Orogastric intubation with dental fixation for enteral nutrition: a proof-of-concept study.

In this crossover trial, we evaluated a new technique for enteral nutrition using orogastric intubation. Twelve volunteers were randomly assigned to both orogastric (OGI) and conventional nasogastric intubation (NGI) with a 15-day interval. The tip of the orogastric tube was fixed intraorally into an upper molar. Participants were asked to remain intubated for 24 hours and rated efficacy and safety using a Likert scale (1: worst / 10: best). Tolerance in hours was longer during OGI (median 21 versus 12.5; p=0.022). OGI was superior in comfort (median 7 versus 3; p=0.002), aesthetic (median 10 versus 1; p=0.002), speech (median 5.5 versus 3; p=0.014) and swallowing (median 8 versus 2; p=0.004). Both procedures were tolerated with mild local complaints. Diet volume through the tube was greater during NGI (p = 0.014). In healthy participants, orogastric intubation with dental fixation showed greater efficacy and similar safety to nasogastric intubation. CLINICAL TRIALS NUMBER: NCT03670238.

A simple and efficient Solid-Phase Microextraction - Gas Chromatography - Mass Spectrometry method for the determination of fragrance materials at ultra-trace levels in water samples using multi-walled carbon nanotubes as innovative coating.

The occurrence of emerging contaminants is becoming of increasing importance to assess the impact of anthropogenic activities onto the environment. The present study reports for the first time the development and validation of an efficient method for the simultaneous determination of fragrance materials in water samples based on the use of a novel multiwalled carbon nanotubes (MWCNTs)-based solid-phase microextraction coating. Helical MWCNTs were selected as adsorbent material due to their outstanding extraction performance. The multicriteria method of desirability functions allowed the optimization of the experimental conditions in terms of extraction time and extraction temperature. Validation proved the reliability of the method for the determination of the analytes at ultra-trace levels, obtaining detection limits in the 0.2-13 ng/L range, good precision, with relative standard deviations lower than 20% and recovery rates in the 80 ± 12%-111 ± 11%. Superior enrichment factors compared to commercial fibers were also calculated. Finally, applicability to real sample analysis was demonstrated.

Direct relationship between the level of p53 stabilization induced by rRNA synthesis-inhibiting drugs and the cell ribosome biogenesis rate.

Many drugs currently used in chemotherapy work by hindering the process of ribosome biogenesis. In tumors with functional p53, the inhibition of ribosome biogenesis may contribute to the efficacy of this treatment by inducing p53 stabilization. As the level of stabilized p53 is critical for the induction of cytotoxic effects, it seems useful to highlight those cancer cell characteristics that can predict the degree of p53 stabilization following the treatment with inhibitors of ribosome biogenesis. In the present study we exposed a series of p53 wild-type human cancer cell lines to drugs such as actinomycin D (ActD), doxorubicin, 5-fluorouracil and CX-5461, which hinder ribosomal RNA (rRNA) synthesis. We found that the amount of stabilized p53 was directly related to the level of ribosome biogenesis in cells before the drug treatment. This was due to different levels of inactivation of the ribosomal proteins-MDM2 pathway of p53 digestion. Inhibition of rRNA synthesis always caused cell cycle arrest, independent of the ribosome biogenesis rate of the cells, whereas apoptosis occurred only in cells with a high rDNA transcription rate. The level of p53 stabilization induced by drugs acting in different ways from the inhibition of ribosome biogenesis, such as hydroxyurea (HU) and nutlin-3, was independent of the level of ribosome biogenesis in cells and always lower than that occurring after the inhibition of rRNA synthesis. Interestingly, in cells with a low ribosome biogenesis rate, the combined treatment with ActD and HU exerted an additive effect on p53 stabilization. These results indicated that (i) drugs inhibiting ribosome biogenesis may be highly effective in p53 wild-type cancers with a high ribosome biogenesis rate, as they induce apoptotic cell death, and (ii) the combination of drugs capable of stabilizing p53 through different mechanisms may be useful for treating cancers with a low ribosome biogenesis rate.

