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Results for “Enhancer”

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PubMed1998

Contrast enhanced magnetic resonance imaging for femoral neck fracture.

Femoral head perfusion was evaluated in 29 patients after acute femoral neck fracture using contrast enhanced fat saturation magnetic resonance imaging. The patients were followed up with T1 and T2 weighted spin echo magnetic resonance imaging without fat saturation, which is suitable in detecting avascular necrosis. The mean interval from injury to the initial contrast enhanced fat saturation magnetic resonance imaging was 24.5 hours. The mean age at the time of injury was 69 years, and the mean followup was 26.9 months. Three distinct patterns of femoral head enhancement were recognized in the acute phase after fracture. When the whole femoral head was well enhanced (Type 3, n = 11), no avascular necrosis developed. In contrast, when the head showed no enhancement (Type 1, n = 6), avascular necrosis developed in all patients. In patients with partial enhancement (Type 2, n = 12), avascular necrosis developed in five patients. These data showed the current method provided an accurate prediction of the development of avascular necrosis in the patients with Type 1 and Type 3 enhancement. However, overall predictive value was 59% (17 of 29 patients) because of the uncertainty in the patients with partial enhancement (Type 2), and additional study is needed for this method to become routine in clinical use.

Adolescent↗

PubMed1997

[Application of T1-weighted images by contrast-enhanced frequency-selective presaturation in magnetic resonance imaging].

In this study contrast-enhanced frequency-selective presaturation T1-weighted images and contrast-enhanced spin echo T1-weighted images in 32 cases were detected and analysed comparatively regarding enhancing lesions and the signal intensity of enhancing lesions. The results showed that in the signal intensity of enhancing lesion, the contrast enhanced frequency-selective presaturation T1-weighted images showing high sign were greater than contrast-enhanced spin echo T1-weighted images. The former was better than the later in accurate evaluation of the margin, size and the differential diagnosis of enhancing lesion, especially in the regions containing more fat and bone marrow.

Bone Diseases↗

PubMed2000

Crohn's disease evaluation: comparison of contrast-enhanced MR imaging and single-phase helical CT scanning.

The purpose of this study was to evaluate the use of gadolinium and barium-enhanced magnetic resonance (MR) imaging in detecting intestinal and extraintestinal Crohn's disease and compare MRI with contrast-enhanced helical computed tomography (CT). Twenty-six patients with Crohn's disease underwent imaging examinations, including gadolinium-enhanced, fat suppressed fast multiplanar spoiled gradient-recalled (FMPSPGR) MR imaging with oral 2% barium sulfate and rectal water and with helical CT using i.v. and positive (13) or negative (13) intestinal contrast material. MR images and CT scans were reviewed separately by two radiologists for bowel wall thickness and enhancement, presence of abscess, phlegmon, and fistula. MR images and CT scans were then compared side by side. Surgical, endoscopic, and histopathologic findings and results of barium studies were reviewed to determine the location and severity of involvement of intestinal Crohn's disease. Depiction of mural thickening and/or enhancement was superior on the MR images, which showed 55 (85%) and 52 (80%) of 65 abnormal bowel segments for the two observers, compared with helical CT, which showed 39 (60%) and 42 (65%; P < 0.001, P < 0.05) of bowel segments affected by Crohn's disease. Segments of bowel with moderate or marked mural thickening were depicted equally on MR imaging and helical CT. In mildly diseased segments of bowel, with only slight thickening and enhancement, MR imaging depicted 22 (79%) and 19 (68%) of 28 segments, compared with helical CT, which depicted 9 (32%; P < 0.01), and 13 (46%; P > 0.05) of 28 segments. In the side-by side comparison, MR imaging was preferred over helical CT for depicting normal bowel wall (MR 71%, CT 4%, equal 25%; P < 0.001), mural thickening (MR 41%, CT 11% equal 48%; P < 0.01), mural enhancement (MR 89%, equal 11%; P < 0.001), and overall GI tract evaluation (MR 52%, CT 10%, equal 38%; P < 0.001). Gadolinium-enhanced MR imaging with oral dilute barium sulfate and rectal water depicts intestinal and extraintestinal changes of Crohn's disease and shows promise as a clinically useful tool.

