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PubMed1996

Infection after open reduction and internal fixation with dynamic compression plates--clinical and experimental data.

Infection rates for open reduction and internal fixation (ORIF) with the DCP in clinical studies are based on heterogeneous data on general risk factors and do not take into account the direct effect of the implant (material, design, surface, technique). The initial degree of bacterial contamination is generally unknown and the applied definition of the term infection is not mentioned. In our own prospective randomized clinical study including 281 cases of ORIF with the DCP (154 steel vs 127 titanium), the influence of the implant material on susceptibility to local infection was examined in relation to initial bacteria contamination (109 non-contaminated / 172 contaminated). Although in the group of contaminated DCPs the difference in the infection rates for stainless steel (sSt) and commercially pure titanium (cpTi) showed no statistical significance, a tendency was apparent. In an animal experiment, the lower rates of infection for c.p.Ti-DCP compared to sSt-DCP in the presence of a local bacterial challenge could be demonstrated with statistical significance. The need for further experimental research in the field of implant related local infection after ORIF will be discussed and strategies for further investigations proposed.

Animals↗
PubMed1977

Evaluation of polymeric materials for maxillofacial prosthetics.

The methods for initial evaluation of a new prospective maxillofacial prosthetic material, MDX-4-4210, have been described and tensile and compressive test data have been obtained. Evaluation of the data indicates that this is a promising material with significant potential for use in maxillofacial prosthetics. Further studies of the material's biologic implant compatibility, its chemical and environmental stabilities, and its clinical performance are being done.

Elasticity↗
PubMed1989

Aortic diameter and pressure-flow sequence identify mechanism of blood flow during external chest compression in dogs.

Aortic flow and pressure relations and aortic diameter were examined during sinus rhythm, internal cardiac massage, vest cardiopulmonary resuscitation, conventional manual cardiopulmonary resuscitation and high impulse manual cardiopulmonary resuscitation in 14 anesthetized large dogs. During sinus rhythm and during internal cardiac massage, ascending aortic flow and pressure increased simultaneously and the rise in ascending aorta pressure preceded the rise in descending aortic pressure by (mean +/- SEM) 28 +/- 4 and 30 +/- 1 ms, respectively. In contrast, during vest, conventional and high impulse cardiopulmonary resuscitation, ascending aortic flow lagged behind the initial rise in aortic pressure by 40 +/- 4 to 46 +/- 4 ms and ascending and descending aortic pressure increased simultaneously (p less than 0.001 for each external compression mode versus sinus rhythm and internal massage). The ratio of pulse pressure to stroke volume increased by an order of magnitude during all modes of external chest compression (p less than 0.001 versus sinus rhythm and internal massage) and aortic diameter decreased during vest and high impulse cardiopulmonary resuscitation (p less than 0.05 versus sinus rhythm and internal massage). The hemodynamics of external chest compression depart from the normal physiologic sequence of stroke volume-induced increase in aortic pressure and diameter. The rise in aortic pressure precedes flow into the aorta, stroke volume does not fully account for pulse pressure, and aortic diameter decreases during chest compression. These data support the hypothesis that blood flow is due to fluctuations in intrathoracic pressure for high impulse as well as vest and conventional cardiopulmonary resuscitation.

Animals↗
PubMed2002

Non-blood contacting biventricular support for severe heart failure.

