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At least 1,783 records · Page 99Linked to original sources
PubMed1993

Evaluation of pulse oximetry during cardiopulmonary resuscitation.

This study evaluates whether the pulse oximeter is useful during cardiopulmonary resuscitation. The instrument was of undoubted benefit in the management of primary respiratory arrest, but of equivocable value in cardiac arrest. Data were displayed during external chest compressions, but were generally unreliable. The ear probe was not able to produce a consistently good signal during cardiopulmonary resuscitation. Nevertheless, the provision of an oximeter amongst the first-line resuscitation equipment available at a cardiopulmonary arrest significantly altered the management of seven out of 20 patients, five of whom survived.

Cardiopulmonary Resuscitation↗
PubMed1989

Long-term clinical results using the artificial urinary sphincter around bowel.

Four patients are presented in whom bowel was used to reconstruct a bladder. As a sphincteric mechanism was absent in all 4, the cuff from the artificial urinary sphincter was placed around the bowel to provide continence. This allowed for "normal" urination. The longest follow-up period was 11 years and the shortest 1.5 years. Both clinical and experimental data show that bowel will tolerate compression from the artificial urinary sphincter provided infection does not supervene and the pressure does not exceed 80 cm of water.

Child↗
PubMed1984

Amorphous spray-dried hydroflumethiazide-polyvinylpyrrolidone systems: physiochemical properties.

Hydroflumethiazide was spray-dried with polyvinylpyrrolidone (PVP) to produce products containing 0-30% PVP. These systems were amorphous and differed from previously prepared coprecipitates of similar composition. Differential scanning calorimetry (DSC) suggested that at low PVP weight fractions both amorphous drug and an amorphous drug-PVP complex can be present in spray-dried systems. The apparent solubility of hydroflumethiazide in spray-dried products increased with increasing PVP content reaching a plateau value approximately four times that of the pure crystalline drug. The estimated free energy and entropy of the spray-dried drug were greater than that of crystalline drug and also increased with increasing PVP content. Dissolution studies with compressed discs supported the apparent solubility data. The results suggest that amorphous phases having different orders of organization are formed in spray-dried systems with increasing PVP content.

Chemical Phenomena↗
PubMed1996

The effects of lossy compression on the detection of subtle pulmonary nodules.

We examined the ability of radiologists to detect pulmonary nodules in computed radiographic (CR) chest images subjected to lossy image compression. Low-contrast 1-cm diameter targets simulating noncalcified pulmonary nodules were introduced into clinical images and presented to ten radiologists in a series of two-alternative forced-choice (2AFC) observer experiments. The percentages of correct observer responses obtained while viewing noncompressed images (1:1) were compared with those obtained for the same images compressed 7:1, 16:1, 44:1, and 127:1. The images were compressed using a standard full-frame discrete cosine transform (DCT) technique. The degree of compression was determined by quantizing Fourier components in various frequency channels and then Huffman encoding the result. The data show a measurable decline in performance for each compression ratio. Through signal-to-noise ratio (SNR) analysis, we found that the reduction in performance was due primarily to the compression algorithm that increased image noise in the frequency channels of the signals to be detected.

Algorithms↗
PubMed1997

Respiratory transfer impedance between 8 and 384 Hz in guinea pigs before and after bronchial challenge.

We report a forced oscillatory technique for noninvasively measuring respiratory transfer impedance (Ztr) between 8 and 384 Hz in guinea pigs. This technique uses a device consisting of two chambers: one surrounding the animal's head that is used as a plethysmograph to measured flow through the airway opening and the other that surrounds the animal's body and is used to apply pressure oscillations to the body surface. Ztr was measured in spontaneously breathing awake guinea pigs and while the animals were anesthetized in normal and methacholine-challenged conditions. An eight-element model consisting of an airway compartment separated from a tissue compartment by a shunt gas compression compartment was fit to the data. Anesthesia increased central and peripheral airway resistance and bronchial airway wall compliance by 13, 31, and 44%, respectively, whereas it decreased tissue compliance by 37%. Compared with the unanesthetized condition, the methacholine challenge (20 micrograms/kg) resulted in an increase in central and peripheral airway resistance (69 and 319%, respectively) and a decrease in bronchial airway wall and tissue compliance (37 and 79%, respectively). This technique is capable of measuring Ztr in anesthetized and awake guinea pigs. Analysis of these data with this eight-element model provides reasonable estimates of airway and tissue parameters.

