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Results for “amplification”

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PubMed2001

Herceptest: HER2 expression and gene amplification in non-small cell lung cancer.

HER2 is an erbB/HER type 1 tyrosine kinase receptor that is frequently over-expressed in malignant epithelial tumours. Herceptin, a humanised mouse monoclonal antibody to HER2, is proven therapeutically in the management of metastatic breast cancer, significantly prolonging survival when combined with cytotoxic chemotherapeutic agents. Immunohistochemical studies suggest that non-small-cell lung cancer (NSCLC) tumours may over-express HER2. Our aim was to evaluate HER2 gene amplification and semi-quantitative immuno-expression in NSCLC. A total of 344 NSCLC cases were immunostained for HER2 expression in 2 centres using the HercepTest. Fluorescence in situ hybridisation (FISH) analysis for HER2 gene amplification was performed on most positive cases and a subset of negative cases. Fifteen cases (4.3%) demonstrated 2+ or 3+ membranous HER2 immuno-expression. There was no correlation between immuno-expression and tumour histology or grade. Tumours from higher-stage disease were more often HercepTest-positive (p < 0.001). All 4 HercepTest 3+ cases demonstrated gene amplification. One of the 5 2+ cases tested for gene amplification showed areas of borderline amplification and areas of polyploidy. None of the 19 HercepTest-negative cases demonstrated gene amplification or polyploidy (p < 0.001). Gene amplification was demonstrated in all HercepTest 3+ scoring NSCLC cases. Unlike breast cancer, gene amplification and HER2 protein over-expression assessed by the HercepTest appeared to be uncommon in NSCLC. Herceptin may therefore target only a small proportion of NSCLC tumours and be of limited clinical value in this disease, particularly in the adjuvant setting.

Adenocarcinoma↗

PubMed1996

Identifying the sex of human preimplantation embryos in X-linked disease: amplification efficiency of a Y-specific alphoid repeat from single blastomeres with two lysis protocols.

INTRODUCTION: Preimplantation diagnosis involves detecting genetic defects in one or two blastomeres biopsied from cleavage stage embryos following a vitro fertilization (IVF). For X-linked recessive disease, identification of the sex of embryos allows transfer of only unaffected females. To examine how critical the preparation of the single blastomere is for amplification of a Y chromosome specific repeat sequence using the polymerase chain reaction (PCR), the incidence of amplification failure has been examined following two lysis protocols. MATERIALS AND METHODS: Amplification of a Y alphoid repeat sequence from single blastomeres disaggregated from cleavage stage embryos was examined after either (1) lysis in distilled water and freeze-thawing twice or (2) a two-step lysis protocol involving an initial treatment in potassium hydroxide and dithiothreitol. Some of the embryos had been previously sexed by cleavage-stage biopsy and fluorescent in situ hybridization with X- and Y-specific probes. RESULTS: Amplification failure occurred in 6 of 50 (12%) and 4 of 60 (7%) single blastomeres from male embryos following lysis in distilled water or using the two-step protocol, respectively. Conversely, amplification from contaminating DNA occurred in 5 of 63 (8%) single blastomeres from female embryos and 6 of 94 (6%) of control medium-blanks. CONCLUSIONS: The incidence of amplification failure was improved but not eliminated using the two-step lysis protocol. At least two cells, therefore, would be necessary for accurate identification of males by amplification of Y-specific repeat sequences alone. Nevertheless, this protocol for preparing cleavage-stage blastomeres is likely to give more consistent amplification of any unique or repeat sequences.

Blastomeres↗

PubMedDate not supplied

Detection of eIF4E gene amplification in breast cancer by competitive PCR.

