Enough with the fantastic voyage: will IVUS pay in Peoria?
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Centers for Medicare and Medicaid Services, U.S.↗
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The inverse problem in electroneurography--II: Computational aspects and evaluation using simulated data.
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Action Potentials↗
Rat heart fatty acid-binding protein is highly homologous to the murine adipocyte 422 protein and the P2 protein of peripheral nerve myelin.
The rat heart contains an abundant cytosolic protein which binds long chain fatty acids. We have determined its primary structure by Edman degradation of peptides generated from chymotryptic, tryptic, and elastase digestions. This polypeptide (Mr = 14,992) contains 134 amino acids and has a blocked (acetylated) NH2 terminus. The sequence of rat heart fatty acid-binding protein (FABP) is remarkably similar to the murine adipocyte 422 protein and the P2 protein of peripheral nerve myelin. Computer-assisted alignment of heart FABP and 422 revealed that 82 of 132 comparable residues are identical (62%). There are 77 identities out of 131 possible matches between this protein and the human myelin P2 protein (59%). Similar comparisons demonstrate that heart FABP has significant homology to several other proteins which bind hydrophobic ligands. The rank of order of similarity to heart FABP is: 422 greater than myelin P2 greater than cellular retinoic acid-binding protein greater than cellular retinol-binding protein II greater than cellular retinol-binding protein greater than intestinal FABP greater than liver FABP. These eight sequences form a family of paralogous homologues. Heart FABP has a region of internal homology involving tandemly arrayed oligopeptides spanning residues 71-100 and 101-131. This feature is not found in the 422 and P2 sequences. The endogenous ligands bound by the 422, P2, and heart FABP sequences have not been defined. Interpretation of the biological significance of their structural similarities and differences will require information about their ligand specificities and affinities.
Amino Acid Sequence↗
A method for continuous on-line monitoring of systemic vascular resistance (COMS) after open heart procedures.
A new method for continuous on-line measurement (COMS) of systemic vascular resistance (SVR) utilizing simple computer analysis of the peripheral arterial waveform is presented. The fundamental equation of this method is: (Formula: see text) where SVR is systemic vascular resistance, dP/dt is the peak dP/dt of the peripheral arterial waveform, and P' is the pressure at the time of peak dP/dt. F and a are calibration constants determined by taking simultaneous measurements by an independent method (thermodilution) before (low SVR) and immediately after (high SVR) aortocoronary bypass operations. In 22 patients 255 COMS of SVR readings were recorded simultaneously with thermodilution cardiac output measurements. Patients were exposed to situations such as temperature changes, volume load, blood loss, and the effect of drugs such as various catecholamines, nitroglycerin, and nitroprusside. Linear regression analysis was performed to compare the SVR calculated from thermodilution with the COMS-SVR measurements. SVR values ranged from 450 to 4400 dynes/sec/-5 and correlation between COMS and thermodilution was r = 0.98. Correlation coefficients of individual patients ranged from r = 0.9 to r = 0.986. We found COMS SVR measurements accurate, reliable, and extremely helpful in the management of hemodynamically unstable patients.
Adult↗
[Determination of the ejection fraction of the left ventricle by videodensitometric analysis of digital angiography. Preliminary results].
Digitalisation enables angiocardiography to be performed by a peripheral intravenous injection. Computer-assisted analysis of the date widens the possibilities of quantification. The authors have developed a videodensitometric method of studying the left ventricular ejection fraction. The research was performed on an experimental model and the technique validated in a series of 10 patients. The experimental model consisted of a series of balloons which, when inflated with contrast medium assumed an allipsoid shape resembling a left ventricle. The balloons were blown up in two stages with an automatic injector to simulate systole and diastole. The images were recorded in the same way as during ventriculography. Videodensitometric measurements showed 3 to 5% variations from the true values. The method was then applied to the calculation of the left ventricular ejection fraction in 10 patients: left ventricular function was also quantified by geometrical methods (Dodge) from the same angiogrammes and the 2 sets of results were then compared. The correlation coefficient between the two methods was 0.97, so validating the new technique. Videodensitometry opens up new perspectives in the study of left ventricular function. On the other hand it can be used to monitor the ejection fraction in severely ill or recently operated patients, and, on the other hand the principle of videodensitometry eliminates the geometrical approximations inherent in the classical methods of angiographic analysis and would therefore seem to be more suitable for the study of pathological left ventricules (aneurysm...). Finally, the technique of videodensitometry represents a new step towards the measurement of true volumes and flow rates.