Airway Resistance↗
PubMed2006

Snoring-related energy transmission to the carotid artery in rabbits.

Epidemiological studies link habitual snoring and stroke, but mechanisms involved are poorly understood. One previously advanced hypothesis is that transmitted snoring vibration energy may promote carotid atheromatous plaque formation or rupture. To test whether vibration energy is present in carotid artery walls during snoring we developed an animal model in which we examined induced snoring (IS)-associated tissue energy levels. In six male, supine, anesthetized, spontaneously breathing New Zealand White rabbits, we surgically inserted pressure transducer-tipped catheters (Millar) to monitor tissue pressure at the carotid artery bifurcation (PCT) and within the carotid sinus lumen (PCS; artery ligated). Snoring was induced via external compression (sandbag) over the pharyngeal region. Data were analyzed using power spectral analysis for frequency bands above and below 50 Hz. For frequencies below 50 Hz, PCT energy was 2.2 (1.1-12.3) cmH2O2 [median (interquartile range)] during tidal breathing (TB) increasing to 39.0 (2.5-95.0) cmH2O2 during IS (P = 0.05, Wilcoxon's signed-rank test). For frequencies > 50 Hz, PCT energy increased from 9.2 (8.3-10.4) x 10(-4) cmH2O2 during TB to 172.0 (118.0-569.0) x 10(-4) cmH2O2 during IS (P = 0.03). Concurrently, PCS energy was 13.4 (8.5-18.0) x 10(-4) cmH2O2 during TB and 151.0 (78.2-278.8) x 10(-4) cmH2O2 during IS (P < 0.03). The PCS energy was greater than PCT energy for the 100-275 Hz bandwidth. In conclusion, during IS there is increased energy around and within the carotid artery, including lower frequency amplification for PCS. These findings may have implications for carotid atherogenesis and/or plaque rupture.

Animals↗
PubMed2001

Accuracy of fine needle aspiration biopsy of thyroid nodules in detecting malignancy in childhood: comparison with conventional clinical, laboratory, and imaging approaches.

In childhood the traditional diagnostic approach to thyroid nodules consists of clinical, laboratory, and imaging evaluations. A safe and accurate procedure is needed to promptly identify patients who require surgery. In regard to the usefulness of fine needle aspiration biopsy, the data in the literature concerning children and adolescents are scanty. The aim of this study was to evaluate and compare the diagnostic accuracies of clinical, laboratory, and imaging data collected retrospectively in a group of pediatric patients with thyroid nodules submitted to fine needle aspiration biopsy. Forty-two patients who underwent surgery for thyroid nodules, recruited in 9 Italian pediatric endocrine units, were retrospectively studied. According to histological diagnosis, they were divided into 2 groups, 22 patients with benign lesions and 20 patients with malignant lesions. From clinical records we obtained data about 1) symptoms of neck compression; 2) cervical adenopathy; 3) thyroid function, calcitonin level, and antithyroid antibody titers; 4) ultrasonography; 5) (99m)Tc scintiscanning; and 6) cytology obtained with fine needle aspiration biopsy. Patients and nodule characteristics were analyzed statistically for associations with the presence of thyroid cancer. Among clinical findings, only adenopathy was significantly higher in the group with cancer (8 of 22 benign lesions vs. 16 of 20 malignant lesions; P = 0.006). Thyroid function and antibody titers were similar in the 2 groups, whereas the serum calcitonin level was elevated only in 1 patient with malignant lesions. Among ultrasonography findings, no significant statistical difference was found between the 2 groups with regard to number, dimensions, growth progression, or hypoechogenic pattern of the nodules. Regarding scintigraphic findings, no significant difference was found between the 2 groups. However, a positive correlation (r = 0.90; P < 0.0001) was found between fine needle aspiration biopsy cytological findings and histological diagnoses. The sensitivity, specificity, and accuracy of fine needle aspiration biopsy were 95%, 86.3%, and 90.4%, respectively. A multiple regression analysis showed that only fine needle aspiration biopsy (beta coefficient = 0.963; P < 0.0001) significantly contributed to detecting malignancy (multiple r = 0.973; P < 0.0001). This study provides strong evidence that fine needle aspiration biopsy is a safe technique even in childhood and adolescence, offering the best sensitivity, specificity, and accuracy in detecting malignancy compared with conventional approaches.