Adult↗

PubMed1998

Magnetization transfer changes in the normal appearing white matter precede the appearance of enhancing lesions in patients with multiple sclerosis.

Serial monthly magnetization transfer (MT) imaging was performed to evaluate whether a change of the normal appearing white matter (NAWM), which precedes the appearance of enhancing lesions, is seen in patients with multiple sclerosis (MS). Every 4 weeks for 3 months, 10 patients with relapsing-remitting MS were scanned with a T1-weighted sequence, 20 minutes after injection with 0.3 mmol/kg gadolinium-DTPA (Gd-DTPA). During each of the monthly sessions, MT and dual echo scans were also performed before Gd-DTPA injection. On coregistered images, the MT ratio (MTR) was measured in NAWM subsequently involved by enhancing lesions, in NAWM areas on the same slices but outside any present or future MR abnormality, and in enhancing lesions at the time of their appearance. Forty-eight new enhancing lesions with no corresponding abnormalities on previous scans were identified. Their average MTR was 33.1% (+/-8.4%). Three, 2, and 1 month before enhancement appearance, the mean MTR in NAWM, measured from areas corresponding to future enhancing lesions, was significantly lower than the mean MTR in NAWM outside enhancing areas; the MTR decreased steadily as the time when the enhanced lesion approached. These results suggest that changes in the NAWM of patients with MS occur before lesions become evident on conventional MRI scans.

Adult↗

PubMedDate not supplied

New enhancers for the chemiluminescent peroxidase catalysed chemiluminescent oxidation of pyrogallol and purpurogallin.

The effects of various boronate compounds, 4-biphenylboronic acid, 4-bromobenzene-boronic acid, trans-4-(3-propionic acid)phenylboronic acid and 4-iodophenylboronic acid, on the horseradish peroxidase (HRP) catalysed chemiluminescent oxidation of pyrogallol and purpurogallin by peroxide were investigated. trans-4-(3-Propionic acid)phenylboronic acid produced a 13.7-fold enhancement in the peak light emission from the chemiluminescent HRP catalysed pyrogallol reaction (detection limit for HRP < 1.25 fmol). At low enhancer concentration a single peak of light emission was observed and as the enhancer concentration increased the time to peak light emission became progressively longer. The chemiluminescence showed two peaks at higher concentrations (> 54.3 mumol/L) and the individual peak times depended upon the concentration of the enhancer. All of the boronates enhanced peak light emission in the chemiluminescent HRP catalysed purpurogallin reaction. 4-Biphenylboronic acid was the most effective and it enhanced peak light emission 314-fold. The practical detection limit for HRP (Type VIA) using this enhancer was 4.18 pmol (peak emission at 20 minutes). This compound also enhanced peak light emission 232-fold from a chemiluminescent HRP-purpurogallin reaction in which molecular oxygen replaced peroxide as the oxidant.

Antioxidants↗

PubMed1977

Enhancing lymphocytes in spleens of tumor-bearing mice: affinity chromatography on insolubilized histamine.

Spleen cells from C57BL mice carrying the metastatic Lewis lung carcinoma (3LL) developed a transient cytotoxic response towards the tumor shortly after tumor transplantation. Later on, the cytotoxic activity was lost and enhancing lymphocytes could be demonstrated in the spleens of the tumor-bearing mice (TBM). Spleen cells that were transferred together with tumor cells into syngeneic recipients enhanced tumor growth. The enhancing activity could be eliminated by the removal of a cell population that bound to histamine/rabbit serum albumin/Sepharose (HRS). The adherent population was enriched for enhancing lymphocytes, since it enhanced tumor growth more than the unfractionated population. The non-adherent cells, on the other hand, lost their enhancing activity in vivo and were sometimes protective against tumor growth. In addition, these cells manifested in vitro cytotoxicity against tumor cells. Hence the suppression of the cytotoxic expression in TBM is, at least in part, due to suppressor lymphocytes that bind to unsolubilized histamine. These cells seem to enhance tumor growth by suppressing host reactivity. Thus the enhancing lymphocyte populations can be separated into two subpopulations, of which one is enriched while the other is depleted of suppressor cells.

