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Results for “Testing sequence”

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At least 415 records · Page 23Linked to original sources
PubMed2001

Locus control region of the human CD2 gene in a lentivirus vector confers position-independent transgene expression.

Vectors derived from murine leukemia virus (MLV) have been used in many human gene therapy clinical trials. However, insertion of the locus control regions (LCRs) derived from the beta-globin gene locus or the CD2 gene into MLV vectors frequently led to vector rearrangement. Since the human immunodeficiency virus (HIV) sequence diverges significantly from the MLV sequence, we tested whether the LCR sequence is more stable in the context of an HIV vector. Clones derived from human fibrosarcoma line HT1080 cells transduced with an HIV vector containing the T-cell-specific CD2 LCR exhibit the same wide range of transgene expression as clones lacking the LCR. In contrast, Jurkat and primary T-cell clones derived from the transduction of the LCR-containing vector show, on average, a three- to fourfold increase in transgene expression relative to that of the control vector. This is consistent with previous observations that the CD2 LCR contains a T-cell-specific enhancer. In addition, the clones derived from the LCR-containing vector have a much lower clonal variation in transgene expression than those derived from the control vector. We also demonstrate that the level of transgene expression is proportional to the vector copy number. These results suggest that the human CD2 LCR sequence is compatible with HIV vector sequences and confers enhanced integration site-independent and copy number-dependent expression of the transgene. Thus, HIV vectors may represent the ideal vehicle to deliver genes controlled by various cis-acting elements such as LCRs.

CD2 Antigens↗
PubMed1999

Detection of mitochondrial DNA mutations by temporal temperature gradient gel electrophoresis.

BACKGROUND: A unique requirement for the molecular diagnosis of mitochondrial DNA (mtDNA) disorders is the ability to detect heteroplasmic mtDNA mutations and to distinguish them from homoplasmic sequence variations before further testing (e.g., sequencing) is performed. We evaluated the potential utility of temporal temperature gradient gel electrophoresis (TTGE) for these purposes in patients with suspected mtDNA mutations. METHODS: DNA samples were selected from patients with known mtDNA mutations and patients suspected of mtDNA disorders without detectable mutations by routine analysis. Six regions of mtDNA were PCR amplified and analyzed by TTGE. Electrophoresis was carried out at 145 V with a constant temperature increment of 1.2 degrees C/h. Mutations were identified by direct sequencing of the PCR products and confirmed by PCR/allele-specific oligonucleotide or PCR/restriction fragment length polymorphism analysis. RESULTS: In the experiments using patient samples containing various amounts of mutant mtDNA, TTGE detected as little as 4% mutant heteroplasmy and identified heteroplasmy in the presence of a homoplasmic polymorphism. In 109 specimens with 15 different known mutations, TTGE detected the presence of all mutations and distinguished heteroplasmic mutations from homoplasmic polymorphisms. When 11% of the mtDNA genome was analyzed by TTGE in 104 patients with clinically suspected mitochondrial disorders, 7 cases of heteroplasmy ( approximately 7%) were detected. CONCLUSIONS: TTGE distinguishes heteroplasmic mutation from homoplasmic polymorphisms and appears to be a sensitive tool for detection of sequence variations and heteroplasmy in patients suspected of having mtDNA disorders.

Alleles↗
PubMed1996

Ankylosing spondylitis and heterogeneity of HLA-B27 in Chinese.

OBJECTIVE: To examine the relationship between ankylosing spondylitis and heterogeneity of HLA-B27 in Chinese. PATIENTS AND METHODS: We subtyped HLA-B27 in 76 patients with ankylosing spondylitis and 1 200 healthy Chinese of Han nationality. Polymerase chain reaction was designed to amplify specific regions of class I (exon 2 and 3). Amplified sequences were tested with eight sequence-specific oligonucleotides to distinguish all HLA-B27 subtypes. RESULTS: The HLA-B27 was closely related to ankylosing spondylitis and at least four subtypes presented in Chinese patients. B2704 was the most common subtype, occurring in 54.8% and 50.85% respectively in HLA-B27 positive ankylosing spondylitis patients and healthy controls. The main HLA-B27 subtypes in the HLA-B27 positive patients distributed in similar proportion to those of HLA-B27 positive healthy controls (P < 0.1). CONCLUSIONS: The prevalences of various subtypes of HLA-B27 vary in different races. HLA-B2704 is the main subtype in Chinese Han nationality. The HLA-B27 specific residues that are shared by the subtypes might be involved in the pathogenesis of ankylosing spondylitis.