MicroRNA and hepatocellular carcinoma: biology and prognostic significance.

Hepatocellular carcinoma (HCC) is the most common primary liver cancer and the third most common cause of cancer-related death worldwide. In 90% of cases, HCC arises on a background of cirrhosis which, in turns, results from hepatitis (HBV and HCV) infections, alcohol abuse, metabolic disorders including NASH, and genetic metabolic diseases, autoimmune hepatitis, primary biliary cirrhosis and exposure to environmental carcinogens. The molecular mechanisms underlying HCC development are still only partially known. Despite a high molecular variability, the deregulation of definite oncogenic pathways has been confirmed as a common finding in HCC. Among these, the molecular ways controlling proliferation, apoptosis and migration play a major role. In recent years, a new class of regulatory RNAs, the microRNAs, has been discovered and their deregulated expression has been linked to the molecular pathogenesis of many cancers because of their ability to strongly impact on the expression of crucial messenger RNAs. This review focuses on some of the most relevant evidence concerning the contribution of microRNA aberrant expression to HCC development.

Contribution of standard oesophageal manometry in sliding hiatal hernia: from the gastro-oesophageal pressure gradient to the diagnosis.

OBJECTIVE: We tested whether gastro-oesophageal pressure gradient is augmented in sliding hiatal hernia and the yield of oesophageal manometry in diagnosing sliding hiatal hernia. METHODS: Patients with equivalent body mass index were categorised according to manometry and endoscopy in groups: (1) no sliding hiatal hernia (n=147); (2) sliding hiatal hernia solely at endoscopy (n=46); and (3) sliding hiatal hernia at manometry (n=22). The yield of manometry was assessed taking endoscopy as referential. RESULTS: Gastro-oesophageal pressure gradient was similar between groups both at inspiration (13.3+/-5.7 mm Hg vs. 13.6+/-5.4 mm Hg vs. 12.6+/-4.4 mm Hg; P=0.874) or expiration (5.1+/-3.8 mm Hg vs. 5.2+/-3.6 mm Hg vs. 5.1+/-3.7 mm Hg; P=0.767). Group 3 patients were older than those of groups 1 and 2 (59+/-10 vs. 42+/-15 vs. 45+/-13 years; P<0.001). Sliding hiatal hernia was larger when characterised by manometry than at endoscopy [4 cm (2.25-4.75) vs. 2 cm (2-3); P<0.001]. Manometry showed sensitivity of 28% (95%CI 19-40%), specificity of 97% (95%CI 93-99%) and positive predictive value of 82% (95%CI 63-92%) in diagnosing sliding hiatal hernia. CONCLUSIONS: By using manometry in patients with equivalent body mass index, sliding hiatal hernia presence and size are related with age rather than gastro-oesophageal pressure gradient. This technique may be clinically useful when positive for sliding hiatal hernia.

Endoscopic implantation of polymethylmethacrylate augments the gastroesophageal antireflux barrier: a short-term study in a porcine model.

BACKGROUND AND AIMS: Endoscopic injection of filler agents into the esophagogastric junction has been developed to augment the antireflux barrier and decrease gastroesophageal reflux (GER). However, evidence of efficacy is lacking and serious complications have been reported in humans. The aim of this study was to assess whether endoscopic implantation of polymethylmethacrylate augments the antireflux barrier in a porcine model for GER. METHODS: Large White pigs underwent esophageal manometry, gastric yield pressure (GYP), and gastric yield volume (GYV) measurements and implantation of PMMA in the distal esophagus under general anesthesia. After follow-up of 28 days, esophageal manometry and gastric yield measurements were repeated and animals sacrificed. RESULTS: Implantation of PMMA was performed in 18 animals, and 14 animals survived 28 days. There was a significant increase in GYP (10.7 mmHg versus 8.1 mmHg; p = 0.017) and GYV (997 ml versus 393 ml; p < 0.001) after PMMA implantation, whereas resting LES pressure did not change significantly. Acute inflammatory changes and fibrous tissue deposits were found surrounding the PMMA implants during histology. One animal died after esophageal perforation and three others due to pneumonia (two) and colon perforation (one) in the postoperative period. CONCLUSIONS: Endoscopic implantation of PMMA in the distal esophagus augments the antireflux barrier 28 days after the procedure. However, esophageal perforation points to the need for technical refinements to make the procedure safer.

