Inhibition of Abl tyrosine kinase enhances nerve growth factor-mediated signaling in Bcr-Abl transformed cells via the alteration of signaling complex and the receptor turnover

Receptor tyrosine kinase-mediated signaling is tightly regulated by a number of cytoplasmic signaling molecules. In this report, we show that Bcr-Abl transformed chronic myelogenous leukemia (CML) cell lines, K562 and Meg-01, express the receptor for nerve growth factor (NGF), TrkA, on the cell surface; however, the NGF-mediated signal is not particularly strong. Treatment with imatinib, a potent inhibitor of Bcr-Abl tyrosine kinase, downmodulates phosphorylation of downstream molecules. Upon stimulation with NGF, Erk and Akt are phosphorylated to a much greater degree in imatinib-treated cells than in untreated cells. Knockdown of expression of Bcr-Abl using small interfering RNA technique also enhanced NGF-mediated Akt phosphorylation, indicating that Bcr-Abl kinase modifies NGF signaling directly. Imatinib treatment also enhanced NGF signaling in rat adrenal pheochromocytoma cell line PC12 that expresses TrkA and c-Abl, suggesting that it is not only restoration of responsiveness to NGF after blocking oncoprotein activity, but also c-Abl tyrosine kinase per se may be a negative regulator of growth factor signaling. Furthermore, inhibition of Abl tyrosine kinase enhanced clearance of surface TrkA after NGF treatment and simultaneously enhanced NGF-mediated signaling, suggesting that as in neuronal cells 'signaling endosomes' are formed in hematopoietic cells. To examine the role of TrkA in CML cells, we studied cell growth or colony formation in the presence or absence of imatinib with or without NGF. We found that NGF treatment induces cell survival in imatinib-treated CML cell lines, as well as colony formation of primary CD34+ CML cells, strongly suggesting that NGF/TrkA signaling contributes to aberrant signaling in CML.

Fluorescence-based functional assay for Wnt/beta-catenin signaling activity

Aberrant activation of beta-catenin signaling has been implicated in the development of human cancers. As a Wnt signal transducer, beta-catenin forms a complex with the lymphocyte enhancer-binding factor/T cell factor transcription factor and activates downstream targets that promote cell proliferation. Here we developed a Wnt-dependent beta-catenin-mediated heterologous transactivation system, which consisted of a chimeric transcription factor constructed by fusing the GAL4 DNA-binding domain with the full-length beta-catenin, and a GAL4-responsive reporter expressing GFP. The chimeric transcription factor was highly unstable and exerted no detectable transactivating effect on the GAL4-responsive reporter. However, lithium and Wnt1 significantly stabilized this chimeric transactivator, indicating that this transactivation system is regulated by beta-catenin in a Wnt-responsive fashion. Thus, this transactivation system could be used as a functional reporter to identify potential upstream factors that deregulate beta-catenin signaling during tumorigenesis, as well as to screen for potential anti-cancer agents that specifically inhibit beta-catenin signaling in human tumors.

Tetracycline-regulated gene expression mediated by a novel chimeric repressor that recruits histone deacetylases in mammalian cells

Regulated gene expression will provide important platforms from which gene functions can be investigated and safer means of gene therapy may be developed. Histone deacetylases have recently been shown to play an important role in regulating gene expression. Here we investigated whether a more tightly controlled expression could be achieved by using a novel chimeric repressor that recruits histone deacetylases to a tetracycline-responsive promoter. This chimeric repressor was engineered by fusing the tetracycline repressor (TetR) with an mSin3-interacting domain of human Mad1 and was shown to bind the tetO(2) element with high affinity, and its binding was efficiently abrogated by doxycycline. The chimeric repressor was shown to directly interact with mSin3 of the histone deacetylase complex. This inducible system was further simplified by using a single vector that contained both a chimeric repressor expression cassette and a tetracycline-responsive promoter. When transiently introduced into mammalian cells, the chimeric repressor system exhibited a significantly lower basal level of luciferase activity (up to 25-fold) than that of the TetR control. When stably transfected into HEK 293 cells, the chimeric repressor system was shown to exert a tight control of green fluorescent protein expression in a doxycycline dose- and time-dependent fashion. Therefore, this novel chimeric repressor provides an effective means for more tightly regulated gene expression, and the simplified inducible system may be used for a broad range of basic and clinical studies.