Animals↗

PubMed1983

Host-specificities of papillomavirus, Moloney murine sarcoma virus and simian virus 40 enhancer sequences.

The bovine papillomavirus (BPV-1), Moloney murine sarcoma virus (MoMuSV) and simian virus 40(SV40) genomes have been shown to contain sequences termed 'enhancers' which activate the expression of linked genes. DNA fragments containing these three enhancers have been inserted into recombinant plasmids upstream from the herpes simplex virus thymidine kinase (tk) gene, and their effect on tk expression monitored. Two types of assay have been used. Firstly, the ability of recombinant plasmids to transform TK- recipient cells to a TK+ phenotype was measured. Secondly, the amount of tk-specific RNA and TK enzyme activity transiently expressed after DNA transfection was determined. Both types of assay gave similar results. The enhancers increased tk gene expression by regulating the amount of full length tk mRNA present shortly after transfection independent of gene copy number. Furthermore, marked species specificity in the relative efficiencies of different enhancers was observed, including that of the BPV-1 enhancer for the first time. The MoMuSV enhancer showed preference for murine fibroblasts, while the papillomavirus enhancer showed a marked preference for bovine cells. In contrast, the SV40 enhancer gave the same relative increase in tk gene expression in the murine, rat, bovine and human cells tested.

Animals↗

PubMed2006

Role of parametric imaging in contrast-enhanced sonography of hepatic focal nodular hyperplasia.

PURPOSE: To assess the value of parametric imaging during contrast-enhanced sonographic examination in the diagnosis of focal nodular hyperplasia (FNH) of the liver. MATERIALS AND METHODS: Thirty-one patients with solitary FNH underwent contrast-enhanced sonographic examination between January 2003 and June 2004 using SonoVue and a Sequoia scanner equipped with Cadence Contrast Pulse Sequencing software. Contrast enhancement from a time sequence of perfusion frames was estimated using QontraXt software, which provides quantification of perfusion parameters. From the time-intensity curves, we obtained the following parameters: peak enhancement value, Tr (time recovery corresponding to time needed to reach 63% of the peak value), beta parameter corresponding to the exponential factor, and slope corresponding to the slope of the tangent to the arterial phase of enhancement. RESULTS: Among the 4 parameters studied, the slope of the arterial phase of enhancement was the most sensitive to image the centrifugal arterial flow originating from the central portion of the lesion, whereas peak enhancement value and Tr were the most sensitive to image full enhancement of the lesion. A blinded review revealed equivalent sensitivity in the diagnosis of FNH between the interpretation of the original videoclips and that of the parametric images. CONCLUSIONS: The results of this study show that parametric imaging can be used in place of original videoclips for clinical reporting of FNH; furthermore, it could help less-experienced sonologists diagnose FNH.

Adult↗

PubMed2002

The potential of contrast-enhanced magnetic resonance imaging for predicting left ventricular remodeling.