Absorptiometry, Photon↗
New concepts of ventilation.
A short survey is given of established methods for ventilatory support. The merits of intermittent mandatory ventilation (IMV) and the new mode of mandatory minute ventilation (MMV) are discussed and compared. The importance of gasflowpressure patterns are analyzed as based on measurements on an awake, non-medicated intubated subject. It can be demonstrated that an inspiratory-assist function minimizes the work of breathing associated with increased airway resistance in the peripheral airways. A metabolic computer system for automatic continuous measurements of oxygen uptake and carbon-dioxide elimination during ventilatory care is described. This metabolic computer is designed to be used with the Engström Erica ventilator and makes it possible to evaluate the caloric demand of the patient as well as the effects of various compositions used for parenteral nutrition.
Airway Resistance↗
A dose table describing fractions of peripheral volume for 125I volume implants.
A dose table that provides the dose as a function of fractions of peripheral volume for 125I implants is presented. The table is based on seed distributions from 50 actual patient implants. Computer dosimetry was used to determine peripheral doses and dose ranges within implant volumes. The effects of seed distribution were also examined. The patient data and a study of computer-generated randomized seed coordinates within a given volume suggest that matched doses do not depend strongly on the exact position of each seed. The table provides the means for planning an implant to obtain a desired peripheral dose that can be directly compared with the postimplant computer dose calculation.
Brachytherapy↗
[An automated system for evaluating the state of peripheral hemodynamics].
A four-channel automated system based on the microelectronic computer "Elektronika-60M" for investigation of human peripheral hemodynamics is described. The block diagram of algorithm of the automated system operation is adduced, search algorithm of characteristic points is described in detail, the fundamental correlations are presented.
Algorithms↗
Use of a touch sensitive screen and computer assisted image analysis for quantitation of developmental changes in pulmonary structure.
The extensive changes in pulmonary function occurring during early development may reflect variations in the anatomic structure of the respiratory apparatus during this period. Accurate definition of these alterations could yield important information concerning the structure-function correlations of the respiratory system. To facilitate the acquisition of morphometric data from histologic sections of pulmonary tissues, we propose the use of a computer assisted image analysis system with a touch sensitive screen as an interactive peripheral. This allows planimetric measurements and computation of the dimensions of areas of selected light intensities within an image. We present the description, design, and applications of such an image analysis system and report representative results regarding developmental changes in pulmonary structure. In addition, we correlate these results with previously published information regarding pulmonary mechanics during early development to help clarify the maturational changes in pulmonary structure-function relationships.
Animals↗
Thermographic presentation of cutaneous sensory and vasomotor activity in the injured peripheral nerve.
Impaired function of cutaneous segments of monkey peripheral nerves experimentally blocked by lidocaine anesthesia was clearly visualized by means of elevated temperature measurements obtained on computerized color telethermography. Mean temperature elevations in the segments of anesthetized primate nerves were 2.40 degrees C at the ulnar segment 17 minutes after nerve block, and 1.20 degrees C at the peroneal nerve at 20 minutes. The vasomotor activity of specific nerves, recorded after local anesthesia and displayed by color telethermographic imaging, corresponded to the distribution of sensory segments identified by more cumbersome means. Telethermography is therefore shown to be a useful tool, both qualitatively and quantitatively, in mapping cutaneous distribution of peripheral nerves and for evaluation of peripheral nerve injuries.
