Repeat-length variation in a wheat cellulose synthase-like gene is associated with altered tiller number and stem cell wall composition.

The tiller inhibition gene (tin) that reduces tillering in wheat (Triticum aestivum) is also associated with large spikes, increased grain weight, and thick leaves and stems. In this study, comparison of near-isogenic lines (NILs) revealed changes in stem morphology, cell wall composition, and stem strength. Microscopic analysis of stem cross-sections and chemical analysis of stem tissue indicated that cell walls in tin lines were thicker and more lignified than in free-tillering NILs. Increased lignification was associated with stronger stems in tin plants. A candidate gene for tin was identified through map-based cloning and was predicted to encode a cellulose synthase-like (Csl) protein with homology to members of the CslA clade. Dinucleotide repeat-length polymorphism in the 5'UTR region of the Csl gene was associated with tiller number in diverse wheat germplasm and linked to expression differences of Csl transcripts between NILs. We propose that regulation of Csl transcript and/or protein levels affects carbon partitioning throughout the plant, which plays a key role in the tin phenotype.

SURF1, encoding a factor involved in the biogenesis of cytochrome c oxidase, is mutated in Leigh syndrome.

Leigh Syndrome (LS) is a severe neurological disorder characterized by bilaterally symmetrical necrotic lesions in subcortical brain regions that is commonly associated with systemic cytochrome c oxidase (COX) deficiency. COX deficiency is an autosomal recessive trait and most patients belong to a single genetic complementation group. DNA sequence analysis of the genes encoding the structural subunits of the COX complex has failed to identify a pathogenic mutation. Using microcell-mediated chromosome transfer, we mapped the gene defect in this disorder to chromosome 9q34 by complementation of the respiratory chain deficiency in patient fibroblasts. Analysis of a candidate gene (SURF1) of unknown function revealed several mutations, all of which predict a truncated protein. These data suggest a role for SURF1 in the biogenesis of the COX complex and define a new class of gene defects causing human neurodegenerative disease.

Kinematic differences between left- and right-handed cricket fast bowlers during the bowling action.

Background: Despite differences between left- and right-handed athletes in other sports, minimal evidence exists regarding biomechanical similarities and differences between left- and right-handed cricket fast bowlers performing an equivalent task. Objectives: This study aimed to compare the kinematics between left and right-handed fast bowlers performing an equivalent task (i.e. bowling 'over the wicket' to a batter of the same handedness as the bowler). Methods: Full body, three-dimensional kinematic data for six left-handed and 20 right-handed adolescent, male, fast bowlers were collected using the Xsens inertial measurement system. Time-normalised joint and segment angle time histories from back foot contact to follow-through ground contacts were compared between groups via statistical parametric mapping. Whole movement and subphase durations were also compared. Results: Left-handed players displayed significantly more trunk flexion from 49%-56% of the total movement (ball release occurred at 54%; p = 0.037) and had shorter back foot contact durations on average (0.153 vs 0.177 s; p = 0.036) compared to right-handed players. Conclusion: Left- and right-handed bowlers displayed similar sagittal plane kinematics but appeared to use non-sagittal plane movements differently around the time of ball release. The kinematic differences identified in this study can inform future research investigating the effect of hand dominance on bowling performance and injury risk.

Rare inherited A2BP1 deletion in a proband with autism and developmental hemiparesis.

Ataxin 2 binding protein 1 (A2BP1 aka FOX1, RBFOX1) is an RNA binding protein responsible for regulation of pre-mRNA splicing events in a number of critical developmental genes expressed in muscle, heart and neuronal cells [Shibata et al. (2000); Mamm Genome 12:595-601; Jin et al. (2003); EMBO J 22:905-912; Underwood et al. (2005); Mol Cell Biol 25:10005-10016]. Rare copy number abnormalities of A2BP1 have been previously associated with cognitive impairment, attention deficit disorder and autism [Martin et al. (2007); Am J Med Gen Part B 144B:869-876; Elia et al. (2010); Mol Psychiatry 15:637-646.]. Using a 1M Illumina SNP microarray, we identified a 1.3 kb deletion in A2BP1, which was subsequently validated by quantitative PCR. Here we present an in depth case study of an individual with autism and mild developmental hemiparesis in whom the deletion was detected. This study provides further support for the possible role of rare copy number variants in A2BP1 in the development of autism and associated motor asymmetries.