PURPOSE: To determine whether the myocardial injury size on day 2 measured after gadolinium (Gd)-mesoporphyrin and Gd-diethylenetriamine-pentaacetic acid (DTPA) administration can be used for predicting left ventricular (LV) remodeling 8 weeks later, and to monitor the structural and functional changes in the infarct, peri-infarct rim, and remote myocardium in reperfused infarction using contrast-enhanced and functional magnetic resonance imaging (MRI) MATERIALS AND METHODS: Myocardial infarction (MI) was induced in 27 rats by 1 hour of coronary occlusion/reperfusion. Rats were imaged 2 days and 8 weeks after MI using MRI to determine LV function and size of myocardial injury. All animals received 0.05 mmol/kg Gd-mesoporphyrin 12 hours before the first MRI. A subgroup of 13 rats received 0.3 mmol/kg Gd-DTPA in addition to Gd-mesoporphyrin, and seven rats received 0.05 mmol/kg Gd-mesoporphyrin 12 hours before the second MRI for detection of healed MI. True infarct size (IS) and LV mass were measured postmortem. LV volumes, mass, function, and wall thickness were determined in both imaging sessions. RESULTS: A close correlation was found between contrast-enhanced MRI and postmortem measurements for IS (r = 0.94, P < 0.001 for Gd-mesoporphyrin; r = 0.91, P < 0.001, N = 13 for Gd-DTPA). IS measured on Gd-mesoporphyrin-enhanced images correlated well with end-systolic LV volumes (r = 0.68, P < 0.001) and ejection fraction (r = -0.75, P < 0.001) 8 weeks after MI. Similar correlation with parameters of LV remodeling were found on Gd-DTPA-enhanced MRI. Healed infarcts showed no enhancement on Gd-mesoporphyrin-enhanced MRI. CONCLUSION: Contrast-enhanced MRI can be used as a noninvasive method for determining the initial size of myocardial injury and predicting later LV remodeling. MRI demonstrates the structural and functional changes in infarct, peri-infarct rim, and remote non-infarcted myocardium. The complementary use of functional and contrast-enhanced MRI may provide reliable assessment of therapeutic interventions to reduce IS and LV remodeling.

Analysis of Variance↗

PubMedDate not supplied

Comparative signal intensity measurements in dynamic gadolinium-enhanced MR mammography.

Increases in signal intensity enhancement were measured in defined regions of interest (ROIs) to allow distinction between malignant and benign tumors with dynamic gadolinium-enhanced magnetic resonance (MR) mammography. Twenty patients with palpable breast lesions (15 malignant, five benign) underwent MR mammography. The dynamic gradient-echo sequence was performed with intravenous bolus injection of gadopentetate dimeglumine and consisted of 25 images with a time resolution of 30 seconds. Contrast enhancement was calculated by comparing user-defined ROIs on pre- and postcontrast images. An increase in signal intensity of 70% or more on the 1-minute postcontrast image was used as the criterion of malignancy. MR mammographic results correlated with histopathologic findings in all patients when the defined ROI was in the most enhancing part of the tumor. For the ROI in areas of submaximal enhancement or when the ROI surrounded the whole lesion, only five and nine tumors, respectively, fulfilled the malignancy criterion. All malignant tumors showed large variations in signal intensity enhancement that depended on the position of the ROI in the tumor. Dynamic, gadolinium-enhanced MR mammography allows distinction of benign from malignant breast tumors when the selected ROI is in the most enhancing part of the lesion.

Breast↗

PubMedDate not supplied

Contrast-enhanced MR imaging of intrahepatic cholangiocarcinoma: pathologic correlation study.

The authors describe the enhanced magnetic resonance (MR) imaging appearance of intrahepatic cholangiocarcinoma. The MR images of eight patients with intrahepatic cholangiocarcinoma who underwent MR examination within 3 weeks before partial hepatectomy were retrospectively studied. The MR images, including a dynamic study, were compared directly with pathologic and histologic findings. The peripheral region of the medullary subtype of cholangiocarcinoma, with many tumor cells, showed greater enhancement relative to liver parenchyma in the early phase. The peripheral region of the scirrhous subtype, with fewer tumor cells showed less enhancement in the early phase. In one patient, the thin rim of the medullary tumor showed less enhancement in the late phase, and this rim corresponded to the peripheral region of the medullary tumor with many tumor cells. The central region of tumors with a large amount of fibrous tissue showed prolonged enhancement in the late and delayed phases. The thin rim of liver parenchyma around the tumor showed less enhancement in the early phase and greater enhancement in the late phase; this rim corresponded to congestive liver parenchyma with dilated sinusoids. Intrahepatic cholangiocarcinoma shows various enhancement patterns, which depend on both the histologic subtype and the degree and distribution of fibrosis within the tumor.

Aged↗

PubMed2004

Spatio-temporal bandwidth-based acquisition for dynamic contrast-enhanced magnetic resonance imaging.

