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At least 1,297 records · Page 72Linked to original sources
PubMed1996

EWS/FLI-1 antagonists induce growth inhibition of Ewing tumor cells in vitro.

Among primitive neuroectodermal tumors, Ewing tumors are characterized by a gene rearrangement recombining the 5'-EWS gene portion with one of two ETS-related proto-oncogenes, FLI-1 or ERG, in roughly 90 and 10% of cases, respectively. We attempted to antagonize EWS/FLI-1 function in Ewing tumor cell lines. As a control, a cell line derived from another small round cell tumor of neuroectodermal origin, neuroblastoma, was used. This cell line was found to express almost identical patterns of ETS proteins except for EWS/FLI-1 and a novel, ELF-related gene product. Stable expression of antisense EWS/FLI-1 cDNA resulted in decreased endogenous EWS/FLI-1 RNA levels and growth reduction of ET cells but not of neuroblastoma cells. DNA-binding FLI-1 derivatives localizing to the nucleus in which the 5'-EWS regulatory domain was replaced by bacterial beta-galactosidase dominantly modulated transcriptional transactivation from a degenerate ETS-binding motif. Transient transfection of these dominant-negative recombinants resulted in a significant decrease in the relative number of mitoses in four Ewing tumor cell lines tested but not in the neuroblastoma cell line. The presented evidence for modulation of tumor cell proliferation by EWS/FLI-1 antagonists suggests a causal role for EWS/FLI-1-mediated gene activation in the malignant transformation of the enigmatic Ewing tumor-precursor cell.

Blotting, Northern↗
PubMed1997

Comparison of cardiac and 60 Hz magnetically induced electric fields measured in anesthetized rats.

Extremely low frequency magnetic fields interact with an animal by inducing internal electric fields, which are in addition to the normal endogenous fields present in living animals. Male rats weighing about 560 g each were anesthetized with ketamine and xylazine. Small incisions were made in the ventral body wall at the chest and upper abdomen to position a miniature probe for measuring internal electric fields. The calibration constant for the probe size was 5.7 mm, with a flat response from at least 12 Hz to 20 kHz. A cardiac signal, similar to the normal electrocardiogram with a heart rate of about 250 bpm, was readily obtained at the chest. Upon analysis of its spectrum, the cardiac field detected by the probe had a broad maximum at 32-95 Hz. When the rats were exposed to a 1 mT, 60 Hz magnetic field, a spike appeared in the spectrum at 60 Hz. The peak-to-peak magnitudes of electric fields associated with normal heart function were comparable to fields induced by a 1 mT magnetic field at 60 Hz for those positions measured on the body surface (where induced fields were maximal). Within the body, or in different directions relative to the applied field, the induced fields were reduced (reaching zero at the center of the animal). The cardiac field increased near the heart, becoming much larger than the induced field. Thus, the cardiac electric field, together with the other endogenous fields, combine with induced electric fields and help to provide reference levels for the induced-field dosimetry of ELF magnetic field exposures of living animals.