Abnormalities of the ARF-p53 pathway in oral squamous cell carcinoma.

Oral squamous cell carcinoma (OSCC) is associated with heavy smoking and drinking, but the molecular pathway of tumorigenesis is not understood. Inactivation of the p53 tumor suppressor gene is likely to play an important role since p53 mutation is frequently found. The p14ARF tumor suppressor gene is functionally linked to p53, because it is activated by oncogenes and causes p53-dependent growth arrest and apoptosis. The relationship between p14ARF and p53 inactivation has not been described for OSCC. We studied 25 cases of OSCC to determine if there is an inverse correlation between p53 mutation and p14ARF inactivation by homozygous deletion or mutation. p53 mutation was found in 16 of 25 cases (64%), including nine missense and seven truncating mutations. While all cases with missense mutations showed abnormal accumulation of p53 protein, there were also five carcinomas which showed increased p53 staining in the absence of mutation. p14ARF deletion or mutation was found in eight cases (32%), six of which also demonstrated p53 mutation. Our findings indicate that OSCC often involves loss of both p14ARF and p53 function and suggest that inactivation of these two tumor suppressor genes are not functionally equivalent during tumorigenesis.

Prediction of recurrence-free survival using a protein expression-based risk classifier for head and neck cancer.

Loco-regional recurrence in 50% of oral squamous cell carcinoma (OSCC) patients poses major challenge for oncologists. Lack of biomarkers that can predict disease aggressiveness and recurrence risk makes the scenario more dismal. On the basis of our earlier global proteomic analyses we identified five differentially expressed proteins in OSCC. This study aimed to develop protein biomarkers-based prognostic risk prediction model for OSCC. Sub-cellular expression of five proteins, S100A7, heterogeneous nuclear ribonucleoproteinK (hnRNPK), prothymosin α (PTMA), 14-3-3ζ and 14-3-3σ was analyzed by immunohistochemistry in test set (282 Indian OSCCs and 209 normal tissues), correlated with clinic-pathological parameters and clinical outcome over 12 years to develop a risk model for prediction of recurrence-free survival. This risk classifier was externally validated in 135 Canadian OSCC and 96 normal tissues. Biomarker signature score based on PTMA, S100A7 and hnRNPK was associated with recurrence free survival of OSCC patients (hazard ratio=1.11; 95% confidence interval 1.08, 1.13, P<0.001, optimism-corrected c-statistic=0.69) independent of clinical parameters. Biomarker signature score stratified OSCC patients into high- and low-risk groups with significant difference for disease recurrence. The high-risk group had median survival 14 months, and 3-year survival rate of 30%, whereas low-risk group survival probability did not reach 50%, and had 3-year survival rate of 71%. As a powerful predictor of 3-year recurrence-free survival in OSCC patients, the newly developed biomarkers panel risk classifier will facilitate patient counseling for personalized treatment.

Impairment of force generation after adenovirus-mediated gene transfer to muscle is alleviated by adenoviral gene inactivation and host CD8+ T cell deficiency.

