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At least 145 records · Page 8Linked to original sources
PubMed1976

Genetic differences in ethanol drinking of the rat following injection of 6-OHDA, 5,6-DHT or 5,7-DHT into the cerebral ventricles.

The preference characteristics for ethanol of four different strains of rats were determined in a two-choice situation by offering water and ethanol in a concentration which was increased from 3 to 30% over a 12-day test sequence. Using stereotaxic procedures, 50 mug 5,6-dihydroxytryptamine (5,6-DHT), 200 mug 6-hydroxydopamine (6-OHDA) or 100 mug 5,7-dihydroxytryptamine (5,7-DHT) were then injected acutely into the lateral cerebral ventricle in a 20 mul volume. Rats of the Sprague-Dawley strain increased their ethanol preference following the lesioning of the serotonergic system by 5,6-DHT, whereas similar destruction of catecholaminergic neurons by 6-OHDA markedly suppressed ethanol intake; Long-Evans rats displayed a similar trend in ethanol drinking patterns. However, animals of the Holtzman strain manifested the increased drinking after 5,6-DHT, but showed no suppression of drinking following 6-OHDA. The preference of rats of the Wistar strain was unaffected by 5,6-DHT but attenuated by 6-OHDA. 5,7-DHT had little or no effect on ethanol consumption in any of these strains. These findings thus suggest that genetic factors are an important determinant in an animal's response to a drug that affects 5-HT or NE systems in the brain, particularly when ethanol selection is investigated.

5,6-Dihydroxytryptamine↗
PubMed1989

Effects of water, speed, and experimental instrumentation on finishing and polishing porcelain intra-orally.

Previous studies indicated that porcelain can be polished smoother than glazed porcelain with instruments suitable for intra-oral use. This study evaluated several experimental instruments and materials to determine if polishing could be done more efficiently. Scanning electron microscopy was used to evaluate the surface texture produced by different combinations of experimental instruments applied with high and moderate speed, wet and dry, to porcelain disks. No sequence matched the polished standard. However, the optimum surface texture was obtained with diamond instruments (with progressively smaller particle sizes) used at a moderate speed with water, followed by a 30-fluted carbide bur at high speed and dry, then diamond polishing paste on a webbed rubber cup. In all polishing sequences tested, the best results were obtained with each individual instrument when diamond instruments were used at moderate speed wet, and when carbide instruments were used at high speed dry.

Dental Polishing↗
PubMed1988

A comparative study and assessment of Doppler ultrasound spectral estimation techniques. Part II: Methods and results.

Various alternative spectral estimation methods are examined and compared in order to assess their possible application for real-time analysis of Doppler ultrasound arterial signals. Specifically, five general frequency domain models are examined, including the periodogram, the general autoregressive moving average (ARMA) model which has the autoregressive (AR) and moving average (MA) models as special cases, and Capon's maximum likelihood spectral model. A stimulated stationary Doppler signal with a known theoretical spectrum was used as the reference test sequence, and white noise was added to enable various signal/noise conditions to be created. The performance of each method representative of each spectral model was assessed using both qualitative and quantitative schemes that convey information related to the bias and variance of the spectral estimates. Three integrated performance indices were implemented for quantitative analysis. The relative computational complexity for each algorithm was also investigated. Our results indicate that both the AR(Yule-Walker) and ARMA(singular value decomposition) models of orders (8) and (4,4), respectively, show good agreement with the theoretical spectrum, and yield estimates with variances considerably less than the Fast Fourier Transform (FFT). Preliminary results obtained with these methods using a clinical, non-stationary Doppler signal supports these observations.

Algorithms↗
PubMed1991

Human pre-mRNA splicing signals.

A sample of 764 pairs of human pre-mRNA exon-intron and intron-exon boundaries, extracted from the European Molecular Biology Laboratory data bank, is analyzed to provide a species-optimized characterization of donor and acceptor sites, evaluate the information content of the two signals (found to be about 8 and 9 bits respectively) and check the independent-base approximation (which holds well) and the "GT-AG" rule (to which, a few well-documented exceptions are found). No correlation is detected between the strength ("discrimination energy") of an actual donor-site signal and that of its corresponding acceptor-site counterpart, nor between that of either signal, or the cumulative strength of both, and the length of the intervening intron. The discrimination-energy distributions of the two signals are determined. Because of the large sample size and its single-species origin, the two distributions can be presumed to be representative of their underlying genomic counterparts. The size distribution of the introns shows a lower cut-off of 70 nucleotides (in essential agreement with published experimental results), and apparently no periodicities. A smaller sample of mammalian branch sites, taken from the literature, is similarly analyzed to attempt a characterization of this rather elusive signal, and provides some indication that at least part of the "long pyrimidine stretch", usually considered an integral constituent of the 3' splice signal, may be just as strongly associated with the branch site, in agreement with recent experimental observations. The usefulness of these characterizations for splice-junction searches is assessed on a test sequence.