Imaging detection of new HCCs in cirrhotic patients treated with different techniques: Comparison of conventional US, spiral CT, and 3-dimensional contrast-enhanced US with the Navigator technique (Nav 3D CEUS)().

INTRODUCTION: The commercially available Navigator system(©) (Esaote, Italy) allows easy 3D reconstruction of a single 2D acquisition of contrast-enhanced US (CEUS) imaging of the whole liver (with volumetric correction provided by the electromagnetic device of the Navigator(©)). The aim of our study was to compare the efficacy of this panoramic technique (Nav 3D CEUS) with that of conventional US and spiral CT in the detection of new hepatic lesions in patients treated for hepatocellular carcinoma (HCC). MATERIALS AND METHODS: From November 2006 to May 2007, we performed conventional US, Nav 3D CEUS, and spiral CT on 72 cirrhotic patients previously treated for 1 or more HCCs (M/F: 38/34; all HCV-positive; Child: A/B 58/14) (1 examination: 48 patients; 2 examinations: 20 patients; 3 examinations: 4 patients). Nav 3D CEUS was performed with SonoVue(©) (Bracco, Milan, Italy) as a contrast agent and Technos MPX(©) scanner (Esaote, Genoa, Italy). Sensitivity, specificity, diagnostic accuracy, and positive and negative predictive values (PPV and NPV, respectively) were evaluated. Differences between the techniques were assessed with the chi-square test (SPSS release-15). RESULTS: Definitive diagnoses (based on spiral CT and additional follow-up) were: 6 cases of local recurrence (LocRecs) in 4 patients, 49 new nodules >2 cm from a treated nodule (NewNods) in 34 patients, and 10 cases of multinodular recurrence consisting of 4 or more nodules (NewMulti). The remaining 24 patients (22 treated for 1-3 nodules, 2 treated for >3 nodules) remained recurrence-free. Conventional US correctly detected 29/49 NewNods, 9/10 NewMultis, and 3/6 LocRecs (sensitivity: 59.2%; specificity: 100%; diagnostic accuracy: 73.6%; PPV: 100%; NPV: 70.1%). Spiral CT detected 42/49 NewNods plus 1 that was a false positive, 9/10 NewMultis, and all 6 LocRecs (sensitivity: 85.7%; specificity: 95.7%; diagnostic accuracy: 90.9%; PPV: 97.7%; NPV: 75.9%). 3D NAV results were: 46N (+9 multinodularN and 6 LR), 3 false-negatives, and one false-positive (sensitivity: 93.9; specificity: 97.9%; diagnostic accuracy: 95.6; PPV: 97.9; NPV: 93.9). CONCLUSIONS: 3D Nav CEUS is significantly better than US and very similar to spiral CT for detection of new HCCs. This technique revealed the presence of lesions that could not be visualized with spiral CT.

MiR-221 controls CDKN1C/p57 and CDKN1B/p27 expression in human hepatocellular carcinoma.