PURPOSE: To develop a k-space formalism that provides a rationale for the design of variable-rate acquisition schemes for dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). METHODS AND MATERIALS: The formalism, termed spatio-temporal bandwidth-based (STBB) analysis, is demonstrated using a priori modeling of object and enhancement characteristics typically observed in DCE-MRI of breast tumors. A temporally enhancing lesion is considered as a two-dimensional (2D) space-time object that possesses a corresponding spatio-temporal (k(y)-k(t)) energy spectrum. The k(y)-k(t) space is segmented based on a threshold such that the total spectral energy in a finite number of k-space samples, constrained by the imaging experiment, is maximized. This thresholded map contains a set of spatial and corresponding temporal sampling prescriptions. These prescriptions are used in designing an acquisition scheme that is adequate for a range of contrast-enhancing breast lesions. The STBB scheme is compared to an equivalent "keyhole" acquisition, in terms of quantification of enhancement rate, K(trans), extracellular volume fraction, nu(e), and spatial fidelity. We chose object sizes Npix = 2, 5, 10, 15, 20, and 30 pixels and enhancement rates K(trans) = 1.5, 1, 0.6, 0.4, 0.3, and 0.2 minute(-1), and nu(e) was held at 0.3. RESULTS: The STBB scheme results in more accurate estimation of the rate and extracellular volume fraction parameters when the object size is small (two and five pixels) and the enhancement rates are rapid (1.5 and 1 minute(-1)), compared to the keyhole acquisition. The STBB scheme provides higher spatial fidelity for very small objects. For large object and slow enhancements, the keyhole and STBB scheme perform comparably. CONCLUSION: We have demonstrated an intuitive formalism applicable to DCE-MRI for a set of targeted/anticipated dynamic events as well as spatial features. This formalism can be extended to any dynamic imaging condition, and a corresponding variable-rate acquisition scheme can be designed.

Computer Simulation↗

PubMed2004

Reversible heterogeneous arterial phase liver perfusion associated with transient acute hepatitis: findings on gadolinium-enhanced MRI.

PURPOSE: To assess a possible correlation between active acute hepatitis and the development of abnormal liver perfusion demonstrated as heterogeneous enhancement on arterial phase gadolinium-enhanced MRI. Dynamically-enhanced MRI of the liver can detect reversible perfusion abnormalities that correlate with acute hepatitis. MATERIALS AND METHODS: Six patients presenting with symptoms and clinical findings in keeping with transient acute hepatitis underwent serial MRI of the liver throughout the course of the disease. Serial liver enzyme analysis was performed for all six patients, and histopathology was assessed for three patients. Imaging included gadolinium-enhanced arterial and venous-phase gradient-echo sequences. RESULTS: Arterial phase gadolinium-enhanced MRI showed abnormal irregular liver perfusion in the setting of acute hepatitis, and the degree of irregularity, as well as the persistence of irregular enhancement into the venous phase, correlated with the clinical severity of the disease. CONCLUSION: Acute hepatitis can cause irregular enhancement of the liver on arterial-phase, gadolinium-enhanced, gradient-echo MRI, a reversible finding that improves with clinical improvement of the disease.

Acute Disease↗

PubMed2006

Hemodynamic characterization of focal hepatic lesions: role of ferucarbotran-enhanced dynamic MR imaging using T2-weighted multishot spin-echo echo-planar sequence.

