Showing papers by "Saint Louis University published in 1987"

Effect of aging on left ventricular diastolic filling in normal subjects.

Abstract: To determine the effect of aging on left ventricular filling, mitral valve flow was evaluated with real-time (color flow) and conventional pulsed Doppler echocardiography in 32 subjects, aged 24 to 68 years, who had no evidence of cardiovascular disease. The diameter of mitral valve flow was measured in early and late diastole in the apical 4-chamber view. Transmitral velocities were measured in early and late diastole with pulsed Doppler echocardiography. The early flow diameter was significantly smaller in patients older than 50 than in those aged 20 to 29 years (p less than 0.05), while atrial flow diameter was significantly larger in patients older than 50 than in those aged 20 to 29 years (p less than 0.05). The ratio of early flow diameter to atrial flow diameter was 1.85 +/- 0.33 in patients 20 to 29 years old and 1.17 +/- 0.28 in those older than 50 (p less than 0.001). The ratio of early to atrial diastolic velocities was 1.98 +/- 0.53 in the younger patients and 1.07 +/- 0.41 in those older than 50 years (p less than 0.001). The ratio of early flow diameter to atrial flow diameter decreased significantly with aging, and this decrease had a negative correlation with aging (r = -0.64). Qualitatively, in these normal subjects, early diastolic flow filled the ventricle centrally, while with atrial contraction, flow entered the ventricle toward the posterolateral wall and was associated with flow moving toward the aortic valve along the ventricular septum.(ABSTRACT TRUNCATED AT 250 WORDS)

Thermal stability of proteins in the presence of poly(ethylene glycols).

Abstract: Thermal unfolding of ribonuclease, lysozyme, chymotrypsinogen, and beta-lactoglobulin was studied in the absence or presence of poly(ethylene glycols). The unfolding curves were fitted to a two-state model by a nonlinear least-squares program to obtain values of delta H, delta S, and the melting temperature Tm. A decrease in thermal transition temperature was observed in the presence of poly(ethylene glycol) for all of the protein systems studied. The magnitude of such a decrease depends on the particular protein and the molecular size of poly(ethylene glycol) employed. A linear relation can be established between the magnitude of the decrease in transition temperature and the average hydrophobicity of these proteins; namely, the largest observable decrease is associated with the protein of the highest hydrophobicity. Further analysis of the thermal unfolding data reveals that poly(ethylene glycols) significantly effect the relation between delta H degrees of unfolding and temperature for all the proteins studied. For beta-lactoglobulin, a plot of delta H versus Tm indicates a change in slope from a negative to a positive value, thus implying a change in delta Cp in thermal unfolding caused by the presence of poly(ethylene glycols). Results from solvent-protein interaction studies indicate that at high temperature poly(ethylene glycol) 1000 preferentially interacts with the denatured state of protein but is excluded from the native state at low temperature. These observations are consistent with the fact that poly(ethylene glycols) are hydrophobic in nature and will interact favorably with the hydrophobic side chains exposed upon unfolding; thus, it leads to a lowering of thermal transition temperature.

The effect of crustal structure on strong ground motion attenuation relations in eastern North America

Abstract: Strong ground motion attenuation relations are usually described by smoothly decreasing functions of distance. However, consideration of wave propagation in the crust suggests that attenuation relations should be more complex. Such complexity may be present in strong ground motion data for eastern North American earthquakes, which show amplitudes in the distance range of 60 to 150 km that lie above the trends at smaller and greater distances. Using a wavenumber integration method to compute Green's functions and close-in recordings of several earthquakes as empirical source functions, we have generated synthetic seismograms that are in good agreement with regional and strong-motion recordings of eastern North American earthquakes. From these synthetic seismograms, we have shown that the observed interval of relatively high amplitudes may be attributable to postcritically reflected S waves from the Moho. The presence and location of the interval of relatively high amplitudes is highly dependent on the crustal velocity structure and may therefore be expected to show regional variation. However, for any realistic structure model, there will be a transition in the attenuation relation from an interval at shorter distances (less than about 100 km) that is dominated by direct waves to an interval at greater distances that is dominated by postcritically reflected waves. The synthetic seismograms have response spectral velocities that match those of the recorded data, and their m_(bLg) values are in good agreement with observed values.

The ventral striatopallidothalamic projection: I. The striatopallidal link originating in the striatal parts of the olfactory tubercle.