Anesthesia↗
PubMed1997

Macrophage inflammatory protein-1alpha and interferon-inducible protein 10 inhibit synergistically induced growth factor stimulation of MAP kinase activity and suppress phosphorylation of eukaryotic initiation factor 4E and 4E binding protein 1.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) and Steel factor (SLF) synergistically stimulate Raf-1 kinase activity, protein synthesis, and proliferation in hematopoietic MO7e cells; synergistic action of these factors is blocked by the suppressive chemokines macrophage inflammatory protein-1alpha (MIP-1alpha) and interferon-inducible protein 10 (IP-10; Aronica et al, J Biol Chem 270:21998, 1995). We assessed the potential for both stimulatory and inhibitory factors to act through the MAP kinase signaling pathway by studying the effects of growth factors and chemokines on MAP kinase activation. Also, because activation of kinase signaling pathways and stimulation of protein synthesis by peptide growth factors are associated with increased phosphorylation of eukaryotic initiation factor 4E (elF-4E) and the translational repressor 4E-binding protein 1 (4E-BP1) in some target cells, we investigated whether growth factor treatment could alter eIF-4E or 4E-BP1 phosphorylation state in MO7e cells. We report that treatment of MO7e cells with GM-CSF and SLF stimulated significant, greater-than-additive increases in MAP kinase activity and the phosphorylation of both eIF-4E and 4E-BP1. Increased 4E-BP1 phosphorylation correlated with a decrease in the association of 4E-BP1 with eIF-4E. Growth factor-induced phosphorylation of 4E-BP1 and dissociation of 4E-BP1 from eIF-4E was blocked in cells treated with rapamycin, wortmannin, or PD098059. Treatment of cells with IP-10 or MIP-1alpha blocked the stimulatory effects of GM-CSF and SLF, resulting in suppression of MAP kinase activity, eIF-4E and 4E-BP1 phosphorylation, and eIF-4E/4E-BP1 dissociation. Our results suggest that GM-CSF and SLF exert part of their combined growth-promoting effects on MO7e cells through activation of MAP kinase and enhancement of eIF-4E and 4E-BP1 phosphorylation and dissociation and that suppression of growth factor-induced protein synthesis by MIP-1alpha and IP-10 involves translational repression at the level of eIF-4E.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMedDate not supplied

[Mechanism of magnetosensitive binding of ions by certain proteins].

For the first time a consistent physical model is proposed that explains a weak ELF magnetic fields effect on biological systems. The probability density changes are calculated in the context of an idealized quantum model for an ion within a protein under the magnetic field modulated on the magnitude. The dissociation probability of an ion-protein complex is shown to depend on the magnetic field parameters. It is the consequence of an interference of angular modes of an ion wave function.

Ions↗
PubMed1997

[The role of antitumor drugs in treating stomach cancer patients].

The treatment of advanced gastric carcinoma is a challenge to oncologists. Within the last 6-7 years several new regimens have been introduced: EAP, FAMTX, MEP, MVP, ELF. Overall response rate of these schemes is 30-40%, a complete response seldom reaching 10%. Anticancer drugs significantly improve quality of life. Chemotherapy of advanced cancer is the method of choice. New combinations and regimens may appear promising.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1996

[A case-control study of childhood leukemia].

A 1:1 matched case-control study was conducted to investigate the etiological factors of childhood leukemia. It was found that there were five risk factors: (1) children living in the environmental pollution area, OR (95% CI) = 2.84 (1.14-7.10); (2) exposure to extreme low frequency electronmagnetic field (ELF), OR (95% CI) = 2.01 (1.18-3.42); (3) history of postnatal X-ray exposure, OR (95% CI) = 4.53 (1.68-12.21); (4) history of taking chloramphenicol, OR (95% CI) = 3.60 (1.62-8.01); (5) history of taking, antipyretic or analgesic drugs, OR (95% CI) = 1.93 (1.09-3.42). A protective factor was also discovered. Mothers often eating fish, pork and other meat foods, OR (95% CI) = 0.33 (0.18-0.59). The analysis of the population attributable risk showed that 91% of the childhood leukemia cases might attribute to these five risk factors. The interaction among these etiological factors was estimated. Results showed that there was a positive interaction between the X-ray exposure and chloramphenicol on additive model, the relative excess risk due to interaction (RERI) of childhood leukemia was 3.04.

Adolescent↗
PubMed1997

Contributions of increased efficiency and capacity of protein synthesis to rapid cardiac growth.

