Removal of ammonium from rare-earth wastewater using natural brucite as a magnesium source of struvite precipitation

This paper presents a study regarding ammonium removal from rare-earth wastewater by struvite precipitation with natural brucite mineral as a source of magnesium. Experimental results indicated that a pH ranging from 8.5 to 9.5 was the optimum for the removal of ammonium using the soluble form of brucite as a magnesium source. Additionally, when solid brucite was used as a magnesium source as well as an alkali reagent, the initial ammonium concentration of 4,535 mg/L decreased to 239-317 mg/L after an reaction time of 12 h in wastewater treated with the S/L (solid brucite/liquid wastewater) ratios ranging from 31.2 to 63.2 g/L. Furthermore, as some non-reacted brucite still remained in the precipitates obtained at the end of reaction, the precipitates were subjected to reuse. The reuse results demonstrated that the reuse of the precipitates obtained with 63.2 g/L was feasible, and almost half of the brucite dose could be saved.

Association between carbamazepine-induced cutaneous adverse drug reactions and the HLA-B*1502 allele among patients in central China

The aim of this study was to investigate the association between carbamazepine (CBZ)-induced cutaneous adverse drug reactions (cADRs) and the HLA-B*1502 allele among patients from central China. Eight patients with Stevens-Johnson syndrome and toxic epidermal necrolysis (SJS/TEN), 28 with mild maculopapular eruptions (MPEs), 50 CBZ-tolerant controls, and 71 healthy volunteers were recruited. HLA genotyping was performed using the polymerase chain reaction sequence-based typing (SBT) method. As a result, the HLA-B*1502 allele was observed at the following rates: (1) 100% (8/8) among those with CBZ-induced SJS/TEN, (2) 10.7% (3/28) among those with CBZ-induced MPEs; (3) 8.0% (4/50) among CBZ-tolerant controls; (4) 8.5% (6/71) among healthy volunteers. The eight patients with SJS/TEN positive for the HLA-B*1502 allele had an odds ratio (OR) of 184 compared with CBZ-tolerant controls. There was no significant difference in frequency between patients with MPEs and CBZ-tolerant controls (P>0.05). Thus, CBZ-induced SJS/TEN, but not MPEs, is strongly associated with HLA-B*1502. Testing for HLA-B*1502 should be recommended for patients from central China prior to initial CBZ treatment.

YAP dysregulation by phosphorylation or ΔNp63-mediated gene repression promotes proliferation, survival and migration in head and neck cancer subsets

Over-expression of Yes-associated protein (YAP), and TP53 family members ΔNp63 and p73 with which YAP may serve as a nuclear co-factor, have been independently detected in subsets of head and neck squamous cell carcinomas (HNSCC). Their potential relationship and functional role of YAP in HNSCC are unknown. Here we reveal that in a subset of HNSCC lines and tumors, YAP expression is increased but localized in the cytoplasm in association with increased AKT and YAP phosphorylation, and decreased expression of ΔNp63 and p73. Conversely, YAP expression is decreased but detectable in the nucleus in association with lower AKT and YAP phosphorylation, and increased ΔNp63 and p73 expression, in another subset. Inhibiting AKT decreased Serine-127 phosphorylation and enhanced nuclear translocation of YAP. ΔNp63 repressed YAP expression and bound its promoter. Transfection of a YAP-Serine-127-Alanine phosphoacceptor-site mutant or ΔNp63 knockdown significantly increased nuclear YAP and cell death. Conversely, YAP knockdown enhanced cell proliferation, survival, migration, and cisplatin chemoresistance. Thus, YAP function as a tumor suppressor may alternatively be dysregulated by AKT phosphorylation at Serine-127 and cytoplasmic sequestration, or by transcriptional repression by ΔNp63, in different subsets of HNSCC. AKT and/orΔNp63 are potential targets for enhancing YAP-mediated apoptosis and chemosensitivity in HNSCC.

Primary oral leiomyosarcoma: a retrospective clinical analysis of 20 cases

PURPOSE

As a review and clinical analysis of primary oral leiomyosarcoma (LMS) cases in West China stomatology Hospital in the past 37 years, this study provides demographic, therapeutic and prognostic information of this rare tumor.