Adolescent↗
PubMed1996

[Ankylosing spondylitis and heterogenity of HLA-B27 in Chinese].

HLA-B27 represents a family of closely related antigens. More than six alleles differing in limited number of nucleotide substitution had been described (B2701-B2706). We subtyped HLA-B27 in 76 patients with ankylosing spondylitis (AS) and 1200 Chinese healthy persons of Han nationality. Polymerase chain reaction was designed to amplify specific regions for class I (exon 2 and 3). Amplified sequences were tested with eight sequence-specific oligonucleotides to distinguish all HLA-B27 subtypes. The results showed: the HLA-B27 was closely related with AS and at least four subtypes existed in Chinese patients. B2704 was the most common subtype occurring in 54.8% and 50.85% respectively in HLA-B27 positive AS patients and healthy controls. The main HLA-B27 subtypes in the HLA-B27 positive patients distributed in similar proportion to that of HLA-B27 positive healthy controls (P > 0.1). We believe that the above results imply that the prevalences of the various subtypes of HLA-B27 vary in different races. The HLA-B27 specific residues that are shared by the subtypes might be involved in the pathogenesis of AS.

Alleles↗
PubMed1995

Use of maximum length sequence analysis in newborn hearing testing.

The use of maximum length sequence analysis (MLSA) with rapid click rates may be of clinical value in newborn hearing screening because a greater number of individual responses can be signal averaged without adding to test time. To examine the potential clinical value of MLSA in newborn screening, auditory brainstem responses (ABRs) from 50 premature newborns were studied. ABRs were acquired with conventional signal averaging at four stimulus intensity levels (50 dB, 40 dB, 30 dB, and 20 dB nHL) using a click rate of 33.3/sec. These responses were directly compared with the ABRs acquired with MLSA using a rate of 227.3/sec. MLSA and conventional signal averaging yielded similar results with no statistically significant differences in the number of responses detected. Across babies, the overall quality of the tracings slightly favored MLSA, particularly when recording conditions were poor. Though the results of this investigation do not support the use of MLSA as the primary technique in newborn screening in the neonatal intensive care unit (NICU), they do support consideration of the use of MLSA as an alternative technique when the responses obtained with conventional signal averaging are poorly defined.

Acoustic Stimulation↗
PubMed1993

Single-strand conformational polymorphism and direct sequencing applied to carrier testing in families with ornithine transcarbamylase deficiency.

Single-strand conformational polymorphism (SSCP) and direct sequencing were used to confirm or deny carrier status in three families with ornithine transcarbamylase (OTC) enzyme deficiency. Two male probands with "late onset" OTC deficiency, whose "private" mutations were previously characterized, inherited the mutations form their heterozygous mothers. One of the heterozygous mothers had a false negative allopurinol test. Three female siblings of the two male probands were tested, one proved to be a carrier of the respective mutation while the other two were found to have normal alleles. In the third family, the proband was a female with "late onset" presentation of OTC deficiency. We found a new point mutation in this girl consisting of a guanine-to-cytosine transversion at nucleotide 520 resulting in a substitution of proline for alanine at amino acid 142 of the mature OTC protein. We confirmed that this mutation occurred spontaneously and that neither of the two parents carries this mutation. We conclude that SSCP, in conjunction with direct sequencing, is a useful technique that can be practically applied for carrier testing in families with OTC deficiency.

Amino Acid Metabolism, Inborn Errors↗
PubMed1978

The role of frontal and parietal cortex in cognitive processing: tests of spatial and sequence functions.

