Effects of acyclo-retinoic acid and lycopene on activation of the retinoic acid receptor and proliferation of mammary cancer cells.

The biochemical mechanisms underlying the inhibitory effects of lycopene, the main tomato carotenoid, on the growth of cancer cells are largely unknown. It has been hypothesized that lycopene derivatives may act as ligands for a nuclear receptor in analogy to retinoic acid, the hormone derived from beta-carotene. The inhibition of human mammary cancer (MCF-7) cell growth and the transactivation of the retinoic acid receptor (RAR) reporter gene by synthetic acyclo-retinoic acid, the open chain analog of retinoic acid, was compared to the effects of lycopene and retinoic acid in the same systems. Acyclo-retinoic acid activated the DR-5 retinoic acid response element with a approximately 100-fold lower potency than retinoic acid. This effect was independent of cotransfection with the RARalpha receptor. Lycopene exhibited only very modest activity in this system. In contrast to the results from the transactivation studies, acyclo-retinoic acid, retinoic acid, and lycopene inhibited cell growth with a similar potency. Preincubation with each of the three compounds slowed down cell cycle progression from G1 to S phase. In summary, acyclo-retinoic acid inhibited cancer cell growth and interacted with RAR. However, it exhibited low affinity for RAR and a correspondingly low efficacy in activating this receptor, indicating that RAR does not mediate the growth inhibitory effect of the compound. In addition, the concentrations of acyclo-retinoic acid and of lycopene required for inducing inhibition of cell growth were similar, suggesting that acyclo-retinoic acid is unlikely to be the active metabolite of lycopene.

Lycopene interferes with cell cycle progression and insulin-like growth factor I signaling in mammary cancer cells.

Recent studies have shown that high insulin-like growth factor I (IGF-I) blood level is a risk factor in breast and prostate cancer. The aim of this study was to determine whether the mitogenic activity of IGF-I in mammary cancer cells can be reduced by the dietary carotenoid lycopene. The anticancer activity of lycopene, the major tomato carotenoid, has been suggested by in vitro, in vivo, and epidemiological studies. Growth stimulation of MCF7 mammary cancer cells by IGF-I was markedly reduced by physiological concentrations of lycopene. The inhibitory effects of lycopene on MCF7 cell growth were not accompanied by apoptotic or necrotic cell death, as determined by annexin V binding to plasma membrane and propidium iodide staining of nuclei in unfixed cells. Lycopene treatment markedly reduced the IGF-I stimulation of tyrosine phosphorylation of insulin receptor substrate 1 and binding capacity of the AP-1 transcription complex. These effects were not associated with changes in the number or affinity of IGF-I receptors, but with an increase in membrane-associated IGF-binding proteins, which were previously shown in different cancer cells to negatively regulate IGF-I receptor activation. The inhibitory effect of lycopene on IGF signaling was associated with suppression of IGF-stimulated cell cycle progression of serum-starved, synchronized cells. Moreover, in cells synchronized by mimosine treatment, lycopene delayed cell cycle progression after release from the mimosine block. Collectively, the above data suggest that the inhibitory effects of lycopene on MCF7 cell growth are not due to the toxicity of the carotenoid but, rather, to interference in IGF-I receptor signaling and cell cycle progression.

Do changes in growth hormone levels correlate with IGF-I levels in patients undergoing IVF-ET?

It has been suggested that adjunctive growth hormone (GH) therapy improves ovarian response and in vitro fertilization (IVF) outcome in specific groups of patients. The correlation between insulin-like growth factor (IGF) and GH is well established. The aim of this study was to determine whether changes in plasma GH correlate with IGF blood levels in patients during IVF treatment. Thirty-six women undergoing IVF and embryo transfer (ET) were examined. Ovarian stimulation was carried out by gonadotropin-releasing hormone agonists (GnRHa) and gonadotropins. Blood was drawn at the early and late follicular phase, on the day of human chorionic gonadotropin (hCG) injection and at the mid- and the late luteal phases. The samples were assayed for IGF-I, IGF-II, IGF-binding protein-3 (IGF BP-3), GH and estradiol. According to the IGF-I and GH plasma levels, patients were divided into three major groups: Group I consisted of patients in whom peak levels of GH reached more than 4 ng/ml and IGF-I decreased significantly. In this group, estradiol levels were 1863 +/- 149 pg/ml. Group II consisted of patients in whom peak blood GH levels did not exceed 2.5 ng/ml and the IGF-I level remained unchanged. In this group estradiol levels were 630 +/- 57 pg/ml. Group III consisted of patients in whom blood GH levels were low and remained unchanged while estradiol levels were 1600 +/- 420 pg/ml. In this group no significant increase in IGF-levels were observed. There was no significant change in the levels of either IGF-II or IGF BP-3 in any of the groups. We can conclude that (1) there is a negative correlation between GH and IGF-I plasma levels in patients undergoing controlled ovarian hyperstimulation (COH)-IVF, when levels of estradiol and GH are elevated; (2) plasma levels of IGF-I under ovarian hyperstimulation are probably regulated by a multifactorial system; and (3) no correlation was found between the plasma levels of IGF-I and those of IGF-II and IGF BP-3 in all patient groups.