PATIENTS AND METHODS

In our study, 20 cases of primary oral LMS treated between 1972 and 2008 in West China Stomatology Hospital were analyzed retrospectively. A thorough review of clinical records was carried out and potential indicators of survival were analyzed.

RESULTS

The most common symptom of oral LMS presented as a painless mass. The median age of patients was 37 years, and the peak incidence age of this tumor was in the 2nd and 5th decades. There was no predilection of gender, and the male-to-female ratio was 11:9. The most frequently occurring site of oral leiomysarcoma was the jawbones. The prognosis of this tumor was poor as a result of the high local recurrence and the estimated 2 year survival was 17.6%. The bony involvement and method of therapy was observed to have an influence on the prognosis and survival of this tumor (P < 0.05).

CONCLUSION

There was a predilection site of jawbones for oral LMS, and bony involvement was a potential indicator suggesting a poorer prognosis. The recommended method of therapy on this tumor was aggressive, radical surgical resection; however, adjuvant radiotherapy and chemotherapy may also have a beneficial effect.

Solution (sup13)C Nuclear Magnetic Resonance Spectroscopic Analysis of the Amino Acids of Methanosphaera stadtmanae: Biosynthesis and Origin of One-Carbon Units from Acetate and Carbon Dioxide

We found that general pathways for amino acid synthesis of Methanosphaera stadtmanae, a methanogen that forms CH(inf4) from H(inf2) and methanol, resembled those of methanogens that form CH(inf4) from CO(inf2) or from the methyl group of acetate. We determined the incorporation of (sup14)C-labeled CO(inf2), formate, methanol, methionine, serine, and acetate into cell macromolecules. Labeling of amino acid carbons was determined by solution nuclear magnetic resonance spectroscopy after growth with (sup13)C-labeled acetate, CO(inf2), serine, and methanol. The (alpha) and (beta) carbons of serine and alanine were formed from carboxyl and methyl carbons of acetate, respectively, and the amino acid carboxyl groups were formed from CO(inf2). This indicates that pyruvate was formed by reductive carboxylation of acetate. Labeling of the methyl carbon of methionine indicated that the major route of synthesis was from the hydroxymethyl carbon of serine that arises from the methyl carbon of acetate. Methanol was a minor source of the methyl of methionine. Unambiguous assignment was made of the sources of all carbons of histidine. Labeling of the histidine 7 position ((epsilon) carbon) was consistent with formation from the C-2 of the purine ring of ATP and the origin of the C-2 from a formyl unit derived from the hydroxymethyl carbon of serine.

Recovery of nickel ions from simulated electroplating rinse water by electrodeionization process

Pure water production and recovery of Ni(2+) from dilute NiSO(4) solution via improved electrodeionization (EDI) process were investigated. It was indicated that, with the feed water containing 50 mg L(-1) Ni(2+), the dilute resistivity of the EDI could achieve 3 MOmega cm which gave a Ni(2+) rejection more than 99.8% while the Ni(2+) was concentrated as high as 1,583 mg L(-1) in the concentrate stream. The current efficiency was as high as 40% and the concentrate factor could reach 31.7. The experiment results demonstrated that, just in a single process, it was feasible to purifying and concentrating dilute nickel wastewater synchronously by the EDI technology.

Functional magnetic resonance imaging study on dysphagia after unilateral hemispheric stroke: a preliminary study

BACKGROUND

Swallowing dysfunction is common and disabling after acute stroke; however, the mechanism of dysphagia or recovery of swallowing from dysphagia remains uncertain. The purpose of this study was to explore cerebral activation of swallowing in dysphagia using functional MRI (fMRI) to compare the functional anatomy of swallowing in unilateral hemispheric stroke patients and healthy adults.

METHODS

In total, five left hemispheric stroke patients with dysphagia, five right hemispheric stroke patients with dysphagia and 10 healthy controls were examined with event related fMRI while laryngeal swallow related movements were recorded. Data were processed using the general linear model.

RESULTS

A multifocal cerebral representation of swallowing was identified predominantly in the left hemisphere, in a bilateral and asymmetrical manner. Cerebral activation during swallowing tasks was localised to the precentral, postcentral and anterior cingulate gyri, insula and thalamus in all groups. Activation of volitional swallowing in dysphagic unilateral hemispheric stroke patients might require reorganisation of the dominant hemispheric motor cortex, or a compensatory shift in activation to unaffected areas of the hemisphere.