Recombinant adenovirus vectors (AdV) hold promise as a means of delivering therapeutic genes to muscle in diseases such as Duchenne muscular dystrophy (DMD). However, we have previously shown that the use of AdV is hampered by the development of reduced force-generating capacity, which occurs within 1 week and is progressive up to at least 1 month after AdV delivery in immune-competent animals. Determinations of muscle force production provide a sensitive and clinically important measure of potential adverse effects of AdV-mediated gene transfer on muscle cell function. In the present study, we investigated the role of AdV-related gene expression and host T lymphocyte responses in the genesis of muscle dysfunction following AdV injection of muscle. We report that UV-irradiation of AdV particles, which reduced AdV transcriptional activity without impairing infectivity (as confirmed by in situ polymerase chain reaction), significantly reversed early (4 days post-injection) AdV-induced contractile impairment in immune-competent mice as well as in mice lacking effective CD8+ T cell activity. The superimposed additional reduction in force-generating capacity normally found between 4 and 30 days post-AdV delivery in immune-competent mice, along with the associated loss of transgene (beta-galactosidase) expression, was largely abrogated by the absence of an intact CD8+ T lymphocyte response. Furthermore, short-term administration of a neutralizing antibody against CD4+ T cells significantly prolonged transgene expression and showed a trend toward mitigation of AdV-induced reductions in force-generating capacity. Cellular infiltration and humoral immune responses against the vector and transgene product were also blunted to varying degrees in the setting of CD8+ or CD4+ T cell deficiency. We conclude that AdV-related gene expression has an early negative (probably toxic) effect on muscle cell function that is independent of CD8+ T cell-mediated immunity. In contrast, further progression of contractile impairment and the accompanying loss of transgene expression from AdV-injected muscle are largely dependent upon the activity of CD8+ T cells. These results have implications for the design of future generation vectors and the potential need for immunosuppressive therapy after AdV-mediated gene transfer to muscle.

Variable distribution of mutant mitochondrial DNAs (tRNA(Leu[3243])) in tissues of symptomatic relatives with MELAS: the role of mitotic segregation.

We studied multiple different postmortem tissue samples from a woman and two of her daughters with the MELAS (mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes) tRNA(Leu(UUR)) mutation at nucleotide 3243 in mitochondrial DNA (mtDNA). All tissues examined were heteroplasmic for the mutation. The mean proportion of mutant mtDNAs in the mother's tissues (0.30 +/- 0.10) was significantly lower than that of each of her daughters' (0.76 +/- 0.11, p < 0.03, and 0.72 +/- 0.13, p < 0.001); there was no difference in the fraction of mutant mtDNAs between the daughters (p < 0.71). This difference in the mean proportion of mtDNA mutants between family members correlates with their clinical profiles; the mother had the latest onset of disease and lived longest, while the two daughters had a strikingly similar clinical course. In individual patients, the mean proportion of mutant mtDNAs was not different in tissues deriving from ectodermal, mesodermal, and endodermal germ layers. Variance in the mutant:wild-type mtDNA ratio was normally distributed about the mean, both when all tissues were considered together and when different regions of the CNS were considered separately. Thus, the proportion of mtDNAs carrying the tRNA(Leu(3243)) mutation was not uniform in members of this pedigree and did not undergo rapid mitotic segregation along germ-layer divisions. These findings are consistent with the hypothesis that the overall proportion of mtDNAs carrying this mutation is primarily determined by segregation during oogenesis or early embryologic development and that random replicative (mitotic) segregation, subsequent to the establishment of primary germ layers, is responsible for the variation between tissues.

Head growth and neurodevelopment of infants born to HIV-1-infected drug-using women.

OBJECTIVE: To describe neurodevelopment and head growth in HIV-1-infected and exposed uninfected infants with and without in utero exposure to opiates and cocaine. METHODS: Using data from a multicenter cohort study of HIV-1-infected women and their children, the authors fit repeated measures regression models to estimate the effects of HIV-1 infection and in utero hard drug exposure on head circumference and Bayley Scales of Infant Development standard scores during the first 30 months. RESULTS: Of the 1,094 infants included in the analysis, 147 (13%) were HIV-1-positive and 383 (35%) were exposed in utero to opiates or cocaine (drug-positive). Mean 4- month Bayley mental scores were lower in infants with only HIV-1 positivity (HIV-positive and drug-negative) (-8.2 points, p < 0.0001) or only drug exposure (HIV-negative and drug-positive) (-4.4 points, p = 0.0001) and tended to be lower in infants with both factors (HIV-positive and drug-positive) (-3.7 points, p = 0.0596), compared with those who were HIV-1-negative and not drug exposed (HIV-negative and drug-negative). However, by 24 months of age, there was no longer a decrement among HIV-negative and drug-positive infants, whereas HIV-1 infection was still associated with a decrement relative to uninfected infants. Similar results were seen for Bayley motor scores and for head circumference Z scores. CONCLUSIONS: HIV-1 infection and in utero opiate and cocaine exposure decrease birth head circumference and slow neurodevelopment at 4 months. At 24 months of age, however, only HIV-1 infection is associated with decreased neurodevelopment and head circumference. There may be some postnatal recovery from the effects of in utero hard drug exposure. Importantly, the detrimental effects of HIV-1 positivity and maternal hard drug use on neurodevelopment at 4 months are not additive, although they are additive for birth head circumference.