A model of fatigue and recovery in paraplegic's quadriceps muscle subjected to intermittent FES.

The objective of this paper was to propose a mathematical model for the fatigue and recovery phases of a paraplegic's quadriceps muscle subjected to intermittent functional electrical stimulation (FES). The model is based on in vivo, noninvasive, recording of fatigue related metabolic parameters recorded during stimulation and recovery. Records of the time variations of the muscle's phosphorus metabolites, particularly the phosphocreatine (PCr) and inorganic phosphorus (Pi), obtained from 31P magnetic resonance spectroscopy (MRS), were used to calculate the intracellular pH level in the muscle and this latter parameter was incorporated in a musculo-tendon model. The fatigue-recovery model allows the transition from the fatiguing phase to the recovery phase as soon as the stimulation terminates and vice versa. This model was incorporated into a Huxley type muscle model expressing the dynamics of the muscle. Two ordinary differential equations describing the musculo-tendon dynamics and the dynamics of the activation were solved simultaneously and records of the force trajectory during intermittent stimulations were obtained. Study cases ranging from 5 to 30 s for each of the stimulation and recovery alternating phases were stimulated. The force and the total impulse in the modeled quadriceps muscle were computed. It was found that the greatest impulse was produced in intermittent stimulation of 40-50 s duty cycle, with a 50 percent ratio between the stimulation and recovery intervals. An additional series of six runs, including two contractions, one of 3 min and one of 1 min, separated by rest periods of 3, 6, 9, 12, 15, and 30 min was performed. From the predicted force trajectories obtained, the maximal force values served for comparison with measured values made on one patient.

Lycopene is a more potent inhibitor of human cancer cell proliferation than either alpha-carotene or beta-carotene.

The antiproliferative properties of lycopene, the major tomato carotenoid, were compared with those of alpha- and beta-carotene. Lycopene, delivered in cell culture medium from stock solutions in tetrahydrofuran, strongly inhibited proliferation of endometrial (Ishikawa), mammary (MCF-7), and lung (NCI-H226) human cancer cells with half-maximal inhibitory concentration of 1-2 microM; alpha- and beta-carotene were far less effective inhibitors. For example, in Ishikawa cells, a 4-fold higher concentration of alpha-carotene or a 10-fold higher concentration of beta-carotene was needed for the same order of growth suppression. The inhibitory effect of lycopene was detected after 24 hours of incubation, and it was maintained for at least three days. In contrast to cancer cells, human fibroblasts were less sensitive to lycopene, and the cells gradually escaped growth inhibition over time. In addition to its inhibitory effect on basal endometrial cancer cell proliferation, lycopene also suppressed insulin-like growth factor-I-stimulated growth. Insulin-like growth factors are major autocrine/paracrine regulators of mammary and endometrial cancer cell growth. Therefore, lycopene interference in this major autocrine/paracrine system may open new avenues for research on the role of lycopene in the regulation of endometrial cancer and other tumors.

Simulation of distal tendon transfer of the biceps brachii and the brachialis muscles.

Rupture of the distal tendons of the biceps brachii and the brachialis often consists of a clean avulsion of the end of the tendons from their tuberosities. In most of the reattachment procedures these tendons are reinserted to the same tuberosities. The purpose of this study was to examine the kinetic activity in the upper limb when the insertion locations of the two prime elbow flexors are altered. The right upper limb was modeled as a two-bar linkage moving in the vertical plane of the scapula. Our Hill-type musculo-tendon actuation system was modeled in terms of five muscles moving in three-dimensional space. The prime elbow flexors, i.e. the biceps brachii and the brachialis, were excited maximally, while the other muscles were left passive and were included as such in the analysis. The limb kinetics was studied in four different insertion locations of the biceps brachii and the brachialis. Data on the elbow kinematics, the muscle tensions histories, the muscle length-tension and velocity-tension relationships and the joint constraint forces were produced. The results indicate that when the new insertions of the biceps brachii and the brachialis are located further away from the elbow joint axis, the moments of these muscles about the joint axis increase. However, the shortening velocities of these muscles are increased as well, which results in a reduced tension. In addition, the magnitudes of the compressive force, the tangential forces and the torsional and bending moments are reduced. These results suggest that, whenever surgically possible, reinsertion of ruptured distal tendons of the biceps brachii and the brachialis more distally to the location of their tuberosities should be beneficial.

A musculotendon model of the fatigue profiles of paralyzed quadriceps muscle under FES.