Abstract: The projections from the striatal part of the olfactory tubercle were examined in rats, both with the aid of experimental silver impregnation methods following superficial laminar heat lesions of the tubercle and by the use of anterograde transport of Phaseolus vulgaris-leucoagglutinin (PHA-L) following injections of the lectin in the dense cell layer of the tubercle. Retrograde transport of fluorescent substances following injections of the tracer in the multiform layer of the tubercle were used to corroborate the results obtained by the anterograde transport and degeneration methods. The main and apparently only significant termination from the striatal cells in the olfactory tubercle is located immediately deep to the dense cell layer in areas that could be identified as part of the ventral pallidum on the basis of either the Nissl method or glutamate decarboxylase immunocytochemistry. Whereas a mediolateral topography is generally maintained by the ventral striatopallidal pathway originating in the dense cell layer, there is a considerable spread of the projection in the rostrocaudal direction. The dense projection field of the olfactory tubercle component of the ventral striatopallidal pathway permeates the ventrolateral part of the ventral pallidum, thereby complementing the termination of the accumbens projection to the more mediodorsal parts of the ventral pallidum.

Emotional symptoms in Prader-Willi syndrome adolescents.

Abstract: Clinical observations and parental reports on the behavior of Prader-Willi syndrome (PWS) patients suggest the development of a wide variety of psychiatric disorders as the PWS child enters adolescence Documentation of these emotional disorders remains unsystematic Here we describe the results of administering the Survey Diagnostic Instrument (SDI) to the parents of 35 PWS adolescents The questionnaire data were supplemented by additional selected demographic and clinical data The SDI is a 134 item questionnaire filled out by one parent It screens for the DSM-III criterion-based diagnostic categories of neurosis (dysphoric, compulsive, anxious), somatization, conduct disorder (antisocial, violent), and hyperactivity The following diagnostic pattern resulted: neurosis, dysphoric, (1 probable); neurosis, compulsive, 3 (6 probable); neurosis, anxious, 4 (and 10 probable); somatization, 0; conduct disorder, violent 0; conduct disorder, antisocial, 0; hyperactivity, 1 (and 1 probable) An odds ratio algorithm is used to uncover possible predisposing factors, and the results are discussed in the context of organic versus psychiatric causes

Self-isolation and insect pollination in the primitive angiosperms: New evaluations of older hypotheses

Abstract: A review of the literature, compiled over the past 40 years suggests new directions for theories discussing the evolution of reproductive isolation and entomophily in angiosperms. Data on breeding systems suggests that the protoangiosperms may have developed gametophytic self-incompatibility. Protogyny is probably ancestral to protandry and herkogamy. Although the proto-flowers were bisexual wide variation in the number of sexual organs within proto-flowers probably led to labile sexuality and early trends towards dicliny. Beetle-pollination in extant relicts appears too specialized to represent an ancestral condition. Rather, the proto-flowers may have been generalist entomophiles incorporating some beetles,Plecoptera, thrips, micropterigid moths and proto-dipterans into their fluctuating spectra of opportunistic pollinators. Bee-pollination is probably polyphyletic in origin evolving repeatedly from angiosperms showing these generalist syndromes. There is still no correlation between primitive bees (especiallyColletidae) and the relictual angiosperms. Pollen that is usually retained within the anthers following dehiscence and the presence of staminal filaments and styles characterizes most of the flowers of those relictual angiosperms pollinated by specialized, modernApoidea.

Pluronic F‐127 gel preparation as an artificial skin in the treatment of third‐degree burns in pigs

Abstract: A blinded study was designed to provide qualitative and quantitative evaluation on the possible therapeutic benefits of the use of Pluronic Polyol F-127 as a substitute skin in standardized third-degree thermal burns. Three separate burns, approximately 1600 mm2, were induced on the shaved backs of young, anesthetized pigs. Each animal served as its own control. One burn site was left untreated while the other two sites were covered with coded preparations of the Pluronic F-127 gel with additives. Polaroid photographs with a fixed focal-length camera were taken of all burn sites for planimetry analysis. Biopsies taken confirmed that third-degree burns were achieved. The pigs were followed for 30 days. The rate of healing of third-degree thermal burns was significantly accelerated over control sites when treated with Pluronic Polyol F-127 plus propylene glycol. When the bacteriostatic agent Garamycin was also added, the rate of healing remained significantly better than untreated controls. With the addition of Piracetam, burn wound healing was actually retarded within 30 days, when applied topically. Thus, wound healing was both accelerated and retarded as a function of the particular Pluronic preparation used to treat specific burn sites. This experimental modulation of wound healing suggests that the non-ionic poloxamer, Pluronic F-127, can significantly enhance the rate of wound healing by some unknown mechanism, possibly by stimulation of epithelial growth factor (EGF).

