[Computer-assisted evaluation of optically recorded biosignals from peripheral circulation].
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Blood Volume↗
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Neurocytoma arising in the pelvis.
Central neurocytoma represents a rare neoplasm of the central nervous system with advanced neurocytic and sometimes focal lipomatous differentiation, a low proliferative potential and a favorable prognosis depending on the efficiency of surgical resection. This entity has been described as an intraventricular tumor near the foramen Monroi. Here, we report a case of a 21-year-old male with peripheral neurocytoma. Using computed tomography, a tumor of unknown origin was located behind the bladder. After complete surgical resection of the tumor, histologically small uniform cells, zones of fibrillarity and neuropil-like islands were seen. Immunohistochemistry revealed positivity for the neuronal markers synaptophysin, neuron-specific enolase and neurofilaments. Vimentin, pan-keratin, desmin, chromogranin, CD-99 and glial fibrillary acidic protein were immuno-negative. A low proliferation rate (1-2%) was found. Several case reports described extraventricular central neurocytomas. A sole publication documented a peripheral neurocytoma arising within a mature cystic teratoma of the ovary. To our knowledge, this is the second reported case of a neurocytoma outside the central nervous system, indicating that this entity may also occur infrequently in peripheral tissues.
Adult↗
Cytokinetic analysis of the impaired proliferative response of peripheral lymphocytes from aged humans to phytohemagglutinin.
The effect of donor age on the rate of cell entry into the proliferating pool and subsequent cell cycle duration for peripheral lymphocytes stimulated by phytohemagglutinin (PHA) were examined by using the bromodeoxyuridine incorporation-differential staining technique. Distribution curves for the appearance of metaphase cells in successive generations as a function of culture time were obtained and analyzed both graphically and by a computer simulation model. Peripheral lymphocytes from aged individuals (approximately 75 yr) were stimulated by PHA at approximately one-half of the rate of peripheral lymphocytes from young individuals (approximately 21 yr). Subsequent cell-cycle durations were estimated to range from 10.0 to 25.0 h for aged individual lymphocyte cultures and 10.6-15.6 h for young individual lymphocyte cultures. The possible significance of these findings to aging in general is discussed.
Adult↗
Is a higher sampling rate desirable in the computer processing of the pediatric electrocardiogram?
A considerably large number of ECGs of pediatric patients had small notches and slurs on QRS complexes. By sampling these ECGs at higher rates, namely 4 KHz, it was shown that the higher rate data accurately reconstructed the notches and slurs on the QRS complex which were occasionally missed or distorted when the sampling rate was 250 Hz. When using the sampling rate of 250 Hz, it was observed that the reduction of the peak-to-peak amplitude of a QRS complex exceeded 0.1 mV in nearly 30 percent of tested cases, even if the ECG did not contain unwanted noise signals. Moreover, if there is relatively more noise in children's ECGs, one should reduce noise in such data in order to prevent measurement errors in the succeeding steps of the computer program. In such circumstances, the higher sampling rate would be preferable since filtering techniques which are used to reduce noise may considerably affect the estimation of the onset, offset and amplitude of the intrinsic ECG signals if the sampling rate is low. The reduction of the price of computers and their peripheral devices may facilitate the adoption of the higher sampling rate. From these considerations it was concluded that the use of the higher sampling rate might be both practical and an effective measure to enhance the diagnostic performance of the computer ECG systems.
Child↗
The effect of stimulus pulse duration on selectivity of neural stimulation.
Choice of stimulus parameters is an important consideration in the design of neural prosthetic systems. The objective of this study was to determine the effect of rectangular stimulus pulsewidth (PW) on the selectivity of peripheral nerve stimulation. Computer simulations using a cable model of a mammalian myelinated nerve fiber indicated that shorter PW's increased the difference between the threshold currents of fibers lying at different distances from an electrode. Experimental measurements of joint torque generated by peripheral nerve stimulation demonstrated that shorter PW's generated larger torques before spillover and created a larger dynamic range of currents between threshold and spillover. Thus, shorter PW's allowed more spatially selective stimulation of nerve fibers. Analysis of the response of a passive cable model to different duration stimuli indicated that PW dependent contributions of distributed sources to membrane polarization accounted for the observed differences in selectivity.