Adolescent↗
PubMed2006

Statistical analysis of a database of absorption spectra of phytoplankton and pigment concentrations using self-organizing maps.

We present a statistical analysis of a large set of absorption spectra of phytoplankton, measured in natural samples collected from ocean water, in conjunction with detailed pigment concentrations. We processed the absorption spectra with a sophisticated neural network method suitable for classifying complex phenomena, the so-called self-organizing maps (SOM) proposed by Kohonen [Kohonen, Self Organizing Maps (Springer-Verlag, 1984)]. The aim was to compress the information embedded in the data set into a reduced number of classes characterizing the data set, which facilitates the analysis. By processing the absorption spectra, we were able to retrieve well-known relationships among pigment concentrations and to display them on maps to facilitate their interpretation. We then showed that the SOM enabled us to extract pertinent information about pigment concentrations normalized to chlorophyll a. We were able to propose new relationships between the fucoxanthin/Tchl-a ratio and the derivative of the absorption spectrum at 510 nm and between the Tchl-b/Tchl-a ratio and the derivative at 640 nm. Finally, we demonstrate the possibility of inverting the absorption spectrum to retrieve the pigment concentrations with better accuracy than a regression analysis using the Tchl-a concentration derived from the absorption at 440 nm. We also discuss the data coding used to build the self-organizing map. This methodology is very general and can be used to analyze a large class of complex data.

Algorithms↗
PubMed2006

Statistical description of the free-space propagation of highly aberrated optical beams.

The free-space propagation of initially aberrated optical beams is considered with an emphasis on aero-optical applications. An exact statistical solution of the paraxial wave equation is derived that can be used to obtain statistics of the beam such as beam center, spread, and higher-order statistics as algebraic functions of propagation distance, wavelength, and statistics of the initial wavefront. Correlations between the proposed description and intensity-based statistics, such as the Strehl ratio, are investigated. It is found that the root-mean-square (rms) of the gradient of the wavefront plays an important role in causing coherence degradation and that the rms of the wavefront error is not always an appropriate measure of the degradation. To illustrate the use of this statistical tool, index of refraction data from a numerical simulation of compressible flow over a cylinder are employed to perform an aero-optical analysis.

Journal Article↗
PubMed2003

Pituitary apoplexy due to prolactinoma in a Taiwanese boy: patient report and review of the literature.

We report a Taiwanese boy who presented with apoplexy of a prolactinoma. A 12 9/12 year-old boy presented to our clinic with headache and visual deficit of bitemporal hemianopsia. Skull X-ray showed an enlarged sella. Magnetic resonance imaging (MRI) of the sella turcica showed a 4 x 2.5 x 2.5 cm mass, located at the sella turcica and extending upward to compress the optic chiasm. Preoperative laboratory data showed hyperprolactinemia, hypothyroidism and hypocortisonism. After a stress dose of i.v. hydrocortisone was given, he underwent transsphenoid surgery to remove the tumor. Immunohistochemical stains were positive for PRL in the tumor cells. After surgery, he suffered from neurogenic diabetes insipidus, hypopituitarism and hyperprolactinemia, with serum PRL level of 491 ng/ml. Visual field examination was normal 4 months later. In conclusion, pituitary apoplexy is rare in children but should be considered if a patient suffers from headache, vomiting, and visual deficit. Brain MRI is preferred for diagnosis. Dopaminergic agonists should be given if residual tumor or recurrence of prolactinoma is found after transsphenoidal surgery.

Child↗
PubMed2003

Relative or absolute standards for child poverty: a state-level analysis of infant and child mortality.