BACKGROUND: Initiation factor eIF4E binds to mRNA as the initial step for protein translation. Overexpression of the eIF4E oncoprotein has been found in breast cancer but not in benign breast tissue. The objective of this study is to determine if eIF4E oncoprotein overexpression is associated with eIF4E gene amplification in breast cancer using Western blots and competitive polymerase chain reaction (PCR). METHODS: Unknown concentrations of DNA extracted from breast specimens were amplified by PCR using a set of primers spanning intron 2/exon 3 of the eIF4E gene. In the same PCR tube, an internal control consisting of a known concentration of an eIF4E DNA template with 20-base pair (bp) deletion was used as the competitive reference standard (CRS) for competitive PCR. Gel electrophoresis of the PCR products was performed and the bands quantified by densitometry. eIF4E gene amplification was then determined relative to a nonamplified gene (gastrin). Using an anti-eIF4E rabbit antibody, Western blots were performed on benign and malignant breast specimens. Quantification was accomplished by developing blots with a color assay using nitro blue tetrazolium (NBT) and 5-bromo-4-chloro-3-indolyl phosphate (BCIP), scanned and analyzed by densitometry. RESULTS: Twenty-two breast specimens (14 cancer, 8 control) from patients were examined for eIF4E gene amplification and oncoprotein expression. In all fourteen specimens from stage I-III breast cancer patients, eIF4E overexpression was detected at 3- to 30-fold ( 16.71 +/- 7.83) elevations. Similarly, all 14 specimens demonstrated eIF4E gene amplification by competitive PCR (3.69 +/- 1.27). In the eight benign breast specimens examined, all were negative for eIF4E overexpression and gene amplification. CONCLUSIONS: Overexpression of eIF4E was associated with eIF4E gene amplification in breast cancer specimens. No overexpression or gene amplification was detected in benign breast tissues. eIF4E gene amplification may be one mechanism for eIF4E oncoprotein overexpression.

Animals↗

PubMed1996

Induction or suppression of SV40 amplification by genotoxic carcinogens, non-genotoxic carcinogens or tumor promoters.

Carcinogens are generally classified into two groups: genotoxic and non-genotoxic. As the final product of genotoxic and non-genotoxic carcinogens is the same, i.e., a clone of genetically altered cells, it could be possible that non-genotoxic carcinogens may yield genotoxic events as a secondary result of cell toxicity having led to mitogenesis/cellular proliferation, or that genetic alterations are induced that are normally neglected in genotoxicity tests. A genetic effect with possible relevance for the ultimate mechanism of carcinogenicity is the amplification of oncogenes. In the present experiments, amplification of SV40-virus DNA in transformed CO631-cells has been measured. In this system, two genotoxic carcinogens (positive control), two non-carcinogens (negative control), and eight non-genotoxic carcinogens have been tested. With the exception of testosterone and BVDU, all substances were tested when given alone. Testosterone and BVDU were tested in combination with either MTX or AMP in the presence or absence of S9-mix. The genotoxic carcinogens TEM and 4-NQO as well as the tumor promoters TPA, coumarin, mezerein and chrysarobin were able to induce SV40 amplification when given alone. The same was for acetamide and thioacetamide. The non-carcinogens acetone and dimethylformamide were ineffective. In case of testosterone, a co-amplification effect was seen in the absence of S9-mix, and an anti-amplification effect in presence of S9-mix. The anti-recombinogen BVDU reduced the SV40 amplification effect of AMP in experiments without addition of S9-mix. In the presence of activating S9-mix, this substance was effective at lower concentrations than without S9-mix, and showed an enhanced anti-amplification effect. Similar effects of testosterone and BVDU had been observed before in respect to stimulation or suppression of recombination. These results can be used as supportive evidence for the assumption that gene amplification is mechanistically related to recombination.

Acetamides↗

PubMed1990

Multiplex PCR amplification and immobilized capture probes for detection of bacterial pathogens and indicators in water.

Detection of pathogens (Legionella species) and indicator bacteria (coliform bacteria) was achieved by multiplex (simultaneous) PCR amplification of diagnostic gene sequences and by hybridization to immobilized poly-dT-tailed capture probes using a dot- or slot-blot approach. Complex manipulations of primer concentrations and staggered additions of primers were required in order to achieve equal amplification of multiple genes. Multiplex PCR amplification of two different Legionella genes, one specific for L. pneumophila (mip) and the other for the genus Legionella (5S rRNA), was achieved by staggered amplification. Multiplex PCR amplification using differing amounts of primers specific for lacZ and lamB genes permitted the detection of coliform bacteria and those associated with human faecal contamination, including the indicator bacterial species E. coli and enteric pathogens Salmonella and Shigella. Hybridization of biotin-labelled amplified DNA, in which the biotin was incorporated during PCR amplification from biotinylated-dUTP, to immobilized 400-dT-tailed capture probes permitted specific and sensitive detection of target gene sequences. The sensitivity of colorimetric detection achieved by PCR amplification of target DNA was at a level equivalent to 1-2 bacterial cells, which is the same level of sensitivity obtained with radioactive detection. The simultaneous amplification of several genes and hybridization to immobilized capture probes with colorimetric detection is an effective, efficient and rapid detection method for various human bacterial pathogens.