Animals↗
Bronchiolitis obliterans after lung transplantation: findings at chest radiography and high-resolution CT. The Toronto Lung Transplant Group.
Although bronchiolitis obliterans (BO) is seen commonly after heart-lung transplantation, its occurrence after lung transplantation appears to be relatively infrequent. In the 55 single- and double-lung transplantations performed at Toronto General Hospital, 41 patients have survived longer than 3 months and four (10%) have developed pathologically proved BO. Chest radiographic findings in these four patients included slight to moderate decreased peripheral vascular markings (n = 3), slight to moderate volume loss (n = 2), subsegmental atelectasis (n = 2), and new, thin, linear, irregular areas of increased opacity (n = 2). High-resolution computed tomography (HRCT) demonstrated mild peripheral bronchiectasis (n = 4) and decreased peripheral vascular markings (n = 3). Although the radiographic and HRCT findings did not appear to be specific for posttransplantation BO, they may be of value in suggesting the diagnosis of BO within this patient population.
Adult↗
Centrol and peripheral correlates of anxiety: a comparative study.
Physiological measurements and mood ratings were recorded in 32 normal subjects at rest and under differing stressful conditions designed to induce anxiety. The physiological measurements were recorded simultaneously using a polygraph and on-line computer analysis; these comprised the peripheral measurements of pulse rate, skin conductance, spontaneous fluctuations in skin conductance, respiratory rate, and finger tremor, and the central measurements of resting electroencephalogram and averaged evoked potentials to an auditory stimulus. Mood rating were recorded using analogue rating scales, the 16 scores obtained being reduced to three mood factors. Correlations were calculated between the mood factors and each of the physiological measurements. The highest correlations were between the anxiety factor and the central measurements, particularly the proportion of electroencephalographic activity between 7.5 and 13.0 Hz, and the latencies of the secondary components of the evoked response. The peripheral measurements correlated rather less well with mood, but skin conductance and fluctuations in skin conductance, pulse rate, and tremor near the peak frequency of 9 Hz all correlated significantly with anxiety. Only two correlations were greater than 0.4, illustrating that no measure was a specific index of anxiety. Refinement of central rather than peripheral measurements is likely to lead to closer correlations with anxiety and other mood states.
Acoustic Stimulation↗
Computer analysis of optokinetic nystagmus in patients with spontaneous nystagmus of peripheral vestibular origin.
The bias of slow phase velocity (SPV) of optokinetic nystagmus (OKN) caused by an acute labyrinthine lesion was examined in 8 patients using differnet optokinetic stimulus velocities. In all patients a directional preponderance of OKN-SPV was found corresponding to spontaneous nystagmus. This was due to enhancement of nystagmus SPV to the side of the lesion and depression of SPV in the opposite horizontal direction. The preponderance of OKN on the average increased with the intensity of spontaneous nystagmus and decreased along with recovery. These vestibularly induced differences in OKN-SPV range up to 70%. A differentiation is discussed between OKN preponderances caused by labyrinthine lesions and brain stem lesions.
Acute Disease↗
Irregular geometries in normal unmyelinated axons: a 3D serial EM analysis.
Axons have generally been represented as straight cylinders. It is not at all uncommon for anatomists to take single cross-sections of an axonal bundle, and from the axonal diameter compute expected conduction velocities. This assumes that each cross-section represents a slice through a perfect cylinder. We have examined the three-dimensional geometry of 98 central and peripheral unmyelinated axons, using computer-assisted serial electron microscopy. These reconstructions reveal that virtually all unmyelinated axons have highly irregular axial shapes consisting of periodic varicosities. The varicosities were, without exception, filled with membranous organelles frequently including mitochondria, and have obligatory volumes similar to that described in other neurites. The mitochondria make contact with microtubules, while the other membraneous organelles were frequently found free floating in the cytoplasm. We conclude that unmyelinated axons are fundamentally varicose structures created by the presence of organelles, and that an axon's calibre is dynamic in both space and time. These irregular axonal geometries raise serious doubts about standard two dimensional morphometric analysis and suggest that electrical properties may be more heterogeneous than expected from single section data. These results also suggest that the total number of microtubules contained in an axon, rather than its single section diameter, may prove to be a more accurate predictor of properties such as conduction velocity. Finally, these results offer an explanation for a number of pathological changes that have been described in unmyelinated axons.
