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At least 433 records · Page 24Linked to original sources
PubMed1975

[Hemodynamic differences between maximal treadmill and bicycle ergometer test in coronary disease].

9 patients with diagnosis of coronary heart disease (CHD) and typical angina pectoris (AP) were studied by means of a multistage, symptom-limited treadmill test and a similar bicycle ergometer (bike)-test. The sequence of tests was determined by chance. Between the tests, the patients rested one hour. Oxygen uptake (vo2) was determined by the Douglas-bag-method, blood pressures were measured via catheters placed in a pulmonary and a brachial or radial artery, respectively. Cardiac output (Q) was calculated by the direct Fick principle. In all tests, with the exception of one bike-test, all patients were limited by AP. They attained high VO2 (mean 1316 ml/min) on the treadmill (TM) while on the TM their mean arterial blood pressure (BP) was significantly (P greater than 0.05), namely 10 mm Hg as an average, lower. Comparing the final minute -3 of the TM-test with the final minute -1 of the bike-test in 5 patients, we found heart rate (HR), BP and pressure rate product (HR times BP) lower on the TM (P greater than 0.05), whereas VO2 was the same. Patients, whose exercise performance is limited by angina pectoris on bike and TM, achieve higher VO2 on the treadmill, together with lower BP. This may be of clinical importance in exercise-testing and -training of patients with CHD.

Aerobiosis↗
PubMed1992

Stability of an ankle arthrodesis fixed by cancellous-bone screws compared with that fixed by an external fixator. A biomechanical study.

Twenty-three fresh-frozen human specimens were subjected to ankle arthrodesis and fixation with two cancellous-bone screws. The specimens were then subjected to four newton-meters of manually applied tibial torque, plantar flexion-dorsiflexion moment, and medial-lateral bending moment; relative rotation between the tibia and the talus was recorded for each mode of testing. A Calandruccio triangular compression device was then applied to threaded pins penetrating the tibia and talus, the screws were removed, and the test sequence was repeated. Tibiotalar motions recorded with both systems of fixation were markedly affected by the quality of the bone. When less than 2 degrees of total tibiotalar rotation was recorded in response to four newton-meters of manually applied internal-external tibial torque, all specimens demonstrated less torsional rotation with the screw fixation than with the external fixator. The mean rotations produced by medial-lateral bending moment were equivalent for both systems of fixation. When torsional rotations with the use of screw fixation were greater than 2 degrees, all specimens demonstrated more torsional rotation with the screws than with the external fixator, and all but one specimen had more medial-lateral rotation with the screws than with the fixator. For applied plantar flexion-dorsiflexion moment, twenty-two of the twenty-three specimens demonstrated more rotation with the Calandruccio fixator than with the screws; this was due in part to motion permitted at the hinge points of the frame itself.

Aged↗
PubMed1987

Body volume changes during simulated weightlessness: an overview.

It has been hypothesized that many of the adaptive processes that occur in man during exposure to space involve the rapid headward shift of tissue fluids, blood, and other fluids during the first few hours of spaceflight. A total of 53 men and women between the ages of 22 and 55 years were tested during four bed rest studies lasting between 4 h and 7 d to define the segmental volume changes that took place during simulated weightlessness. Impedance plethysmography can be used to measure baseline resistance (Ro) changes of the calf, thigh, total leg, pelvic, torso, and arm segments before, during, and after each bed rest exposure. Records of Ro were analyzed to determine the fluid volume and volume change of each segment during each test sequence.

Adaptation, Physiological↗
PubMed1984

The parental origin of X chromosomes in XX males determined using restriction fragment length polymorphisms.