Pedigree analysis of French Canadian families with T14484C Leber's hereditary optic neuropathy.

We analyzed the clinical phenotype and determined the recurrence risks to relatives of patients with T14484C Leber's hereditary optic neuropathy (LHON). LHON is a maternally inherited optic neuropathy that primarily affects adolescent males. It is usually associated with one of three mtDNA mutations: G3460A, G11778A, or T14484C. Definition of recurrence risks for the T14484C mutation previously has not been possible due to the relative scarcity of families with this mutation. We obtained blood samples from index patients and their consenting family members, all of whom were of French Canadian ancestry and screened for LHON mutations in mtDNA. Referring ophthalmologists furnished clinical summaries and patients provided pedigree data. T14484C was the most common mutation in the pedigrees analyzed and was always homoplasmic. In these pedigrees, the ratio of affected males to females was 8:1. Median age at onset for males was 19 years (95th percentile, 40.8 years; range, 6 to 48 years). Some improvement of vision was observed in 58% of patients. Recurrence risks to brothers were 28%, sisters 5%, nephews 30%, nieces 3%, male matrilineal first cousins 19%, and female matrilineal first cousins 4%. Recurrence risks to brothers and nephews were not different; however, recurrence risks to brothers and male cousins and to nephews and male cousins were significantly different. There were no differences in recurrence risks to sisters and nieces or to either group compared with their female cousins. Affected females did not have more affected children than unaffected females. The clinical characteristics of French Canadian patients with T14484C LHON were strikingly similar to those in previous reports, suggesting that recurrence risks are generalizable to other T14484C LHON populations for genetic counseling of T14484C LHON families.

Homozygosity (E140K) in SCO2 causes delayed infantile onset of cardiomyopathy and neuropathy.

OBJECTIVE: To report three unrelated infants with a distinctive phenotype of Leigh-like syndrome, neurogenic muscular atrophy, and hypertrophic obstructive cardiomyopathy. The patients all had a homozygous missense mutation in SCO2. BACKGROUND: SCO2 encodes a mitochondrial inner membrane protein, thought to function as a copper transporter to cytochrome c oxidase (COX), the terminal enzyme of the respiratory chain. Mutations in SCO2 have been described in patients with severe COX deficiency and early onset fatal infantile hypertrophic cardioencephalomyopathy. All patients so far reported are compound heterozygotes for a missense mutation (E140K) near the predicted CxxxC metal binding motif; however, recent functional studies of the homologous mutation in yeast failed to demonstrate an effect on respiration. METHODS: Here we present clinical, biochemical, morphologic, functional, MRI, and MRS data in two infants, and a short report in an additional patient, all carrying a homozygous G1541A transition (E140K). RESULTS: The disease onset and symptoms differed significantly from those in compound heterozygotes. MRI and muscle morphology demonstrated an age-dependent progression of disease with predominant involvement of white matter, late appearance of basal ganglia lesions, and neurogenic muscular atrophy in addition to the relatively late onset of hypertrophic cardiomyopathy. The copper uptake of cultured fibroblasts was significantly increased. CONCLUSIONS: The clinical spectrum of SCO2 deficiency includes the delayed development of hypertrophic obstructive cardiomyopathy and severe neurogenic muscular atrophy. There is increased copper uptake in patients' fibroblasts indicating that the G1541A mutation effects cellular copper metabolism.