Rapid cardiac growth depends upon faster synthesis than degradation of protein. The rate of protein synthesis is determined by the efficiency with which the existing components of the ribosome cycle make protein and by the quantity of the components that are present. The tissue content of RNA is taken as an index of the capacity of synthesis and efficiency is expressed as the amount of protein formed per amount of RNA over a certain time period. The efficiency of synthesis is regulated by hormones, including insulin, agents that increase cAMP, alpha-adrenergic agonists, endothelin I and angiotensin II. In addition, provision of non-carbohydrate substrates and mechanical factors such as stretch and contraction increase efficiency. Impaired energy availability as occurs in anoxic or ischemic muscle decreases efficiency. Increased phosphorylation of ribosomal protein, S6, or of the peptide chain initiation factor, elF-4E, have been suggested as mechanisms to regulate efficiency of mRNA translation. Increased efficiency of synthesis accounts for cardiac growth in the first few days following aortic banding, pulmonary artery constriction and thyroxine administration. Decreased efficiency accounts for cardiac atrophy in heterotopic transplanted hearts during the first 3 days following transplantation. The capacity of synthesis is increased by insulin, thyroid hormone, activators of protein kinase C, agents that increase cAMP, and endothelin-1. Stretch of the ventricular wall and contraction of cultured neonatal myocytes accelerates ribosome formation. An increased rate of ribosomal DNA transcription accounts for accelerated ribosome formation and depends on increased activity of a transcription factor, upstream binding factor (UBF). The activity of UBF is increased either by increased rates of synthesis or by phosphorylation of the protein. Increased capacity of synthesis is a major contributor to rapid cardiac growth in the newborn heart and after several days of pressure overload.

Animals↗
PubMed1998

Effects of 50 Hz EMF exposure on micronucleus formation and apoptosis in transformed and nontransformed human cell lines.

Effects of applying extremely low-frequency electromagnetic fields (ELF-EMF) for different durations (24, 48, and 72 h) and different field intensities (0.1-1.0 mT) on micronucleus (MN) formation and induction of apoptosis were examined in a human squamous cell carcinoma cell line (SCL II) and in a human amniotic fluid cell line (AFC). A statistically significant increase of MN frequency and of induction of apoptosis in SCL II cells after 48-h and 72-h continuous exposure to 50 Hz magnetic field (MF) (0.8 and 1.0 mT) was found. However, exposure of AFC cells to EMF of different intensities and for different exposure times showed no statistically significant differences when compared with controls. These results demonstrate that different human cell types respond differently to EMF. Dose-dependent induction of apoptosis and genotoxic effects, resulting in increased micronucleus formation, could be demonstrated in the transformed cell line, whereas the nontransformed cell line did not show statistically significant effects. These findings suggest that EMF could be a promotor but not an initiator of carcinogenic effects.

Amniotic Fluid↗
PubMed1998

[William's syndrome. Report of a case with family involvement].

Williams' syndrome (WS) is a rare genetic condition of autosomal dominant inheritance with varying penetrance, which consists of supravalvular aortic stenosis, a characteristic dysmorphic facies named "elf face", mental retardation and other clinical manifestations including transient infantile idiopathic hypercalcemia, growth retardation, and frequent dental problems. It usually presents sporadically, and there are only a few cases of family involvement reported in the literature. Recent studies show that mutations in the elastin gene at chromosome 7q11.23, which occur approximately in 90% of cases, could be the cause of the different clinical manifestations in this syndrome. In this paper we report a case of family involvement with five family members involved with WS (three siblings, the mother, and the siblings' maternal uncle) and all had cardiac structural disorders (supravalvular aortic stenosis being the most frequent), a characteristic face and a low intellectual coefficient. The complementary tests included blood chemistry, chest X-ray, and echocardiogram, which led to the diagnosis of the associated valve pathology. Three patients required therapeutic catheterism with Stent valve implant and valve prosthetic replacement to control cardiac manifestations.

Female↗
PubMed1998

[Neo-adjuvants, adjuvants and palliative therapy for gastric carcinoma].