CONCLUSIONS

The results indicate that unilateral stroke of either cerebral hemisphere can produce dysphagia. Effective recovery is associated with cerebral activation related to cortical swallowing representation in the compensating or recruited areas of the intact hemisphere. Functional MRI is a useful method for exploring the spatial localisation of changes in neuronal activity during tasks that may be related to recovery. Therefore, the subsequent information gleaned from changes in neural plasticity could be useful for assessing the prognosis of dysphagic stroke.

Recurrent lower gastrointestinal bleeding secondary to cytomegalovirus-associated colonic ulcer in a non human immunodeficiency virus infected patient: timely diagnosis and treatment averted surgery

Mr C, a 68-year-old Chinese male with diabetes mellitus, previous stroke and ischaemic cardiomyopathy on clopidogrel, presented with haematochezia. Colonoscopy showed a sigmoid ulcer, which was treated endoscopically. Histology of the biopsy from the ulcer revealed non-specific changes. However, he presented with recurrent bleeding from this non-healing sigmoid ulcer. A review of the histologic specimen revealed CMV intranuclear inclusion bodies. He was treated with intravenous ganciclovir, with no further hematochezia.

The expression of voltage-gated ca2+ channels in pituicytes and the up-regulation of L-type ca2+ channels during water deprivation

The primary components of the neurohypophysis are the neuroendocrine terminals that release vasopressin and oxytocin, and pituicytes, which are astrocytes that normally surround and envelop these terminals. Pituicytes regulate neurohormone release by secreting the inhibitory modulator taurine in an osmotically-regulated fashion and undergo a marked structural reorganisation in response to dehydration as well as during lactation and parturition. Because of these unique functions, and the possibility that Ca2+ influx could regulate their activity, we tested for the expression of voltage-gated Ca2+ channel alpha1 subunits in pituicytes both in situ and in primary culture. Colocalisation studies in neurohypophysial slices show that pituicytes (identified by their expression of the glial marker S100beta), are immunoreactive for antibodies directed against Ca2+ channel alpha1 subunits Ca(V)2.2 and Ca(V)2.3, which mediate N- and R-type Ca2+ currents, respectively. Pituicytes in primary culture express immunoreactivity for Ca(V)1.2, Ca(V)2.1, Ca(V)2.2, Ca(V)2.3 and Ca(V)3.1 (which mediate L-, P/Q-, N-, R- and T-type currents, respectively) and immunoblotting studies confirmed the expression of these Ca2+ channel alpha1 subunits. This increase in Ca2+ channel expression may occur only in pituicytes in culture, or may reflect an inherent capability of pituicytes to initiate the expression of multiple types of Ca2+ channels when stimulated to do so. We therefore performed immunohistochemistry studies on pituitaries obtained from rats that had been deprived of water for 24 h. Pituicytes in these preparations showed a significantly increased immunoreactivity to Ca(V)1.2, suggesting that expression of these channels is up-regulated during the adaptation to long-lasting dehydration. Our results suggest that Ca2+ channels may play important roles in pituicyte function, including a contribution to the adaptation that occurs in pituicytes when the need for hormone release is elevated.

Enhanced Field Emission from Argon Plasma-Treated Ultra-sharp alpha-Fe(2)O(3) Nanoflakes

Hematite nanoflakes have been synthesized by a simple heat oxide method and further treated by Argon plasmas. The effects of Argon plasma on the morphology and crystal structures of nanoflakes were investigated. Significant enhancement of field-induced electron emission from the plasma-treated nanoflakes was observed. The transmission electron microscopy investigation shows that the plasma treatment effectively removes amorphous coating and creates plenty of sub-tips at the surface of the nanoflakes, which are believed to contribute the enhancement of emission. This work suggests that plasma treatment technique could be a direct means to improve field-emission properties of nanostructures.