The identification of target mRNAs is a key step for assessing the role of aberrantly expressed microRNAs in human cancer. MiR-221 is upregulated in human hepatocellular carcinoma (HCC) as well as in other malignancies. One proven target of miR-221 is CDKN1B/p27, whose downregulation affects HCC prognosis. Here, we proved that the cyclin-dependent kinase inhibitor (CDKI) CDKN1C/p57 is also a direct target of miR-221. Indeed, downregulation of both CDKN1B/p27 and CDKN1C/p57 occurs in response to miR-221 transfection into HCC-derived cells and a significant upregulation of both CDKN1B/p27 and CDKN1C/p57 occurs in response to antimiR-221 transfection. A direct interaction of miR-221 with a target site on the 3' UTR of CDKN1C/p57 mRNA was also demonstrated. By controlling these two CDKIs, upregulation of miR-221 can promote growth of HCC cells by increasing the number of cells in S-phase. To assess the relevance of these studies in primary tumors, matched HCC and cirrhosis samples were assayed for miR-221, for CDKN1B/p27 and CDKN1C/p57 expression. MiR-221 was upregulated in 71% of HCCs, whereas CDKN1B/p27 and CDKN1C/p57 proteins were downregulated in 77% of cases. A significant inverse correlation between miR-221 and both CDKN1B/p27 and CDKN1C/p57 was found in HCCs. In conclusion, we suggest that miR-221 has an oncogenic function in hepatocarcinogenesis by targeting CDKN1B/p27 and CDKN1C/p57, hence promoting proliferation by controlling cell-cycle inhibitors. These findings establish a basis toward the development of therapeutic strategies aimed at blocking miR-221 in HCC.

[Peri-inguinal strangulated hernia: report of a case]. / Un caso di ernia peri-inguinale strozzata.

Peri-inguinal hernias are rare defects of ventral lateral abdominal wall, just above the inguinal region. These hernias are due to congenital defects of internal oblique and transverse muscles. Since their rarity and the complex anatomy of the region, their correct classification is still debated. It is possible to make diagnosis by clinical examination; imaging can help the physician to recognize this rare pathology. The Authors describe a case of strangulated peri-inguinal hernia, that required urgent surgery.

[A case of primitive amyloid goiter]. / Gozzo amiloide primitivo. Case report.

Amyloid goiter is a rare pathology due to massive amyloid infiltration of thyroid tissue, which cause diffuse or localized enlargement of the gland. It can be totally asymptomatic or cause only non-specific symptoms (compression of adjacent structures, tracheal deviation). Thyroid disfunction (hypothyroidism or hyperthyroidism) is rare. It is important to differentiate primitive amyloid goiter from other kinds of amyloid infiltration of the thyroid, such as in systemic amyloidosis. The correct diagnosis can be difficult because of the common presence of amyloid in thyroid neoplasms, such as medullary thyroid carcinoma (MTC). The Authors present a case of primitive amyloid goiter, that needed immunohistochemical analysis for a correct diagnosis, and a review of the concerning literature.

Ultrasound guided fine needle biopsy of early hepatocellular carcinoma complicating liver cirrhosis: a multicentre study.

BACKGROUND: Because hepatic cirrhosis is a major risk factor for hepatocellular carcinoma, recent guidelines by the European Association for the Study of the Liver (EASL) on clinical management of hepatocellular carcinoma recommend periodic ultrasound surveillance of cirrhotic patients with immediate workup for nodules >1 cm; an increase in the frequency of screening is considered sufficient for smaller lesions. AIMS: To determine the actual risk of hepatocellular carcinoma associated with the latter lesions and to assess the role of ultrasound guided-fine needle biopsy in their diagnosis. PATIENTS AND METHODS: Data were analysed for 294 new nodular lesions <20 mm, including 48 that were <10 mm, detected during a prospective multicentre study involving ultrasound surveillance of 4375 patients with hepatic cirrhosis. In the absence of alpha fetoprotein (AFP) levels diagnostic of hepatocellular carcinoma, ultrasound guided-fine needle biopsy was performed (n = 274). AFP and fine needle biopsy diagnoses of malignancies (hepatocellular carcinoma and lymphoma) were considered definitive. Non-malignant fine needle biopsy diagnoses (dysplastic or regenerative nodule) were verified by a second imaging study. Diagnoses of hepatocellular carcinoma based on this study were considered definitive; non-malignant imaging diagnoses were considered definitive after at least one year of clinical and ultrasound follow up. RESULTS: Overall, 258/294 (87.6%) nodules proved to be hepatocellular carcinoma, including 33/48 (68.7%) of those < or =10 mm. Overall typing accuracy of ultrasound guided-fine needle biopsy was 89.4%, and 88.6% for lesions < or =10 mm. CONCLUSIONS: In a screening population, well over half of very small nodules arising in cirrhotic livers may prove to be hepatocellular carcinoma, and approximately 90% of these malignancies can be reliably identified with ultrasound guided-fine needle biopsy.