Patients with gastric cancer have a poor prognosis. Because curative surgery is often impossible (metastatic disease) or extremely difficult (locally advanced tumors), and the majority of patients undergoing curative resection relapse, chemotherapy has been actively studied in gastric cancer. Several combination chemotherapy regimens have been developed with high activity in locally advanced and metastatic disease. Among them are 5-fluorouracil (5-FU) plus high dose methotrexate plus doxorubicin (FAMTX). It represents the reference treatment in many clinical trials. Recent schedules like etoposid plus cisplatin (EAP); etoposid plus leucovorin plus 5-FU (ELF) and epirubicin plus cisplatin plus 5-FU (ECF) show encouraging response rates, their toxicity is considerable, however. Randomized trials comparing chemotherapy with best supportive care showed an increase in overall survival and in quality-of-life. Up to now adjuvant chemotherapy has failed to improve survival as compared with surgical controls. Only half of the patients with locally advanced gastric cancer (LAGC) undergo macroscopic and microscopic tumor-free resection. Preoperative chemotherapy has shown very promising results even in patients who had primarily unresectable tumors. Approximately half undergo R0 resection after downstaging induced by active chemotherapy and the long-term survival rises to about 20%. There are hopes that the newest regimes may do this: new cytostatic drugs and the immuno-chemical approach to combine cytostatic drugs with cytokines will be of great importance.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1998

[Biological effects of non-ionizing electromagnetic radiation].

Since the mid 1970's, when Adey discovered that extremely-low-frequency electromagnetic field (ELF EMF) may affect the calcium ions efflux from various cells, bioeffects of non-ionizing radiation (NIR) have become the subject of growing interest and numerous research projects. At present, the fact that NIR exerts both stimulatory and inhibitory effects on different physiological cellular parameters is rather unquestionable. At the same time, some epidemiological studies suggest that exposure to EMF is potentially harmful even if its intensity is very low. It has been proved that thermal factors are not responsible for these effects, therefore nowadays, they are called 'non-thermal effects'. Our paper deals with three different aspects of biological effects of non-ionizing radiation, bioelectromagnetism, electromagnetobiology and electromagnetic bioinformation. Firstly, we describe how EMF and photons can be produced within a living cell, how biological cycles are controlled, and what are the features of endogenous electromagnetic radiation. Secondly, we discuss various facets of external EMF interactions with living matter, focusing on extremely-low-frequencies, radio- and microwaves. Possible mechanisms of these interactions are also mentioned. Finally, we present a short overview of current theories which explain how electromagnetic couplings may control an open and dissipative structure, namely the living organism. The theory of electromagnetic bioinformation seems to explain how different physiological processes are triggered and controlled, as well as how long-range interactions may possibly occur within the complex biological system. The review points out that the presented research data must be assessed very carefully since its evaluation is crucial to set the proper limits of EMF exposure, both occupational and environmental. The study of biological effects of non-ioinizing radiation may also contribute to the development of new diagnostic and therapeutic methods.

Animals↗
PubMed1998

Differential withdrawal of retinal axons induced by a secreted factor.

To understand the development of the topographic map in the chick retinotectal projection, we studied the long-term interactions between retinal axons and tectal cell processes using a novel coculture system, the ryomen chamber. Both nasal and temporal retinal axons initially grew equally well on a substrate consisting of posterior tectal cell processes; however, subsequently most temporal axons withdrew from this surface, whereas most nasal axons did not. Experiments using conditioned media indicate that posterior tectal cells induced withdrawal of the temporal axons by secreting a soluble factor. This withdrawal seems to be distinct from the immediate repulsive effect of ephrin-A2 (ELF-1) and ephrin-A5 (RAGS) seen in the stripe assay because (1) the withdrawal-inducing factor was diffusible, whereas ephrin-A2 and -A5 are membrane-bound, and (2) the withdrawal-inducing factor appeared later in development than ephrin-A2 and -A5. Furthermore, sensitivity to the withdrawal-inducing factor decreased continuously from the temporal to nasal retina. These results suggest that target cell-induced axonal withdrawal may be involved during a late stage of the development of the retinotectal map.

Animals↗
PubMed1998

Enolase activity in chicken embryo primary retina cells is not affected by exposure to a 60-Hz electric field.