OBJECTIVES: The purpose of the present study was to compare the associations of state-referenced and federal poverty measures with states' infant and child mortality rates. METHODS: Compressed mortality and Current Population Survey data were used to examine relationships between mortality and (1) state-referenced poverty (percentage of children below half the state median income) and (2) percentage of children below the federal poverty line. RESULTS: State-referenced poverty was not associated with mortality among infants or children, whereas poverty as defined by national standards was strongly related to mortality. CONCLUSIONS: Infant and child mortality is more closely tied to families' capacity for meeting basic needs than to relative position within a state's economic hierarchy.

Adolescent↗
PubMed1993

Comparison of tibiofemoral joint forces during open-kinetic-chain and closed-kinetic-chain exercises.

The purpose of this study was to analyze forces at the tibiofemoral joint during open and closed-kinetic-chain exercises. Five healthy subjects performed maximum isometric contractions at 30, 60, and 90 degrees of knee flexion during open-kinetic-chain extension, open-kinetic-chain flexion, and closed-kinetic-chain exercises. Electromyographic activity of the quadriceps and hamstrings, as well as load and torque-cell data, were recorded. Tibiofemoral shear and compression forces were calculated with use of a two-dimensional biomechanical model. The results showed that, during the open-kinetic-chain extension exercise, maximum posterior shear forces (the resisting forces to anterior drawer) of 285 +/- 120 newtons (mean and standard deviation) occurred at 30 degrees of knee flexion and maximum anterior shear forces (the resisting forces to posterior drawer) of 1780 +/- 699 newtons occurred at 90 degrees of knee flexion. The closed-kinetic-chain exercise produced significantly less posterior shear force at all angles when compared with the open-kinetic-chain extension exercise. In addition, the closed-kinetic-chain exercise produced significantly less anterior shear force at all angles except 30 degrees when compared with the open-kinetic-chain flexion exercise (p < 0.05). Analysis of tibiofemoral compression forces and electromyographic recruitment patterns revealed that the closed-kinetic-chain exercise produced significantly greater compression forces and increased muscular co-contraction at the same angles at which the open-kinetic-chain exercises produced maximum shear forces and minimum muscular co-contraction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1999

Subluxation of the talocalcaneal joint in adults who have symptomatic flatfoot.

BACKGROUND: When flatfoot is acquired during adulthood, the shape of the foot changes. In addition to a decreased arch, there may be valgus angulation of the hindfoot or abduction of the forefoot, or both. However, there is little objective information to provide a better understanding of the anatomical or morphological changes that occur in acquired adult flatfoot. We wondered if such an understanding of the three-dimensional anatomy might shed light on the pathway by which these changes occur. We designed this study to measure the three-dimensional position of the talocalcaneal joint in patients who have painful flatfoot. METHODS: Computed tomography scans of the feet of eight patients who had symptomatic flatfoot were used to construct a model of the talocalcaneal articulation. The scans were performed on a custom loading frame developed to simulate weight-bearing with the foot in a neutral position while a seventy-five-newton axial compressive load was applied. The digital data from the scans were used to make three-dimensional computer models of the articular surfaces of the talus and calcaneus of each foot. These models then were used to calculate the percentage of the articular surface that was in contact and, conversely, the percentage that was subluxated. Two surfaces were modeled for each bone; the posterior facet formed one surface, and the anterior and middle facets were combined to form the second surface. The data were compared, with use of Mann-Whitney nonparametric U analysis, with those derived from scans of the feet of four patients without a deformity of the hindfoot who served as controls. RESULTS: A mean (and standard deviation) of 68+/-9 percent of the posterior facet of the calcaneus was in contact with the talus in the patients who had flatfoot compared with 92+/-2 percent in the controls, and a mean of 51+/-23 percent of the anterior and middle facets of the calcaneus was in contact with the talus in the patients who had flatfoot compared with 95+/-6 percent in the controls. These differences were significant (p = 0.0066 for both). CONCLUSIONS: Marked subluxation of the talocalcaneal joint occurs in some patients who have symptomatic planoabductovalgus deformity.

Adult↗
PubMed1993

Magnetic resonance angiography: a three-dimensional database for assessing arteriovenous malformations. Technical note.