Bacteriological Techniques↗

PubMed2001

Protein overexpression and gene amplification of c-erb B-2 in pulmonary carcinomas: a comparative immunohistochemical and fluorescence in situ hybridization study.

Amplification of the c-er bB-2 gene (located on 17q11.2--12) is accompanied by overexpression of its cell surface receptor product, p185(ERBB2). In pulmonary carcinomas, however, there has been disagreement between the reported frequencies of gene amplification and overexpression. To clarify their relationship, the correlation between the cellular expression of p185(ERBB2) and the level of c-erb B-2 gene amplification was studied. A total of 195 pulmonary carcinomas (182 primary and 13 metastatic) were examined immunohistochemically using a polyclonal antibody, which recognizes the internal domain of the human c-erb B-2 protein, and positive tumors were further examined for the gene amplification by dual-color fluorescence in situ hybridization using probes for centromere 17 and 17q11.2--12. By immunohistochemistry, distinct membrane staining was found in an adenocarcinoma, a large cell carcinoma and a metastatic carcinoma from the breast, and cytoplasmic and/or faint membranous staining was observed in 23 non-small cell lung carcinomas. It was in the two primaries and the metastatic carcinoma that more than 8-fold amplification of c-erb B-2 was found by fluorescence in situ hybridization. Especially, in the two primary carcinomas, tumor cells had amplified genes with the signals forming one or two clusters, indicating that the amplified gene was present in homogeneously staining regions. Among the 23 tumors, three tumors showed low-level amplification (less than 3-fold), which was differentiated from polysomy 17 found in the other two. In the 30 non-small cell lung carcinomas selected at random from 151 with negative immunostaining, there were five trisomy 17, but no tumors with the gene amplification. This suggests that although c-erb B-2 amplification in pulmonary carcinoma is rare, it occurs in the form of a homogeneously staining region and is thought to control the overexpression of the protein in the cell membrane. New adjuvant therapy using a humanized antibody to the oncoprotein may be beneficial to patients with these tumors.

Carcinoma, Non-Small-Cell Lung↗

PubMed2003

Amplification of HSD17B1 and ERBB2 in primary breast cancer.

Estrogens play a crucial role in the development of breast cancer. Estradiol can be produced in the breast tissue in situ, and one of the enzymes involved in this process is 17beta-hydroxysteriod dehydrogenase (17beta-HSD) type 1 that catalyzes the interconversion of estrone (E1) to the biologically more potent estradiol (E2). The gene coding for 17beta-HSD type 1 (HSD17B1) is located at 17q12-21, close to the more studied ERBB2 and BRCA1. The aim of this study was to investigate if HSD17B1 shows an altered gene copy number in breast cancer. We used real-time PCR and examined 221 postmenopausal breast tumors for amplification of HSD17B1 and ERBB2. In all, 32 tumors (14.5%) showed amplification of HSD17B1 and 21% were amplified for ERBB2. Amplification of the two genes was correlated (P=0.00078) and in 14 tumors (44%) with amplification of HSD17B1, ERBB2 was co amplified. The patients with amplification in at least one of the genes had a significantly worse outcome than patients without (P=0.0059). For estrogen receptor (ER)-positive patients who received adjuvant tamoxifen, amplification of HSD17B1 was related to decreased breast cancer survival (P=0.017), whereas amplification of ERRB2 was not. Amplification of HSD17B1 might be an indicator of adverse prognosis among ER-positive patients, and possibly a mechanism for decreased benefit from tamoxifen treatment.

17-Hydroxysteroid Dehydrogenases↗

PubMed2002

TFDP1, CUL4A, and CDC16 identified as targets for amplification at 13q34 in hepatocellular carcinomas.