Animals↗
PubMed1991

Effects of preceding context on the voice-onset-time category boundary.

The category boundary on a voice-onset-time (VOT) continuum ranging from bin to pin shifts when the stimuli are preceded by different carrier phrases. By using a variety of precursor phrases, by varying the temporal interval between precursor and test word, and by selectively eliminating either voicing information or spectral structure from the precursors, the present experiments show that the context effect is caused by the presence or absence of voicing in the precursor's final segment. The effect decreases with temporal separation but persists over several seconds. In addition, the "baseline" VOT boundary for isolated test words interspersed in a test sequence shifts depending on what precursor stimuli occur in the same sequence. The perception of VOT thus seems to be sensitive to both close and distant manifestations of laryngeal activity, always in an assimilative fashion, which suggests an integrative perceptual mechanism with a long time constant.

Adult↗
PubMed1986

Effect of clonidine on plasma cortisol concentrations.

There is a debate whether the fall in plasma cortisol concentrations after the early morning dosing of clonidine represents drug effect or normal diurnal variation. We compared the cortisol patterns of children after a 7:30 AM oral dose of clonidine (0.075 or 0.150 mg/m2) with the cortisol concentrations that resulted from diurnal variation. Some subjects had the diurnal study on day 1 and the clonidine study on day 2, whereas for others the testing sequence was reversed. Our results indicate that clonidine, in either dose, does not cause a fall in plasma cortisol levels greater than that with normal diurnal variation.

Administration, Oral↗
PubMed1985

Early sensory-perceptual changes in Huntington's disease.

Forty-four patients at risk for Huntington's disease and seventeen diagnosed as having the disease were studied longitudinally over a nine-year period to assess the evolution of cognitive impairment. Results showed that there were measurable changes in sensory-perceptual functions well in advance of the emergence of the movement disorder. Discrimination between patients with Huntington's disease and those at risk for the disease based on tests of sensory-perceptual functioning resulted in a correct classification rate of 95.1%. Subjects who had changed from being at risk to having the disease nearly all had discriminant scores from their first test sequence lying in either the disease range or the pre-symptomatic disease range. The present organic model of Huntington's disease is discussed in light of these findings and implications of the mathematical model underlying prediction are discussed.

Adolescent↗
PubMed1978

Renal plasma flow and cardiac output during hydralazine and propranolol treatment in essential hypertension.

Eleven patients with essential hypertension were given hydralazine (25 mg b.i.d.) for 2 weeks, hydralazine and propranolol (80 mg b.i.d.) for the next 2 weeks, and propranolol alone for the last 2 weeks. The changes in the renal and systemic circulation elicited by the drugs were studied before start of medication and bi-weekly during the treatment, using non-invasive radioisotope techniques. Hydralazine alone did not alter mean arterial blood pressure (MAP), heart rate (HR), cardiac index (CI), effective renal plasma flow (ERPF), peripheral renin activity (PRA) and plasma aldosterone (Aldo) but when propranolol was added MAP fell 15.2%, HR 22.5% and CI 18.4%, while ERPF was unchanged. When hydralazine was withdrawn and propranolol was given alone, ERPF decreased 13.2%. Plasma aldosterone was unchanged, whereas PRA decreased during propranolol treatment. The reduction in ERPF elicited by propranolol, was highly significant (P less than 0.01). From the test sequence it appears that dihydralazine prevents this effect of propranolol on kidney function. These findings might have a direct bearing on the choice of antihypertensive treatment.

Adult↗
PubMed1988

Activity of the adenosine deaminase promoter in transgenic mice.