PURPOSE: To investigate the role of ferucarbotran-enhanced dynamic MR imaging using multishot spin-echo echo-planar sequence in the evaluation of hemodynamics of focal hepatic lesions. MATERIALS AND METHODS: Sixty-three focal hepatic lesions (24 benign and 39 malignant) from 53 consecutive patients who underwent both ferucarbotran-enhanced MR imaging and dynamic computed tomography (CT) were included in this study. MR imaging was performed with a 1.5-T scanner with a phased-array coil. T2-weighted multishot spin-echo echo-planar sequences (TR/TE = 1714-2813/80 msec) were obtained during a single breathhold before and 15, 60, 120, 180, and 600 seconds after intravenous injection of ferucarbotran. The enhancement patterns of lesions were classified into three categories by a study coordinator on the basis of dynamic CT images as hypervascular, hypovascular, and hemangioma type. The study coordinator created mean contrast-to-noise ratio of lesions vs. time curves for each enhancement pattern for quantitative analyses. Moreover, three radiologists separately and blindly reviewed MR images, and then assigned three confidence scores for the three enhancement patterns to each lesion. Sensitivity, specificity, and receiver operating characteristic analyses were performed. RESULTS: Quantitative analyses showed characteristic enhancement curves for each enhancement pattern. Mean sensitivities/specificities were 0.816/0.882, 0.897/0.863, and 0.800/0.989 for hypervascular, hypovascular, and hemangioma types, respectively. Mean areas under the receiver operating characteristic curve were 0.886 for hypervascular type and 0.913 for hypovascular type. CONCLUSION: Ferucarbotran-enhanced dynamic MR imaging can be used to successfully characterize the hemodynamics of focal hepatic lesions.

Adult↗

PubMed1990

Infection enhancement of influenza A H1 subtype viruses in macrophage-like P388D1 cells by cross-reactive antibodies.

The contribution of cross-reactive hemagglutination inhibition (HI) antibodies to infection enhancement of influenza A H1 subtype NWS virus and two antigenic drift strains was investigated in a macrophage-like cell line P388D1. When P388D1 cells, previously treated with neuraminidase (NA) to remove the viral receptors, were infected with NWS virus exposed to rabbit antiviral immunoglobulin (IgG) showing various levels of cross-HI titers, virus yields were enhanced in the presence of a subneutralizing antibody, depending on their cross-HI titers. By flow cytometric analysis using a fluorescein isothiocyanate (FITC)-labeled NWS virus, the efficiency of attachment of virus-rabbit IgG complexes to Fc receptors on NA-treated cells showed close correlation with its cross-HI titer. These data suggest that cross-reactive HI antibodies could contribute to infection enhancement through the formation of potent infectious immune complexes with drift strains to mediate virus infection via Fc receptor uptake. Two monoclonal antibodies (mAB) in mouse IgG subclasses IgG1 and IgG2a showing strain-specific or cross-reactive HI activity were tested for their infection enhancement characteristics. A strain-specific mAB enhanced infection of homologous NWS virus, but not that of two other drift strains in either antibody dilution. In contrast, a cross-reactive mAB caused infection enhancement of all three virus strains in the presence of the subneutralizing antibody. This indicates that cross-reactivity, but not the IgG subclass, acts as an enhancing factor to this phenomenon. The antibody, with the same specificity as cross-reactive mAB, was detected semiquantitatively by competitive enzyme-linked immunosorbent assay (ELISA) with results almost consistent with cross-HI titers of polyclonal rabbit antiviral IgGs. These data suggest that the antibody detected by this assay might be one of the potent antibodies governing cross-HI activity as a whole antibody and causing infection enhancement of drift strains.

Animals↗

PubMed2002

Investigation of nail permeation enhancement by chemical modification using water as a probe.

Our objective was to screen molecules that could interact with keratin in the human nail and thereby improve the topical penetration of actives into and through the nail plate. We used specialized Franz-type diffusion cells for our permeation experiments and water as a marker molecule. Aqueous/hydroalcoholic gels containing the enhancers were spiked with tritiated water and compared with a control (without enhancer). We computed the normalized water flux (defined as a product of flux and nail thickness) for each gel. We defined an enhancement factor for water as the ratio of the normalized water flux from a gel containing enhancer to that of the control. Our results indicate that the chemical structure of the modifier is most important in determining its ability to enhance penetration. The best enhancement effect was obtained using N-(2-mercaptopropionyl) glycine, a mercaptan derivative of an amino acid, in combination with urea. The concentration of each chemical modifier was linearly related to normalized water flux and mercaptan levels were more important that urea levels in penetration enhancement. Barrier integrity of nails was compromised after treatment with effective chemical modifiers. Thus, we have developed a suitable technique to screen nail penetration enhancers using water as a probe.