Ferroelectric transistors with nanowire channel: toward nonvolatile memory applications

We report the fabrication and characterization of ZnO nanowire memory devices using a ferroelectric Pb(Zr(0.3)Ti(0.7))O(3) (PZT) film as the gate dielectric and the charge storage medium. With a comparison to nanowire transistors based on SiO(2) gate oxide, the devices were evaluated in terms of their electric transport, retention, and endurance performance. Memory effects are observed as characterized by an eminent counterclockwise loop in I-V(g) curves, which is attributed to the switchable remnant polarization of PZT. The single-nanowire device exhibits a high (up to 10(3)) on/off ratio at zero gate voltage. Our results give a proof-of-principle demonstration of the memory application based on a combination of nanowires (as channels) and ferroelectric films (as gate oxide).

Multifunctional CuO nanowire devices: p-type field effect transistors and CO gas sensors

We report the properties of a field effect transistor (FET) and a gas sensor based on CuO nanowires. CuO nanowire FETs exhibit p-type behavior. Large-scale p-type CuO nanowire thin-film transistors (10(4) devices in a 25 mm(2) area) are fabricated and we effectively demonstrate their enhanced performance. Furthermore, CuO nanowire exhibits high and fast response to CO gas at 200 degrees C, which makes it a promising candidate for a poisonous gas sensing nanodevice.

Recycle use of magnesium ammonium phosphate to remove ammonium nitrogen from rare-earth wastewater

This paper presents a recycle MAP process (magnesium ammonium phosphate) to remove NH4-N from a typical rare-earth wastewater. The optimum conditions for the MAP precipitation and recycle use of the MAP with a newly-designed process were investigated in laboratory. The results showed that the pH value and dosages of P (phosphate) and Mg reagents have a significant influence on NH4-N removal, with a maximum removal efficiency of 99.4% at the conditions of pH=9 and Mg:N:P molar ratio=1.2:1:1.2. In the process of recycle use of the MAP, adding some HCl to dissolve MAP decomposition residues could effectively enhance NH4-N removal. The NH4-N removal efficiency reached 99.6% by adding an HCl amount of H+:OH- molar ratio=0.8 into the reused MAP decomposition residues, whereas the NH4-N removal efficiency without addition of HCl was only 96.4%. Moreover, the residual PO4-P from the end of reaction was recovered and the optimum recovery efficiency was achieved at a Mg:P molar ratio=6 and pH=10. Under these optimum conditions, the residual NH4-N and PO4-P concentrations in the treated wastewater, through 6 times of the recycling, were less than 15 mg/L and 1 mg/L, respectively. On the basis of this, an economic evaluation of the recycling MAP was made, and this recycle process could save 48.6% cost used in the chemicals for treating per cubic meter of the rare-earth wastewater, compared to the conventional MAP process.

The pathogenesis of Salmonella enteritidis in experimentally infected ducks: a quantitative time-course study using taqman polymerase chain reaction

Ducks were subcutaneously infected with a high-virulence strain of Salmonella enterica ssp. enterica serovar Enteritidis (Salmonella Enteritidis). The kinetics of the Salmonella Enteritidis genomic DNA loads, the immunohistochemical localization of the bacterial antigens, and the histopathological examination in various tissues were investigated. The results showed that the time course of the appearance of the Salmonella Enteritidis bacterial antigens and the lesions in various tissues was coincident with the bacterial load of the organism in various infected tissues. This suggests that Salmonella Enteritidis loads in systemic organs are closely correlated with the progression of the infection.

Replication kinetics of Salmonella enteritidis in internal organs of ducklings after oral challenge: a quantitative time-course study using real-time PCR

This research was undertaken to understand the replication kinetics of Salmonella enteritidis (S. enteritidis) in the internal organs of ducklings after oral challenge over a 2 wk period. A serovar-specific real-time, fluorescence-based quantitative polymerase chain reaction (FQ-PCR) assay was used to detect genomic DNA of S. enteritidis in the blood and the internal organs at different time points respectively. The results showed that the spleen was positive at 12 h post inoculation (PI) and the blood was at 14 h PI. The organism was detected in the liver and heart at 16 h PI, the pancreas and kidney were positive at 20 h PI, and the final organ to show a positive results was the gallbladder at 22 h PI. The copy number of S. enteritidis DNA in each tissue reached a peak at 24 h-36 h PI, with the liver and spleen containing the highest concentration of S. enteritidis. The blood, heart, kidney, pancreas, and gallbladder had low concentrations. S. enteritidis populations began to decrease and were not detectable at 3 d PI, but were still present up to 2 wk for the spleen without causing apparent symptoms. To make the results meaningful, a side-by-side bacteriology method (IFA) was performed. The results of IFA were similar to the FQ-PCR assay. This research provided a significant data for understanding the life cycle of S. enteritidis in the internal organs, and may help to understand the pathogenesis of S.entertidis in the future.