BACKGROUND: Direct mechanical ventricular actuation (DMVA) is a non-blood contacting method of biventricular support. DMVA employs a vacuum attached, pneumatically regulated, flexible membrane to transfer both systolic and diastolic forces to the ventricular myocardium. The purpose of this study was to determine if DMVA effectively restores pump performance when applied to the severely failing heart. METHODS: Bovines (n = 10) underwent thoracotomy and were instrumented for continuous hemodynamic monitoring. Cardiac failure was induced by beta1-blockade to achieve a cardiac index of < 1.5 l/min/m2 for 1 hour. Heart rate was maintained at 100 bpm by atrioventricular sequential pacing. Synchronous DMVA support was then applied for 3 hours. RESULTS: Eight animals achieved significant reductions in cardiac index and mean arterial pressures (35%* and 43%* control, respectively; *p < 0.05). DMVA restored cardiac index to baseline and significantly increased arterial pressures (p < 0.05; DMVA versus cardiac failure). Pulmonary flow and mean pulmonary artery pressures were similar to baseline during DMVA (p = NS). Pathologic exam did not demonstrate evidence of significant device trauma. CONCLUSIONS: DMVA support can effectively restore pump performance of the acutely failing heart. Synchronization may be inherent to the stimulus of cardiac compression. These data further substantiate DMVA's potential as an adjunct to the field of circulatory support.

Animals↗
PubMed1999

Confined and unconfined stress relaxation of cartilage: appropriateness of a transversely isotropic analysis.

Previous studies have shown that stress relaxation behavior of calf ulnar growth plate and chondroepiphysis cartilage can be described by a linear transverse isotropic biphasic model. The model provides a good fit to the observed unconfined compression transients when the out-of-plane Poisson's ratio is set to zero. This assumption is based on the observation that the equilibrium stress in the axial direction (deltaz) is the same in confined and unconfined compression, which implies that the radial stress deltar = 0 in confined compression. In our study, we further investigated the ability of the transversely isotropic model to describe confined and unconfined stress relaxation behavior of calf cartilage. A series of confined and unconfined stress relaxation tests were performed on calf articular cartilage (4.5 mm diameter, approximately 3.3 mm height) in a displacement-controlled compression apparatus capable of measuring delta(z) and delta(r). In equilibrium, delta(r) > 0 and delta(z) in confined compression was greater than in unconfined compression. Transient data at each strain were fitted by the linear transversely isotropic biphasic model and the material parameters were estimated. Although the model could provide good fits to the unconfined transients, the estimated parameters overpredicted the measured delta(r). Conversely, if the model was constrained to match equilibrium delta(r), the fits were poor. These findings suggest that the linear transversely isotropic biphasic model could not simultaneously describe the observed stress relaxation and equilibrium behavior of calf cartilage.

Animals↗
PubMed1997

Experimental induction of equine protozoal myeloencephalitis in horses using Sarcocystis sp. sporocysts from the opossum (Didelphis virginiana).

Sarcocystis sp. sporocysts isolated from eight feral opossums (Didelphis virginiana) were pooled and fed to 18 commercially reared budgerigars (Melopsittacus undulatus), 14 wild-caught sparrows (Passer domesticus), one wild-caught slate-colored Junco (Junco hyemalis) and five weanling horses (Equus caballus). All budgerigars died within 5 weeks post inoculation (wpi). Histologic examination revealed meronts within the pulmonary epithelia and typical Sarcocystis falcatula sarcocysts developing in the leg muscles. Sparrows were euthanized 13 and 17 wpi and their carcasses were fed to four laboratory raised opossums. Sporocysts were detected in the feces of two opossums on 15 days post inoculation (dpi) and in a third opossum on 40 dpi. Fecal samples from the fourth opossum remained negative; however, sporocysts were found in intestinal digests from all four opossums. Sporocysts were not found in feces or intestinal digest of an additional opossum that was fed three uninoculated sparrows. Five foals were fed sporocysts (Foals 2, 3, 4, 5, and 7) and two foals were maintained as uninoculated controls (Foals 1 and 6). Sporocysts from two additional feral opossums also were fed to foals. Foal 5 was given 0.05 mg kg-1 dexamethasone sodium phosphate daily beginning 2 days before inoculation for a total of 2 weeks. Horse sera were tested three times per week, and cerebrospinal fluid (CSF) samples were tested biweekly for anti-Sarcocystis neurona antibodies by Western blot analysis. No foals had any S. neurona-specific antibodies by Western blot analysis prior to sporocysts ingestion. Seroconversion occurred in Foals 3, 5, and 7 by 24 dpi, followed by positive CSF tests on 28 dpi. Foals 2 and 4 seroconverted by 40 dpi. Cerebrospinal fluid from Foal 2 tested positive by 42 dpi, but Foal 4 remained seronegative throughout the study. Sera and CSF from control Foals 1 and 6 remained seronegative. All foals with positive CSF developed neurologic clinical signs. Neurologic disease was evident in Foals 2 and 3 by 42 dpi and in Foal 7 by 28 dpi. The severity of clinical signs progressed to marked spasticity, hypermetria and ataxia in Foal 7 by the end of the trial. Necropsy examination of inoculated foals did not reveal gross lesions; however, microscopic lesions consistent with equine protozoal myeloencephalitis (EPM) were found in Foals 2, 3, and 7. Protozoa were not observed in the tissue sections. Microscopic lesions consistent with EPM were not found in Foals 4 and 5 or in uninoculated control Foals 1 and 6. Foal 5 had unilateral non-inflammatory lesions in the cervical and thoracic spinal cord consistent with cord compression. These data indicate that the opossum is a definitive host of S. neurona.