Lg attenuation and source studies using 1982 Miramichi data

Abstract: Using data from earthquakes in the 1982 Miramichi earthquake source zone, spectral excitation and attenuation of the Lg phase are studied. With data in the distance range of 135 to 994 km, interpretation is complicated by the presence of high-frequency Sn and Pn waves which interfere with the Lg wave. At the larger distances, the signal at frequencies above 7 Hz is completely dominated by the non- Lg arrivals. A frequency-dependent Lg-Q is determined which rises from 300 at 0.5 Hz to about 1400 at 10 Hz, at which it flattens at higher frequency. The Sn coda apparent Q rises above 3000 at frequencies higher than 10 Hz. Seismic moment and corner frequency estimates are made using Lg-Q corrected spectra. The moment estimates compare well with those obtained from long-period surface waves and short distance spectral estimates. The Lg corner frequency estimates are substantially lower than the short distance estimates. This discrepancy is the subject of discussion, but the Lg moment-corner frequency estimates do model observed data well using a Brune (1970) source model and the derived attenuation relation.

Prejunctional and postjunctional effects of neuropeptide Y at the noradrenergic neuroeffector junction of the perfused mesenteric arterial bed of the rat.

Abstract: The effect of neuropeptide Y (NPY) on periarterial nerve stimulation-induced release of norepinephrine (NE) and increase in perfusion pressure in the perfused mesenteric arterial bed of the rat was examined. Perfusate effluents were continuously collected and assayed for endogenous NE by high-pressure liquid chromatography (HPLC) coupled to electrochemical detection. Perfusion pressure was continuously monitored by means of a pressure transducer. Periarterial nerve stimulation (8 or 16 Hz, 60 V, 2-ms duration for 30 s) resulted in a readily detectable increase in NE release and perfusion pressure that was attenuated by the prior administration of tetrodotoxin (TTX) (10(-5) M) or guanethidine (5 X 10(-5) M). NPY exerted both prejunctional and postjunctional effects on noradrenergic neurotransmission in this preparation. The peptide produced a concentration-dependent reduction in the release of NE over a concentration range of 10(-10) - 10(-7) M. A similar inhibition effect occurred at 8, 10, and 16 Hz. In contrast, low concentrations (10(-10) and 10(-9) M) decreased the effect of nerve stimulation on perfusion pressure, whereas higher concentrations (10(-7) M) produced a marked potentiation. The alpha 2-adrenoceptor antagonist, yohimbine, did not alter the inhibitory effect of NPY on evoked NE release or the effect on perfusion pressure. Prazosin similarly did not alter the inhibitory effect of NPY on NE release but prevented the increase in perfusion pressure. We conclude that NPY modulates noradrenergic neurotransmission in the mesenteric arterial bed by decreasing the evoked release of NE and producing a concentration-dependent biphasic response on vascular smooth muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary artery bypass surgery in patients aged 80 years or older

Abstract: Between August 1980 and January 1986, 23 patients aged 80 years or older underwent coronary artery bypass grafting (CABG) operations. These patients had a higher incidence of severe left main coronary artery narrowing (p

Left ventricular systolic and diastolic flow abnormalities determined by doppler echocardiography in obstructive hypertrophic cardiomyopathy

Abstract: To analyze the relation of systolic anterior motion (SAM) of the mitral valve, peak left ventricular (LV) outflow tract velocity, aortic flow and mitral flow, 17 patients with obstructive hypertrophic cardiomyopathy (HC) (8 men, 9 women), aged 19 to 88 years (mean 45), were studied using M-mode and 2-dimensional echocardiography and pulsed and continuous-wave Doppler echocardiography and results were compared with those from 18 age-matched normal subjects. SAM was present in all patients with HC and absent in normal subjects. Time to peak outflow velocity as a percentage of LV ejection time was 63% in patients with HC and 29% in normal subjects (p less than 0.001). In 13 patients, time from the R-wave peak to the closest approximation of the mitral valve to the ventricular septum or initial contact during SAM was determined and was 242 +/- 66 ms and time from the R-wave peak to the peak LV outflow tract velocity was 242 +/- 73 ms (r = 0.90). In 11 patients time from the R-wave peak to cessation of flow in the ascending aorta was measured and was 286 +/- 80 ms; time from the R-wave peak to the peak LV outflow tract velocity was 246 +/- 75 ms. The ratio of early to late diastolic filling velocities of the left ventricle was 1.47 +/- 0.40 in the normal subjects and 1.26 +/- 0.84 in patients with HC (difference not significant). The early to late ratio of the 12 patients without mitral regurgitation was 0.99 +/- 0.52 (p less than 0.01 vs normal subjects).(ABSTRACT TRUNCATED AT 250 WORDS)