The promoter of the human gene for adenosine deaminase (ADA) is extremely G/C-rich, contains several G/C-box motifs (GGGCGGG) and lacks any apparent TATA or CAAT boxes. These features are commonly found in promoters of genes that lack a strong tissue specificity, and are referred to as "housekeeping genes". Like other housekeeping genes, the ADA gene is expressed in all tissues. However, there is a considerable variation in the levels of expression of the ADA protein in different tissues. In order to study the activity of the ADA promoter, transgenic mice were generated that harbor a chimeric gene composed of the ADA promoter linked to a reporter gene encoding the bacterial enzyme Chloramphenicol Acetyl Transferase (CAT). These mice reproducibly showed CAT expression in all tissues examined, including the hemopoietic organs (spleen, thymus and bone marrow). However, examination of the actual cell types expressing the CAT gene revealed the ADA promoter to be inactive in the hemopoietic cells. This was substantiated by a transplantation experiment in which bone marrow from ADA-CAT transgenic mice was used to reconstitute the hemopoietic compartment of lethally irradiated mice. The engrafted recipients revealed strongly reduced CAT activity in their hemopoietic organs. The lack of expression in hemopoietic cells was further shown to be correlated with a hypermethylated state of the transgene. Combined, our data suggest that the ADA promoter sequences tested can direct expression in a wide variety of tissues as expected for a regular housekeeping gene promoter. However, the activity of the ADA promoter fragment did not reflect the tissue-specific variations in expression levels of the endogenous ADA gene. Additionally, regulatory elements are needed for expression in the hemopoietic cells.

Adenosine Deaminase↗
PubMed1988

Comparison of the reliability of the Orthoranger and the standard goniometer for assessing active lower extremity range of motion.

The purpose of this study were to determine 1) the reliability of the Orthoranger for assessing active lower extremity joint range of motion, 2) specific methods for applying the Orthoranger, and 3) whether a correlation exists between the measurements obtained with the Orthoranger and those obtained with a standard goniometer. Ten men and 10 women, mean ages 28.3 +/- 5.1 and 30.0 +/- 10.1 years, respectively, participated in the study. Random selection was used to determine testing sequences. The Orthoranger and the goniometer were used to measure each joint three times during the five sessions. Results indicated that both instruments were reliable for assessing active lower extremity joint ROM. The goniometer showed greater intraclass correlations and confidence levels for all movements except hip lateral rotation, which demonstrated a higher intraclass correlation for the Orthoranger. In addition, all motions except hip adduction and knee extension demonstrated a positive relationship between instruments. Compared with a manual goniometer, the added costs for purchase and use of the Orthoranger appear to be unnecessary until such time that factors enhancing its inherent reliability are identified.

Adult↗
PubMed1987

Chemotherapy of advanced colorectal cancer. A randomized trial of sequential methotrexate and 5-fluorouracil.

Fifty-five patients with advanced colorectal cancer were entered into a randomized controlled clinical trial to evaluate order of administration and sequential methotrexate (MTX) and 5-fluorouracil (5-FU) therapy. Patients were randomized to receive either MTX, 250 mg/m2, followed 1 h later by 5-FU, 600 mg/m2, or 5-FU followed 1 h later by MTX in the same doses. Fifty-four patients were evaluable for response, of whom 15 (28%) achieved objective partial tumor response. There were no significant differences between the two sequences in response rate, time to treatment failure, or survival duration. The results of this study do not indicate a clinically significant difference between the two sequences tested, in which MTX preceded or followed 5-FU by 1 h. Determination of the value of these drugs given sequentially at longer intervals must await appropriate controlled trials.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2025

KpSC-ID: a multiplex real-time PCR assay for the simultaneous detection of the Klebsiella pneumoniae species complex and specific identification of Klebsiella pneumoniae, Klebsiella quasipneumoniae and Klebsiella variicola.

The Klebsiella pneumoniae species complex (KpSC) comprises five closely related bacterial species, namely Klebsiella pneumoniae, Klebsiella quasipneumoniae, Klebsiella variicola, Klebsiella quasivariicola and Klebsiella africana. The KpSC is ubiquitous in the environment and is also an important human pathogen, particularly associated with healthcare-associated infections. The accurate detection and differentiation of the KpSC is challenging owing to the close phenotypic and genotypic identity (93-95% average nucleotide identity) shared between these members. Current diagnostic assays either fail to detect and identify all KpSC members or misidentify some KpSC members as K. pneumoniae sensu stricto. It is currently estimated that ~20% of human infections are caused by members of the KpSC other than K. pneumoniae. This leads to underreporting of some KpSC members in both clinical and environmental settings, which impacts our understanding of the importance of each species. Furthermore, it limits our understanding of the global and local epidemiological impact of some members of the KpSC. In this study, a rapid multiplex real-time PCR assay (KpSC-ID) was designed and developed to detect all KpSC members while simultaneously identifying the predominant human pathogens K. pneumoniae, K. quasipneumoniae and K. variicola. Assay performance was verified in silico using a panel of over 1,000 publicly available genome sequences and experimentally validated using a panel of genomic DNA extracted from 54 Enterobacteriaceae. The assay displayed excellent specificity against over 1,000 genome sequences tested in silico. During in vitro validation, the pan-KpSC assay detected each (29/29) KpSC species and strains tested. For the species-specific assays, 100% specificity was demonstrated in the K. pneumoniae, K. quasipneumoniae and K. variicola assays, respectively. Sensitivity of 10 genomic equivalents was demonstrated for each assay. Ultimately, the diagnostic assay developed in this study can improve our understanding of the significance of KpSC members, which is important when investigating their routes of transmission and epidemiology.

