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At least 163 records · Page 9Linked to original sources
PubMed1975

Viewbox seminar: a new method for teaching roentgenology.

The American College of Radiology designed a "crash" program to train radiologists to interpret and classify the radiological manifestations of coal workers' pneumoconiosis. This Viewbox Seminar combines two pedagogic techniques, group viewbox study, and a test-teach-test sequence of instruction that compels active participation in the learning process. Weekend scheduling and good location and transportation connections facilitate attendance, making this an excellent way to teach large groups of radiologists certain subtleties of radiology in a short time.

Audiovisual Aids↗
PubMed1990

Dynamic and static conditioning pressures evoke equivalent rapid resetting in rat aortic baroreceptors.

A recent study suggested that exposure of carotid sinus baroreceptors to pulsatile pressures for a period of minutes can decrease the static threshold pressure at which they begin to discharge; that is, the exposure can sensitize baroreceptors. Another study found that the rapid resetting of carotid sinus baroreceptors to elevated conditioning pressures was reduced or eliminated by pulsatile conditioning. In the present study, we tested the responses of aortic baroreceptors in an in vitro preparation to a range of static and dynamic conditioning pressures lasting 15 minutes. Slow test ramps of increasing pressure were used to assess static discharge properties (threshold and gain). To be accepted for analysis (n = 12), each baroreceptor had to successfully complete static and dynamic test sequences for at least three different conditioning mean arterial pressure levels. We measured aortic diameter simultaneously with pressure and baroreceptor discharge. Generally, we found no significant difference between the static pressure threshold measured before and after dynamic conditioning. The static pressure threshold was linearly related to the mean level of the conditioning pressure, and no differences in the slopes of these relations (a measure of the ability of a baroreceptor to rapidly reset) were found between static and dynamic conditioning. After dynamic conditioning, discharge rates returned to near control levels in all cases within a few seconds of the return to static conditioning. Two baroreceptors exposed to the vasodilator nitroprusside throughout the experiment showed similar results. Diameter measurements indicated no role of vessel diameter changes during dynamic or static conditioning. In conclusion, we found no evidence of a long-lasting sensitization of aortic baroreceptors by dynamic pressure inputs.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMedDate not supplied

Decision tables and logic in decision analysis.

Unmanageable bushy decision trees result when a decision analysis involves several investigations. They can be simplified for riskless tests by deriving the maximum expected utility decision table for the problem as an intermediate step. This table can be logically summarized as Boolean expressions involving the tests. A minimum-cost testing sequence may then be found by manipulation of the Boolean formulas. The relationship between the resulting decision criteria and the receiver operating characteristic is shown.

Decision Theory↗
PubMed1978

Anxiety levels of beginning Scuba students.

Anxiety levels of 29 beginning Scuba students in college classes were determined at rest and prior to standardized Scuba tests. Resting trait and state anxiety levels were significantly lower than norms. Only moderate increases in state anxiety were noticed throughout the testing sequence.

Anxiety↗
PubMed1983

Sensory storage of fragmentary displays.

A partial-report version of the Eriksen-Collins paradigm was devised to test iconic storage. The test lay in presenting arrays of 12 partial letters, one of which was randomly chosen for completion. Additional conditions checked whether the completed letters were legible and to what extent the completion fragments were guessable. Test sequences included dark or light inter-stimulus intervals and 4 different delay times, which had no significant effects. Analysis showed that subjects were no better able to report a synthesis of the first and second fragments than to guess the letters from separate fragments. A second experiment demonstrated some integration of successive single-letter presentations, although subjects apparently do not have iconic access to full arrays of letter fragments.

Attention↗
PubMed1975

The constipating effect of diphenoxylate (Retardinr) in ulcerative colitis. A double-blind controlled trial.

A double-blind study of 20 patients with ulcerative colitis during treatment with diphenoxylate 5 mg three times daily and placebo is reported. There were two treatment periods of 14 days each, with cross-over technique and randomized sequence. Test variable for constipating effect was the mean number of defaecations per day. The criterion for inclusion of patients was the presence of 4 or more daily bowel movements; 2 patients did not complete the investigation. Significant difference (p less than 0.01) in constipating effect between diphenoxylase and placebo was demonstrated both during a period of 12 days and a period of 6 days (Tables II and III). The average number of bowel movements were reduced by 0.7 and 1.3 per day respectively. Side-effects during treatment with diphenoxylate were seen in 53% (Table III) with significant difference against placebo (p less than 0.05). On the basis of the small absolute reduction of defaecation frequency side-effects, it is concluded that diphenoxylate has no place in the routine treatment of ulcerative colitis.

Adolescent↗
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↗
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↗
PubMed1991

Conflicting phylogenetic hypotheses for the parasitic platyhelminths tested by partial sequencing of 18S ribosomal RNA.

Partial sequencing of the 18S ribosomal RNA in nine parasitic and one free-living species of platyhelminth was used to test hypotheses on the phylogenetic relationships among the major groups. The eucestodes, amphilinideans, gyrocotylideans and monopisthocotylideans appeared as a monophyletic assemblage in a cladistic analysis of the data, with a very close association between the gyrocotylideans and monopisthocotylideans. The polyopisthocotylidean monogeneans were paraphyletic to the monopisthocotylideans. The digeneans appeared to be a sister group to the monogeneans and eucestodes, while the temnocephalidean was closely related to the free-living polyclad.

Animals↗
PubMed1987

Processing of Escherichia coli 16S rRNA with bacteriophage lambda leader sequences.

To test whether any specific 5' precursor sequences are required for the processing of pre-16S rRNA, constructs were studied in which large parts of the 5' leader sequence were replaced by the coliphage lambda pL promoter and adjacent sequences. Unexpectedly, few full-length transcripts of the rRNA were detected after the pL promoter was induced, implying that either transcription was poor or most of the rRNA chains with lambda leader sequences were unstable. Nevertheless, sufficient transcription occurred to permit the detection of processing by S1 nuclease analysis. RNA transcripts in which 2/3 of the normal rRNA leader was deleted (from the promoter up to the normal RNase III cleavage site) were processed to form the normal 5' terminus. Thus, most of the double-stranded stem that forms from sequences bracketing wild-type 16S pre-rRNA is apparently not required for proper processing; the expression of such modified transcripts, however, must be increased before the efficiency of processing of the 16S rRNA formed can be assessed.

Bacteriophage lambda↗
PubMed1987

Sequence selectivity, a test of the nature of the covalent adduct formed between benzo[a]pyrene and DNA.

A theoretical study is presented of the energetic and structural properties of covalent adducts of benzo[a]pyrene and a DNA fragment. Energy optimisation is performed with the use of minimiser with constraints and an advanced semiempirical energy formula. Three types of adducts are studied: an external complex with the benzopyrene located in the DNA minor groove and two types of intercalative complexes with the carcinogen situated on the 3' side and 5' side of the covalently bound guanine. For each of the adducts the effects of DNA base sequence are examined. It is shown that the results for the intercalative complex with the carcinogen situated on the 5' side of the modified guanine correlate with the experimentally determined sequence preference.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