Adenoviral vector-mediated gene transfer for human gene therapy

Human gene therapy promises to change the practice of medicine by treating the causes of disease rather than the symptoms. Since the first clinical trial made its debut ten years ago, there are over 400 approved protocols in the United States alone, most of which have failed to show convincing data of clinical efficacy. This setback is largely due to the lack of efficient and adequate gene transfer vehicles. With the recent progress in elucidating the molecular mechanisms of human diseases and the imminent arrival of the post genomic era, there are increasing numbers of therapeutic genes or targets that are available for gene therapy. Therefore, the urgency and need for efficacious gene therapies are greater than ever. Clearly, the current fundamental obstacle is to develop delivery vectors that exhibit high efficacy and specificity of gene transfer. Recombinant adenoviruses have provided a versatile system for gene expression studies and therapeutic applications. Of late, there has been a remarkable increase in adenoviral vector-based clinical trials. Recent endeavors in the development of recombinant adenoviral vectors have focused on modification of virus tropism, accommodation of larger genes, increase in stability and control of transgene expression, and down-modulation of host immune responses. These modifications and continued improvements in adenoviral vectors will provide a great opportunity for human gene therapy to live up to its enormous potential in the second decade.

Peroxisome proliferator-activated receptors: roles in tumorigenesis and chemoprevention in human cancer

Peroxisome proliferator-activated receptors are nuclear receptors that were isolated for their ability to modulate lipid metabolism. Similar to other members of the nuclear receptor family, peroxisome proliferator-activated receptors bind ligand as heterodimers and exert their effects via transcriptional regulation through their DNA binding domains. During the past decade, it has become clear that peroxisome proliferator-activated receptors also contribute to a variety of different biologic processes, including atherosclerosis, insulin resistance, and more recently, cancer. In this review, we discuss the evidence for the different peroxisome proliferator-activated receptors' roles in tumorigenesis and also their potential application for the treatment and prevention of neoplastic diseases.

[Tumoral angiogenesis--hot topic in science again]

Angiogenesis is the formation of new capillary blood vessels. It has a very important role not only in physiological conditions but in the process of malignant tumors growth. Weak muscular layer, chaotical branching and irregular shape, are the characteristics of newly formed tumorous vessels. The number and arrangement of blood vessels differ between benign and malignant tumors. Latest data suggesting that drugs inhibiting angiogenesis can stop growth of malignant tumors made the research on tumorous angiogenesis a hot topic recently. Although reliable in differentiating benign from malignant tumors, two-dimensional ultrasound with color and pulsed Doppler, can not make spatial image of vascular architecture. Three-dimensional (3D) ultrasound with color Doppler allows the investigator to have a three-dimensional architectural picture of tumorous vascular network, and according to the findings it is possible to detect malignant tumors even in doubtful cases.

Glycoprotein and ganglioside changes in human trophoblasts after exposure to pulsed Doppler ultrasound

Changes in glycoprotein and ganglioside composition in human trophoblasts (eighth week of gestation) after in vitro exposure to pulsed Doppler ultrasound (pulse duration 1.22 microseconds; repetition frequency 11.1 kHz; center frequency 4 MHz; ISPPA = 175.5 W/cm2; ISPTA = 0.59 W/cm2) were investigated. Evacuated trophoblasts were divided in two halves and insonated for 10 min on top of a 6-cm layer of 5% gelatin in 50-mL tubes (Falcon) at 37 degrees C. One half of each trophoblast was sham insonated and served as an internal control. After insonation trophoblasts were maintained at 37 degrees C for 24 h. Glycoproteins were detected using alpha-D-mannose specific lectins from Galanthus nivalis and Narcissus pseudonarcissus. A decrease in the expression of mannose containing glycoprotein mgp47 and an increase in expression of mgp54 were observed. Ganglioside composition was also significantly altered. Concentrations of two gangliosides migrating similarly to GM2, and one similarly to GQ1, decreased by more than 75%. At the same time, concentrations of one ganglioside migrating similarly to GM3, and two other unidentified gangliosides increased two- to fourfold.

Characteristics of blood flow in cancer of the uterine cervix

Blood flow characteristics were measured in patients with histologically proved cervical cancer and compared to normal values. Flow parameters were derived by color and pulsed Doppler ultrasound. The results showed a significant difference in the mean values of resistance index and pulsatility index among the diseased patients and healthy controls. However, the method does not have the required sensitivity for screening purposes, so that its value may mainly be in the follow-up of patients treated conservatively with radiation and chemotherapy.