We carried out molecular cytogenetic characterization of 11 cell lines derived from hepatocellular carcinomas (HCCs) and 51 primary HCCs. Comparative genomic hybridization (CGH) revealed frequent amplification at 13q34, where we had detected amplification in several other types of tumor, including esophageal squamous cell carcinomas (ESC). Previously, we suggested possible involvement of TFDP1, encoding a transcription factor DP-1, in the 13q34 amplification observed in a primary ESC. Therefore, we investigated amplifications and expression levels of 5 genes mapped on the amplified region, including TFDP1, for exploring amplification targets at 13q34 in HCCs. 3 of those genes, TFDP1, CUL4A (cullin 4A), and CDC16 (cell division cycle 16), showed distinct amplification and consequent over-expression in some cell lines. Moreover, each was amplified in 3 or 4 of the 51 primary HCCs, and all 3 were amplified in 2 tumors, in which their expression patterns correlated with amplification patterns. To elucidate the functional role of TFDP1 in HCC, we examined expression levels of genes downstream of TFDP1 with real-time quantitative polymerase chain reaction (PCR). Expression of cyclin E gene (CCNE1) correlated closely with that of TFDP1 in not only cell lines, but also primary tumors. Treatment of HCC cells with the antisense oligonucleotide targeting TFDP1 resulted in down-regulation of CCNE1, suggesting that TFDP1 overexpression led to up-regulation of CCNE1 that encoded a positive regulator for cell cycle G1/S transition. In conclusion, our findings suggest that TFDP1, CUL4A, and CDC16 are probable targets of an amplification mechanism and therefore may be involved, together or separately, in development and/or progression of some HCCs.

Apc6 Subunit, Anaphase-Promoting Complex-Cyclosome↗

PubMed2004

Balanced-PCR amplification allows unbiased identification of genomic copy changes in minute cell and tissue samples.

Analysis of genomic DNA derived from cells and fresh or fixed tissues often requires whole genome amplification prior to microarray screening. Technical hurdles to this process are the introduction of amplification bias and/or the inhibitory effects of formalin fixation on DNA amplification. Here we demonstrate a balanced-PCR procedure that allows unbiased amplification of genomic DNA from fresh or modestly degraded paraffin-embedded DNA samples. Following digestion and ligation of a target and a control genome with distinct linkers, the two are mixed and amplified in a single PCR, thereby avoiding biases associated with PCR saturation and impurities. We demonstrate genome-wide retention of allelic differences following balanced-PCR amplification of DNA from breast cancer and normal human cells and genomic profiling by array-CGH (cDNA arrays, 100 kb resolution) and by real-time PCR (single gene resolution). Comparison of balanced-PCR with multiple displacement amplification (MDA) demonstrates equivalent performance between the two when intact genomic DNA is used. When DNA from paraffin-embedded samples is used, balanced PCR overcomes problems associated with modest DNA degradation and produces unbiased amplification whereas MDA does not. Balanced-PCR allows amplification and recovery of modestly degraded genomic DNA for subsequent retrospective analysis of human tumors with known outcomes.

Artifacts↗

PubMed1995

The relationship between listening conditions and alternative amplification schemes for multiple memory hearing aids.

OBJECTIVE: The aim of this study was to determine a relationship among selected listening conditions and amplification schemes that could be provided in a multiple memory hearing aid. DESIGN: The study consisted of three laboratory tests: 1) A screening test to select hearing impaired subjects who appeared to benefit from multiple amplification schemes. 2) A category scaling test to rank 16 amplification schemes in 15 listening conditions. The 16 schemes were simulated with a digital master hearing aid and comprised 5 linear systems and 11 compression characteristics. The 15 listening conditions comprised 6 listening environments combined with 2 or 3 response criteria. 3) A paired comparison test in which the two highest ranked amplification schemes were evaluated together with a reference linear frequency response (NAL) in a round-robin test. RESULTS: The screening test demonstrated that 21 hearing impaired people out of 25 with mild or moderate, flat or gently sloping hearing losses appeared to benefit from multiple amplification schemes. Age or audiometric factors did not serve to discriminate between those who selected different schemes and those who did not. In general, the NAL-response was preferred or was as good as any other for listening to speech in quiet, speech in reverberation, speech in babble-noise, and for naturalness of all listening environments. The subjects consistently selected an amplification scheme other than the NAL-response for four specific listening conditions. The findings suggest that substantial high-frequency compression is preferred for the ease of understanding multiple talkers, whose voices differ in overall level, in quiet environments. The annoyance of low-frequency background noise can be reduced by low-frequency compression, whereas a frequency response steeper than the NAL-response makes it easier to understand speech in low frequency background noise. Finally, a frequency response flatter than the NAL-response can be used to make a high-frequency background noise sound less annoying. CONCLUSION: Hearing aid users with mild or moderate, flat or gently sloping hearing losses, fitted with equal and sufficient variation in amplification, prefer different amplification schemes depending on the number of talkers, the background noise and the response criterion.