Gallstone disease and related risk factors in a large cohort of diabetic patients.

BACKGROUND AND AIM: The aim of this study of a large cohort of consecutive patients with diabetes mellitus was to investigate the still controversial questions concerning the prevalence and possible risk factors of gallstone disease in diabetics. PATIENTS AND METHODS: We enrolled 1337 consecutive patients (710 males aged 63 +/- 11 years and 627 females aged 65 +/- 11 years), of whom 1235 (92%) had type 2 and 102 (8%) had type 1 diabetes mellitus. The data were statistically analysed using multiple logistic regression analysis. RESULTS: The prevalence of gallstone disease was significantly higher in diabetics than in the general population with comparable characteristics (MICOL study) (332/1337 (24.8%) versus 4083/29684 (13.8%); z = 11.208, P = 0.0001) and this difference maintained its statistical significance even when only the North Italian centers involved in this nation-wide survey were considered (332/1337 (24.8%) versus 2469/18091 (13.6%); z = 11.225, P = 0.0001). A total of 332 diabetics (25%) had gallstone disease: 261 had stone(s) and 71 had previously undergone cholecystectomy for gallstone disease after a diagnosis of diabetes mellitus. The prevalence of gallstone disease was higher in the females (29% versus 22%, P = 0.003), and increased with age (13, 20 and 30% in patients aged < or = 40, 41-65 and > 65 years, respectively; P = 0.001), body mass index (24% in patients with a body mass index of < or = 30 and 30% in those with a body mass index of > 30 kg/m2; P = 0.001) and a positive family history of gallstone disease (31% versus 23%; P = 0.001). Gallstone disease was not significantly related to the type of diabetes, plasma total and HDL cholesterol and triglyceride levels, alcohol intake, smoking habits, physical activity, weight reduction in the last year, the use of oral contraceptives, parity or menopause. At multivariate analysis, increasing age, a higher body mass index and a positive family history maintained their statistical significance. CONCLUSIONS: In patients with type 1 or type 2 diabetes mellitus, the prevalence of gallstone disease was significantly related to age, body mass index and a family history of gallstone disease.

Percutaneous radio-frequency thermal ablation of nonresectable hepatocellular carcinoma after occlusion of tumor blood supply.

PURPOSE: To evaluate the usefulness of percutaneous radio-frequency (RF) thermal ablation of nonresectable hepatocellular carcinoma (HCC) after occlusion of the tumor arterial supply. MATERIALS AND METHODS: Sixty-two patients with cirrhosis and biopsy-proved HCC underwent RF ablation after interruption of the tumor arterial supply by means of occlusion of either the hepatic artery with a balloon catheter (40 patients) or the feeding arteries with gelatin sponge particles (22 patients). RESULTS: After a single RF procedure in 56 patients and after two procedures in six patients, spiral computed tomography (CT) demonstrated a nonenhancing area corresponding in shape to the previously identified HCC, which was suggestive of complete necrosis. No major complications occurred. Two patients subsequently underwent surgical resection; the remaining 60 patients were followed up with spiral CT. During a mean follow-up of 12.1 months, 11 HCC nodules showed areas of local progression; 49 were identified as nonenhancing areas with a 40%-75% reduction in maximum diameter. The 1-year estimate of failure risk was 19% for local recurrence and 45% for overall intrahepatic recurrence. The estimated 1-year survival was 87%. Histopathologic analysis of one autopsy and two surgical specimens revealed more than 90% necrosis in one specimen and 100% necrosis in two. CONCLUSION: HCC nodules 3.5-8.5 cm in diameter can be ablated in one or two RF sessions after occlusion of the tumor arterial supply.