Possibilities of ultrasound catheters

Ultrasound catheters offer the possibility of various non-imaging applications. Some of these applications, now in different stages of development, have been studied and will be described here in some detail. Ultrasonically marked catheters have different applications. The catheter has a miniature marker transducer mounted at the tip or some other place of interest. Initially, this device was used to localize the pacing lead tip in the heart. Connected to a transponder of a passive type this device can generate a visible localization mark on the echograph screen. The basically same system can be used for early detection of cracking of the pacing lead insulation. In this case the marker transducer works as a high-frequency signal generator and detects characteristic capacitance changes better than other methods. The electronic circuit for measurement is built into the pacemaker. Other non-imaging applications have also been studied. The marker transducer can be used for echo ranging of the distance between a His bundle fulguration electrode and the structure to be destroyed. Such an automatic 'proximity fuse' can help to avoid the firing of energy at too great a distance from the His bundle. Technology of implantable defibrillators yields the possibility for a double transducer arrangement, one transducer mounted at the patch and the other being the marker transducer. Using on-line distance measurement this arrangement enables early detection of abnormal movement of the ventricle wall, thus detecting deterioration of the muscle function before it is electrically evident. The measurement was simulated in-vitro. Measurement of axial blood flow using transit time methods, instead of Doppler, was also experimentally studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Properties of ultrasonically marked leads

We have developed an ultrasonic marking system for pacing leads and the electrophysiological study of catheters. The aim of this study was to evaluate the accuracy of our system, its usability in the measurement of performance of implanted leads, and to investigate the potential of electrical shock and ultrasonic hazard. The measurements have shown that different applications require specific electronic design, involving some compromise between accuracy and sensitivity. A higher sensitivity at the beginning of the ultrasonically guided cardiac lead implantation yields poorer accuracy. Quantitative measurements show that accuracy can be subsequently improved by reduction of sensitivity of the marking system. The transponder marking circuit is better suited for general use and the passive electronic circuit is better suited for multiple electrode electrophysiological studies. Experiments concerning electrical safety show that in the worst failure case, the energy of the marking system released within the heart is less than 10(-9) J per pulse within the pacing frequency spectrum and the current was below 50 microamperes. Ultrasound intensities were within the safety limits set by international and national organizations. The experiments using the marking system for detection of the pacing lead failure showed that the system can yield an early warning of the lead malfunction. The system can significantly reduce the exposure of the medical staff and the patients to x rays as well as improve patient follow-up accuracy.

Color flow mapping in obstetrics

Blood flow studies are now used extensively in evaluating fetal peripheral circulation. By using continuous and pulsed Doppler ultrasonic equipment the raw Doppler shifts caused by blood moving in the vessels can be analyzed in different ways. Spectral data can be used to estimate blood velocity and volume in the vessel, and pulsatility characteristics and turbulence. All these data are obtained from very restricted areas within the body so that aiming of the probe is critical, and obtaining data from an area requires long and tedious effort. Color flow mapping which has recently been introduced into clinical practice provides an overview of flow velocities and directions within an area. Color coded flow can be displayed by applying the moving target identification principle (as in radar) to an ultrasonic diagnostic instrument where sound waves are used instead of radio waves. The value of flow mapping has already been recognized in the diagnosis of congenital and acquired heart disease in adults and children. Direct visualization of intracardiac flow provides for a fast and accurate diagnosis of various cardiac defects, such as the ventricular septal defect, without cardiac catheterization. In the present study we have investigated the potential of color flow mapping in obstetrics. 211 pregnant women were examined between the 15th and 40th weeks of pregnancy. 193 of them had normal pregnancies; 18 were abnormal, including 11 cases of insulin dependent diabetes, 2 cases of Rh-immunization, 2 cases of nonimmunologic fetal hydrops, 2 cases of fetal cardiac structural defects and 1 case of intrauterine growth retardation. Intracardiac flow was clearly seen in 78% (35/45) of cases at the gestational age between the 20th and 24th weeks. After the 24th week the heart flow visualization rate gradually decreased to 31% (11/36) before term. In 2 cases of congenital heart abnormality flow mapping enabled clear visualization of reverse flow through the tricuspid valve and diagnosis of valvular insufficiency. The best results in studies of flow in peripheral vessels were obtained from umbilical vessels which were seen in all cases after the 15th week. The flow visualization rate was much lower when the fetal aorta, intrahepatic umbilical vein and internal carotid artery were studied. The comparison between the diameter of the umbilical vein measured on the B-scan and flow width in the same vessel showed no significant difference (t = 0.26; p less than 0.01; N = 209).(ABSTRACT TRUNCATED AT 400 WORDS)