Animals↗
[Potentialities of temporal bone computed tomography in the study of the facial nerve and in the diagnosis of peripheral pareses of thr 7th pair of cranial nerves].
Computed tomography (CT) was used to examine 200 patients (400 temporal bones) aged 3 to 74 years who had no signs of facial nerve lesion and 28 patients who had clinical manifestations of peripheral paresis of the facial nerve of varying genesis. Multipositional CT of the temporal bone is the most informative mode of visualization of the fallopian canal which is embodied on tomographic scans in 100% of cases irrespective of the age of a patient. CT data indicate that the formation of the facial nerve canal brings to completion by the age of 6 years. The following causes of n. facialis paresis were identified: facial neuroma; sarcoma of the temporal bone sarcoma; dehiscence of the canal wall in otitis media acuta; destruction of the tympanic wall of the canal in otitis nedia chronica, fractures of the temporal bone, anomalies of the fallopian canal in temporal bone malformations; stenosis of the canal in fibrous dysplasia. The detected alterations of the n. facialis canal permits further policy of management of a patient to be defined.
Adolescent↗
The peripheral zone of increase density in cranial computed tomography.
The band of increased attenuation seen on in vivo CCT images of adults, frequently designated as the cerebral cortex, has been proved clinically and experimentally to be an artifact in the reconstructed image. Recognition of this artifact may be of help in identifying intracranial lesions, such as shallow subdural hematomas. Attenuation values of isolated cortex and white matter were also studied and do not account for the band of high attenuation.
Adult↗
[Fully automatic computer-analysis of electrocardiograms in clinical routine (author's transl)].
A fully automated Ecg recording and interpretation system (Hewlett Packard HP 5) consisting of a central computer and two peripheral units was evaluated during a four-month period. Ecgs were transmitted via public telephone lines, as was the report from central station to peripheral recording and print-out unit. Within a few seconds after recording and print-out unit. Within a few seconds after recording and transmission a preliminary report is available in printed format. The transmitted Ecgs are stored at the central computer and are being retrieved and evaluated manually there. Three cardiologists read the tracings and furnished final reports. 468 Ecgs were thus compared in our test time of 10 days for statistical evaluation with the following results: 1. 73.1% of all statements were read correctly by the computer. 2. There is a large range of diagnostic accuracy between 0% and 100%. 3. The evaluation of Ecg changed by cardiologists reflects the individual experience of the controllers regarding the Ecg statements as well as computer-dependent possibilities like modification etc. of Ecg. 4. As an example the diagnosis "myocardial infarction" is compared with other Ecg computer programs by means of a quality index calculated from sensitivity and specificity: HP 5 with 158.5 points reaches a similar level as the Pipberger program with 162.6 and the Bonner with 159.5 points. 5. Referring to false negative results this program is acceptable in all diagnostic groups with ca. 8%, except conduction defects with 17.7%. 6. Referring to false positive results the diagnostic groups myocardial infarction/ischemia and conduction defects are not satisfactory with 36.5% and 23.4%. 7. In all the tested system seems to be very useful in routine Ecg interpretation of bigger hospitals.
Cardiology↗
[Differential x-ray diagnosis of peripheral formations in the lungs using digital computers. II. Training programs, minimization of the number of signs, differential diagnosis].
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Computers↗
Screening for lung cancer.
PURPOSE OF REVIEW: With the development of newer forms of technology such as low-dose spiral computed tomography, there has been a resurgent interest in screening for lung cancer. The purpose of this review is to highlight recent advances in screening for lung cancer. Articles published since September 2002 are reviewed here. RECENT FINDINGS: More frequent screenings (every 4 or 6 months) showed increased mortality from lung cancer, compared with annual screening. A mass screening conducted in 1990 was effective in a case-control study. The results of lung cancer screening by low-dose spiral computed tomography were reported from the Milan group and the Mayo Clinic. Computed tomography depicted peripheral early lung cancer, especially adenocarcinoma. These results are consistent with previous reports from other groups. Screening with imaging becomes more sensitive with automated computerized methods. SUMMARY: A high percentage of stage IA lung cancers were detected by screening with low-dose helical computed tomography. The characteristics of the nodules detected by low-dose spiral computed tomography have been clarified. There have been many controversial discussions about cost effectiveness and overdiagnosis. There is still no evidence that screening tests reduce the rate of cancer-specific mortality. Several studies of screening for lung cancer are under way.