In a previous work, we studied the mechanical and the metabolic profiles of fatigue of paralyzed quadriceps muscle under activation by FES. The metabolic state of the muscle during stimulation of paraplegic patients was monitored, simultaneously with the decaying force, by using 31P nuclear magnetic resonance spectroscopy. In the present work, a musculotendon model was developed to enable prediction of the force output during continuous electrical stimulation. The model consisted of five elements, including the tendon, the parallel elastic, contractile and damper muscle elements, as well as the muscle mass. The mechanism of the contractile element was based upon the length-tension and the velocity-tension curves, the activation trajectory, and the experimentally obtained relationship between force and intracellular pH. In the equations obtained, three sets of parameters were used: 1) general muscle parameters, associated with the length-tension curves of tendon, fascia, and muscle and the velocity-tension curve of the contractile element; 2) specific anthropometric parameters of the muscle; and 3) fatigue parameters which were obtained from our previously recorded experimental data. The model was formulated to allow prediction of the quadriceps muscle force under dynamic activation and at various levels of stimulation. The model solution was for isometric contraction in supermaximal stimulation, and it provided the force decaying profiles, which were compared to those obtained experimentally. The parameters yielding the best fit between the model and the experimental results were indicated. Particularly, two muscle nonspecific parameters, namely, the muscle stress parameter and the parameter representing the ratio between the muscle's slack length and its length in vivo at various knee angles, were determined using the model. The muscle stress parameter was found to be between 60 and 64 N/cm2, and the length ratio was 0.952, 0.935, 0.920, and 0.901 for the 0, 30, 60, and 90 degrees knee angle, respectively. Finally, a sensitivity analysis was conducted of the model to perturbations of these two estimated parameters, revealing that the model was sensitive to these parameters.

Integrated plasma cortisol concentration in children with asthma receiving long-term inhaled corticosteroids.

We assessed the effect of long-term therapy with inhaled beclomethasone dipropionate (BDP) on the pituitary-adrenal axis, by measuring the integrated concentration (IC) of plasma cortisol in eight children with asthma (age, 6-16 years) who regularly used inhaled BDP in doses ranging from 8 to 26.5 micrograms/kg (200-450 micrograms/day) for 6 months to 4 years. The control group included six children (age, 6-16 years) who had the IC of plasma cortisol measured as part of an endocrinological evaluation and were found to be healthy. Cortisol concentration was measured in blood samples collected continuously over a 24-hr period. Mean IC of plasma cortisol in the study group was significantly lower than in the healthy controls (mean +/- SD, 4.9 +/- 3.3 vs 9.1 +/- 1.9 micrograms/mL; P less than 0.02). Cortisol response to 0.25 mg ACTH (iv) was abnormal in one of the eight BDP-treated patients. No correlation was found between IC of plasma cortisol and the BDP dose, severity of asthma, height percentile, or the Tanner stage. We conclude that long-term therapy, even with relatively conventional doses of inhaled BDP may cause reduction in the normal physiological secretion of cortisol. The clinical relevance of low IC of plasma cortisol is not clear, but it may reflect partial suppression of the pituitary-adrenal axis.

The toxicity of guanidino compounds in the red blood cell in uremia and the effects of hemodialysis.

The presence of creatine, guanidinopropionic acid (GPA) and guanidinobutyric acid (GBA) was demonstrated in red blood cells from uremic patients; they were found only in trace amounts in red blood cells of normal controls. The levels of creatine, GPA and GBA in the red cell did not change during dialysis in contrast to the simultaneous decrease in plasma level. Both creatine and GPA inhibited glucose-6-phosphate dehydrogenase (G6PD) in vitro in physiological concentration, while creatine also activated erythrocyte transketolase (ETK). These effects are consistent with the low red cell G6PD level and high ETK activity that were observed in our uremic patients. The unchanging levels of creatine and GPA in the red cell despite hemodialysis may explain the continuing autohemolysis in otherwise adequately hemodialyzed end-stage renal failure patients.

An automated technique for the analysis of plasma guanidino acids, and some findings in chronic renal disease.

A sensitive method for the quantitative determination of all guanidino compounds in human serum, including basic compounds such as methylguanidine, was developed by the adaptation of the Technicon automatic amino acid analyzer. Elution buffers with very high pH and molarity are employed for the elution of very basic compounds from the column. Automatic quantitative determination of the plasma guanidino compounds was performed with biacetyl alpha-naphthol, a specific reagent for the guanidino group. This method permitted the quantitative automatic determination of guanidino compounds in less than 1 ml of serum of normal or uremic patients. Guanidino propionic acid and guanidino succinic acid were identified in high concentrations in uremic sera. Methyl guanidine, and guanidine were in smaller concentrations. Guanidino acetic acid and guanidino butyric acid were present in normal plasma in quantities not significantly different from those in uremic plasma.