The inheritance of several X-linked restriction fragment length polymorphisms ( RFLPs ) is examined in seven 46,XX males and their immediate relatives. The XX males are shown to have inherited a paternal and a maternal RFLP allele in each of the five (of seven) families in which these X-linked markers are informative. In the other two families, a maternal X-chromosomal contribution is demonstrated, but a paternal contribution cannot be determined. We conclude that most, if not all, XX males inherit one paternal and one maternal X chromosome. A segment of single-copy DNA specific to the short arm of the Y chromosome is found to be absent from the genomes of eight XX males. In one of these XX males, an Xp-Yp translocation had previously been inferred from chromosome-banding studies. Our findings argue against mosaicism involving a Y-containing cell line in the XX males examined here, but they do not exclude an X-Y (or Y-autosome) translocation during paternal meiosis. If such a translocation has occurred, the translocation product received by the XX males does not include the Yp-specific sequence tested here.

Alleles↗
PubMed1984

Stereoscopic cerebral evoked potentials of Air Force pilots and civilian comparison groups.

Dynamic random-dot stereograms were presented to Air Force jet pilots (N = 14) through a new visual display system. Games which simulated target-detection exercises were included in the test sequence. Event-related potentials were recorded at scalp sites 01, 02, T5, T6, referenced to an anterior midline site. Comparisons were made where possible with the data from recent studies on three civilian groups. A pattern of response was revealed in the event-related potential measures. In general, left-hemisphere amplitudes exceeded right and the predominant response was recorded at the left-temporal site. Amplitudes of responses in subjects able to describe the stimuli in subjective report (perceivers) exceeded those of non-perceivers. Stimuli with definite boundaries evoked stronger and earlier-latency responses than stimuli with nebulous boundaries. The response patterns of subjects make a contribution to normative data on the cerebral electrical indices of stereoscopic vision.

Adult↗
PubMed1995

[Cerebral ischemia during implantation of automatic defibrillators].

In order to study the influence of repetitive episodes of ventricular fibrillation (VF) during defibrillator implantation on the electrical activity of the brain, we performed an electroencephalographic (EEG) monitoring during implantation procedure in 18 patients. For defibrillation threshold testing 62 episodes of VF (1-6 episodes per patient) were induced. The mean duration of VF was 20 +/- 12 s; the mean duration of hypotension during an episode (defined as a mean arterial pressure of 50 mm Hg or less) was 33 +/- 16 s. EEG monitoring was performed using the International 10-20 System. The duration of cardiac arrest-related EEG alteration was assessed by an experienced neurologist and could be determined in 41 test-episodes; in 21 episodes analysis was not possible due to poor recordings. Ischemia-related EEG changes started 7.8 +/- 4.6 s after VF induction and lasted 64 +/- 49 s (range, 12-240). The duration of EEG alteration was significantly (p < .001) correlated with the duration of VF episodes (r = .71) and the associated hypotension (r = .82). With regard to patients the duration of ischemia related EEG changes also correlated significantly (p = .001) with the individual cumulative duration of VF (r = .85) and the associated hypotension (r = .88). In females EEG changes lasted longer than in males (p = .03); this finding, however, was only based on 2 women. Other clinical parameters, such as patient age, degree of congestive heart failure, left ventricular ejection fraction, stroke volume and cardiac index, the order of episodes within the testing sequence, and the time interval between episodes did not correlate with the duration of EEG alteration after VF induction. The duration of ischemia-related EEG alteration during VF episodes depends on the duration of cardiac arrest. In females EEG changes tended to last longer than in males, however, this finding has to be confirmed. An association with other clinical parameters has not been observed. Limitation of VF duration appears to be the most important factor to avoid prolonged cerebral ischemia.

Adult↗
PubMed1995

Plethysmographic measurements in the clinical assessment of infants with bronchopulmonary disease.