Hyalinizing trabecular tumor of the thyroid: a variant of papillary carcinoma proved by molecular genetics.

Hyalinizing trabecular tumors of the thyroid are interesting but uncommon neoplasms. They have been classified as benign hyalinizing trabecular adenomas or malignant hyalinizing trabecular carcinomas. They share both epidemiologic and morphologic features with papillary carcinoma, and there has been much speculation about the relationship between these two entities. Because RET/PTC gene rearrangements are specific to papillary thyroid carcinoma, the authors examined the presence of RET/PTC-1, -2, and -3 in eight hyalinizing trabecular tumors using reverse transcription-polymerase chain reaction with Southern hybridization and immunohistochemistry. They detected the presence of a RET/PTC gene rearrangement in six of the eight hyalinizing trabecular tumors. This confirms the long-standing suspicion that hyalinizing trabecular tumors do indeed represent a morphologic variant of papillary carcinoma.

Lymphoepithelial carcinoma of the larynx and hypopharynx: study of eight cases with relationship to Epstein-Barr virus and p53 gene alterations, and review of the literature.

Eight cases of lymphoepithelial carcinoma (LEC) of the larynx and hypopharynx were evaluated for clinicopathologic features, and the presence of the Epstein-Barr virus (EBV) and p53 alterations. The seven men and one woman, all of non-Asian descent, averaged 64 years of age. Eighty-eight percent had histologically confirmed cervical lymph node metastasis at diagnosis. None had systemic disease. Seven of eight patients available for follow-up (mean, 17.7 months) were alive and free of disease, although one did develop recurrent tumor in the neck. Four tumors were composed, histologically, of pure LEC. Four others had foci of both LEC and conventional squamous cell carcinoma. All eight tumors exhibited alterations in p53 expression, but none was positive for EBV. Combining these 8 cases with the 15 previously published cases in the English literature indicate that LEC in this site is a rare, rather aggressive tumor, primarily of older adults (mean, 62 years) with a propensity for early cervical lymph node metastasis and eventual distant dissemination and death from disease in about one third of patients. Although p53 alterations are common and of no apparent prognostic significance, LEC at this site seems to have little, if any, relationship to the EBV in patients of non-Asian origin.

Timing of perinatal human immunodeficiency virus type 1 infection and rate of neurodevelopment. The Women and Infant Transmission Study Group.

BACKGROUND: Identifying HIV-1-infected children who are at greatest risk for disease-related morbidities is critical for optimal therapeutic as well as preventive care. Several factors have been implicated in HIV-1 disease onset and severity, including maternal and infant host characteristics, viral phenotype and timing of HIV-1 infection. Early HIV-1 culture positivity, i.e. intrauterine infection, has been associated with poor immunologic, virologic and clinical outcomes in children of HIV-infected women. However, a direct effect of timing of infection on neurodevelopmental outcome in infancy has not yet been identified. METHODS: Serial neurodevelopmental assessments were performed with 114 infants vertically infected with HIV-1 in a multicenter natural history, longitudinal study. Median mental and motor scores were compared at three time points. Longitudinal regression analyses were used to evaluate the neurodevelopmental functioning of children with early positive cultures and those with late positive cultures. RESULTS: Early infected infants scored significantly lower than late infected infants by 24 months of age and beyond on both mental (P = 0.05) and motor (P = 0.03) measures. Early HIV-1 infection was associated with a decline in estimated motor scores of 1 standard score point per month compared with 0.28 point in the late infected group (P < 0.02). Estimated mental scores of the early infected group declined 0.72 point/ month, whereas the average decline of the late infected group was 0.30 point/month (P < 0.13). CONCLUSION: Early HIV-1 infection increases a child's risk for poor neurodevelopmental functioning within the first 30 months of life.

Cerebrovenous oxygen saturation monitoring: practical considerations and clinical relevance.

