A bedside clinical prediction rule for detecting moderate or severe aortic stenosis

OBJECTIVE

To evaluate a bedside clinical prediction rule for detecting moderate or severe aortic stenosis.

DESIGN

Cross-sectional study with independent comparison to a diagnostic reference standard, doppler echocardiography.

SETTING

Urban university hospital.

PARTICIPANTS

Consecutive hospital inpatients (n = 124) who had been referred for echocardiography.

MEASUREMENTS AND MAIN RESULTS

Participants were examined by a third-year general internal medicine resident and a staff general internist. We hypothesized in advance that absence of a murmur over the right clavicle would rule out aortic stenosis, while the presence of three or four associated findings (slow carotid artery upstroke, reduced carotid artery volume, maximal murmur intensity at the second right intercostal space, and reduced intensity of the second heart sound) would rule in aortic stenosis. Study physicians were unaware of echocardiographic findings. The outcome was echocardiographic moderate or severe aortic stenosis, defined as a valve area of 1.2 cm2 or less, or a peak instantaneous gradient of 25 mm Hg or greater. Absence of a murmur over the right clavicle ruled out aortic stenosis (likelihood ratio [LR] 0.10; 95% confidence interval [CI] 0.01, 0.44). The presence of three or four associated findings ruled in aortic stenosis (LR 40; 95% CI 6.6, 240). If a murmur was present over the right clavicle, but no more than two associated findings were present, then the examination was indeterminate (LR 1.8; 95% CI 0.93, 2.9).

CONCLUSION

A clinical prediction rule, using simple bedside maneuvers, accurately ruled in and ruled out aortic stenosis.

Liposome-anchored vascular endothelial growth factor aptamers

Nuclease-resistant aptamers identified from randomized nucleic acid libraries represent a novel class of drug candidates. Aptamers are synthesized chemically and therefore can be readily modified with functional groups that modulate their properties. We report here on the preparation, initial characterization, and functional properties of a nuclease-resistant vascular endothelial growth factor (VEGF) aptamer anchored in liposome bilayers through a lipid group on the aptamer. While the high-affinity binding to VEGF is maintained, the plasma residence time of the liposome-anchored aptamer is considerably improved compared with that of the free aptamer. The lipid group attachment and/or liposome anchoring leads to a dramatic improvement in inhibitory activity of the aptamer toward VEGF-induced endothelial cell proliferation in vitro and vascular permeability increase and angiogenesis in vivo.

Kinetic analyses of Biolog community profiles to detect changes in inoculum density and species diversity of river bacterial communities

The kinetics of response curves from Biolog community profiles for heterotrophic bacteria from a river in Nova Scotia, Canada have been analyzed to generate lag, slope, and asymptote parameters. The river water samples were treated with one of three supplements of Escherichia coli (in situ levels, 10(3) CFU/mL, or 10(6) CFU/mL) and one of five concentrations of chlorine (0, 1, 3, 5, or 7 ppm) to satisfy a full factorial design. The chlorine treatments decreased the inoculum density by up to 2 log values and decreased the species evenness. The E. coli supplements increased the inoculum density and decreased the species richness. Examination of the asymptotes did not reveal any significant effects owing to E. coli, but differences owing to the chlorine were detected. Analyses of the slopes showed a similar insignificance of the effects of E. coli and a lack of treatment effect owing to chlorine. The lag analyses also showed no significant E. coli effects, but showed a significant effect owing to chlorine. The discrepancy produced with the slope analysis (i.e., no chlorine effect) may represent an anomaly of the Biolog community approach. The use of lag phase was impaired because of the problem of infinite lags from wells that had no response, but a principle component analysis with a reduced set of substrates did suggest some influence of E. coli on the community profile. An examination of the substrates metabolized by the river water compared with pure E. coli revealed that the Biolog profiles of the river communities were not a simple summation of the component parts. In light of the lack of uniformity between these analyses, where the outcome depended on which parameter was used, caution is advised in interpreting Biolog community profiles on the basis of only one parameter.