Whole-body plethysmography makes it possible, to measure, during the same test sequence, the end-expiratory resting level (thoracic gas volume (TGV)), and, hence, an estimate of lung volume, and its close inter-relationship to airway function (airway resistance (Raw), or its reciprocal value airway conductance (Gaw). An overview is given of the physiological background and some equipment required for this technique. Furthermore, the attractive usefulness of whole-body plethysmography in clinical routine is discussed. Based on plethysmographic data obtained in 118 infant survivors of respiratory distress syndrome (RDS), in wheezy infants and infants with cystic fibrosis (CF), the important inter-relationship between changes in end-expiratory resting level (TGV) and the deficit in airway mechanics (Gaw) is shown, and special emphasis is given to the absolute need to obtain these measurements simultaneously. It can be shown that this recommendation is of even greater clinical importance in view of the fact that the younger the child the more frequent and severe the pulmonary hyperinflation present. Finally, this inter-relationship has to be borne in mind when reversibility of functional abnormalities on adrenoceptor agonists is assessed by lung function measurements.

Airway Resistance↗
PubMed1994

A biomechanical comparison evaluating the use of intermediate screws and cross-linkage in lumbar pedicle fixation.

In lumbar fusion, controversy remains regarding the effectiveness of cross-linking and the necessity of placing pedicle screws at the intermediate levels of the segment to be fused. The purpose of this study is to evaluate the stiffness of various rod/screw constructs used to instrument a three-level fusion with specific emphasis on the effect of cross-linking and the intermediate pedicle screws. Nine lumbar calf spines were mounted at L1 and L5. Pedicle screws (TSRH, Danek, Memphis, TN) were then placed bilaterally in the L2, L3, and L4 pedicles. Random sequence testing of the following constructs was then conducted: TSRH rods connected bilaterally to the L2 and L4 pedicles with and without a cross-link, and rods connected bilaterally at the L2, L3, and L4 levels with and without a cross-link. The tests were conducted on a modified MTS testing machine (MTS, Minneapolis, MN) and consisted of cyclic application of axial load, torsion, and flexion and extension. The tests yielded axial, sagittal, and torsional stiffness values. Statistical analysis was performed using log transformation and Fischer's test of least significant difference. In axial testing the use of additional screws in the intermediate pedicles increased stiffness an average of 160% (p = .007). The addition of a cross-link did not increase stiffness with axial loading. In flexion testing the six-screw construct was 84% stiffer when compared with the four-screw construct (p = 0.0001). There was no significant change in flexion stiffness with addition of cross-links. In torsional testing the six-screw construct was 38% stiffer than the four-screw construct (p = 0.042).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

An improved technique for measuring in vivo intervertebral motion in the canine.

STUDY DESIGN: An experimental animal study using an established technique for measuring in vivo motion in canines was designed to improve measurement techniques and to eliminate the effects of the instrument mounting technique on the tissue and subsequently on the motion being measured. OBJECTIVES: The purpose of this study was to improve a technique for measuring in vivo intervertebral motion in canines, so that the measuring technique did not affect the motion being measured. SUMMARY OF BACKGROUND DATA: Biplanar radiography has been used to measure in vivo intervertebral motion, but involves radiation exposure and expensive equipment. Electromechanical devices have been used more recently but have had significant effects on the motion over extended time periods. METHODS: Intervertebral motion was measured using an instrumented spatial linkage in eight adult canines divided into two groups that differed regarding the method of "mounting pin" placement. Group I had open surgical placement of the pins and Group II had pins placed into the spinous processes. After pin implantation, the instrumented spatial linkage was attached and motion data were recorded during walking. This testing sequence was repeated 3 weeks later. Animals were killed and intervertebral and facet motion were calculated from the experimental data and compared statistically. RESULTS: Facet motion decreased 1 to 3 weeks after pin implantation for animals of group I (3.4 +/- 0.2 mm to 1.1 +/- 0.3 mm), whereas the facet excursion of animals in Group II showed no change (3.0 +/- 0.2 mm and 3.1 +/- 0.3 mm). CONCLUSIONS: A new method of measuring in vivo intervertebral motion in canines has been developed and shown to have no significant affect on the segment mechanics.