Animals↗
PubMed1982

Internal carotid blood flow velocity in children with cerebral palsy by Doppler Ultrasound method.

Cerebral blood flow assessed noninvasively by Doppler ultrasound technique in 30 children with cerebral palsy. The average maximal blood velocity (A/L) and end-diastolic blood velocity (d) of internal carotid artery were measured before and during brief digital compression of contralateral common carotid artery. Both A/L and d values in children with cerebral palsy were significantly lower than those observed in normal healthy children. In 13 children with spastic hemiplegia, no significant difference in either A/L or d was seen between the non-affected side and affected side both before and during brief digital compression. This data suggests that mean cerebral blood flow decreases in our children with cerebral palsy, and that no lateralization of the decrease in hemispheric cerebral circulation in hemiplegic children may explain by supposing the existence of generalized bilateral brain damage in those subjects.

Adolescent↗
PubMed2002

Venous leg ulcer pain and its characteristics.

This study investigated the prevalence, severity and characteristics of pain associated with venous leg ulceration. Sixty-five patients suffering with venous leg ulceration were randomised to one of three treatment groups over a 12-week treatment period. All patients received short-stretch compression bandaging. Data were collected by use of a visual analogue scale and the McGill Pain Questionnaire. Seventy per cent of patients reported pain on entry to the study and within 2 weeks of effective treatment initial pain was dramatically reduced. Patients typically described their pain as throbbing, sharp, itchy, sore and tender. The affective nature of pain was often described as tiring and patients evaluated their pain as being annoying and nagging. This study highlights the importance of pain associated with venous leg ulceration.

Adult↗
PubMed2002

Paraphrasing for condensation in journal abstracting.

When authors of empirical science articles write abstracts, they employ a wide variety of distinct linguistic operations which interact to condense and rephrase a subset of sentences from the source text. An on-going comparison of biological and biomedical journal articles with their author-written abstracts is providing a basis for a more linguistically detailed model of abstract derivation using syntactic representations of selected source sentences. The description makes use of rich dictionary information to formulate paraphrasing rules of differing degrees of generality, including some which are sublanguage-specific, and others which appear valid in several languages when formulated using "lexical functions" to express important semantic relationships between lexical items. Some paraphrase operations may use both lexical functions and rhetorical relations between sentences to reformulate larger chunks of text in a concise abstract sentence. The descriptive framework is computable and utilizes existing linguistic resources.

Abstracting and Indexing↗
PubMed2003

Development of an emergency medical video multiplexing transport system. Aiming at the nation wide prehospital care on ambulance.

