-amniotically in eight women with high-risk pregnancies in which premature delivery was inevitable or indicated. Fetal lung maturity was evaluated by a recently developed, accurate, and rapid method using the microviscosity value epsilon (this being the linear expression of the polarization value P) of the lipid assembly of the amniotic fluid as a parameter of the surfactant content. epsilon Values, which were very high before T4 injection, dropped steeply to below the value of 4.344, indicating fetal lung maturity. Eight newborn infants delivered, five by caesarean section, soon after the T4 injection did not develop respiratory distress syndrome, although they were born prematurely. Intra-amniotic injection of T4 appears to be of therapeutic value in enhancing fetal lung maturity.

Amnion↗
PubMed1978

Effect of intraamniotic fluid thyroxine injection on fetal serum and amniotic fluid iodothyronine concentrations.

Seven hundred micrograms of T4 were injected into the amniotic cavity 24 h before delivery of five pregnant women scheduled for elective cesarean section at term. T4, T3, and rT3 concentrations were measured by RIA in amniotic fluid obtained at the time of the injection and in amniotic fluid and cord serum samples collected at delivery. Iodothyronine concentrations also were determined on cord samples from 24 full term control infants. The geometric mean serum T4 concentration in the experimental infants was 27.2 micrograms/dl, almost 3 times that of the control population (10.3 micrograms/dl); serum rT3 concentrations were markedly elevated to a mean of 657 ng/dl, compared to 254 ng/dl in control infants. The mean serum T3 concentration was slightly but significantly increased to 61.3 ng/dl (control, 48.3 ng/dl; P less than 0.02). Amniotic fluid T4, T3, and rT3 concentrations all increased significantly. T4 injection into the amniotic fluid is an effective method of increasing fetal serum T4 concentrations. The preferential pathway of monodeiodination of the injected T4 in the human fetus is to rT3 rather than T3.

Amnion↗
PubMed1978

Elevation of serum IgE in Japanese-American children.

Serum IgE levels were determined in Japanese-American and White-American children--ages 6 to 14. The mean serum IgE level was significantly higher in the Japanese-American children (444 vs. 67; p less than .01). There was also a suggested incidence of personal allergic disease or familial allergy in a small sample of the Japanese-American children.

Adolescent↗