This study was to determine the extent of alteration of enolase specific activities in chicken embryo retina primary cells in culture when exposed to an ELF (extremely low frequency) electric field at 60 Hz. Results showed no alteration of enolase activity and enolase mRNA levels. In this study, sham vs. control experiments were also conducted to neutralize ambient AC magnetic fields, stray magnetic fields and variations in field uniformity. Under similar conditions, the specific activity of enolase is decreased in neuroblastoma cell line (NG108). It is apparent from this study that primary cells either are not affected by these exposure conditions or the effect is transient and warrants no damage.

Animals↗
PubMed2002

Changes in sex steroid levels in yolks of the leghorn chicken, Gallus domesticus, during embryonic development.

Yolk steroid hormones have been documented to have growth and behavior effects on hatchlings in several avian species. The purpose of these investigations was to determine initial levels of androstenedione (A), dihydrotestosterone (DHT), estradiol (E(2)), and testosterone (T), and document any changes in those hormones during the course of embryonic development in the Leghorn chicken, Gallus domesticus. Eggs were collected, labeled for hen of origin and egg sequence, incubated at 37.8 degrees C, and sacrificed at predetermined times during development. The embryos were staged, the yolk material collected, homogenized and hormones extracted. A, DHT, E(2), and T were separated via column chromatography and hormone levels determined using radioimmunoassays (RIAs). Results indicate a significant decrease in A and T during embryonic development, similar to that reported by our laboratory for the alligator, with A levels being significantly greater initially than levels of all other hormones. Changes in DHT mirrored changes in T levels. Chicken E(2) yolk content dynamics differ from those we have measured in both the turtle and the alligator. After an initial decline, E(2) in the yolks of chicken eggs undergoes a significant increase at the end of development, between embryonic stages 40 and 45 (days 14 and 20 of development). As the increase is much larger than could be accounted for by hormones present in the yolk material, this may represent early embryonic production of steroid hormones by the developing gonads.

Animals↗
PubMed1997

Yolk steroids decline during sexual differentiation in the alligator.

The leading explanation of temperature-dependent sex determination (TSD) in reptiles postulates that (1) ovarian differentiation is directed by estrogen and that (2) estrogen is synthesized in the developing gonad following induction of aromatase expression. However, the source of steroid substrate for aromatization has not yet been identified. In addition, sex ratios vary as a function of clutch, but such biases are as yet unexplained. To address these issues, we measured estradiol, testosterone, and androstenedione in yolks of the American alligator (Alligator mississippiensis) before, during, and after the period of gonadal differentiation in this TSD species. Eggs were collected from a wild population in Louisiana and were incubated at male- and female-determining constant temperatures in the lab, as well as at intermediate temperatures that produced both sexes. Steroids were assayed in yolk extracts after celite column chromatography. All three steroids were found to be in the range of nanograms/gram of yolk at stage 16. Androstenedione was the predominant steroid, 2- to 3-fold higher in concentration than estradiol and 15- to 20-fold higher than testosterone. The levels of these steroids declined (5- to 30-fold) between stages 16 and 25, most markedly between stages 21 and 23, regardless of incubation temperature. The chronology of this sharp decline in steroid levels in our study coincides with the timing of gonadal differentiation in this species, between stages 21 to 23 based on previous reports. Estradiol levels in yolks differed by 3-fold in some clutches relative to others, whereas, no clutch differences were apparent for either androstenedione or testosterone. These data demonstrate that alligator yolk contains high concentrations of two steroid substrates utilized for estrogen synthesis, as well as significant quantities of estradiol itself. We hypothesize that estradiol levels in yolk provide a steroid background, variable among and within clutches, on which gonadal development is initiated and proceeds. As a consequence, we suggest that yolk provides an epigenetic maternal contribution that modulates the effect of incubation temperature on hatchling sex.

Alligators and Crocodiles↗
PubMed2001

Comparison of repressor and transcriptional attenuator systems for control of amino acid biosynthetic operons.