The Emergency Medical Video Multiplexing Transport System (EMTS) is designed to support prehospital cares by delivering high quality live video streams of patients in an ambulance to emergency doctors in a remote hospital via satellite communications. The important feature is that EMTS divides a patient's live video scene into four pieces and transports the four video streams on four separate network channels. By multiplexing four video streams, EMTS is able to transport high quality videos through low data transmission rate networks such as satellite communications and cellular phone networks. In order to transport live video streams constantly, EMTS adopts Real-time Transport Protocol/Real-time Control Protocol as a network protocol and video stream data are compressed by Moving Picture Experts Group 4 format. As EMTS combines four video streams with checking video frame numbers, it uses a refresh packet that initializes server's frame numbers to synchronize the four video streams.

Ambulances↗
PubMed2003

Development of an Emergency Medical Video Multiplexing Transport System (EMTS): aiming at the nation-wide prehospital care in ambulance.

The Emergency Medical Video Multiplexing Transport System (EMTS) is designed to support prehospital care by delivering high quality patient's live video streams in an ambulance to emergency doctors in a remote hospital on the basis of satellite communications. The feature is that EMTS divides a patient's live video scene into four pieces and transports the four video streams on four separate network channels. By multiplexing the four video streams, EMTS is able to transport high quality videos through low data transmission rate networks such as satellite communications and cellular phone networks. In order to transport live video streams constantly, EMTS adopts Real-Time Transport Protocol/Real-Time Control Protocol as a network protocol, and video stream data are compressed by Moving Picture Experts Group 4 format. As EMTS combines four video streams with checking video frame numbers, it uses a refresh packet that initializes server's frame numbers to synchronize the four video streams.

Ambulances↗
PubMed2000

Fred Hollows lecture: digital screening for eye disease.

The purpose of this study was to explore progress, in the adaptation to community screening for blinding eye disease, of digital imaging devices and technology for storage and transmission. Available imaging systems were compared to gold standard clinical photography in terms of sensitivity and specificity for diagnosis of common blinding eye conditions. Since the use of expensive non-portable imaging devices is likely to be limited for widespread community screening purposes, a portable fundus camera (Nidek, Chiyoda-ku, Japan) and a prototype monocular digital indirect ophthalmoscope constructed at the Lions Eye Institute (LEI) were selected for comparative trials for the screening of optic disc cupping, glaucoma and clinical signs of diabetic retinopathy. Fifty-one eyes of 27 consecutive patients being assessed at the LEI clinic for glaucoma were dilated and photographed with a Zeiss retinal camera, and digital images were taken with the portable Nidek NM100 fundus camera (Carl Zeiss, Oberkochen, Germany) or with a prototype digital monocular indirect ophthalmoscope. Vertical cup: disc ratios (VCDR) were measured on the disc photographs by one ophthalmologist while three other clinicians were presented with compressed digital images in random order to estimate VCDR. Field trials were also carried out to demonstrate the practicality of compression, local storage and then transmission by mobile telephone ISDN lines and satellite, of optic discs and fundus images of patients with diabetes in either rural Western Australia or Surabaya, Indonesia. Kappa values of correlations of measurement of agreement between measured and estimated VCDR were 0.87, 0.45 and 0.84, respectively, for the three observers, corresponding to a specificity of 79-97% and a sensitivity of 70-95%. The portable Nidek fundus camera was also assessed for specificity and sensitivity in the diagnosis of diabetic retinopathy in comparison to standard Zeiss fundus camera photographs. Of 49 eyes in 25 consecutive patients attending the LEI clinic for assessment of diabetic retinopathy, three ophthalmologists assessed photographs and images in random order. When used for screening diabetic retinopathy, the digital images of the Nidek camera were graded as adequate quality in only 56% of eyes compared to 93% of the photographs. The kappa value of agreement in analysis of diabetic retinopathy was only 0.30. The prototype digital monocular indirect ophthalmoscope compared favourably with the Nidek camera. At 1:5 compression, images of size 36 kB transmitted from Surabaya to Perth took 29 s on the mobile telephone, while uncompressed images took 170 s. Images compressed 1:5 were transmitted in 60 s using the satellite telephone, while the uncompressed images took 240 s. Satellite transmission was more expensive but the lines were more stable than telephone connections from Indonesia. Digital imaging is becoming a powerful tool for ophthalmology in clinical records, teaching and research, and interoffice diagnostic opinions. It also has enormous potential for community screening for blinding eye diseases, such as glaucoma and diabetic retinopathy. Inexpensive portable imaging devices that are easy to use, and on which local health workers might be trained, must be developed and validated in terms of sensitivity and specificity of performance. The technology of image capture, image compression, transmission, data base storage and analysis is rapidly evolving and becoming less expensive.