Diffusion Chambers, Culture↗

PubMed2006

Carbopol-mediated paracellular transport enhancement in Calu-3 cell layers.

The interaction of Carbopol polymers with mucus producing Calu-3 human bronchial epithelial cells was evaluated to test for potential paracellular transport enhancement. Using desmopressin (1-deamino-8-arginine-vasopressin, DDAVP) as the model peptide, apical treatment with Carbopol polymer gel formulations resulted in molecular size-dependent permeability enhancement with a concomitant drop in the transepithelial electrical resistance (TEER). Permeability enhancement of DDAVP was dependent on the formulation vehicle composition and polymer concentration, was noncytotoxic, and completely reversible. Carbopol 971P displayed the greatest permeability enhancement across Calu-3 cells compared to other more viscous Carbopol polymers 934P and 974P, and other mucoadhesive cellulosic polymers. The greatest enhancement was observed when C971P formulation was prepared in water at a concentration of 0.25% w/v. Enhancement was confirmed in rabbit dosed with intranasal fluorescent dextran 4400. The C(max) and absorption rate each increased by 48% in C971P formulations compared to control, while the relative exposure increased 30%. In conclusion, Carbopol polymers are potentially useful excipients to enhance intranasal peptide absorption. We hypothesize that the permeation enhancement is related to the chelation of extracellular or tight-junctional Ca(2+) by charged polymer carboxylate groups that leads to temporary disruption of tight-junctions, thereby facilitating paracellular transport.

Acrylic Resins↗

PubMed1990

Enhancement of viral and DNA mediated transformation of cloned rat embryo fibroblast cells by 3-aminobenzamide.

We have analyzed the effect of the poly(ADP-ribose) synthesis inhibitor 3 aminobenzamide (3AB) on de novo and methyl methanesulfonate (MMS) and gamma irradiation enhancement of viral transformation of a cloned rat embryo fibroblast cell line, CREF, by a cold-sensitive host-range mutant of type 5 adenovirus, H5hr1. Additionally, we have evaluated the effect of 3AB on the transformation of CREF cells following transfection with a gene conferring resistance to hygromycin (hygr) or the neomycin analogue G418 (neor) in combination with a cloned type 5 adenovirus E1A transforming gene (Ad5 E1A) or the Ha-ras (T24) oncogene. 3AB induced a dose- and time-dependent increase in the level of de novo MMS-enhanced and gamma irradiation-enhanced transformation of CREF cells by H5hr1, whereas it did not induce morphological transformation in uninfected control, MMS-pretreated, or gamma irradiation-pretreated CREF cells. Temporal kinetic studies indicated that 3AB was most effective in enhancing de novo and MMS-enhanced and gamma irradiation-enhanced viral transformation when applied early after viral and carcinogen plus viral infection and when present for extended time periods (4-5 wk). 3AB also increased the frequency of resistant colonies following transfection with several cloned genes, including hygr, neor, and protein kinase C (which also contained a neor gene), and the frequency of morphological transformation of CREF cells following cotransfection with a hygr gene and an Ad5 E1A or an activated Ha-ras (T24) gene. In contrast, 3AB exerted the opposite effect, i.e., an inhibitory effect, when applied to NIH 3T3 cells transfected with a hygr or neor gene, alone or in combination with a T24 gene. The ability of 3AB to enhance the frequency of transformation of CREF cells was not associated with a selective effect on the growth of H5hr1-transformed CREF cells in monolayer or agar culture. Similarly, 3AB did not alter the percentage of MMS- or gamma irradiated-pretreated H5hr1-infected cells retaining free Ad5 DNA or the random pattern or quantity of viral DNA integration in control or carcinogen-treated H5hr1-transformed cells. These results suggest that cellular processes regulated by the nuclear enzyme ADPRT, or additional processes modified by 3AB, may be important mediators of stable transformation induced by transfected DNA and both de novo and carcinogen-enhanced viral transformation of specific target cells.

Adenoviridae↗