Fetal heart rate in relation to body mass

In contrast to the inverse relation of heart rate to body mass in adult mammals, the heart rate of immature fetuses is unrelated to body mass and approximately constant among different species. With maturation, fetal heart rate decreases in a large mammal but tends to increase in a small mammal. These maturational changes reduce the difference between the heart rate of a term fetus and the heart rate which is "appropriate for body mass" as calculated by means of the allometric equation for adults. The comparative physiology of fetal heart rate supports the hypothesis that immature fetuses of small and large mammals have similar oxygen consumption rates per unit body mass.     

The influence of nerve section on the metabolism of polyamines in rat diaphragm muscle.

Concentrations of spermidine, spermine and putrescine have been measured in rat diaphragm muscle after unilateral nerve section. The concentration of putrescine increased approx. 10-fold 2 days after nerve section, that of spermidine about 3-fold by day 3, whereas an increase in the concentration of spermine was only observed after 7-10 days. It was not possible to show enhanced uptake of either exogenous putrescine or spermidine by the isolated tissue during the hypertrophy. Consistent with the accumulation of putrescine, activity of ornithine decarboxylase increased within 1 day of nerve section, was maximally elevated by the second day and then declined. Synthesis of spermidine from [14C]putrescine and either methionine or S-adenosylmethionine bt diaphragm cytosol rose within 1 day of nerve section, but by day 3 had returned to normal or below normal values. Activity of adenosylmethionine decarboxylase similarly increased within 1 day of nerve section, but by day 3 had declined to below normal values. Activity of methionine adenosyltransferase was elevated throughout the period studied. The concentration of S-adenosylmethionine was likewise enhanced during hypertrophy. Administration of methylglyoxal bis(guanylhydrazone) produced a marked increase in adenosylmethionine decarboxylase activity and a large increase in putrescine concentration, but did not prevent the rise in spermidine concentration produced by denervation. Possible regulatory mechanisms of polyamine metabolism consistent with the observations are discussed.     

Activation of adrenal function in fetal sheep by the infusion of adrenocorticotropin to the fetus in utero

We determined whether ACTH1-24, infused into fetal lambs at a rate that is known to cause premature labor, elicits changes in the responsiveness of the fetal adrenal glands, and alters the pattern of corticosteroid output. Plasma cortisol (F), corticosterone (B) and progesterone (P4) were measured during 72 h of infusion of saline or ACTH (10 micrograms/h) beginning on Day 127 of pregnancy. Adrenals were then dispersed into isolated cells, and the output of F, B and P4 after exogenous ACTH determined in vitro. Plasma concentrations of F and B were higher in ACTH-treated fetuses. The increment in F (5-to 7-fold) was greater than that in B (2-fold) such that the F:B ratio in plasma of ACTH-treated fetuses on Days 2 and 3 of infusion was 2.5 times higher than in controls. After 72 h of infusion, the adrenal weights in ACTH-treated fetuses (741 +/- 38 mg, +/- SEM; n = 4) were greater than in the control animals (349 +/- 11 mg). There was a significant effect of ACTH pretreatment in vivo on F output by isolated adrenal cells in vitro. Mean increments in F output after addition of ACTH1-24 (5000 pg/ml) in vitro rose from 368 +/- 235 pg/50,000 cells in controls, to 64,639 +/- 19,875 pg/50,000 cells after ACTH in vivo. There was no significant effect of ACTH in vivo on B output in vitro; the ratio of F:B output, either in the absence or presence of ACTH in vitro, was significantly higher in cells from ACTH-pretreated fetuses. There was a significant effect of in vivo ACTH on in vitro P4 output. After ACTH treatment in vivo there was an increase in the vitro output ratio of F:P4, but no change in the output ratio of B:P4. We conclude that ACTH treatment of the fetal lamb in vivo results in activation of fetal adrenal function, increased fetal adrenal responsiveness to ACTH, and directed corticosteroid biosynthesis towards cortisol. Our results are consistent with an increase in fetal adrenal 17 alpha-hydroxylase activity after ACTH treatment.     

Bacteriological quality of fabrics washed at lower-than-standard temperatures in a hospital laundry facility

We determined whether the bacteriological quality of fabrics cleaned in a hospital laundry could be maintained at wash temperatures lower than 75 degrees C by the use of economically reasonable formulas and wash conditions. Three groups of bacteria were examined to determine bacteriological quality: aerobic, nonexacting chemoorganotrophs, staphylococci, and total coliforms. The distribution of bacteria on soiled fabric was patchy, with staphylococci and total coliforms ranging from less than 0.1 to greater than 4 X 10(3) CFU/cm2 and chemoorganotrophs ranging from less than 0.1 to greater than 5 X 10(5) CFU/cm2. The washing process routinely produced fabric containing less than 1 CFU/cm2. Low-temperature (47.8 to 60.0 degrees C) wash procedures eliminated all bacterial groups at least as effectively as did high-temperature procedures. The effectiveness of bacterial density reduction at low temperature was augmented by increased concentrations of bleach. Successful low-temperature washing such as that shown here may save both energy and money for hospitals.     