A simple device for checking the acoustic beam of ultrasonic therapy equipment

Ultrasound of time average acoustic intensities between 0.5 and 3 W cm-2 is widely used in physiotherapy. A simple device for semiquantitative checking of output power and beam shape has been designed. The beam tester consists of an absorbing plate and a sheath liquid crystal thermometer for temperature distribution display. The ultrasonic beam is fed to the absorber through a simple water tank.

A study of explicit greytone perception on TV video monitors

46 persons have been tested in their ability to resolve grey tones in quantitatively callibrated transparencies. The transparencies were designed as phantoms matched in lightness and dynamics to TV monitors. The results show that on average not more than 9 grey tones can be counted in such phantoms and that dark gaps between the fields decrease the confidence of viewers.

[Ultrasonic evaluation of fetal weight by comparing the circumference and area of the trunk]

Birthweight estimation has clinical importance in routine practice. The method used at present is the measuring of the circumference of the fetal abdomen at the umbilical vein level. The aim of this study was to check the theoretical hypothesis that a simple method of the trunk area measurement is a better birthweight estimator than the circumference measurement (when elliptic elongation is changed). In order to make this measurement simple, an ellypsoid approximation of the trunk cross section was used, i.e. the longest and the shortest diameters were measured. The area is proportional to the product of the diameters while the circumference is proportional to the sum of the two. The longest and the shortest diameters were measured in 200 patients up to two days prior to delivery, perpendicular to the spine at the umbilical vein level. The results have shown that in fetuses whose cross-section of the abdomen is elongated, the product of the longest and the shortest diameter gives a significantly better correlation to birthweight than their sum.

Ultrasonic mammography without specialized equipment. Comparison with clinical examination and x-rays

Ultrasonic mammography has been compared with clinical examination and X-ray mammography. Results for the years 1977-79 are shown. A general purpose compound scanner and a custom made water delay bath are used. Twenty three percent of patients undergoing breast examination had an ultrasonic scan. The lowest limit for cyst detection in 4 mm diameter and for solid tumours about 10 mm. Comparison of the three methods shows an agreement of approx. 87% in benign lesions (i.e. agreement in the type of benign disease), and between 16/18 and 17/18 in malignant lesions (comparison of suspicion of malignancy only). As a result of these findings ultrasound is used in our department as a useful auxiliary method.

Noise in ultrasonic imaging

The feasibility of noise measurement in medical ultrasonic imaging has been studied and a theoretical evaluation of stochastic noise influence upon the perceived image has been undertaken. The influence of noise on a perceived image has been calculated by considering the light intensity perception characteristic of the human eye and it has been found taht the additive noise in the video signal pushes the small signals in the image towards the invisible (black) region. Impulse noise measurements of amplitude and time jitter have been set up using a standard water/CCl4 interface and pulse amplitude analysis to take into account the random nature of noise by distribution measurements.

Effects of patient positioning and of thickness variations on radiotherapy

Correct patient positioning is essential for good aiming in radiotherapy. This can be achieved using back and side pointers, but sometimes these devices are not being used in order to simplify and make the positioning faster. The effects of such a simplification have been studied and measured. The results of this experimental study show that in thicker patients (over 24 cm) the use of back and side pointers is of great importance, because the variation of the patient thickness and angulation can significantly influence the aiming angles and dose percentages.

Estimation of fetal weighty by ultrasonic abdominometry

The fetal abdomen was measured with an ultrasonic contact scanner in order to correlate abdomenal circumference and birth weight. A sample of 134 measurements was used to calculate a standard graph, which was then tested against a subsequent 280 measurements, giving a mean estimation error of 105 Gm. Head-to-abdomen circumference ratio measurements were used to assess the type of growth retardation.

The energy response of LiF, film and a chemical dosemeter to high energy photons and electrons

The physical responses of LiF, film and a chemical dosemeter in high energy photon and electron beams has been studied. It is shown that the response for film and the chemical dosemeter does not change significantly up to 42 MeV, while for LiF it decreases by about 10%. Analysis of calculations and measurements showed that this decrease could not be explained by existing theories.