Adult↗

PubMed1996

Comparison of conventional amplification and an assistive listening device in elderly persons.

OBJECTIVE: To assess the impact of personal amplification systems on quality of life of elderly persons and to compare conventional hearing aid with assistive listening device. DESIGN: Audiologic, neuropsychologic, and quality-of-life measures were prospectively administered to 180 elderly, hearing-impaired persons before and after randomized 6 wk trials of four treatment conditions-a no-amplification condition and three different types of amplification: 1) conventional hearing aid, 2) assistive listening device, and 3) a combination of the two systems. All subjects volunteered to participate in a study comparing different amplification systems and were paid for their participation. RESULTS: Both self-perceived handicap and speech understanding were improved significantly by all three amplification systems. There were no significant group differences between new users and previous users of amplification in self-assessed handicap after amplification use. Anecdotally, subjects preferred the sound quality of the assistive listening device, but an overwhelming majority (97.3%) still chose the conventional aid for use in daily living. CONCLUSIONS: Results affirm the significant impact of amplification on the quality of life of elderly persons. The strong preference for the conventional hearing aid in everyday use undoubtedly reflects the fact that elderly users usually are not willing to endure the difficulties associated with the use of remote-microphone systems.

Adult↗

PubMed1999

Somatic amplification of distally generated subthreshold EPSPs in rat hippocampal pyramidal neurones.

1. Intracellular recordings from hippocampal CA1 pyramidal neurones revealed that EPSPs evoked by selective stimulation of the isolated afferent input to the distal third of the apical dendrites were relatively insensitive to changes in dendritic membrane potential (Vm) but amplified by depolarizations of the somatic Vm. The amplification was present at potentials depolarized from resting membrane potential (RMP) but was most marked when the EPSPs were close to threshold for action potential generation. The amplification consisted of a uniform component and a variable component which was only present when the EPSPs were threshold straddling. 2. The somatic amplification was caused by an intrinsic membrane current which was blocked by somatic application of tetrodotoxin (TTX, 10 microM), but was insensitive to bath application of NiCl2 (100-200 microM). We therefore suggest that the amplification of the subthreshold EPSP is due primarily to the activation of a non-inactivating Na+ current (INaP). 3. Injection of 4-aminopyridine (4-AP, 25-50 mM) during intradendritic recordings resulted in amplification of the EPSPs in 37% of the dendrites, which was similar to that observed in somatic recordings. However, in the one case in which somatic application of TTX was tested, dendritic amplification was blocked, suggesting that it is a reflection of the somatic amplification. 4. Because the shift to variable amplification was very abrupt and it is present in only a very narrow voltage range close to threshold, we suggest that the variable component is caused by the regenerative activation of INaP. The variability itself is probably due to the simultaneous activation of different outward K+ currents. 5. The present results indicate that the somatic region of CA1 pyramidal neurones can function as a voltage-dependent amplifier of distally evoked EPSPs and that this is due to the activation of a somatic INaP. The presence of this amplifying mechanism will have important functional consequences for the way in which distally generated EPSPs are integrated.

Afferent Pathways↗

PubMed1999

Benefits of linear amplification and multichannel compression for speech comprehension in backgrounds with spectral and temporal dips.

People with cochlear hearing loss have markedly higher speech-receptions thresholds (SRTs) than normal for speech presented in background sounds with spectral and/or temporal dips. This article examines the extent to which SRTs can be improved by linear amplification with appropriate frequency-response shaping, and by fast-acting wide-dynamic-range compression amplification with one, two, four, or eight channels. Eighteen elderly subjects with moderate to severe hearing loss were tested. SRTs for sentences were measured for four background sounds, presented at a nominal level (prior to amplification) of 65 dB SPL: (1) A single female talker, digitally filtered so that the long-term average spectrum matched that of the target speech; (2) a noise with the same average spectrum as the target speech, but with the temporal envelope of the single talker; (3) a noise with the same overall spectral shape as the target speech, but filtered so as to have 4 equivalent-rectangular-bandwidth (ERB) wide spectral notches at several frequencies; (4) a noise with both spectral and temporal dips obtained by applying the temporal envelope of a single talker to speech-shaped noise [as in (2)] and then filtering that noise [as in (3)]. Mean SRTs were 5-6 dB lower (better) in all of the conditions with amplification than for unaided listening. SRTs were significantly lower for the systems with one-, four-, and eight-channel compression than for linear amplification, although the benefit, averaged across subjects, was typically only 0.5 to 0.9 dB. The lowest mean SRT (-9.9 dB, expressed as a speech-to-background ratio) was obtained for noise (4) and the system with eight-channel compression. This is about 6 dB worse than for elderly subjects with near-normal hearing, when tested without amplification. It is concluded that amplification, and especially fast-acting compression amplification, can improve the ability to understand speech in background sounds with spectral and temporal dips, but it does not restore performance to normal.