Animals↗
PubMed1993

Chemotherapy and radiation in the nonoperative management of stage III non-small-cell lung cancer: the right chemotherapy works in the right setting.

Approximately one-quarter of all American patients with NSCLC present with stage III disease. At least to this juncture, standard management for the large majority of these patients is nonoperative, except for staging mediastinoscopy. Radiation therapy alone to 6000 cGy or above given in once-daily fractions 5 days per week is usually considered "standard" therapy. While this approach causes disease shrinkage in one-third to two-thirds of patients treated, long-term local control with this benchmark radiotherapy is poor, the median time to progression is less than 6 months, and median survival for treated patients is less than 1 year. Combination CT is more effective in inducing tumor regression in stage III than in stage IV NSCLC patients. The administration of a short course of induction CT (two to three cycles) prior to definitive XRT improves median and overall survival among stage III patients. In individuals with stage III disease selected for good performance status (0 to 1), minimum weight loss (< 5%), and no supraclavicular node involvement, sequential CT/XRT is associated with a survival plateau above 20% at 2 years, 3 years, and beyond. Local failure and distant failure both remain as problems despite the survival improvements produced by sequential CT/XRT. Concurrent chemoradiation, especially utilizing daily low-dose cisplatin, improves local control significantly and lengthens survival. Increased intensity of TRT using multifraction-per-day schedules or more active induction CT programs also may improve local control and perhaps affect overall survival. Trials now underway are testing sequences of induction CT followed by concurrent CT/XRT or rapid fractionation schemes and concurrent cisplatin-based combination CT. These strategies will hopefully produce yet another step up for the plateau phase of the survival curve for patients with stage III NSCLC.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1993

Expression of AML1-ETO fusion transcripts and detection of minimal residual disease in t(8;21)-positive acute myeloid leukemia.

The t(8;21) translocation breakpoint, which is observed in acute myeloid leukemia (AML), has recently been cloned and a fusion transcript identified. We have now designed primer sets capable of amplifying the breakpoint junction of the fusion transcript by the reverse transcription-polymerase chain reaction (RT-PCR). Primer set 821U/821D1 amplified a 200-bp DNA fragment, and primer set 821U/821D2 amplified a 1.2-kb DNA fragment in all t(8;21)-positive AML tested. Sequence analysis of the amplified DNA fragments demonstrated that all fusion transcripts were fused at exactly the same site, indicating that this translocation breakpoint occurs within a single intron of the AML1 and ETO genes. Forty-five cycles of RT-PCR were used to detect residual t(8;21)-positive leukemia cells in three patients who had been in complete remission for 1, 3 and 5 years. Minimal residual disease was found in all three samples. Northern blot analysis demonstrated that two fusion transcripts of 7 and 10 kb were expressed in the t(8;21)-positive AML and that the ETO gene is not normally expressed in the hematopoietic system. Expression of a normal 5.5-kb ETO mRNA was found in the lung. From these results we concluded that expression of the ETO gene in t(8;21)-positive AML was activated as a result of the translocation.

Base Sequence↗
PubMed1997

Effect of aging on human postural control during cognitive tasks.

The purpose of this study was to investigate the effect of aging on human postural control during cognitive tasks. Forty-eight subjects between the ages of 20 to 60 years underwent a series of balance tests that placed increasingly more demand on sensorimotor and cognitive mechanisms. Balance tests were based on a dynamic posturography device called EquiTest. The standard clinical protocol consisted of assessing the subject's stability in six different sensory conditions as the inputs from the proprioceptive and visual systems were altered in a systematic manner. The subjects were also tested with the head extended backwards. This represents an additional sensory condition in which the input from the vestibular system is modified. In order to investigate the role of cognitive function on the postural control mechanisms, the balance tests were performed either with or without an attention-demanding task. The test sequence was randomized to account for simple order effects. The relative contribution and interaction of sensory modification, cognitive tasking, and age were assessed. The results showed that head extension significantly increased postural sway in sensory conditions in which the proprioceptive input was altered. The effects of cognitive tasking and age group assignment were only approaching significance.