Pindolol augmentation of sertraline in resistant depression and its effect on sleep

A case is reported of a 34-year-old lady with a 2-year history of resistant depression who responded to pindolol augmentation of sertraline. It also illustrates the use of sleep electroencephalogram measures as a way of assessing changes in brain 5-hydroxytryptamine function.

Amplitude modulation following response in children as a clinical audiometric tool

The current study was designed to investigate the clinical application of amplitude modulation following response (AMFR) in cochlear implant candidates. A new digital signal processor (DSP)-assisted PC-based hardware and software was developed to perform both simultaneous generation of amplitude-modulated stimuli and the recording, and synchronized signal processing of the electrode signals. Our first results show that AMFR can be recorded in adults as well as in children without any contamination by response-like stimulus artifacts. Very high sound pressure levels can be applied, allowing frequency-specific assessment of residual hearing. Response threshold detection, using spectral analysis, proved to be superior compared to visual evaluation of average time waveforms.

Colonic structural and ion transport abnormalities in suckling rabbits infected with Escherichia coli K12

BACKGROUND

Escherichia coli K12 is a laboratory strain considered nonpathogenic. The purpose of this study was to examine the effect of E. coli K12 infection on colonic structure and function.

METHODS

Suckling rabbits were infected at 10 days of age with 6 x 10(9) CFU E. coli by intragastric inoculation and were examined 4 to 5 days later. Segments of ileum and proximal and distal colon were removed for light and electron microscopy, and NaCl transport was examined in vitro under short-circuited conditions in Ussing chambers.

RESULTS

Infection did not cause weight loss or diarrhea. Colonic mucosa was inflamed with infiltration by polymorphonuclear neutrophils mainly in the lamina propria. The proximal and distal colon exhibited reduced Na+ absorption. The proximal colon also showed increased Cl- secretion; the ileum was unaffected.

CONCLUSIONS

Infection with E. coli K12 disrupts the epithelium and alters ion transport in the colon, probably as a result of mucosal inflammation. The changes indicate that nonpathogenic E. coli have the potential to cause intestinal disease.

Isolation and characterization of 2'-fluoro-, 2'-amino-, and 2'-fluoro-/amino-modified RNA ligands to human IFN-gamma that inhibit receptor binding

CD4+ Th cells produce cytokines that play a pivotal role in the induction and regulation of cell-mediated and humoral immunity. Th1 cells, characterized by their secretion of IFN-gamma, induce macrophage cytotoxicity, delayed hypersensitivity, and enhanced cellular immunity. Secretion of IFN-gamma may even suppress Th2-enhanced humoral immunity. A counterproductive Th1 response and concomitant secretion of IFN-gamma may result in inflammatory and autoimmune diseases. IFN-gamma regulation of T cell function has potential for therapeutic intervention. To isolate high affinity oligonucleotide inhibitors of IFN-gamma activity, combinatorial libraries of RNA molecules modified at the 2' position of pyrimidine nucleotides with fluoro (F), amino (NH2), or a mixture of F and NH2 (2'-F/NH2) were screened using the SELEX (systematic evolution of ligands by exponential enrichment) combinatorial chemistry process. Each modified library of RNA molecules provides an expanded repertoire of molecules with increased structural diversity and unique binding properties. This added diversity increases the possibility of isolating molecules with the desired functional properties. These RNAs modified at the 2' position have also been shown to be nuclease resistant. High affinity ligands to human IFN-gamma from each modified library were isolated and characterized. The K(d)s of these ligands were determined and their secondary structures were predicted. The specificity of these ligands for IFN-gamma binding was confirmed, and their ability to inhibit binding of IFN-gamma to its receptor on A549 human lung carcinoma cells was determined. A 2'-NH2-modified ligand (2'-NH2-30) is described that binds IFN-gamma with high affinity and inhibits IFN-gamma-induced expression of MHC class I and ICAM-1 by human myeloid leukemia cells.