Normal monkeys and monkeys with resection of anterior frontal or posterior parietal cortex were trained to press a panel next to a green panel as a test of extrapersonal spatial orientation and to press a panel next to their own prior press as a test of personal spatial orientation. All monkeys also learned two sets of sequence problems in which the solutions were made independent of spatial location by randomly shifting the locations of the stimuli after each response within a trial. The Parietal Group was significantly impaired on the extrapersonal 'next-to' task but not the more difficult personal 'next-to' task. The Frontal Group was impaired on both the personal and the extrapersonal 'next-to' tasks but only when the relevant cues shifted spatial locations from trial to trial. The performance of the Parietal Group completely overlapped that of the Normal Group on the sequence problems regardless of the level of testing sophistication the monkeys had attained. In contrast, the Frontal Group demonstrated a significant impairment in learning sequences but only when the monkeys were naive. Once they became sophisticated they learned each sequence at a normal rate. Their poor performance was attributed to the lack of stability in the spatial location of the stimuli. The data support the view that a distinction between personal and extrapersonal spatial orientation is relevant to posterior parietal function but indicate that neither sequencing per se nor personal spatial orientation or spatial memory per se is dependent on intact frontal functioning. Rather, the frontal cortex is involved with a higher-order control essential to allow the monkey to perceive the reliable aspects of stimuli contained in a stimulus context full of unreliable noise and to further allow for flexible response pattern appropriate to the demands of a variable context.

Animals↗
PubMed2000

Evidence for effector independent and dependent representations and their differential time course of acquisition during motor sequence learning.

To investigate the representation of motor sequence, we tested transfer effects in a motor sequence learning paradigm. We hypothesize that there are two sequence representations, effector independent and dependent. Further, we postulate that the effector independent representation is in visual/spatial coordinates, that the effector dependent representation is in motor coordinates, and that their time courses of acquisition during learning are different. Twelve subjects were tested in a modified 2x10 task. Subjects learned to press two keys (called a set) successively on a keypad in response to two lighted squares on a 3x3 display. The complete sequence to be learned was composed of ten such sets, called a hyperset. Training was given in the normal condition and sequence recall was assessed in the early, intermediate, and late stages in three conditions, normal, visual, and motor. In the visual condition, finger-keypad mapping was rotated 90 degrees while the keypad-display mapping was kept identical to normal. In the motor condition, the keypad-display mapping was also rotated 90 degrees, resulting in an identical finger-display mapping as in normal. Subjects formed two groups with each group using a different normal condition. One group learned the sequence in a standard keypad-hand setting and subsequently recalled the sequence using a rotated keypad-hand setting in the test conditions. The second group learned the sequence with a rotated keypad-hand setting and subsequently recalled the sequence with a standard keypad-hand setting in the test conditions. Response time (RT) and sequencing errors during recall were recorded. Although subjects committed more sequencing errors in both testing conditions, visual and motor, as compared to the normal condition, the errors were below chance level. Sequencing errors did not differ significantly between visual and motor conditions. Further, the sequence recall accuracy was over 70% even by the early stage when the subjects performed the sequence for the first time with the altered conditions, visual and motor. There were parallel improvements thereafter in all the conditions. These results of positive transfer of sequence knowledge across conditions that use dissimilar finger movements point to an effector independent sequence representation, possibly in visual/spatial coordinates. Initially the RTs were similar in the visual and the motor conditions, but with training RTs in the motor condition became significantly shorter than in the visual condition, as revealed by significant interaction for the testing stage and condition term in the repeated measures ANOVA. Moreover, using RTs for single key pressing in the three conditions as baseline indices, it was again observed that RTs in the visual and motor conditions were not significantly different in the early stage, but motor RTs became significantly shorter by the late testing stage. These results support the hypothesis that the motor condition benefits more than the visual because it uses identical effector movements to the normal condition. Further, these results argue for the existence of effector dependent sequence representation, in motor coordinates, which is acquired relatively slowly. The difference in the time course of learning of these two representations may account for the differential involvement of brain areas in early and late learning phases found in lesion and imaging studies.

Adult↗
PubMed2000

Effects of test administration order on children's neuropsychological performance: emerging one-word expressive and receptive language skills.

Differences in neuropsychological performance associated with specific test presentation sequences have been reported in adults. However, these effects have received little attention in children. The EOWPVT-R, a measure of one-word expressive language, and the PPVT-R, a measure of receptive language, were administered to 6- to 14-year-olds (control [n = 17] and experimental [n = 22] groups) in a counterbalanced fashion to investigate the potential effects of test presentation sequence on neuropsychological performance. Group findings were not evidenced subsequent to variation in test administration sequence. In contrast, order of test presentation revealed differences in performance. Administration of the PPVT-R prior to the EOWPVT-R resulted in enhanced EOWPVT-R expressive language scores in both groups of participants. Presentation of the PPVT-R after the EOWPVT-R did not affect performance. Applied and theoretical implications associated with these findings are discussed.

Adolescent↗