Identification, characterization, and homologous up-regulation of latent (cryptic) receptors for tumor necrosis factor-alpha in rat liver plasma membranes

A population of latent (cryptic) receptors for tumor necrosis factor-alpha (TNF) has been characterized in the rat liver plasma membrane (PM). 125I-TNF bound to high (Kd = 1.51 +/- 0.35 nM) and low (Kd = 13.58 +/- 1.45 nM) affinity receptors in PM. Solubilization of PM with 1% Triton X-100 prior to incubation with 125I-TNF increased both high affinity (from 0.33 +/- 0.04 to 1.67 +/- 0.05 pmol/mg of protein) and low affinity (from 1.92 +/- 0.16 to 7.57 +/- 0.50 pmol/mg of protein) TNF binding without affecting the affinities for TNF. Digestion of intact PM with chymotrypsin abolished most of the TNF binding capacity of PM. However, substantial binding activity was recovered by solubilization of chymotrypsin-treated PM with 1% Triton X-100, suggesting the presence of a large latent pool of TNF receptors. The affinities of the high and low affinity sites recovered from chymotrypsin-treated membranes were similar to those of intact PM. Affinity labeling of receptors whether from PM, solubilized PM, or membranes digested with chymotrypsin and then solubilized resulted in cross-linking of 125I-TNF into Mr 130,000, 90,000, and 66,000 complexes. Thus, the properties of the latent TNF receptors were similar to those initially accessible to TNF. To determine if exposure of latent receptors is regulated by TNF, 125I-TNF binding to control and TNF-pretreated membranes was assayed. Specific binding was increased by pretreatment with TNF (p less than 0.05), demonstrating that hepatic PM contains latent TNF receptors whose exposure is promoted by TNF. Homologous up-regulation of TNF receptors may, in part, be responsible for sustained hepatic responsiveness during chronic exposure to TNF.     

High Levels of Malic Enzyme Activities in Vicia faba L. Epidermal Tissue

Specific activities of NADP-malic enzyme, NAD-malic enzyme, phosphoenolpyruvate carboxykinase and pyruvate, orthophosphate dikinase in various cells of Vicia faba L. leaflets were determined. Expressed on dry weight, chlorophyll or protein basis, the averages for NADP- and NAD-malic enzyme specific activities were higher in guard cells than in photosynthetic parenchyma cells. Malic enzyme-specific activities were also high in epidermal cells. Phosphoenolypyruvate carboxykinase activity was not detected in Vicia leaf extracts or guard cells; the assay techniques were validated by mixed Vicia-Brachiaria leaf extraction and assays on nanogram samples of Brachiaria bundlesheath cells. It was inferred from these data that guard cell malate depletion is by decarboxylation to pyruvate in the epidermal layer, but how the various epidermal cells interact remains obscure.     

Compartmental analysis of sulphate transport in Lemna minor L., taking plant growth and sulphate metabolization into consideration

Rat hepatoma cells accumulate considerably less 2-aminoisobutyrate after cultivating in the absence of serum the change in rate of aminoisobutyrate uptake takes place within 1 h of serum starvation. Starvation of amino acids by contrast raises aminoisobutyrate uptake in the presence or absence of serum, but the cells are much less responsive to amino acid supply than to availability of serum. Phosphate (10 mM) reduced aminoisobutyrate uptake by cells grown in serum to that exhibited by serum-starved cells. Aminoisobutyrate uptake by cells grown in serum was reduced by glycine, proline, alanine, serine, glutamine, methylaminoisobutyrate and 2-aminonorbornane-2-carboxylate, the effects of methylaminoisobutyrate and 2-aminonorbornane-2-carboxylate being additive. However, similar inhibition phenomena were not seen for cells deprived of serum where aminoisobutyrate uptake tended to a relatively constant level insensitive to inhibitory influences, yet substantially greater than that arising by simple diffusion. The comparative insensitivity of our hepatoma line when starved of serum to competition and repression phenomena is in contrast to findings of others. Our results also suggest a lack of clear delineation of specificities for the A and L transport systems as usually defined.