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1.
Using a parallel implementation of the multi-state Kalman filtering algorithm, we have developed an accurate method of reliably detecting and identifying trends, abrupt changes, and artifacts from multiple physiologic data streams in real-time. The Kalman filter algorithm was implemented within an innovative software architecture for parallel computation: a parallel process trellis. Examples, processed in real-time, of both simulated and actual data serve to illustrate the potential value of the Kalman filter as a tool in physiologic monitoring.  相似文献   
2.
We have created BIO-SPEAD (pronounced speed), a BIOlogical Signal Processing Environment for Algorithm Development. BIO-SPEAD is designed to accelerate development of complex algorithms which integrate information derived from single or multiple physiologic waveforms. BIO-SPEAD currently performs all of the basic analyses of several arterial blood pressure waveforms, and allows the user to utilize the results of those low-level analyses for development of more complex algorithms. We utilized a parallel programming architecture called the Process Trellis which keeps the different tasks, or processes, within BIO-SPEAD independent of each other. Additionally, we have developed a graphics interface to enable the user to visualize the waveform under analysis, the low-level system analysis, and the internal workings of the algorithm under development. The system has been used for several algorithm development projects and has demonstrated its utility.  相似文献   
3.
A morphologic study of the small (50 to 200 micron) intramyocardial coronary arteries was performed. The cases chosen for study were selected from a relatively young group of patients without clinical evidence of alcoholic cardiomyopathy or pathologic evidence of large coronary artery disease, in order to evaluate alterations in the small vessels which could possibly be attributed to the chronic alcoholic state. Five basic vascular abnormalities were described. The most common alteration found in all nine cases was vascular wall edema (48 per cent), followed by perivascular fibrosis (42 per cent), vascular sclerosis (36 per cent), subendothelial humps (13 per cent), and vascular wall inflammation (11 per cent). The significance and pathogenesis of these changes were discussed. Primary endothelial cell damage was proposed as a common pathogenic mechanism for all five types of vascular abnormality. It was suggested that following endothelial damage, fluid and macromolecules penetrate into the vessel wall or into the perivascular space where, by incompletely understood processes, they induce vascular wall myocytes to produce collagen, elastin, and basement membrane-like substances. Evidence supporting this mechanism was derived from the common observation of vascular wall edema, from the occasional presence of erythrocytes and leukocytes within the vessel wall, and from experimental data in the literature. Several possible etiologic agents were implicated in the pathogenesis of endothelial and vessel wall injury. These included alcohol itself, acetaldehyde, biogenic amines, and magnesium deficiency. It is probable, however, that there are multiple etiologic factors which affect the small cardiac vessels of the chronic alcoholic. Finally, the proposal was advanced that the nonspecific pathology of the myocardium in chronic alcoholism may be a result of ischemia secondary to disease of the small intramyocardial coronary ateries.  相似文献   
4.
The gastrointestinal hormone, glucagon-like peptide-1(7-36)amide (GLP-1) is released after a meal. The potency of synthetic GLP-1 in stimulating insulin secretion and in inhibiting glucagon secretion indicates the putative physiological function of GLP-1. In vitro, the nonmammalian peptide, exendin(9-39)amide [ex(9-39)NH2], is a specific and competitive antagonist of GLP-1. This in vivo study examined the efficacy of ex(9-39)NH2 as an antagonist of exogenous GLP-1 and the physiological role of endogenous GLP-1. Six healthy volunteers underwent 10 experiments in random order. In each experiment, a 30-min period of euglycemia was followed by an intravenous infusion of glucose for 150 min that established a stable hyperglycemia of 8 mmol/liter. There was a concomitant intravenous infusion of one of the following: (1) saline, (2) GLP-1 (for 60 min at 0.3 pmol . kg-1 . min-1 that established physiological postprandial plasma levels, and for another 60 min at 0.9 pmol . kg-1 . min-1 to induce supraphysiological plasma levels), (3-5) ex(9-39)NH2 at 30, 60, or 300 pmol . kg-1 . min-1 + GLP-1, (6-8) ex(9-39)NH2 at 30, 60, or 300 pmol . kg-1 . min-1 + saline, (9 and 10) GIP (glucose-dependent insulinotropic peptide; for 60 min at 0.8 pmol . kg-1 . min-1, with saline or ex(9-39)NH2 at 300 pmol . kg-1 . min-1). Each volunteer received each of these concomitant infusions on separate days. ex(9-39)NH2 dose-dependently reduced the insulinotropic action of GLP-1 with the inhibitory effect declining with increasing doses of GLP-1. ex(9-39)NH2 at 300 pmol . kg-1 . min-1 blocked the insulinotropic effect of physiological doses of GLP-1 and completely antagonized the glucagonostatic effect at both doses of GLP-1. Given alone, this load of ex(9-39)NH2 increased plasma glucagon levels during euglycemia and hyperglycemia. It had no effect on plasma levels of insulin during euglycemia but decreased plasma insulin during hyperglycemia. ex(9-39)NH2 did not alter GIP-stimulated insulin secretion. These data indicate that in humans, ex(9-39)NH2 is a potent GLP-1 antagonist without any agonistic properties. The pancreatic A cell is under a tonic inhibitory control of GLP-1. At hyperglycemia, the B cell is under a tonic stimulatory control of GLP-1.  相似文献   
5.