Adenocarcinoma↗
A comparison of a computer and pencil and paper assignment.
Colleges are challenged to provide students with diverse teaching-learning experiences. Educators who introduce new teaching-learning experiences must evaluate the outcomes of these experiences. Three faculty members instituted a new multimedia computer-based assignment for undergraduate nursing students enrolled in a pediatric clinical course and then evaluated their knowledge and satisfaction. Students were asked to design a computer program about peripherally inserted central catheters, and to complete tests and summaries. During two semesters, 45 students participated in the assignment. As compared to another group of students who were asked to participate in a pencil and paper independent study assignment, these students were more satisfied with their computer assignment. Students in both groups, however, produced thought-provoking work and improved their knowledge base about central catheters. In many ways, the results support the use of a computer assignment.
Adult↗
Initial blood pressure fall on stand up and exercise explained by changes in total peripheral resistance.
To elucidate the underlying mechanisms of the initial fall in blood pressure on standing upright from the supine position, we measured the beat-to-beat changes in intra-arterial pressure in eight healthy male subjects in response to standing. Changes in stroke volume, cardiac output, and total peripheral resistance were computed from the pressure waveform using a pulse contour method. To determine possible mechanisms for the changes observed on standing, similar measures were made on passive tilting and a brief (3-s) bout of cycle exercise. Standing elicited a transient 25% (23-mmHg) fall in mean blood pressure as a result of a 36% fall in total peripheral resistance. Head-up tilt elicited a gradual change in haemodynamic parameters, which reached plateau levels in 20-30 s. Cycling elicited a transient 17% (18-mmHg) fall in blood pressure and a 41% fall in total peripheral resistance. In addition, we measured right atrial and esophageal pressures in two subjects on standing and cycling and found a 10- to 15-mmHg rise in right atrial pressure without a corresponding change in esophageal pressure. This points to the cardiopulmonary reflex as the primary effector of peripheral vasodilation, but we cannot exclude the possibility that 1) local metabolic vasodilation and 2) central command-mediated cholinergic vasodilation contributed to the fall in vascular resistance.
Adult↗
Scanning laser ophthalmoscopy and angiography with a wide-field contact lens system.
OBJECTIVE: To perform fluorescein and indocyanine green angiography for large or peripheral chorioretinal structures using a contact lens system that provides a 5-fold increase in the field of view of a confocal scanning laser ophthalmoscope (SLO). METHODS: Separate handheld contact and noncontact ophthalmoscopic lenses were manually aligned with the optical axis of a confocal SLO to demonstrate the feasibility of wide-field SLO angiography. An integrated, wide-field contact lens system was then designed and constructed to increase the SLO's 10 degrees , 20 degrees , and 30 degrees imaging fields to 50 degrees , 100 degrees , and 150 degrees , respectively. RESULTS: Simultaneous fluorescein and indocyanine green angiography was performed with the integrated, wide-field contact lens system for more than 50 patients with disorders that affect their peripheral retina and choroid. Retinal and choroidal abnormalities, including neovascularization and capillary nonperfusion, are easily detected and documented well beyond the range of conventional fundus cameras and SLOs. Peripheral retinal and choroidal hemodynamics can be readily observed and recorded. CONCLUSIONS: A confocal SLO has adequate resolution for clinically useful reflectance and angiographic imaging even when its field size is increased 5-fold by a wide-field contact lens system. Dynamic and static wide-field angiography can be performed without the limitations of manual or computer-automated photomontages. Peripheral retinal conditions can be studied and recorded to confirm observations from indirect ophthalmoscopy and to facilitate retinal photocoagulation and vitreoretinal surgery.
Adult↗
Comparison of peripheral and portal routes of insulin infusion by a computer-controlled insulin infusion system (artificial endocrine pancreas).
This study was undertaken to determine the different consequences of portal and peripheral routes of insulin administration by the artificial endocrine pancreas. Intraportal glucose was infused (10 mg./min./kg. for 60 minutes) in anesthetized normal and pancreatectomized dogs while blood glucose concentrations were monitored continuously. During computer-controlled insulin administration normal glucose tolerance was restored by both portal and peripheral routes of insulin delivery. There were also no significant differences in (1) glycemic patterns, (2) insulin infusion patterns, (3) peripheral IRI levels, and (4) total insulin requirements between the two routes. It is apparent that the peripheral route, which is more readily accessible than the portal route, may be an appropriate infusion site for an implantable or portable prosthesis for controlling blood glucose concentration.