Lanthanide (Eu3+, Tb3+) centered hybrid materials using modified functional bridge chemical bonded with silica: molecular design, physical characterization, and photophysical properties

1,3-Bis(2-formylphenoxy)-2-propanol (BFPP) was first synthesized and then grafted to 3-(triethoxysilyl)propyl isocyanate (TESPIC) to achieve a molecular precursor BFPP-Si through the hydrogen-transfer nucleophilic addition reaction between the hydroxyl group of BFPP and the isocyanate group of TESPIC. Then, a chemically bonded lanthanide/inorganic/organic hybrid material (BFPP-Si-Ln) was constructed using BFPP-Si as a bridge molecule that can both coordinate to lanthanide ions (Eu3+ or Tb3+) and form an inorganic Si-O network with tetraethoxysilane (TEOS) after cohydrolysis and copolycondensation processes. Furthermore, two types of ternary rare-earth/inorganic/organic hybrids (BFPP-Si-Dipy-Ln and BFPP-Si-Phen-Ln) were assembled by the introduction of the second ligands (4,4'-bipyridyl and 1,10-phenanthroline) into the above system. All of these hybrid materials exhibit homogeneous microstructures and morphologies, suggesting the occurrence of self-assembly of the inorganic network and organic chain. Measurements of the photoluminescent properties of these materials show that the ternary rare-earth/inorganic/organic hybrids present stronger luminescent intensities, longer lifetimes, and higher luminescent quantum efficiencies than the binary hybrids, indicating that the introduction of the second ligands can sensitize the luminescence emission of the lanthanide ions in the ternary hybrid systems.

Attenuation of heart rate control and neural degeneration in nucleus ambiguus following chronic intermittent hypoxia in young adult Fischer 344 rats

Chronic intermittent hypoxia (CIH) attenuates baroreflex control of heart rate (HR). In this study, we assessed whether CIH exposure reduced nucleus ambiguus (NA) control of HR and induced neural degeneration in the NA. Fischer 344 (age: 3-4 months) rats were exposed to either room air (RA: normoxia) or intermittent hypoxia for 35-50 days. At the end of these exposures, animals were anesthetized with pentobarbital. HR responses to arterial blood pressure (AP) changes induced by phenylephrine (PE) and sodium nitroprusside (SNP) were measured. In another set of rats, HR and AP responses to L-glutamate (L-Glu) microinjections (10 mM, 20 nl) into the left NA and electrical stimulation of the left cervical vagus nerve at 1-30 Hz (0.5 mA, 1 ms) for 20 s were measured. Brainstem slices at the level of -800, -400, 0, +400, +800 microm relative to the obex were processed in additional rats using Nissl staining. The NA was identified by retrogradely labeling vagal motoneurons using the tracer tetramethylrhodamine dextran (TMR-D) which was injected into the ipsilateral nodose ganglion. We found that CIH significantly 1) reduced the baroreflex control of HR (slope RA: -1.2+/-0.2 bpm/mmHg; CIH -0.5+/-0.1 bpm/mmHg; P<0.05); 2) attenuated the HR responses to l-Glu injections into the NA [HR: -280+/-15 (RA) vs. -235+/-16 (CIH) beats/min; P<0.05]; 3) augmented the HR responses to electrical stimulation of the vagus (P<0.05); 4) induced a significant cellular loss in the NA region (P<0.05). Thus, CIH induces a cell loss in the NA region which may contribute to attenuation of baroreflex sensitivity and NA control of HR following CIH.