Measurement of the saturation of brain effluent blood gives a global estimate of cerebral oxygenation. It may provide clinicians with information to assist in reducing secondary insults to the brain with potential benefits to a range of patients with actual or potential acute brain injury such as trauma and cardiac bypass procedures. The technology to continuously measure this variable is simple to use but requires attention to detail; it is limited in its ability to detect discrete regions of ischaemia or hyperaemia unless these are of sufficient magnitude to influence the saturation of brain effluent blood. There are few complications that result from this invasive technique and they are usually of a minor nature. The technique also enables research opportunities from the ability to sample blood as it leaves the cranium. Poor outcomes are seen in patients with traumatic brain injury who exhibit either reduced or increased cerebrovenous oxygen saturation and it remains to be seen if detection and correction of these anomalies will produce patient benefits.

Pulmonary and cardiac sequelae of subarachnoid haemorrhage: time for active management?

Cardiac injury and pulmonary oedema occurring after acute neurological injury have been recognised for more than a century. Catecholamines, released in massive quantities due to hypothalamic stress from subarachnoid haemorrhage (SAH), result in specific myocardial lesions and hydrostatic pressure injury to the pulmonary capillaries causing neurogenic pulmonary oedema (NPO). The acute, reversible cardiac injury ranges from hypokinesis with a normal cardiac index, to low output cardiac failure. Some patients exhibit both catastrophic cardiac failure and NPO, while others exhibit signs of either one or other, or have subclinical evidence of the same. Hypoxia and hypotension are two of the most important insults which influence outcome after acute brain injury. However, despite this, little attention has hitherto been devoted to prevention and reversal of these potentially catastrophic medical complications which occur in patients with SAH. It is not clear which patients with SAH will develop important cardiac and respiratory complications. An active approach to investigation and organ support could provide a window of opportunity to intervene before significant hypoxia and hypotension develop, potentially reducing adverse consequences for the long-term neurological status of the patient. Indeed, there is an argument for all SAH patients to have echocardiography and continuous monitoring of respiratory rate, pulse oximetry, blood pressure and electrocardiogram. In the event of cardio-respiratory compromise developing i.e. cardiogenic shock and/or NPO, full investigation, attentive monitoring and appropriate intervention are required immediately to optimise cardiorespiratory function and allow subsequent definitive management of the SAH.

Accuracy of a miniature intracranial pressure monitor, its function during magnetic resonance scanning, and assessment of image artifact generation.

OBJECTIVE: We examined the accuracy and repeatability of an intracranial pressure (ICP) monitor (Codman MicroSensor; Johnson & Johnson Professional, Inc., Raynham, MA) in a nonmagnetic environment and during magnetic resonance imaging (MRI). The resulting image artifact generation was calculated. ICP monitoring is essential in management of severe head injury, but few ICP monitoring devices are compatible with use in an MRI scanner. The use of MRI to assess head injury is increasing, and developing safe methods of continuously monitoring ICP may improve patient care. METHODS: A water manometer was used as the standard for comparison. We assessed pressure readings from the ICP monitor in a nonmagnetic environment using a standard and a long connector cable between the pressure transducer and display unit. This long cable permitted testing during MRI sequences because the display unit could be distanced from the magnet. Accuracy was determined during T2-weighted imaging, proton spectroscopy, and diffusion-weighted imaging, and artifact generation was assessed. RESULTS: We found a high degree of accuracy for repeated measurements over a clinical pressure range using both standard and long connector cables outside the MRI room. During MRI scanning, the ICP monitor was accurate during T2 and proton spectroscopy sequences. Accuracy during diffusion-weighted imaging, however, was clinically unacceptable. This ICP monitor creates a reduction in signal-to-noise ratio in the received signal during T2-weighted imaging and proton spectroscopic imaging, with the obtained images still radiologically interpretable. CONCLUSION: The Codman ICP monitor is sufficiently accurate and free of artifact generation to be used during most clinical MRI applications. This could enhance patient monitoring and safety.