Klebsiella↗
PubMed1981

Limitations of pacemaker system analyzers for the evaluation of implantable pulse generators.

A variety of commercial pacemaker system analyzers have been used to evaluate the electrical performance of pulse generators prior to implant or at the time of reoperation for pacemaker malfunction. We evaluated the ability of seven commercially available pacemaker system analyzers to provide the data required to determine if a given pulse generator was operating according to its manufacturer's specifications. While all pacemaker system analyzers provided accurate data for rate and pulse duration, values displayed for amplitude and sensitivity were inconsistent due to the methods each pacemaker system analyzer employed to measure these parameters. Overall, 22% of representative test sequences yielded data which would have resulted in the inappropriate rejection of the subject pulse generators for implantation. These observations suggest that pacemaker system analyzers are not suitable for evaluating all pulse generators. Moreover, physicians must be aware of these deficiencies in order to avoid the pitfalls of relying exclusively on pacemaker system analyzer data when troubleshooting pacemaker malfunction.

Cardiology↗
PubMed1980

Anticipation and fusimotor activity in preparation for a voluntary contraction.

1. Multi-unit and single-unit recordings were made of muscle spindle afferent activity from the pretibial muscles of human subjects who were initially relaxed. The muscles were subjected to a stretching perturbation of 1 s duration, occurring irregularly, on average once every 5 s. In test sequences, an auditory or visual warning was provided 1 . 06 s before some of the perturbations. Subjects were required to oppose every perturbation by contracting the receptor-bearing muscle as rapidly as possible. 2. Following the warning all subjects sometimes tensed the receptor-bearing muscle unintentionally in preparation for the perturbation. In these contractions, the discharge of a spindle ending accelerated only if the contraction strength exceeded the ending's threshold for activation, established in control voluntary contractions performed under isometric conditions. 3. When the receptor-bearing muscle did not contract in the interval between warning and perturbation, there was no detectable change in the multi-unit recordings of spindle activity or in recordings from twelve of thirteen single spindle afferents. The thirteenth spindle afferent discharged prior to the perturbation in the absence of detectable e.m.g. in response to (only) three of twenty-three warning stimuli. However, this ending had been so responsive during isometric voluntary contractions that a contraction level at which it did not respond could not be established, and it is suggested that the findings with this ending resulted from its low threshold rather than from selective activation of the fusimotor system. 4. When subjects were warned of the perturbations, the dynamic response of spindle endings to the perturbations was not increased in size or altered in latency. 5. The motor response to perturbations without warning generally contained only long-latency (volitional) e.m.g. activity occurring 107--200 ms after the onset of the perturbation. When a warning was given, short-latency (reflex) e.m.g. activity was also recorded, beginning 46--76 ms after the onset of the perturbation. 6. It is concluded that anticipation of the need to contract a muscle does not result in selective activation of fusimotor neurones in preparation for the contraction. The change in stretch reflex gain that occurs as a result of 'anticipation' occurs through a central process which does not involve the fusimotor system.

Acoustic Stimulation↗
PubMed1973

Directionality of rewarding impulses within the medial forebrain bundle self-stimulation system of the rat.

Self-stimulation performance of rats was tested with conditioning pulses to the anterior preoptic area of the medial forebrain bundle followed at various intervals by test pulses to the contralateral posterior hypothalamic area of this bundle. Alternatively, conditioning pulses were delivered through the posterior electrode and test pulses were sent through the anterior electrode. The animals' performance in these two test sequences was indicative of (i) synaptic facilitation and (ii) a posterior convergence site of "self-stimulation impulses" in the medial forebrain bundle.

Animals↗
PubMed1986

Multiple protein-binding sites in the 5'-flanking region regulate c-fos expression.

We tested sequences flanking the mouse c-fos gene for the ability to form specific DNA-protein complexes with factors present in crude nuclear extracts prepared from mammalian cells. Three such complexes were detected. One complex formed in a region necessary for the induction of c-fos expression by serum growth factors. Two additional complexes formed at sequences that contribute to basal c-fos promoter activity in vivo. These complexes represent three novel sequence-specific DNA-binding activities which appear to participate in the regulation of c-fos transcription.

Animals↗
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↗