Isolation and characterization of 2'-fluoro-, 2'-amino-, and 2'-fluoro-/amino-modified RNA ligands to human IFN-gamma that inhibit receptor binding

CD4+ Th cells produce cytokines that play a pivotal role in the induction and regulation of cell-mediated and humoral immunity. Th1 cells, characterized by their secretion of IFN-gamma, induce macrophage cytotoxicity, delayed hypersensitivity, and enhanced cellular immunity. Secretion of IFN-gamma may even suppress Th2-enhanced humoral immunity. A counterproductive Th1 response and concomitant secretion of IFN-gamma may result in inflammatory and autoimmune diseases. IFN-gamma regulation of T cell function has potential for therapeutic intervention. To isolate high affinity oligonucleotide inhibitors of IFN-gamma activity, combinatorial libraries of RNA molecules modified at the 2' position of pyrimidine nucleotides with fluoro (F), amino (NH2), or a mixture of F and NH2 (2'-F/NH2) were screened using the SELEX (systematic evolution of ligands by exponential enrichment) combinatorial chemistry process. Each modified library of RNA molecules provides an expanded repertoire of molecules with increased structural diversity and unique binding properties. This added diversity increases the possibility of isolating molecules with the desired functional properties. These RNAs modified at the 2' position have also been shown to be nuclease resistant. High affinity ligands to human IFN-gamma from each modified library were isolated and characterized. The K(d)s of these ligands were determined and their secondary structures were predicted. The specificity of these ligands for IFN-gamma binding was confirmed, and their ability to inhibit binding of IFN-gamma to its receptor on A549 human lung carcinoma cells was determined. A 2'-NH2-modified ligand (2'-NH2-30) is described that binds IFN-gamma with high affinity and inhibits IFN-gamma-induced expression of MHC class I and ICAM-1 by human myeloid leukemia cells.

Does this patient have an abnormal systolic murmur?

Our objective was to review the available evidence of the precision and accuracy of the clinical examination for abnormal systolic murmurs. We conducted a MEDLINE search, manually reviewed all reference lists, and contacted authors of published studies. Each study was independently reviewed by 2 observers and graded for methodologic quality. We found that most studies were conducted using cardiologist examiners. In the clinical setting, the reliability of detecting systolic murmurs was fair (kappa, 0.30-0.48). The most useful findings for ruling in aortic stenosis are a slow rate of rise of the carotid pulse (positive likelihood ratio, 2.8-130), mid to late peak intensity of the murmur (positive likelihood ratio, 8.0-101), and decreased intensity of the second heart sound (positive likelihood ratio, 3.1-50). The most useful finding for ruling out aortic stenosis is the absence of murmur radiation to the right carotid artery (negative likelihood ratio, 0.05-0.10). Smaller, lower-quality studies indicate that cardiologists can accurately rule in and rule out mitral regurgitation, tricuspid regurgitation, hypertrophic cardiomyopathy, and echocardiographic mitral valve prolapse. We conclude that the clinical examination by cardiologists is accurate for detecting various causes of abnormal systolic murmurs. Studies of the clinical examination by noncardiologists are needed.

Premedication in the United States: a status report

We undertook a mailing survey study to assess the current practice of sedative premedication in anesthesia. A total of 5396 questionnaires were mailed to randomly selected physician members of the American Society of Anesthesiologists. Forty-six percent (n = 2421) of those sampled returned the questionnaire after two mailings. The reported rate of sedative premedication in the United States varied widely among age groups and geographical locations. Premedicant sedative drugs were least often used with children younger than age 3 years and most often used with adults less than 65 years of age (25% vs 75%, P = 0.001). Midazolam was the most frequently used premedicant both in adults and children (> 75%). When analyzed based on geographical locations, use of sedative premedicants among adults was least frequent in the Northeast region and most frequent in the Southeast region (50% vs 90%, P = 0.001). When the frequency of premedication was examined against health maintenance organization (HMO) penetration (i.e., HMO enrollment by total population) in the various geographical regions, correlation coefficients (r) ranged from -0.96 to -0.54. Multivariable analysis revealed that HMO penetration is an independent predictor for the use of premedication in adults and children. The marked variation among geographical areas in premedicant usage patterns underscores the lack of consensus among anesthesiologists about the need for premedication. The data suggest that HMO participation may affect delivery of this component of anesthetic care.