Aged↗

PubMed2003

High-throughput tissue microarray analysis of erbB-2 gene amplification in urinary bladder cancer. A study of Bulgarian patients.

INTRODUCTION: Overexpression of the receptor Her-2 leads to increased proliferative response to epidermal growth factors which plays a key role in tumor development and growth. Increased oncoprotein level, in the majority of cases, is caused by erbB-2 gene amplification. To define the frequency of amplifications of erbB-2 in bladder cancer, and to determine their association with the tumor phenotype we utilized tissue microarray (TMA) approach. MATERIALS AND METHODS: We analyzed a TMA consisting of 159 transitional cell bladder carcinomas for erbB-2 gene amplification by dual-color FISH. RESULTS: The frequency of erbB-2 amplification was 5.3% of all successfully analyzed samples (4 of 75). It increased from minimally invasive (pT1) to muscle-invasive (pT2-4) tumors, as well as with advanced tumor grade (G1 to G2 to G3). All amplifications were cluster amplifications confirming the fact that erbB-2 amplification occurs intrachromosomally in bladder cancer. CONCLUSIONS: We concluded that despite its low incidence, erbB-2 amplification is of importance for the bladder tumor invasion and progression.

Adult↗

PubMed2004

Adaptive amplification and point mutation are independent mechanisms: evidence for various stress-inducible mutation mechanisms.

"Adaptive mutation" denotes a collection of processes in which cells respond to growth-limiting environments by producing compensatory mutants that grow well, apparently violating fundamental principles of evolution. In a well-studied model, starvation of stationary-phase lac(-)Escherichia coli cells on lactose medium induces Lac(+)revertants at higher frequencies than predicted by usual mutation models. These revertants carry either a compensatory frameshift mutation or a greater than 20-fold amplification of the leaky lac allele. A crucial distinction between alternative hypotheses for the mechanisms of adaptive mutation hinges on whether these amplification and frameshift mutation events are distinct, or whether amplification is a molecular intermediate, producing an intermediate cell type, in colonies on a pathway to frameshift mutation. The latter model allows the evolutionarily conservative idea of increased mutations (per cell) without increased mutation rate (by virtue of extra gene copies per cell), whereas the former requires an increase in mutation rate, potentially accelerating evolution. To resolve these models, we probed early events leading to rare adaptive mutations and report several results that show that amplification is not the precursor to frameshift mutation but rather is an independent adaptive outcome. (i) Using new high-resolution selection methods and stringent analysis of all cells in very young (micro)colonies (500-10,000 cells), we find that most mutant colonies contain no detectable lac-amplified cells, in contrast with previous reports. (ii) Analysis of nascent colonies, as young as the two-cell stage, revealed mutant Lac(+)cells with no lac-amplified cells present. (iii) Stringent colony-fate experiments show that microcolonies of lac-amplified cells grow to form visible colonies of lac-amplified, not mutant, cells. (iv) Mutant cells do not overgrow lac-amplified cells in microcolonies fast enough to mask the lac-amplified cells. (v)lac-amplified cells are not SOS-induced, as was proposed to explain elevated mutation in a sequential model. (vi) Amplification, and not frameshift mutation, requires DNA polymerase I, demonstrating that mutation is separable from amplification, and also illuminating the amplification mechanism. We conclude that amplification and mutation are independent outcomes of adaptive genetic change. We suggest that the availability of alternative pathways for genetic/evolutionary adaptation and clonal expansion under stress may be exploited during processes ranging from the evolution of drug resistance to cancer progression.

Adaptation, Biological↗

PubMed2005

Unilateral versus bilateral amplification for adults with impaired hearing.