Evidence that the apoptotic actions of etoposide are independent of c-Jun/activating protein-1-mediated transregulation.

We recently demonstrated that physiological induction of apoptosis by cytotoxic sphingolipid messengers proceeds via activating protein-1 (AP1)-dependent and AP1-independent mechanisms in U937 human monoblastic leukemia cells. Here we examine involvement of the stress-activated protein kinase (SAPK) cascade and AP1 in the initiation of apoptosis in U937 cells by podophyllotoxin-derived inhibitors of topoisomerase II. Induction of apoptotic cell death and DNA damage by treatment of U937 cells with etoposide (100 microM) was associated with phosphorylation and activation of the c-Jun NH(2)-terminal kinase (JNK1) SAPK enzymes p46 and p54-JNK2 and transient increases in expression of the transcription factor c-Jun, a primary JNK substrate. These responses were accompanied by a modest, but sustained, recruitment of the mitogen-activated protein kinases p42-extracellular signal receptor-activated kinase (ERK)1 and p44-extracellular signal receptor-activated kinase 2. The capacity of etoposide to promote double-stranded DNA degradation and cell death was unaffected by manipulations that interfere with SAPK signaling outflow through c-Jun/AP1, including: 1) pharmacological inhibition of AP1 activity by diferuloylmethane and 2) molecular ablation of normal c-Jun function by the Jun dominant-negative mutant TAM-67. Cytotoxicity of the structurally related compound teniposide was similarly unaffected. In parallel trials, the lethal actions of ceramide (but not of sphingosine) were markedly diminished by pretreatment with diferuloylmethane or expression of TAM-67, confirming the effectiveness of these interventions in suppression of SAPK/AP1-dependent apoptosis. The involvement of AP1 in the proapoptotic actions of other inhibitors of topoisomerase II activity was also evaluated. Induction of cell death by the anthracyclines daunorubicin, daunorubicin, and idarubicin was found to be insensitive to pretreatment with diferuloylmethane or expression of TAM-67. Collectively, the present data indicate that induction of apoptosis by etoposide and related inhibitors of topoisomerase II is mediated through a cell death pathway that does not require SAPK-dependent recruitment of AP1. These findings additionally suggest that activation of the SAPK represents a consequence, rather than an underlying cause, of etoposide-induced apoptosis in myeloid leukemia cells.

[Carotid body tumors. Apropos a case and a review of the literature]. / Tumori del glomo carotideo. A proposito di un caso e revisione della letteratura.

Chemodectomas are rare tumors arising from paraganglionic cells located at the level of carotid bifurcation. They are usually benign and non functioning, presenting as a slow growing cervical mass. A preoperative diagnosis is mandatory, based on doppler color flow imaging and angiography. Surgery is the only therapy providing total eradication of this tumor. Subadventitial resection is the most established technique, although resection of a large mass may require carotid replacement by interposition graft. Cranial nerve palsy and stroke are the perioperative complications most frequently encountered. The Authors report here a case of carotid body tumor and a review of the literature in order to define clinical characteristics of the tumor and proper diagnostic and therapeutic approaches to this rare neoplasm.

Evidence for involvement of mitogen-activated protein kinase, rather than stress-activated protein kinase, in potentiation of 1-beta-D-arabinofuranosylcytosine-induced apoptosis by interruption of protein kinase C signaling.

