The determination of nutritional requirements in rats: mathematical modeling of sigmoidal, inhibited nutrient-response curves.

The Saturation Kinetics Model (SKM) is useful in describing many physiological responses as functions of a limiting dietary nutrient. However, as nutrients are fed at higher dietary concentrations, responses become inhibited and diminish from their usual plateaus. By adding an inhibition constant (Ks) to the SKM in a manner consistent with substrate inhibition (based on enzyme kinetics), it becomes possible to predict the inhibited portions of the nutrient-response curve.

Ascorbic acid facilitates chicken myoblast fusion in vitro.

Addition of low concentrations of ascorbic acid (5 micrograms/ml to 10 micrograms/ml) to myogenic chick embryo cultures resulted in an early fusion. At 30 h cultures receiving small amounts of ascorbic acid presented fusion rates 3 times that of the control. However, control rates of fusion were not different from those of experimentals at 50 h.

Cholesterol and apolipoprotein distribution in plasma high-density-lipoprotein subclasses from zinc-deficient rats.

Effect of zinc deficiency on the composition of plasma high-density-lipoprotein (HDL) subclasses was investigated in adult male rats (ZD) fed a diet containing 2.8 micrograms of Zn/g as compared with pair-fed (PF) and ad libitum-fed (CT) controls given 30.8 micrograms of Zn/g.

Hemodynamic and electrophysiological effects of mercury in intact anesthetized rabbits and in isolated perfused hearts.

Using intact anesthetized rabbits and isolated perfused hearts, the hemodynamic and electrophysiological effects of mercury (Hg) were examined in order to assess the role of cardiovascular dysfunction in Hg intoxication. The most consistent and prominent cardiovascular effect was a significant reduction in blood pressure. This cardiodepressive action was probably brought about by the primary action of Hg on the heart rather than by altered sympathetic activity, as evidenced by normal renal nerve activity at times when the hemodynamic actions of Hg were clearly manifest.

Interaction of amiodarone and desethylamiodarone with the cardiac muscarinic receptor in vitro.

We studied the interaction of amiodarone hydrochloride (Cordarone) and its major metabolite desethylamiodarone with the muscarinic receptor in purified canine cardiac sarcolemmal vesicles by measuring equilibrium binding of the muscarinic antagonist [3H]quinuclidinyl benzilate (QNB) and carbachol displacement of [3H]-QNB. At a [3H]-QNB concentration of 0.02 nM, equilibrium binding was inhibited by amiodarone and desethylamiodarone with an IC50 of 6.

Effects of dipyridamole on the cardiovascular response to +Gz stress in miniature swine.

Eight conscious female miniature swine experienced acceleration levels of 3, 5, and 7 +Gz before and after infusion of dipyridamole (1-2 mg.kg-1). Each animal was instrumented to measure ECG, heart level arterial pressure (AP), eye level arterial pressure (ELBP), left arterial pressure (LAP), heart rate (HR), and regional tissue blood flows.

Effect of marginal zinc deficiency on lipoprotein lipase activities in postheparin plasma, skeletal muscle and adipose tissues in the rat.

The activities of lipoprotein lipase in postheparin plasma, retroperitoneal adipose and gastrocnemius muscle tissues were determined in the rats fed 2.8 ppm of dietary zinc for eight weeks, as compared with pair-fed and ad libitum-fed rats given 30.8 ppm of zinc.

Effect of septal ablation on choline acetyltransferase in the paraventricular nucleus.

To determine whether there is a cholinergic projection from the lateral septum to the paraventricular nucleus of the hypothalamus (PVH), a quantitative histochemical analysis of the effects of unilateral ablation (0.5 microliter of a 10 micrograms/ml solution of ibotenic acid) of the lateral septum (LSV) on the choline acetyltransferase (ChAT) activity of the PVH and surrounding perinuclear area was undertaken. Comparisons of the ChAT activity of the PVH region ipsilateral to the LSV lesion (lesioned side) with that of the PVH contralateral (nonlesioned side) to the ablated LSV showed a 20% reduction (p less than 0.

Effect of systemic fluoride on rat molar morphology. Stereophotogrammetric analysis.

Female Sprague-Dawley rats were divided into three groups. All three groups were given the same solid diet (with 1.6 ppm F).

Brain histidine and food intake in rats fed diets deficient in single amino acids.

Histidine (His) is elevated in plasma and brain during protein deficiency as well as in several pathological conditions, leading to the possibility of a direct effect on central nervous system (CNS) function. In this study, groups of weanling rats were fed diets containing graded levels of casein or a single indispensable amino acid (IAA: Leu, Val, Ile, Phe, Trp, Thr, Met or Lys) in order to produce nutritionally-deficient states. Body weight gains and food intakes were recorded daily for 2 wk.

Vascular responses to vasoactive agents in dietary alcohol-treated rats.

1. Young male Sprague-Dawley rats were fed on either solid regular rat chow, control liquid diet or liquid diet containing alcohol for 26 weeks. 2.

Cancer prevention and detection centers: an overview and critique.