Diabetic Retinopathy↗
PubMed2001

Directional bonding in compacted microcrystalline cellulose.

The mechanical properties of compacts of microcrystalline cellulose (MCC) and silicified microcrystalline cellulose (SMCC) were evaluated by tensile testing, diametric compression testing, and compression testing. For tensile and compression testing, cubic specimens were carefully machined from MCC and SMCC compacts, and the tensile and compression strengths were evaluated both normal and parallel to the compaction direction. The cubic tensile strengths were compared to values obtained from the diametric compression test. The results obtained using the diametric compression test suggested compacts of SMCC exhibit greater strength than those of MCC. In addition, the cubes machined from compacts of MCC and SMCC exhibited directional strength; the direction normal to the compaction direction display ed the greater tensile strength, and the parallel direction had greater compression strength. The diametric compression test afforded strength values with reduced spread compared to the values collected from the cubic tensile test, suggesting that the errors involved in collecting diametric compression test data of compacts are less than those for the cubic tensile test. Analysis of the cubes using X-ray diffraction (XRD) suggested that they display directional structural anisotropy, with the direction normal to the compaction direction being more crystalline than the parallel direction. However, it is not clear whether the difference in the directional strength is solely a consequence of the increased crystallinity or a culmination of crystallographic and mechanical keying effects.

Algorithms↗
PubMed2002

Using personal digital assistants to access drug information.

The use of personal digital assistants (PDAs) to access drug information in a health system is described. Given the widespread use of PDAs at an 872-bed university health system, an opportunity existed to provide current drug information to physicians via these devices. As part of the health system's intranet, extensive online content had been made available through a browser; extension to PDAs was a natural next step. There were two primary requirements: the ability to synchronize information with the database server when a PDA was used and the development of content and applications by using existing staff. Mobile enterprise software was chosen that supports multiple PDA platforms, is easy to use, and does not require programming skills. The software works through customized "channels," or collections of information from a content provider. The customized channel service works over the Internet. Two channels of content were created, an ambulatory care channel and an inpatient care channel. The ambulatory care channel contains a list of preferred ambulatory care agents, poison control information, the locations of outpatient pharmacies, drug information, and safety tips for prescribing. The inpatient channel contains the inpatient formulary, current news and events, information on currrent drug shortages and recalls, pharmacy contact information, and medication safety tips. When a user synchronizes his or her PDA, the software contacts the department's intranet servers and processes the request. The data are compressed and downloaded to the user's PDA. A university health system successfully used PDAs to access drug and other information.

Clinical Pharmacy Information Systems↗
PubMed1994

Trends in firearm suicide among older American males: 1979-1988.

Elderly men are more likely to commit suicide than any other age group in the United States. Moreover, their rate of suicide steadily increased between 1979 and 1988. National Center for Health Statistics (NCHS) Compressed Mortality data were used to perform an age-specific analysis of linear trends. Males 65 and over were the most likely to use firearms followed by those 55-64. In 1988, nearly 8 out of 10 suicides by males 65 and over were committed with a firearm. Firearm-related suicide rates were much lower for blacks than whites 65 and over; however, suicides among blacks were more likely to involve firearms than among whites in this age group. The authors call for a broad public policy effort directed at reducing the availability of firearms.

Adolescent↗
PubMed1995

Reasons for the weak correlation between prostate volume and urethral resistance parameters in patients with prostatism.