The stress-activated protein kinase (SAPK) and mitogen-activated protein kinase (MAPK) cascades mediate cytotoxic and cytoprotective functions, respectively, in the regulation of leukemic cell survival. Involvement of these signaling systems in the cytotoxicity of 1-beta-D-arabinofuranosylcytosine (ara-C) and modulation of ara-C lethality by protein kinase C PKC inhibition/down-regulation was examined in HL-60 promyelocytic leukemia cells. Exposure to ara-C (10 microM) for 6 hr promoted extensive apoptotic DNA damage and cell death, as well as activation of PKC. This response was accompanied by downstream activation of the SAPK and MAPK cascades. PKC-dependent MAPK activity seemed to limit ara-C action in that the toxicity of ara-C was enhanced by pharmacological reductions of PKC, MAPK, or both. Thus, ara-C action was (1) partially attenuated by diradylglycerols, which stimulated PKC and MAPK, but (2) dramatically amplified by sphingoid bases, which inhibited PKC and MAPK. The cytotoxicity of ara-C also was substantially increased by pharmacological reductions of PKC, including down-regulation of PKC by chronic preexposure to the macrocyclic lactone bryostatin 1 or inhibition of PKC by acute coexposure to the dihydrosphingosine analog safingol. Significantly, both of these manipulations prevented activation of MAPK by ara-C. Moreover, acute disruption of the MAPK module by AMF, a selective inhibitor of MEK1, suppressed both basal and drug-stimulated MAPK activity and sharply increased the cytotoxicity of ara-C, suggesting the direct involvement of MAPK as a downstream antiapoptotic effector for PKC. None of these chemopotentiating agents enhanced ara-CTP formation. Ceramide-driven SAPK activity did not seem to mediate drug-induced apoptosis, given that (1) neutralization of endogenous tumor necrosis factor-alpha with monoclonal antibodies or soluble tumor necrosis factor receptor substantially reduced ceramide generation and SAPK activation by ara-C, whereas the induction of apoptosis was unaffected; (2) pharmacological inhibition of sphingomyelinase by 3-O-methoxysphingomyelin reduced ceramide generation and SAPK activation without limiting the drug's cytotoxicity; and (3) potentiation of ara-C action by bryostatin 1 or safingol was not associated with further stimulation of SAPK. These observations collectively suggest a primary role for decreased MAPK, rather than increased SAPK, in the potentiation of ara-C cytotoxicity by interference with PKC-dependent signaling.

Identification and hydropathic characterization of structural features affecting sequence specificity for doxorubicin intercalation into DNA double-stranded polynucleotides.

The computer molecular modeling program HINT (Hydropathic INTeractions), an empirical hydropathic force field function that includes hydrogen bonding, coulombic and hydrophobic terms, was used to study sequence-selective doxorubicin binding/intercalation in the 64 unique CAxy, CGxy, TAxy, TGxy base pair quartet combinations. The CAAT quartet sequence is shown to have the highest binding score of the 64 combinations. Of the two regularly alternating polynucleotides, d(CGCGCG)2and d(TATATA)2, the HINT calculated binding scores reveal doxorubicin binds preferentially to d(TATATA)2. Although interactions of the chromophore with the DNA base pairs defining the intercalation site [I-1] [I+1] and the neighboring [I+2] base pair are predominant, the results obtained with HINT indicate that the base pair [I+3] contributes significantly to the sequence selectivity of doxorubicin by providing an additional hydrogen bonding opportunity for the N3' ammonium of the daunosamine sugar moiety in approximately 25% of the sequences. This observation, that interactions involving a base pair [I+3] distal to the intercalation site play a significant role in stabilizing/destabilizing the intercalation of doxorubicin into the various DNA sequences, has not been previously reported. In general terms, this work shows that molecular modeling and careful analysis of molecular interactions can have a significant role in designing and evaluating nucleotides and antineoplastic agents.

Induction of DNA damage, inhibition of DNA synthesis, and suppression of c-myc expression by the topoisomerase I inhibitor, camptothecin, in MCF-7 human breast tumor cells.