Animals↗
[Evaluation of the dose in permanent implants of I-125].
The Anderson's nomograph is currently used in 125I implants planning. For a given treatment volume, this method provides the activity and the seeds number and spacing. In order to obtain indications of the dose delivered in that 125I volume implants, we computed the average peripheral dose (APD), the average tumor dose (ATD) and the "matched peripheral dose" (MPD), for spherical, ellypsoidal and cylindrical volumes. By using the 125I source dosimetric data, we found that both the APD and the ATD are independent of sources randomizing in both position and orientation. Therefore the 125I seeds can be considered as point sources, provided that the dose values are scaled down by a factor which accounts for the spatial distribution anisotrophy. Since the computed parameters are only dependent on the implanted activity, the L. L. Anderson method can be applied even if brachytherapy treatments are associated with external beam radiotherapy ("boost"-therapy).
Brachytherapy↗
Computation of flow and heat transfer in rotating cavities with peripheral flow of cooling air.
Numerical solutions of the Navier-Stokes equations have been used to model the flow and the heat transfer that occurs in the internal cooling-air systems of gas turbines. Computations are performed to study the effect of gap ratio, Reynolds number and the mass flow rate on the flow and the heat transfer structure inside isothermal and heated rotating cavities with peripheral flow of cooling air. Computations are compared with some of the recent experimental work on flow and heat transfer in rotating-cavities. The agreement between the computed and the available experimental data is reasonably good.
Journal Article↗
Association of peripheral total and differential leukocyte counts with metabolic syndrome and risk of ischemic cardiovascular diseases in patients with type 2 diabetes mellitus.
BACKGROUND: There is increasing evidence that leukocytes play a central role in obesity, glucose intolerance, type 2 diabetes mellitus (T2DM), and cardiovascular diseases, but the role of differential leukocytes in metabolic syndrome (MetS) and atherosclerosis is largely unknown. The aim of this study was to examine the relationship between the component features of MetS and peripheral leukocyte counts and to explore whether leukocyte counts are associated with clustering of MetS and macrovascular diseases in patients with T2DM. METHODS: 1872 subjects with T2DM who enrolled in a diabetes disease management program were studied. The definition of MetS was modified from that outlined by the criteria of NCEP-ATP III. Areas under the receiver-operating characteristic curve and odds ratios at various intervals of the WBC counts were computed. RESULTS: The peripheral total leukocyte, monocyte, and neutrophil cell counts are increased parallel to the clustering of components of MetS. When white cell counts were analyzed per quartile and as continuous variables after adjustment for age, sex, and other known risk factors with multiple regression analysis, peripheral total leukocyte, monocyte, neutrophils, and lymphocyte counts were independently and significantly associated with specific features of clustering of MetS and prevalence of ischemic cardiovascular diseases. Leukocyte counts, especially neutrophil/lymphocyte ratio, in addition with MetS is associated with the risk of ischemic cardiovascular diseases. CONCLUSION: Our results indicate that differential leukocyte counts are associated with MetS and that peripheral leukocytes may play a role in the pathogenesis of macrovascular complications in patients with T2DM.
Aged↗
Temporal and spatial complexity measures for electroencephalogram based brain-computer interfacing.
There has been much interest recently in the concept of using information from the motor cortex region of the brain, recorded using non-invasive scalp electrodes, to construct a crude interface with a computer. It is known that movements of the limbs, for example, are accompanied by desynchronisations and synchronisations within the scalp-recorded electroencephalogram (EEG). These event-related desynchronisations and synchronisations (ERD and ERS), however, appear to be present when volition to move a limb occurs, even when actual movement of the limb does not in fact take place. The determination and classification of the ERD/S offers many exciting possibilities for the control of peripheral devices via computer analysis. To date most effort has concentrated on the analysis of the changes in absolute frequency content of signals recorded from the motor cortex. The authors present results which tackle the issues of both the interpretation of changes in signals with time and across channels with simple methods which monitor the temporal and spatial 'complexity' of the data. Results are shown on synthetic and real data sets.
Computer User Training↗