In an attempt to increase our understanding of the clinical syndrome of benign prostatic hyperplasia (BPH) an analysis was made of the association between prostate volume as measured by transrectal ultrasound and several reported urodynamically determined urethral resistance parameters. Two types of obstruction can be recognized on the basis of urodynamic data: a compressive type characterized by a high urethral opening pressure and a prolonged isovolumetric contraction phase before urine flow can start, and a constrictive type characterized by a normal opening pressure and an increased slope of the urethral resistance relation. A combination of both types is often seen in BPH. In our study, parameters that selectively quantify compression correlate weakly to moderately with prostate volume, whereas parameters that mainly quantify constriction do not correlate at all with prostate volume. Parameters that combine a measure for compression and constriction correlate less well with prostate volume than parameters that mainly quantify compression. The variation in prostate volume was found to determine the variation in urethral resistance by 15% or less depending on the parameter used, which implies that the different pathophysiological mechanisms that can increase urethral resistance in the complex process of clinical BPH are mainly determined by factors other than the volume of the prostate. Thus, despite the lack of correlation between prostate volume and urethral resistance, pressure-flow studies and the determination of urethral resistance parameters provide a valuable contribution to the understanding of the pathophysiology of voiding dysfunction in men with symptoms of prostatism.

Adult↗
PubMed1998

Distortion-product otoacoustic emission monitoring of cochlear blood flow.

Distortion-product otoacoustic emissions (DPOAEs) have been shown to be ideally sensitive to interruptions of the cochlear blood flow. However, a 15- to 30-second latency typically occurs between cessation of circulation and measurable DPOAE level changes. DPOAEs can also be characterized by phase measures. The aim of the present study was to determine in 10 rabbits the effects on DPOAE phase of repetitively compressing the internal auditory artery. In contrast to the delays measured by DPOAE level, phase changes were detected 1 to 5 seconds after internal auditory artery compression. These data suggest that the essentially "real time" monitoring of cochlear function with DPOAE phase can be used to ensure hearing preservation during surgery involving the porus acousticus and skull base.

Acoustic Stimulation↗
PubMed1997

A model for chronic nerve root compression studies. Presentation of a porcine model for controlled, slow-onset compression with analyses of anatomic aspects, compression onset rate, and morphologic and neurophysiologic effects.

STUDY DESIGN: Compression onset rate, anatomic aspects, and morphologic and neurophysiologic effects in spinal nerve roots were studied in a nerve root compression model in pigs. OBJECTIVES: To analyze the compression onset rate by measuring the gradual reduction of the inner diameter of the constrictor, the motor nerve conduction velocity by electromyography, the morphologic changes by light microscopy, and the gross and vascular anatomy by dissection and ink injections, respectively, in a model for experimental chronic nerve root compression. SUMMARY OF BACKGROUND DATA: Chronic nerve root compression is recognized to be related to back pain syndromes, including sciatica. Various aspects of morphologic and physiologic changes have been studied previously in models for acute compression and chronic nerve root irritation, but a controlled, graded chronic nerve root compression model has not been described. METHODS: An ameroid constrictor was applied around a spinal nerve root just cranial to the dorsal root ganglion. The inner diameter of this constrictor gradually becomes reduced. After 1 week or 4 weeks, electromyographic measurements were performed, and tissue samples were harvested for histologic analyses. The gross and vascular anatomy of the pigs' spinal nerve roots were studied by dissection and ink injections. RESULTS: There was a statistically significant decrease in the nerve conduction velocity in compressed compared with noncompressed spinal nerve roots after 1 week and after 4 weeks. The ameroid constrictors induced nerve fiber damage, endoneural hyperemia, bleeding, and inflammation at the compression zone. There was often a severe reduction in the number of myelinated fibers after 4 weeks. CONCLUSION: A model for controlled, chronic, partial nerve root injury using a gradual compression-onset constrictor is presented. This model allows for induction of a controlled graded chronic nerve root injury and can be used for research on basic pathophysiologic mechanisms and on the effects of various interventions on nerve root injury development.

Animals↗