Tumor necrosis factor-α is a potent endogenous mutagen that promotes cellular transformation

21104

Background: It is estimated that chronic inflammation is an important underlying condition for sporadic human tumor development, accounting for approximately 20% of human cancers. TNFa is an inflammation cytokine playing an important role in inflammation- associated cancers. However, the underlying mechanism of how TNFa leads to cancer is not clear. Before we initiated this study, TNFa is not known to have a direct effect on DNA. Methods: We studied genetic mutations, cellular transformation in cells and mice treated with TNFa. DNA damages and genetic aberrations caused by TNFa treatment were measured by gene amplification assay, micronucleus assay, cytogenetic analysis for chromosomal aberrations and immunostaining of 8-OHdG (8-hydroxydeoxyguanine; marker for DNA damage and oxidative stress). Cellular transformation was studied by standard transformation assay using mouse embryo fibroblast cells. Results: In this study, we found that TNFa can cause DNA damages through induction of reactive oxygen species (ROS). Our findings include: (1) The mutagenic effect of TNFa is comparable to that of ionizing radiation. TNFa treatment in cultured cells resulted in increased gene amplification, micronuclei formation and chromosomal instability. (2) Antioxidants significantly reduced TNFa-induced genetic mutations. (3) TNFa also induced oxidative stress and nucleotide damages in mouse tissues in vivo. (4) Moreover, TNFa treatment alone led to increased malignant transformation of mouse embryo fibroblasts, which could be partially suppressed by antioxidants. (5) The mutagenic effect of TNFa is independent that of NF?B which was shown to be a mediator in inflammation-associated cancers. Conclusions: As TNFa is known to be involved in chronic inflammatory diseases such as chronic hepatitis, ulcerative colitis and chronic skin ulcers and these diseases predispose the patients to cancer development, our results suggest a novel pathway through which TNFa promotes cancer development through induction of gene mutations, in addition to the previously reported mechanisms in which NF-?B activation was implicated.

No significant financial relationships to disclose.

Proton magnetic resonance spectroscopy in childhood brainstem lesions

BACKGROUND

Diagnosis of brainstem lesions in children based on magnetic resonance imaging alone is a challenging problem. Magnetic resonance spectroscopy (MRS) is a noninvasive technique for spatial characterization of biochemical markers in tissues and gives information regarding cell membrane proliferation, neuronal damage, and energy metabolism.

METHODS

We measured the concentrations of biochemical markers in five children with brainstem lesions and evaluated their potential diagnostic significance. Images and spectra were acquired on a 1.5-T imager. The concentrations of N-acetylaspartate, tetramethylamines (e.g., choline), creatine, phosphocreatine, lactate, and lipids were measured within lesions located at the brainstem using Point-resolved spectroscopy sequences.

RESULTS

Diagnosis based on localized proton spectroscopy included brainstem glioma, brainstem encephalitis, demyelination, dysmyelination secondary to neurofibromatosis type 1 (NF 1), and possible infection or radiation necrosis. In all but one patient, diagnosis was confirmed by biopsy or by clinical follow-up.

CONCLUSIONS

This small sample of patients suggests that MRS is important in the differential diagnosis between proliferative and nonproliferative lesions in patients without neurofibromatosis. Unfortunately, in cases of NF 1, MRS can have a rather misdiagnosis role.

Regulation of mammalian horizontal gene transfer by apoptotic DNA fragmentation

Previously it was shown that horizontal DNA transfer between mammalian cells can occur through the uptake of apoptotic bodies, where genes from the apoptotic cells were transferred to neighbouring cells phagocytosing the apoptotic bodies. The regulation of this process is poorly understood. It was shown that the ability of cells as recipient of horizontally transferred DNA was enhanced by deficiency of p53 or p21. However, little is known with regard to the regulation of DNA from donor apoptotic cells. Here we report that the DNA fragmentation factor/caspase-activated DNase (DFF/CAD), which is the endonuclease responsible for DNA fragmentation during apoptosis, plays a significant role in regulation of horizontal DNA transfer. Cells with inhibited DFF/CAD function are poor donors for horizontal gene transfer (HGT) while their ability of being recipients of HGT is not affected.