Cancer screening is ideally carried out in free standing centers that are located near shopping centers, are quite visible, and have a warm, friendly appearance. This chapter describes the basic elements of such a center, including the use of a mobile mammogram van based at the center. While the precise size, location, and design of a center will vary depending on the specific demographics of an area, these data should facilitate such planning.

Iron and glucose affecting growth and haemolysin production in human strains of group B streptococci.

Seven strains of group B streptococci aetiologically related to humans were investigated in order to observe the role of glucose and medium iron on their growth and haemolysin production, and the necessity of a 'carrier' molecule to ensure the stability of the haemolysin. Both growth and haemolysin production were significantly influenced by glucose and medium iron concentrations. Iron concentrations between 5 and 7 micrograms/ml and 0.

Screening for colorectal carcinoma.

Colorectal carcinoma will occur in some 147,000 Americans this year. This disease accounts for 15% of all cancers and 12% of all cancer deaths. Screening for colorectal carcinoma may allow the disease process to be found earlier and, in some situations such as when polyps are found and removed, may even prevent the disease.

Screening for lung cancer.

Lung cancer incidence is increasing. Survivability has increased over the last few years particularly in certain subsets and has also been shown to increase with early detection. Chest X-ray and sputum cytology have been the mainstays of screening programs.

Head and neck cancer: early detection.

Head and neck cancers are discussed in four categories: oral cavity, pharynx, larynx, and salivary glands. The incidence of head and neck cancers varies with the site of the lesion and ranges from the most common area of involvement, the lip, to those of the nasopharynx, which are extremely rare. The exact etiology of most of these malignancies has not been determined, but an association has been made with many factors, such as immune impairment, environmental (tobacco, chemical, radiation), and genetic.

Skin cancer--early detection.

Skin cancer, the most frequently occurring of all cancers, shows an encouragingly high rate of cure if detected early and treated properly. Etiologies of nonpigmented and pigmented premalignant lesions and malignant lesions are discussed, where known, with solar exposure frequently cited. Criteria for diagnosis are discussed; however, the clinical similarity of some malignant lesions to premalignant or nonmalignant conditions makes excision necessary in order to establish a definitive diagnosis--when in doubt, take it out.

Cytopathogenicity of Naegleria fowleri in mammalian cell cultures.

A total of 13 strains of Naegleria fowleri were cytopathogenic for lung, kidney, foreskin, ovary, connective tissue, neuroblastoma, laryngeal carcinoma, and cervical carcinoma mammalian cell lines. The strains of N. fowleri varied considerably in their ability to produce a cytopathic effect (CPE).

Quantitative distribution of six amino acids in rat retinal layers.

Concentrations of glutamate, aspartate, glutamine, glycine, GABA, and taurine were determined in samples microdissected from rat retinal layers and assayed by HPLC. Glutamate and glutamine were relatively high in the inner nuclear (INL) and ganglion cell (GCL) layers; aspartate was relatively high in the outer nuclear layer (ONL), outer plexiform layer, and INL. Distributions of glutamate and aspartate did not correlate well with those of enzymes involved in their metabolism.

Effect of copper deficiency on the composition of three high-density lipoprotein subclasses as separated by heparin-affinity chromatography.

Copper deficiency in rats produces a hypercholesterolemia with a marked increase in HDL fraction. This study investigated changes in the plasma distribution and composition of HDL subclasses as affected by copper deficiency. Plasma HDL were separated into the following three subclasses by heparin-affinity chromatography: HDL containing no apo E but high in apo A-I (HDL-E0); HDL with an intermediate level of apo E (HDL-E1); and HDL highly enriched in apo E but low in apo A-I (HDL-E2).

Effect of melittin on pituitary-adrenal responsiveness to stress.

We previously have shown that melittin evokes a sustained increase in plasma corticosterone levels of the female rat. Significant increases occurred only during the morning and the duration of the response was increased from 48 h to 8 days by a second milittin injection 3 days after initial exposure to melittin. To further evaluate the effect of melittin on adrenocortical function, rats were given melittin at 09.

Evaluation of the variety of plasmid profiles in S epidermidis isolates from hospital patients and staff.

Plasmid profiling was used to determine the variability of normal flora isolates of Staphylococcus epidermidis in order to evaluate the usefulness of plasmid profiling for identifying pathogens. Fifteen hospital staff members and patients repeatedly had cultures taken from the hands and nares, and multiple isolates were examined for plasmid profiles. S epidermidis isolated from the nares of 15 neonates were also examined.

Regulation of mouse trophoblast giant cell nucleus development in hatched mouse blastocysts by cyclic cytidine 3',5'-monophosphate (cCMP).

The dibutyryl analog of cCMP enlarged the nuclei of trophoblast giant cells and promoted blastocyst development. The result suggests that cCMP has a trophic effect on embryonic development, specifically by altering the size of the trophoblast cell nucleus but does not enhance trophoblast cell proliferation processes.

Effect of copper deficiency on the lymphatic absorption of cholesterol, plasma chylomicron clearance, and postheparin lipase activities.

The lymphatic absorption of cholesterol and plasma clearance of chylomicrons were investigated in Cu-deficient rats (CuD) fed 0.5 mg Cu/kg diet, as compared with Cu-adequate control rats (CuA) fed 7.5 mg/kg diet.