This study compared unilateral and bilateral aided speech recognition in background noise in 28 patients being fitted with amplification. Aided QuickSIN (Quick Speech-in-Noise test) scores were obtained for bilateral amplification and for unilateral amplification in each ear. In addition, right-ear directed and left-ear directed recall on the Dichotic Digits Test (DDT) was obtained from each participant. Results revealed that the vast majority of patients obtained better speech recognition in background noise on the QuickSIN from unilateral amplification than from bilateral amplification. There was a greater tendency for bilateral amplification to have a deleterious effect among older patients. Most frequently, better aided QuickSIN performance was obtained in the right ear of participants, despite similar hearing thresholds in both ears. Finally, patients tended to perform better on the DDT in the ear that provided less SNR loss on the QuickSIN. Results suggest that bilateral amplification may not always be beneficial in every daily listening environment when background noise is present, and it may be advisable for patients wearing bilateral amplification to remove one hearing aid when difficulty is encountered understanding speech in background noise.

Age Factors↗

PubMed1999

Real-time quantitative PCR for the measurement of MYCN amplification in human neuroblastoma with the TaqMan detection system.

BACKGROUND: Neuroblastoma is the most common extracranial malignant solid tumor in children under 5 years and is characterized by a wide clinical and biological heterogeneity, from spontaneously regressive forms to cancers with a rapid and fatal progression. MYCN oncogene amplification is considered the most important prognostic factor to evaluate survival and therapeutic choices in these patients. METHODS: Here we present a new assay for rapid and accurate measurement of MYCN amplification, based on real-time quantitative PCR with the TaqMan(TM) reaction. The degree of MYCN amplification was derived from the ratio of the MYCN oncogene and the single-copy reference gene, beta-actin. The absolute abundance of these two genes in tumor sample DNA was obtained by extrapolation on external calibration curves generated with reference DNA. RESULTS: We found a variable degree of MYCN amplification, from 2 to 29, in 26 of 49 (53%) neuroblastomas. These results were well correlated to those obtained with a competitive PCR assay in the same samples (r = 0. 987). MYCN amplification was associated mainly with advanced cancer stages, and the analysis of overall survival confirmed that the measurement of MYCN amplification is a predictor of patient outcome in neuroblastoma. Patients without MYCN amplification had a cumulative survival significantly higher than patients with low (<9; P = 0.02) and high (>/=9; P = 0.03) oncogene amplification. CONCLUSION: The assay is rapid and reproducible and does not require any post-PCR analytical procedure.

Calibration↗

PubMed1994

Amplification and overexpression of HER-2/neu in carcinomas of the salivary gland: correlation with poor prognosis.

There are few reliable prognostic markers of biological aggressiveness for head and neck carcinomas in general. For salivary gland carcinomas, anatomic location, tumor size, histological grade, and extent of disease involvement are considered to be clinically important risk factors for recurrent disease. Molecular genetic alterations in salivary gland carcinomas have not been characterized, and tumor cell proteins have not been shown to be prognostically significant. Here a cohort of mucoepidermoid carcinomas of the major (parotid and submandibular) salivary glands are analyzed for a molecular genetic alteration, HER-2/neu gene amplification, and gene amplification and expression results are compared with long-term clinical follow-up information. Archival tissues resected from 58 patients with mucoepidermoid carcinoma of salivary glands were evaluated for HER-2/neu gene amplification by fluorescence in situ hybridization and for gene expression by immunohistochemistry in a blinded fashion. Clinical follow-up information was compared with the results of these analyses to determine whether there were significant associations. Overexpression, identified as membrane immunostaining by immunohistochemistry, was observed in 22 of 58 (38%) mucoepidermoid carcinomas. Gene amplification, characterized by fluorescence in situ hybridization, was observed in 12 (21%) cases. Eleven of the 12 cases with gene amplification were also immunostained for HER-2/neu. Both gene amplification (P = 0.0001, P < 0.0001) and immunostaining (P < 0.0001, P < 0.0001) were correlated with shorter disease-free interval and poorer overall patient survival, respectively. Multivariate analysis showed that HER-2/neu immunostaining and amplification were markers of poor prognosis independent of histopathological grade, tumor size, and involvement of regional lymph nodes. HER-2/neu is amplified and/or overexpressed in approximately one-third of mucoepidermoid carcinomas of salivary glands. Amplification and/or overexpression appears to be an independent marker of poor prognosis in mucoepidermoid carcinomas of the salivary glands as it is in carcinomas of the breast, ovary, and endometrium.

Adolescent↗