Previous work from this laboratory has demonstrated an association between the suppression of c-myc expression and the antiproliferative activity of both topoisomerase II inhibitors and ionizing radiation in MCF-7 breast tumor cells. These findings suggested that suppression of c-myc expression could be related to the induction of DNA damage in this cell line. The present studies were designed to determine whether the inhibition of topoisomerase I (and the consequent induction of DNA strand breaks) would also result in the suppression of c-myc expression. At camptothecin concentrations of 1 microM and below, there was no detectable damage (single- or double-strand breaks) in bulk DNA or suppression of c-myc expression. At camptothecin concentrations of 5, 10, and 25 microM, where suppression of c-myc expression was observed, strand breaks in bulk DNA were also detected. These findings are consistent with the idea that suppression of c-myc expression could be a component of the DNA damage response pathway in MCF-7 breast tumor cells. In contrast to the absence of detectable damage to bulk DNA or suppression of c-myc expression at the lower concentrations of camptothecin, DNA synthesis was inhibited over the entire range of drug concentrations and demonstrated a strong correspondence with growth inhibition. These observations support the concept that growth inhibition of MCF-7 cells by camptothecin is closely related to the early suppression of DNA synthesis.

Induction of DNA damage, inhibition of DNA synthesis and suppression of c-myc expression by the anthracycline analog, idarubicin (4-demethoxy-daunorubicin) in the MCF-7 breast tumor cell line.

PURPOSE: Studies were designed to elucidate the basis for the antiproliferative activity of the anthracycline antibiotic, idarubicin (4-demethoxy-daunorubicin) in MCF-7 breast tumor cells. METHODS: Growth inhibition was evaluated using the MTT tetrazolium dye assay, induction of DNA strand breaks was determined by alkaline elution, inhibition of DNA synthesis was assessed by measuring the incorporation of labelled thymidine into DNA, modulation of the expression of the c-myc oncogene was determined by Northern blotting and the induction of apoptosis was evaluated by alkaline unwinding, static field gel electrophoresis, terminal end labelling and assessment of cell morphology. RESULTS: MCF-7 cells were relatively sensitive to idarubicin, with an IC50 value for growth inhibition of approximately 0.01 microM. While DNA strand breakage was not evident below a concentration of 0.1 microM idarubicin, where growth inhibition exceeded 70%, both the inhibition of DNA synthesis and suppression of c-myc expression closely paralleled the profile of antiproliferative activity for idarubicin. Finally, while exposure to idarubicin resulted in a substantial loss of viable cells within 48-72 h, there was no morphological evidence of apoptotic body formation. The absence of apoptosis in cells exposed to idarubicin was supported by studies demonstrating the absence of DNA fragmentation using gel electrophoresis, alkaline elution and in situ DNA end-labelling assays. CONCLUSIONS: The results of these studies extend previous results from this laboratory indicating an association between suppression of c-myc expression, inhibition of DNA synthesis and growth arrest by topoisomerase II inhibitors, as well as the lack of induction of apoptotic cell death by topoisomerase II inhibitors in MCF-7 breast tumor cells.

Influence of ionizing radiation on proliferation, c-myc expression and the induction of apoptotic cell death in two breast tumour cell lines differing in p53 status.

PURPOSE: To determine the capacity of ionizing radiation to inhibit proliferation, to suppress c-myc expression and to induce apoptotic cell death in the p53 wild-type MCF-7 cell line and the p53 mutated MDA-MB231 cell line. MATERIALS AND METHODS: Growth inhibition and cell killing were determined by cell number and trypan blue exclusion. Apoptosis was assessed through cell morphology and fluorescent end-labelling. c-myc expression was monitored by Northern blotting. RESULTS: Inhibition of cell proliferation by ionizing radiation was similar in both cell lines. MDA-MB231 cells accumulated in G2 while MCF-7 cells accumulated in both the G1 and G2 phases of the cell cycle after irradiation. There was no evidence of apoptosis in either cell line. In MCF-7 cells, growth inhibition correlated closely with an early dose-dependent suppression of c-myc expression; in MDA-MB231 cells, there was no correspondence between growth inhibition and a transient, dose-independent reduction in c-myc message. CONCLUSIONS: These findings suggest that in the absence of classical apoptotic cell death, radiosensitivity is not predictably related to the p53 status of the cell. While both p53 and c-myc may be linked to the DNA damage response pathway, neither p53 nor c-myc are essential for growth arrest in response to ionizing radiation.