Tricuspid regurgitation by Doppler echocardiography after orthotopic cardiac transplantation.

Abstract: The incidence and severity of Doppler-detected tricuspid regurgitation (TR) and associated clinical variables was studied in 20 patients who underwent cardiac transplantation. Eighteen of the 20 patients had Doppler detectable TR after cardiac transplantation, 14 had moderate to severe TR and 4 mild TR. Echocardiographic evidence of right ventricular volume overload was present in 13 of 14 patients with moderate to severe TR and in none of the other 6 patients. Patient age, primary disease process, cold ischemic time of the transplanted heart, and the frequency or severity of organ rejection did not correlate with the development of TR. Two patients with significant TR had a torn or partially torn tricuspid chordae, indicating an organic etiology, and the remaining patients had functional TR. All 8 patients with a pulmonary artery systolic pressure of 55 mm Hg or more before transplantation had significant functional TR after transplantation (p less than or equal to 0.05). Pulmonary vascular resistance before transplantation was not predictive; however, after transplantation pulmonary vascular resistance was significantly greater in patients with moderate to severe TR (101.6 +/- 41.3 vs 50.2 +/- 16.6 dynes s cm-5, p less than or equal to 0.01).

Shear velocities, Qβ, and the frequency dependence of Qβ in stable and tectonically active regions from surface wave observations

Abstract: Summary. Velocities and attenuation coefficient values of Rayleigh waves within the South American continent and Indian subcontinent have been determined in order to study velocity structure and Qp structure, as well as their lateral variation, in those regions. Single-station and two-station data are combined to yield dispersion and attenuation data from periods of a few seconds to periods between 60 s and 100 s for each region. Both types of data are inverted using differential inversion schemes. This inversion process is found to sometimes allow the location of velocity discontinuities in the models directly from the dispersion data. Qp models obtained from the inversion process are not constrained to have high values at large depths, a problem with earlier methods used to invert surface-wave attenuation data. The shear-velocity models for the Indian shield and eastern South America are similar to one another, and have somewhat slower velocities than those reported for shield regions of North America. The shear-velocity models for the Himalaya and Andes are similar to one another in crustal thickness but the velocities in the Andes are lower than those in the Himalayas in the uppermost mantle. A low-velocity zone can marginally be resolved in the upper mantle beneath the Himalaya, but not beneath the other regions in this study. Qp models obtained for the stable regions of eastern North America and eastern South America exhibit similar Qp values at mantle depths. The Indian shield, however, has much lower Qp values, in both the crust and upper mantle, a result which may be related to the unusually high heat-flow observed for that stable region. for the tectonically active regions of western North America, western South America, and the Himalaya is considerably lower than Qp for the stable regions throughout most of the crust and upper mantle. Minimum mantle values appear to be about 120 for stable regions and 40 or less for tectonically active regions. Thus, Qp values in the upper mantle appear to vary regionally by a factor of 3 or more, whereas shear velocities in the same regions vary by no more than 13 per cent.

Lg magnitudes of selected East Kazakhstan underground explosions

Abstract: The amplitude of 1-sec period Lg waves, as recorded on seismograms of WWSSN stations in southern Asia and Scandinavia, are used to determine m b ( Lg ) values for 62 underground nuclear explosions in the eastern portion of the East Kazakhstan Test Site. The explosions were selected to be of m b ( P ) = 5.5 or greater in the period 1965 to 1985. The yields of the explosions are estimated, assuming that a Nevada Test Site-derived relation between m b ( Lg ) and yield for water-saturated rock is also applicable to the East Kazakhstan Test Site. Assuming that lateral variations in crustal structure and in depth of emplacement of the explosion do not affect m b ( Lg ) values, the Lg data indicate that the m b ( P ) bias between the Nevada Test Site and East Kazakhstan is 0.35 magnitude units.