Stereotactic angiography has long been the "gold standard" in the diagnosis of patients with arteriovenous malformations (AVM's). Although orthogonal or stereoshift images may suffice in discerning the shape and location of spherical malformations, an exact analysis and assessment of most nonspherical malformations are hampered by the fact that stereotactic angiographic images compress three-dimensional (3-D) data into two-dimensional views. As a consequence, the complex 3-D shape of an AVM can never be fully and truly discerned from conventional angiography. With the recent explosion of radiosurgical techniques, more and more AVM's are being treated noninvasively. These radiosurgical techniques require 3-D visualization to maximize nidus coverage and minimize normal brain irradiation. Alternatives to stereotactic angiography are therefore desperately needed. An entire new family of pulse sequences is now available that permits visualization of the vascular system using magnetic resonance imaging. A brief technical review of magnetic resonance angiography is presented, and its potential role(s) in the assessment and radiosurgical treatment of AVM's is explored.

Humans↗
PubMed2000

[Inflammatory abdominal aortic aneurysm].

A 58-years-old man, with no medical past history, was examined for abdominal pain and weight loss. An enlarged kidney could be palpated, and abdominal echography showed left hydronephrosis due to ureteral compression by abdominal aortic aneurysm. Laboratory data showed an inflammatory syndrome. CT scan suggested the diagnosis of inflammatory abdominal aortic aneurysm. The use of corticosteroids brought about the regression of the symptoms and the resolution of the ureteral obstruction, permitting aneurysmectomy and prosthesis replacement without ureterolysis. This report shows the interest of preoperative radiological diagnosis of the inflammatory character of abdominal aneurysm. For uncomplicated cases, preoperative treatment using corticosteroids could allow partial regression of the periaortic inflammation and easier surgical repair.

Abdominal Pain↗
PubMedDate not supplied

Fracture resistance of teeth restored with the bonded amalgam technique.

This study evaluated the fracture resistance of maxillary premolars with MOD Class II cavity preparations restored with silver amalgam (G1), Scotchbond Multi Purpose Plus and silver amalgam (G2) and Panavia F and silver amalgam (G3). After the restorations were made, the specimens were stored at 37 degrees C for 24 hours at 100% humidity and submitted to the compression test. Statistical analysis of the data (ANOVA and Tukey Test) revealed no significant differences among the three groups that were studied.

Analysis of Variance↗
PubMed1975

Pulse code modulation telemetry in ski injury research. II. Preliminary results.

The excitation between the boot and the ski was measured in maneuvers skied over a variety of snow conditions. A precision pulse-code modulation (PCM) - frequency modulation (FM) telemetry system was custom built to transmit data from strain-gage force transducers mounted inside the test ski to a receiving station about 3 km distant. Field tests gathered cruising data from three basic maneuvers - snowplow, stem christiana, and parallel christiana. Some classic falls resulting from inadvertent release of the ski bindings were also recorded. For comparative purposes, the maneuvers were skied over a standard five-turn slalom course. Examination of the loading histories reveals that: (1) the data are nonstationary random; (2) boot compression for the test binding system exceeds 500 N and is caused by ski flexure; (3) an 80 Hz resonance of the particular toe binding mechanism is excited; (4) combined impulsive loading is significant; (5) the loading is related to the maneuver type; (6) bending components during forward falls exceed the tibia flexural strength even though heel binding release occurs at the laboratory setting, and (7) torsion and bending components exceed tibia fracture levels during elementary ski maneuvers.

Athletic Injuries↗
PubMed1992

[New approaches in diagnosis and therapy of the thoracic outlet syndrome].

The results of diagnosis and treatment of the thoracic outlet syndrome (TOS) in 35 patients have been analysed. Compression of the subclavicular neurovascular bundle at the site of its outlet from the thoracic cavity was most frequent cause of TOS development. A degree of compression was assessed quantitatively by the data of a modified functional dynamic test. The modified operation, including resection of the I rib (and of a cervical one in its presence), scalene muscle, musculus pectoralis minor, periarterial sympathectomy of the subclavicular artery, was performed. In narrow (less than 1.5 cm) costoclavicular space, the II rib was additionally resected. An excellent long-term result is indicative of the effectiveness of the method.

Adolescent↗