Anticancer Activity of 5-Benzylidene-2-Phenylimino-1, 3-Thiazolidin-4-one (BPT) Analogs

We recently identified two compounds of 5-benzylidene-2-phenylimino-1,3-thiazolidin-4-one (BPT) analog, 5-(4-methylbenzylidene)-2-phenylamino-1,3-thiazolidin-4-one (MMPT) and 5-(2,4-dihydroxybenzylidene)-2-phenylimino-1,3-thiazolidin-4-one (DBPT), that can effectively induce apoptosis in cancer cells but not in normal cells, independently of P-glycoprotein status. To further investigate the antitumor activity of BPT analogs, we obtained 18 commercially available analogs of BPT and synthesized 7 analogs in our lab, and analyzed their antitumor activity in various cancer cells, including paclitaxel- and vinorelbine-sensitive and -resistant human lung cancer cells. Two of the compounds were more potent than MMPT or DBPT in induction of apoptosis in certain cancer cell lines and remained tumor selective. Seven compounds did not induce any cytotoxic effects in any of the cell lines tested at the highest concentration tested (31 microM). The other compounds induced cytotoxic effects in some cancer cells but not in others or were less potent than MMPT and DBPT. Cell uptake studies showed that analogs that effectively induced cell killing in paclitaxel- and vinorelbine-resistant cells could be taken up easily by those cells despite their high levels of P-glycoprotein expression. These data further demonstrate that thiazolidinone analogs are not P-glycoprotein substrates and could be useful for treatment of P-glycoprotein overexpressing refractory cancers.

Symptomatic and asymptomatic carotid stenosis: just when we thought we had all the answers

The management of symptomatic and asymptomatic carotid stenosis has been a hotly debated topic for decades. The publication of four randomized controlled trials of carotid endarterectomy has clarified many of the issues. Patients with symptomatic carotid stenosis >70% benefit most with an absolute risk reduction of 17% over 2 years with numbers needed to treat of 3-6, whereas in patients with asymptomatic carotid stenosis >60%, the absolute risk reduction is 1% per annum (numbers needed to treat = 14-17). There is doubt about the benefit in women >70 years of age with asymptomatic stenosis. Carotid angioplasty and stenting is in its infancy and may one day supplant carotid endarterectomy as the treatment of choice; however, currently indications for this procedure include participation in randomized controlled trials, surgically inaccessible stenosis, in patients with combined symptomatic carotid and symptomatic coronary artery disease or in patients with severe co-morbidities that preclude formal carotid endarterectomy.

A novel role of DNA fragmentation factor as a tumor suppressor through maintaining genomic stability

10023

Background: DNA fragmentation is a hallmark of apoptosis. However, the biological function of apoptotic DNA fragmentation remains unclear. Genes encoding the nuclease responsible for DNA fragmentation, DFF40/CAD and DFF45/ICAD, are deleted, mutated, or aberrantly expressed in many human tumor types. Abnormalities in this gene are associated with aggressive tumors and poor prognosis in cancer patients. Tumor-specific DFF45 gene mutations were identified in human tumors, indicating the involvement of this gene in tumor development. Methods: We studied genetic instability, cellular transformation and tumorigenesis in cells and mice deficient in DNA fragmentation. We applied two methods to inhibit DNA fragmentation, overexpressing a modified ICAD which inhibits DNA fragmentation during apoptosis in stable cell lines and disrupting cad gene in transgenic mice. Genetic instability was studied by gene amplification assay, mutation assay and cytogenetic analysis including chromosomal aberrations and translocations. Cellular transformation was studied by soft agar assay using CAD-/- MEF cells. Tumorigenesis in DFF/CAD-knockout mice was studied by radiation carcinogenesis and two-stage skin chemical carcinogenesis. Results: (1) Human and mouse cancer cell lines with their CAD activity inhibited exhibited significantly more genetic instability under spontaneous or mutagen (ionizing radiation) induced conditions. These are reflected as elevated frequencies of chromosomal aberrations, gene amplifications, and gene mutations; (2) Mouse cells with targeted disruption of the cad gene exhibit a similar, increased level of genetic instability when the host animal is irradiated; (3) Mechanistically, CAD maintains genetic instability through the removal of cells with DNA damage, a role that is similar to genomic “gatekeepers” like p53; (4) CAD-null mouse embryo fibroblasts exhibited enhanced cellular transformation; (5) Significantly enhanced susceptibility to chemical and radiation-induced tumor development was observed in mice with targeted disruption of the CAD gene, indicating that it plays a role in suppressing tumor development. Conclusions: CAD plays an important role in maitaining genetic stability and suppressing tumor development.

No significant financial relationships to disclose.