In bacteria, expression from amino acid biosynthetic operons is transcriptionally controlled by two main mechanisms with principally different modes of action. When the supply of an amino acid is in excess over demand, its concentration will be high and when the supply is deficient the amino acid concentration will be low. In repressor control, such concentration variations in amino acid pools are used to regulate expression from the corresponding amino acid synthetic operon; a high concentration activates and a low concentration inactivates repressor binding to the operator site on DNA so that initiation of transcription is down or up-regulated, respectively. Excess or deficient supply of an amino acid also speeds or slows, respectively, the rate by which the ribosome translates mRNA base triplets encoding this amino acid. In attenuation of transcription, it is the rate by which the ribosome translates such "own" codons in the leader of an amino acid biosynthetic operon that decides whether the RNA polymerase will continue into the operon, or whether transcription will be aborted (attenuated). If the ribosome rate is fast (excess synthesis of amino acid), transcription will be terminated and if the rate is slow (deficient amino acid supply) transcription will continue and produce more messenger RNAs. Repressor and attenuation control systems have been modelled mathematically so that their behaviour in living cells can be predicted and their system properties compared. It is found that both types of control systems are unexpectedly sensitive when they operate in the cytoplasm of bacteria. In the repressor case, this is because amino acid concentrations are hypersensitive to imbalances between supply and demand. In the attenuation case, the reason is that the rate by which ribosomes translate own codons is hypersensitive to the rate by which the controlled amino acid is synthesised. Both repressor and attenuation mechanisms attain close to Boolean properties in vivo: gene expression is either fully on or fully off except in a small interval around the point where supply and demand of an amino acid are perfectly balanced.Our results suggest that repressors have significantly better intracellular performance than attenuator mechanisms. The reason for this is that repressor, but not attenuator, mechanisms can regulate expression from biosynthetic operons also when transfer RNAs are fully charged with amino acids so that the ribosomes work with maximal speed.

Acylation↗
PubMed2001

Oral health and quality of life among patients with head and neck cancer or haematological malignancies.

The aim of the present study was to monitor the health-related quality of life (HRQOL) of patients with head and neck cancer or haematological malignancies during a period from before to after medical treatment, and to investigate the relationships between patient experiences of oral symptoms and HRQOL. The sample consisted of 41 consecutive patients. At the start, during and end of radiotherapy or the second/third cycle of chemotherapy, patients rated their experiences of oral symptoms on a 100-mm visual analogue scale and completed the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ) C30 and the EORTC QLQ H&N35 (head and neck patients). At the end of treatment, an interview was done regarding the perceived influence of oral status on HRQOL. Among patients receiving radiotherapy, HRQOL tended to decrease over time, and oral symptoms increased. Patients who reported that their oral symptoms had influenced their everyday life (56%) reported more severe oral symptoms and lower HRQOL scores at the end of treatment when the oral symptoms were most intense. The findings from correlational analyses support the patients' reports from the interviews. For patients receiving chemotherapy for haematological malignancies, the quality of life did not change during the chemotherapy cycle. They reported very few oral symptoms, and very few reported that oral symptoms had any influence on their HRQOL. However, the correlational data indicate a relation between oral symptoms and HRQOL. Patients who reported more severe oral symptoms also reported lower HRQOL scores. The results demonstrate that oral status is related to HRQOL in these patient groups.

Adult↗
PubMed2005

Time-place learning in the cichlid angelfish, Pterophyllum scalare.

The ability of the cichlid angelfish, Pterophyllum scalare, to associate time and place to locate food, provided twice a day in two different places, was tested. Food was delivered daily in one corner of the tank in the morning and in the diagonally opposite corner in the afternoon, for a 3-week period, and the distribution of the fish in the tank was noted prior to and during feeding time. The results indicate that, in a fairly uniform environment and in the absence of external time cues, angelfish can discriminate and associate time and place to obtain a food reward. It is suggested that they do so by means of an endogenous timing mechanism.

Animals↗