The generation and subtraction of sensory expectations within cerebellum-like structures

The generation of expectations about sensory input and the subtraction of such expectations from actual input appear to be important features of sensory processing. This paper describes the generation of sensory expectations within cerebellum-like structures of four distinct groups of fishes: Mormyridae; Rajidae; Scorpaenidae; and Apteronotidae. These structures consist of a sheet-like array of principal cells. Apical dendrites of the principal cells extend out into a molecular layer where they are contacted by parallel fibers. The basilar regions of the arrays receive primary afferent input from octavolateral endorgans, i.e., electroreceptors, mechanical lateral line neuromasts, or eighth nerve endorgans. The parallel fibers in the molecular layer convey various types of information, including corollary discharge signals associated with motor commands, sensory information from other modalities such as proprioception, and descending input from higher stages of the sensory modality that is processed by the structure. Associations between the signals conveyed by the parallel fibers and particular patterns of sensory input to the basal layers lead to the generation of a negative image of expected sensory input within the principal cell array. Addition of this negative image to actual sensory input results in the subtraction of expected from actual input, allowing the unexpected or novel input to stand out more clearly. Intracellular recording indicates that the negative image is probably generated by means of anti-Hebbian synaptic plasticity at the parallel fiber to principal cell synapse. The results are remarkably similar in the different fishes and may generalize to cerebellum-like structures in other sensory systems and taxa.

Potent 2'-amino-, and 2'-fluoro-2'-deoxyribonucleotide RNA inhibitors of keratinocyte growth factor

Reiterative in vitro selection-amplification from random oligonucleotide libraries allows the identification of molecules with specific functions such as binding to specific proteins. The therapeutic usefulness of such molecules depends on their high affinity and nuclease resistance. Libraries of RNA molecules containing 2'amino-(2'NH2)- or 2'fluoro-(2'F)-2'-deoxypyrimidines could yield ligands with similar nuclease resistance but not necessarily with similar affinities. This is because the intramolecular helices containing 2'NH2 have lower melting temperatures (Tm) compared with helices containing 2'F, giving them thermodynamically less stable structures and possibly weaker affinities. We tested these ideas by isolating high-affinity ligands to human keratinocyte growth factor from libraries containing modified RNA molecules with either 2'NH2 or 2'F pyrimidines. We demonstrated that 2'F RNA ligands have affinities (Kd approximately 0.3-3 pM) and bioactivities (Ki approximately 34 pM) superior to 2'NH2 ligands (Kd approximately 400 pM and Ki approximately 10 nM). In addition, 2'F ligands have extreme thermo-stabilities (Tm approximately 78 degrees C in low salt, and specificities).

Detection of jun but not fos protein during developmental cell death in sympathetic neurons

A large proportion of neurons die during normal development of the nervous system via an active process known as apoptosis. We counted the total number of neurons and apoptotic neurons in the superior cervical ganglion of the GH Wistar rat strain, which possesses a neurotrophic deficit leading to excessive perinatal cell death, and in its normal counterpart (N) by using the optical disector method to quantify the extent of apoptosis during postnatal development. Total neuron numbers fell between postnatal days 3 and 14 by 10 and 40% in N and GH, respectively. In GH ganglia, 1.5% of neurons were apoptotic at any given time, as determined by the presence of condensed chromatin clumps. Some types of cell death have been associated with expression of the immediate-early genes c-fos and c-jun. Therefore, we used histological and immunocytochemical techniques to characterise individual neurons and to detect the products of these immediate-early genes during developmental cell death. All apoptotic cells were immunopositive for c-jun protein, whereas no c-jun protein was detected in nonapoptotic cells. Conversely, members of the fos family of transcription factors were detected in the nucleus of 60% of nonapoptotic cells but in only a minor proportion of cells undergoing apoptosis. These results indicate that c-jun occurs in neurons that are committed to die. This is the first situation in which the presence of jun protein has been correlated with normal programmed cell death in individual apoptotic neurons.

Digital infarction in a patient with Raynaud's phenomenon associated with treatment with a specific serotonin reuptake inhibitor. A case report

The authors report the worsening of preexisting Raynaud's phenomenon during treatment of depression with a selective serotonin reuptake inhibitor, fluvoxamine.