Self-stimulation of the lateral hypothalamus and ventrolateral tegmentum: excitability characteristics of the directly stimulated substrates.

Recovery from refractoriness in the neural substrate for self-stimulation of the ventrolateral tegmentum (VLT) was estimated using psychophysical techniques, and compared to recovery in the substrate for self-stimulation of the lateral hypothalamus (LH). A computer-controlled testing setup was developed to minimize experimenter error and testing time. In order to assess the performance of this setup, refractory period estimates obtained in the newly designed, computer-controlled equipment were compared to those obtained in the hand-operated equipment used in previous experiments of this type. No meaningful differences were found. Thus, the more convenient computer-controlled setup was used to collect refractory period estimates from the VLT and LH. A comparison of these values revealed differences in the slopes of the recovery curves, and in the C-T intervals bracketing their rising portions. The VLT curves rose more gradually, and both began to rise and levelled off at longer C-T intervals than the LH curves. One explanation of these results is that the distribution of excitability in the LH substrate is shifted towards higher values than the VLT distribution. The overlapping portions of the recovery curves could reflect the contribution of a common bundle of reward-related fibers.

Telomerase activity is upregulated in laryngeal squamous cell carcinoma.

OBJECTIVE/HYPOTHESIS: The immortalizing enzyme telomerase has been linked to carcinogenesis and is being targeted as a novel molecular marker. This study investigated telomerase expression in patients with laryngeal squamous cell carcinoma and correlated telomerase activity with conventional prognostic parameters. STUDY DESIGN: A consecutive series of patients with laryngeal squamous cell carcinoma undergoing surgical salvage for persistent or progressive disease after failed radiation therapy. METHODS: Twenty patient samples of laryngeal squamous cell carcinoma and 20 adjacent histologically normal mucosal samples were assayed using the telomeric repeat amplification protocol (TRAP) method for detection of telomerase activity. The leukemic cell line, K562, acted as a positive control and the human fibroblast line, Hs21Fs, as a negative control. A sample was classified as telomerase positive when an RNase-sensitive hexameric repeat ladder was observed. Absence of laddering was considered a negative result. RESULTS: Seventeen of 20 (85%) tumor samples and 4 of 20 (20%) adjacent histologically normal samples were telomerase positive. No statistically significant difference was observed when densitometric readings were compared by T category, tumor grade, or site (by ANOVA). CONCLUSIONS: Although telomerase activity is present in laryngeal cancer, levels of activation do not correlate with conventional parameters used for prognostication. Our study indicates that the marker may be a useful adjunctive method in the diagnosis of malignancy after radiation failure.

Telomerase activity in oral squamous cell carcinoma.

BACKGROUND: The riboprotein telomerase has been linked to cellular immortality and is believed to play a key role in tumorigenesis. OBJECTIVE: To determine if telomerase is expressed in patients with oral squamous cell carcinoma. DESIGN: Twenty patient samples of oral squamous cell carcinoma and 20 adjacent histologically normal mucosal samples were assayed using the telomeric repeat amplification protocol (TRAP) method for detection of telomerase activity. The leukemic cell line, K562, was used as a positive control and the human fibroblast line, Hs21Fs, as a negative control. PATIENTS: Consecutive series of patients with oral squamous cell carcinoma presenting to a tertiary referral center. MAIN OUTCOME MEASURE: A sample was classified as telomerase positive when an RNase-sensitive hexameric repeat ladder was observed. Absence of laddering was considered a negative result. RESULTS: Eighteen (90%) of 20 tumor samples and 7 (35%) of 20 adjacent histologically normal samples were telomerase positive. A statistically significant difference was observed in telomerase activity for T1 and T2 cancers compared with T4 cancers (P<.05 by analysis of variance). No statistically significant difference was observed in activity for T1 and T2 cancers vs T3 cancers. CONCLUSIONS: The finding of telomerase activity in 90% of tumor samples is consistent with the concept of telomerase playing a key role in tumorigenesis. Further study is needed to determine the usefulness of this enzyme as a molecular marker.