Improved DNA hybridization method for detection of acyclovir-resistant herpes simplex virus.

Abstract: A simplified DNA hybridization method was developed to detect acyclovir-resistant isolates of herpes simplex virus. Herpes simplex virus-infected cell cultures in microtiter plates were treated with concentrations of acyclovir ranging from 8 to 0.015 micrograms/ml. At 48 h postinfection, infected cells were lysed by a one-step procedure and lysates were absorbed to membranes. Without further treatment, membranes were hybridized by using a herpes simplex virus-specific radioiodinated probe. The membranes were then washed and counted in a gamma counter. The elapsed time for assay performance was 4 h. Parallel plaque reduction assays were performed for comparison. The mean 50% inhibitory dose of in vivo- and in vitro-derived acyclovir-resistant, thymidine kinase-negative isolates was greater than 2 micrograms/ml by DNA hybridization. The 50% inhibitory dose of acyclovir-susceptible, thymidine kinase-positive isolates ranged from 0.01 to 1.1 micrograms/ml. This assay is simple and objective and should facilitate antiviral susceptibility testing in diagnostic laboratories.

Redirected growth of pyramidal tract axons following neonatal pyramidotomy in cats

Abstract: After the pyramidal tract at the pontomedullary junction in neonatal cats had been cut and the ipsilateral frontoparietal cortex injected with intra-axonal markers at 40 to 74 days of age, cortical axons were labeled in aberrant pathways that descended into the caudal medulla and spinal cord. Some labeled axons from the damaged pyramidal tract crossed the midline, descended with fibers in the intact pyramidal tract through the pyramidal decussation, and entered the lateral corticospinal tract. Another group of aberrant projections descended bilaterally along the ventrolateral edge of the medulla and either ended in the lateral reticular nuclei or continued into the spinal cord. Finally, some axons descended individually through the central medullary tegmentum and ended bilaterally in the spinal trigeminal, dorsal column, and lateral reticular nuclei. Although these findings suggest that pyramidal tract axons regenerate after injury, the findings from a second series of experiments refute this conclusion. In 2- to 5-day-old cats, the fluorescent dye Fast Blue was injected into the spinal cord, and 7 to 8 days later the contralateral pyramidal tract was cut. In these animals, there were never any cortical neurons retrogradely labeled with Fast Blue in the frontoparietal cortex ipsilateral to the pyramidotomy, although numerous neurons were labeled contralaterally. Control experiments confirmed that the interval between the Fast Blue injections and the pyramidotomies was long enough for retrogradely labeling cortical neurons, that the spinal cord injections did not adversely affect the retrogradely labeled cortical neurons, and following axotomy dying cortical neurons could be demonstrated directly using silver impregnation techniques. We conclude that neonatal pyramidotomy causes the death of all axotomized cortical neurons in kittens, and, therefore, the aberrant cortical projections seen caudal to the lesion must be redirected, late-developing, and undamaged cortical axons, and not regenerated axons.

Independent value of signal-averaged electrocardiography and left ventricular function in identifying patients with sustained ventricular tachycardia with coronary artery disease

Abstract: To determine if the signal-averaged electrocardiographic detection of late potentials is an independent marker of sustained ventricular tachycardia (VT) in patients with documented chronic coronary artery disease (CAD), 57 patients underwent signal-averaged electrocardiography. Mean ejection fraction was 47 +/- 13% in the 14 patients with sustained VT and 56 +/- 19% in the 43 patients without VT (difference not significant). The sensitivity, specificity and accuracy of late potentials for detecting patients with VT were 64% (9 of 14), 79% (34 of 43), and 75% (43 of 57), respectively. Univariate analysis and stepwise logistic regression of angiographic and electrocardiographic variables identified late potentials as an independent marker of the patient with sustained VT. The odds ratio for late potentials to detect patients with prior sustained VT was 2.6. Six-month follow-up revealed a cardiac mortality rate of 11% and an arrhythmia event rate of 22% in patients with late potentials vs a cardiac mortality rate of 3% and an arrhythmia event rate of 13% in patients without late potentials. Thus, signal-averaged electrocardiographic detection of late potentials is useful in identifying patients with prior sustained VT independent of left ventricular function.