Diffusion-weighted MR imaging lesions after filter-protected stenting of high-grade symptomatic carotid artery stenoses

BACKGROUND AND PURPOSE

The clinical efficacy of filter devices in internal carotid artery (ICA) stent placement has been a matter of controversy. The aim of this retrospective study was to assess the number and extent of cerebral emboli, as represented by new lesions on diffusion-weighted MR imaging (DWI), in patients treated with filter-protected carotid stent placement.

METHODS

Standard DWI (B0 = 1000) was performed within 48 hours before and 48 hours after filter-protected carotid stent placement in 50 patients with symptomatic, high grade (>70%), atherosclerotic ICA stenosis. Number, extent, and vascular territory of new DWI lesions after stent placement were assessed by consensus of 2 experienced neuroradiologists. Multifactorial statistical analysis was performed to determine risk factors associated with DWI lesions.

RESULTS

New punctate DWI lesions with a median diameter of 2 mm were detected in 14 of 50 cases in the territory of the stented ICA and in 7 of 50 cases in other vascular territories. Median lesion load was 1 lesion (range, 1-15) per positive case in the stented ICA and 1 lesion (range, 1-7) in other vascular territories. All DWI lesions were clinically asymptomatic. Because of 1 hyperperfusion syndrome with temporary brain swelling, the 30-day stroke and death rate was 2%. Age >or =70 years was the only significant predictor for new DWI lesions, whereas sex, degree and site of stenosis, vascular risk factors, and stent and filter type showed no significant correlation.

CONCLUSIONS

New DWI lesions after filter-protected carotid stent placement are substantially more frequent in the ipsilateral ICA territory compared with other vascular territories. Therefore, intraluminal filters cannot completely protect the brain from procedure-related embolization. However, individual lesion load and the risk of clinically relevant ischemia is low.

Apoptotic DNA fragmentation factor maintains chromosome stability in a P53-independent manner

DNA fragmentation factor (DFF)/caspase-activated DNase (CAD) is responsible for DNA fragmentation, a hallmark event during apoptosis. Although DNA fragmentation is an evolutionarily conserved process across species, its biological function is not clearly understood. In this study, we constructed cell lines expressing a mutant ICAD (inhibitor of CAD) protein that is resistant to caspase cleavage and therefore constantly binds to DFF/CAD and inhibits DNA fragmentation. We found that irradiation of these cells led to increased chromosome aberrations and aneuploidy when compared with their parental controls. The increased chromosome instability is observed irrespective of cellular P53 status, suggesting that the effect of DFF/CAD is independent of P53. Inhibition of apoptotic DNA fragmentation resulted in increased clonogenic survival of irradiated cells and a delay in removal of cells with DNA damages induced by radiation, an effect similar to that in cells with p53 mutations. Consistent with DFF/CAD's effect on clonogenic survival, tumors established from cells deficient in DNA fragmentation showed enhanced growth in nude mice. Therefore, our results suggest that DFF/CAD plays an important and P53-independent role in maintaining chromosome stability and suppressing tumor development.

The expression of antiapoptotic protein survivin is transcriptionally upregulated by DEC1 primarily through multiple sp1 binding sites in the proximal promoter

Human differentially expressed in chondrocytes (DEC), mouse stimulated with retinoic acid and rat split and hairy related proteins constitute a structurally distinct class of the basic helix-loop-helix proteins. DEC1 is abundantly expressed in tumors and protects against apoptosis induced by serum starvation. In this study, we report that DEC1 antiapoptosis is achieved by inducing survivin, an antiapoptotic protein. In paired tumor-normal tissues, survivin and DEC1 exhibited a paralleled expression pattern. Tetracycline-induced expression of DEC1 in stable lines proportionally increased the expression of survivin. In reporter assays, DEC1 transactivated the survivin promoter but repressed the DEC2 promoter. In contrast to the repression, the activation was delayed and varied depending on serum concentrations and cycle blockers. Studies with reporter mutants located, in the survivin promoter, two Sp1 sites that supported DEC1 transactivation. Electrophoretic mobility shift assay and chromatin immunoprecipitation detected the presence of DEC1 in the survivin promoter. These findings establish that the survivin gene is a transcription target of DEC1, and induction of survivin is at least in part responsible for DEC1 antiapoptosis.