Study of the Double-Layer by A.C. Polarography

Possible effects of the structure of the double-layer on the a.c. polarographic phenomena observed have been considered. Results obtained in the reduction of zinc and uranium, at potentials more negative than the e.c.m., and of copper at potentials more positive than the e.c.m., were explicable in terms of double-layer influences. A.C. polarograms sometimes showed changes in double-layer structure much more clearly than double-layer measurements per se, suggesting the utility of a.c. polarography specifically in double-layer studies.

Alternating current polarography of organic compounds. V. Quantitative treatment of the adsorption process

Equations are derived to express the adsorption equilibrium subsisting at an adsorbent surface in the presence of two adsorbable species. These equations are applied to the case of the reduction of organic compounds at the dropping mercury electrode. It is well known that adsorption at the electrode can produce irreversibility in the D.C. step, and a qualitative explanation is provided. The same treatment is used to explain the shape of the A.C. calibration curves.

Alternating current polarography of organic compounds

In previous papers of this series (Breyer, Bauer, and Hacobian 1954 ; Breyer and Bauer 1956) it was shown that the A.C. polarographic behaviour of organic com- pounds can be explained by postulating adsorption of the substances at the electrode. Empirical and theoretical expressions for the dependence of the alternating current on the bulk concentration of depolarizer were qualitatively correlated. In the present paper, the theoretical treatment is developed further, permitting the evaluation of the adsorption coefficients of the oxidized and reduced forms at the electrode surface.

The influence of the supporting electrolyte on tensammetric waves

The influence of the supporting electrolyte on the height and frequency dependence of tensammetric waves is examined. Anions generally affect the positive tensammetric waves whereas cations have little effect on either positive or negative waves. A tentative explanation of the underlying phenomena is given and the possible mechanism discussed.

Alternating current polarography of organic compounds. III. Chloranilic acid

The behaviour of chloranilic acid at the dropping mercury electrode has been techniques of ordinary and of alternating current polarography. A new type of tensammetric wave has been encountered, which is probably an outcome either of multilayer adsorption and/or of a change in state of the adsorbed film. At the same time, a new tensammetric phenomenon, the exchange of one species of surface-active molecules against another, has been observed. Alternating current polarography can be used for estimating chloranilic acid at concentrations as low as 10-7M, whereas conventional polarography does not permit analysis at concentrations below 10-5M.

Theory of alternating current polarography. II. Significance of the Heyrovsky-Ilkovic equation and its relation to the production of A.C.Polarogrphic waves

The significance of the Heyrovsky-Ilkovic equation is discussed and the relationship between reversibility of the electrochemical reaction and polarographic reversibility critically examined. It is shown that even reversible electrochemical processes might yield D.C. polarograms of the irreversible type. The relationship between different types of electrode reactions and the production of A.C. polarographic waves is elucidated.

Theory of alternating current polarography. III. Frequency of alternating field and reaction rate

The equation of the A.C. polarographic current for processes where the frequency of the alternating field is comparable with the rate of the electrode reaction is derived. Relative values of equilibrium rate constants of some first order electrode reactions are evaluated experimentally.

Alternating current polarography of Organic compounds. IV. Perinaphthenone

The behaviour of perinaphthenone at the dropping mercury electrode has been investigated by the combined techniques of conventional (D.C.) and alternating current (A.C.) polarography. Two D.C. steps were observed, but an A.C. polarographic wave was found only at the potential of the more positive D.C. step. Two tensammetric waves were also seen, one of which appears to be the outcome of multilayer adsorption or of a change in state of the adsorbed film.

Alternating current polarography of organic compounds

The alternating current polarography of quinone and hydroquinone has been investigated. The calibration curves follow an equation of the type of the Langmuir isotherm. The method can be used for quantitative analysis, the accuracy being greatest at low temperatures and in a concentration rang between 10-5 and 10-4M.

Alternating current polarography of organic compounds. I. General introduction and theory

The theoretical principles governing the alternating current polarography of organic compounds are presented. The role of adsorption, and the relationship between the A.C. and D.C. criteria of polarographic reversibility are discussed.

Theory of alternating current polarography. I. Equation of the reversible AC polarographic wave

An equation for the A.C. polarographic current is derived from considerations of concentration changes produced at the dropping mercury electrode in virtue of the superposition of a small sinusoidal alternating voltage onto the direct potential, for the case of reversibly reduced inorganic ions. The equation predicts the magnitude of the A.C. polarographic current at any point on the polarogram.