Transforming growth factor beta-1 (TGF-beta1) is a potent inhibitor of hepatocyte growth both in vivo and in vitro. In this study, we analyzed the effects of TGF-beta1 on both naturally occurring and diethylnitrosamine-induced hepatocarcinogenesis using single transgenic TGF-beta1 and double transgenic c-myc/TGF-beta1 mice in which the expression of both transgenes was targeted to the liver. Hepatocellular tumors developed spontaneously in 59% (10 of 17) of the TGF-beta1 mice by 16-18 months of age. Coexpression of TGF-beta1 and c-myc transgenes in the liver accelerated hepatic tumor growth in both the presence and absence of carcinogenic treatment. Moreover, diethylnitrosamine-initiated tumors in the c-myc/TGF-beta1 mice showed a high rate of malignant conversion associated with a reduced expression or lack of TGF-beta receptor type II. The results suggest that overexpression of TGF-beta1 may contribute to liver carcinogenesis and that loss of TGF-beta receptor type II transduced inhibitory growth signals and up-regulation of c-myc are critical steps in liver tumor progression.  相似文献   
6.
We have recently shown that overexpression of c-myc and transforming growth factor alpha (TGF-alpha) in the liver of double-transgenic mice results in severe DNA damage, aberrant hepatic growth, and development of tumors at a much younger age than that observed in c-myc single-transgenic mice. We now report that double-transgenic TGF-alpha/c-myc hepatocytes rapidly lose their ability to proliferate upon mitogenic stimulation following partial hepatectomy (PH). At 4 weeks of age, the overall rate of bromodeoxyuridine (BrdU) incorporation following PH was comparable in c-myc and TGF-alpha/c-myc livers and exceeded that seen in wild-type (WT) mice. However, by 10 weeks of age, c-myc single-transgenic hepatocytes showed proliferative advantages over the WT cells, whereas TGF-alpha/c-myc double-transgenic hepatocytes had a decreased capacity to proliferate upon mitogenic stimulation. This decreased proliferative response was accompanied by a reduction in the total fraction of proliferating hepatocytes, as well as by a decline in the induction of cyclin A, cyclin B, and cdc2 gene expression. These data show that constitutive coexpression of c-myc and TGF-alpha accelerates age-related loss in the regenerative potential following PH, and suggest that early replicative senescence of differentiated hepatocytes may have a role in providing a selective growth advantage to initiated cell populations in this model.  相似文献   
7.
A selection of WC-Co and Cr3C2-25%NiCr coatings deposited by plasma spraying and high velocity oxygen fuel (HVOF) were tested. The microstructures of the coatings were characterized, and their mechanical properties were assessed using Knoop microindentation procedures. The coatings were also subjected to various wear tests. All of the coatings were at least 200 μm thick and were deposited onto stainless steel substrates. The wear tests simulated abrasion, cavitation wear, sliding wear, and particle erosion wear. In this first part of a two-part contribution, the microstructures of the coatings are characterized and a discussion on the evaluation of mechanical properties from the microindentation response is presented. The nature of microhardness testing as applied to thermal spray coatings is evaluated as a means of assessing resistance to plastic flow, elasticity, and brittleness. In Part 2, the results of the various wear simulations are reported, and the utility of microhardness as an indicator of wear resistance is examined.  相似文献   
8.
Informed by research over the past two years and the work of colleagues in peer institutions, the IFI Irish Film Archive developed a six-year Digital Preservation and Access strategy which launched in 2014. Fundamental to this Strategy was the design and installation of digital archive tools for long term preservation and the redesign of workflow practices to facilitate accession and management of high resolution digital film and broadcast assets and associated metadata. This article outlines the steps taken and standards applied in developing a future proof digital audiovisual archive.  相似文献   
9.
A 6-week-old male infant with a capillary hemangioma of the right atrioventricular groove adjacent to the right coronary artery and conduction system underwent successful resection with the aid of microneurosurgical instrumentation. The technical challenge was thought to be analogous to that encountered by microneurosurgeons in their dissection of brain tumors.  相似文献   
10.
Bilateral peripeduncular (PPN) lesions made on the 7th postpartum day (L7) with either radiofrequency (RF) current or N-methyl-d,l-aspartic acid (NMDA)/phosphate buffered saline (PBS) reduced maternal aggression (MA) and partially inhibited lactation without producing significant deficits in other items of maternal behavior (MB). RF-PPN lesions did not interfere with prolactin secretion, which suggests that there was deficient oxytocinergic activity. The deficit in MA was not due to interruption of afferent suckling input to the PPN: either thelectomizing females (Day L6) or producing bilateral knifecuts in the mesencephalon (placed caudal to the level of the PPN; Day L7) had no effect on MA, but both procedures impaired lactation. Deficits in MA produced by RF-PPN lesions developed gradually between Days L4 and L7; lesions made either prepartum or on Day L1 did not impair MA or MB. Deficits in lactation first appeared after RF-PPN lesions on Day L1. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
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