Animals↗
Concurrent lumbar spinal stenosis and peripheral vascular disease. A report of nine patients.
Intermittent claudication from peripheral vascular disease is sometimes difficult to distinguish from neurogenic claudication secondary to lumbar spinal stenosis. Of 172 patients with symptoms of claudication and lumbar spinal stenosis proved by myelography or computed tomography (CT), nine had peripheral vascular disease identified with ultrasonography and arteriography. All of the nine patients had a laminectomy performed to decompress the narrow spinal canal, and two had an additional posterolateral fusion. Two patients were treated with an excision of their abdominal aortic aneurysm, while one of those patients later required a bypass graft for iliac stenosis. One patient had had an aortofemoral bypass graft, one a femoropopliteal graft, and one a lumbar sympathectomy. Follow-up study ranged from three to eight years, with an average of five years after their last surgical procedure. Paresthesias generally dissipated after the spinal surgery. The cramping-type discomfort associated with walking was not easily attributed either to vascular or a neurogenic etiology. Five patients had initial weakness, which invariably improved. A secondary etiology contributing to claudication must be excluded in those patients with persistent discomfort following previous lumbar spinal or vascular surgery for arterial insufficiency.
Aged↗
[On the peripheral refraction of the human eye (author's transl)].
As the measurements of the peripheral refraction of the living human eye published till now point out a confusing abundance of variants but no clear results, the peripheral refraction of fictitious model eyes is computed to find out which components influence the refraction and how they do it. Then for some special selected representative eyes the peripheral refraction and the astigmatism are computed and the results analyzed. The result consists in three typical refractioncurves which can be reduced to simple rules. This paper intends to stimulate future experiments on exactly defined conditions.
Astigmatism↗
Peripheral limitations to exercise.
We present a computer simulation of a two-compartment model of the systemic circulation which demonstrates how this model can be used to understand the mechanism(s) for the maximal exercise cardiac output (Q). The model consists of two parallel vascular channels, the splanchnic channel (all blood draining through the hepatic veins) and the peripheral channel (all other vascular beds). The distinguishing characteristic of each channel is the product of its venous compliance and venous resistance. Model parameters for the human circulation were estimated from similar parameters obtained directly from animal experiments. "Exercise" was achieved by decreasing the compliance of both channels to 40% of their initial value and by redistributing the Q such that the fraction of Q perfusing the splanchnic channel fell from 38 to 5%, while that perfusing the peripheral channel (skeletal muscles) increased from 62 to 95%. These combined changes increased Q from 4.4 to 22.0 l X min-1 and suggest that maximal adjustments of the two-compartment model parameters lead to a prediction of a maximal Q that approaches the maximal Q usually obtained by humans during exercise.
Blood Circulation↗
High definition computed tomography in rheumatoid arthritis associated pulmonary disease.
Eighteen patients with rheumatoid arthritis (American Rheumatism Association definition) were selected consecutively from a rheumatology clinic. All patients were examined with plain chest radiographs, thin slice computed tomography, and pulmonary function tests. Four patients with normal chest radiographs, and normal pulmonary function tests were found to have normal CT scans. In ten patients, abnormalities consistent with rheumatoid associated lung disease were demonstrated, including changes of interstitial fibrosis in seven cases. This fibrosis had a predominantly peripheral pattern on CT scan. Computed tomography was found to be more sensitive than plain radiographs in detecting abnormalities; however, all the patients in this series with CT lung changes had abnormalities on pulmonary function testing.
Adult↗