Adult↗
PubMed1998

Application of the restriction site mutation technique to N-methyl-N-nitrosourea-induced mutations in the rat.

The restriction site mutation (RSM) assay was developed in this laboratory for the detection of point mutations that occur within restriction endonuclease recognition sequences in the genomic DNA of the rat. Mutations were detected and identified in a number of tissues from N-methyl-N-nitrosourea (MNU)-treated rats. Resistant restriction enzyme products were detected in 5 of the 13 restriction endonuclease recognition sequences tested (NcoI, BslI, CfoI, DdeI, and HindIII). These mutations were detected in the p53 tumor suppressor gene and the H-ras protooncogene. No resistant RSM products were detected in any of the samples taken from untreated animals. The MNU-induced mutations were identified as G to A and A to G transitions. Our results describe the first successful application of the RSM assay in detecting induced mutations in the rat and highlight the usefulness of the RSM assay in the analysis of mutagen-induced base changes without the requirement for selection of a mutant phenotype. Given the increasing use of the rat as an animal model in genotoxicity studies, the development of such tests is essential for future genotoxicity investigations.

Animals↗
PubMed2026

Nucleic acid amplification testing and genome sequencing for WHO priority viruses in Africa: a scoping review.

Emerging viruses continue to pose serious public health threats across Africa, with recurrent outbreaks exposing gaps in diagnostics and surveillance systems. Nucleic acid amplification tests (NAATs) and genome sequencing are increasingly important for diagnostics and outbreak responses; however, their routine implementation is fragmented. This scoping review examines NAATs and genome sequencing technologies for viral detection and surveillance in Africa from 2019 to 2024, mapped to the 2024 updated WHO R&D Blueprint for Epidemics pathogen priority list. We identified 117 studies from 34 African countries reporting applications across 20 virus families, including ten designated as priorities by WHO. PCR-based assays were the most frequently reported NAATs. Illumina platforms predominated sequencing, and Oxford Nanopore Technologies were commonly used in outbreak investigations. Genome sequencing applied to priority viruses was largely reactive. NAAT-capable mobile laboratories were reported in 13 countries. Our findings underscore the need for proactive integration of NAATs into diagnostic and surveillance systems to strengthen decentralised testing, sustain genomic surveillance beyond outbreak periods, and improve early detection and preparedness for viral threats.

Journal Article↗
PubMed1975

Nucleotide sequence of salmon testes and salmon liver cytoplasmic initiator tRNA.

Initiator tRNAs from the cytoplasm of salmon testes and salmon liver have been purified. The nucleotide sequence of these initiator tRNAs has been determined and found identical to that of initiator tRNA from mammalian cytoplasm. The only difference is the extent of modification of the nuceloside located between the dihydrouridine and the anticodon stems. In the salmon tRNAs, this modified nucleoside is predominantly N2N2-dimethyl guanosine, whereas in the mammalian initiator tRNA it is N2-methyl guanosine.

Animals↗
PubMed2000

Assignment of enzyme substrate specificity by principal component analysis of aligned protein sequences: an experimental test using DNA glycosylase homologs.

We have studied the relationship between amino acid sequence and substrate specificity in a DNA glycosylase family by characterizing experimentally the specificity of four new members of the family. We show that principal component analysis (PCA) of the sequence family correctly predicts the substrate specificity of one of the novel homologs even though conventional sequence analysis methods fail to group this homolog with other sequences of the same specificity. PCA also suggested, correctly, that another homolog characterized previously differs in its specificity from those sequences with which it clusters by conventional criteria. These results suggest that principal component analysis of sequence families can be a useful tool in annotating genome sequences when there is ambiguity concerning which subfamily a new homolog belongs to. Published 2000 Wiley-Liss, Inc.

Amino Acid Sequence↗