William E. Blevins

Bio: William E. Blevins is an academic researcher from Purdue University. The author has contributed to research in topics: Self-healing hydrogels & Metrizamide. The author has an hindex of 21, co-authored 67 publications receiving 1858 citations. Previous affiliations of William E. Blevins include University of Illinois at Urbana–Champaign.

Small Intestinal Submucosa as a Small-Diameter Arterial Graft in the Dog

Abstract: Autogenous saphenous vein, human umbilical vein, modified bovine collagen, Dacron, and PTFE have been used as small-diameter arterial grafts with moderate success. We tested autogenous small intestine submucosa as a small-diameter arterial graft in both a carotid and femoral artery (mean ID 4.3 mm) of 18 dogs (total of 36 grafts). All dogs received aspirin and warfarin sodium for the first 8 weeks after surgery. Graft patency was evaluated by Doppler ultrasound techniques and angiography. Two grafts ruptured and 5 grafts occluded by 21 days after surgery. One graft became occluded at 14 weeks. Fifteen dogs were sacrificed at periodic intervals until 48 weeks after surgery. Patent grafts had no evidence of infection, propagating thrombus, or intimal hyperplasia. Graft aneurysmal dilation occurred in 4 grafts (11%). The grafts were composed of a dense organized collagenous connective tissue with no evidence of endothelial cell growth on the smooth luminal surface. Three dogs are alive at 76 to 82 weeks after surgery. Overall, graft patency was 75%. Graft patency after cessation of anticoagulation therapy was 92.3% (12 of 13 grafts). We conclude that autogenous small intestinal submucosa can be used as a small-diameter arterial graft in the dog and is worthy of further investigation.

Songbirds tune their vocal tract to the fundamental frequency of their song

Abstract: In human speech, the sound generated by the larynx is modified by articulatory movements of the upper vocal tract, which acts as a variable resonant filter concentrating energy near particular frequencies, or formants, essential in speech recognition. Despite its potential importance in vocal communication, little is known about the presence of tunable vocal tract filters in other vertebrates. The tonal quality of much birdsong, in which upper harmonics have relatively little energy, depends on filtering of the vocal source, but the nature of this filter is controversial. Current hypotheses treat the songbird vocal tract as a rigid tube with a resonance that is modulated by the end-correction of a variable beak opening. Through x-ray cinematography of singing birds, we show that birdsong is accompanied by cyclical movements of the hyoid skeleton and changes in the diameter of the cranial end of the esophagus that maintain an inverse relationship between the volume of the oropharyngeal cavity and esophagus and the song’s fundamental frequency. A computational acoustic model indicates that this song-related motor pattern tunes the major resonance of the oropharyngeal–esophageal cavity to actively track the song’s fundamental frequency.

Regional limb perfusion for antibiotic treatment of experimentally induced septic arthritis.

Abstract: Septic arthritis was induced in one antebrachiocarpal joint of seven horses by the intra-articular injection of 1 mL Staphylococcus aureus suspension containing a mean of 10(5) colony-forming units. Twenty-four hours after inoculation, four horses were treated by regional perfusion with 1 g of gentamicin sulfate, and three horses received 2.2 mg/kg gentamicin sulfate intravenously (IV) every 6 hours. Synovial fluid was collected for culture and cytology at regular intervals, and the synovial membranes were collected for culture and histologic examination at euthanasia 24 hours after the first treatment. Gentamicin concentration in the septic synovial fluid after three successful perfusions was 221.2 +/- 71.4 (SD) micrograms/mL; after gentamicin IV, it was 7.6 +/- 1.6 (SD) micrograms/mL. The mean leukocyte count in the inoculated joints decreased significantly by hour 24 in the successfully perfused joints. Terminal bacterial cultures of synovial fluid and synovial membranes were negative in two horses with successfully perfused joints. S. aureus was isolated from the infected joints in all three horses treated with gentamicin IV.

Regional perfusion of the equine carpus for antibiotic delivery.

Abstract: Regional perfusion of carpal tissues by forced intramedullary administration of fluids was evaluated in 10 horses. Results of subtraction radiography after perfusion with a contrast medium demonstrated that perfusate was delivered to the carpal tissues by the venous system. Perfused India ink was distributed uniformly in the antebrachiocarpal and middle carpal synovial membranes. Histologically, the ink was within the venules of the synovial villi. Immediately after perfusion with gentamicin sulfate (1 g), the gentamicin concentrations in the synovial fluid and synovial membrane of the antebrachiocarpal joint were 349 +/- 240 micrograms/mL and 358 +/- 264 micrograms/g, respectively. When gentamicin concentrations in the synovial fluid of the antebrachiocarpal joint and serum were measured 0, 0.5, 1, 4, 8, 12, and 24 hours after carpal perfusion, the mean peak gentamicin concentration in the synovial fluid was 589 +/- 429 micrograms/mL. At hour 24, the mean gentamicin concentration in the synovial fluid was 4.8 +/- 2.0 micrograms/mL. The resulting peak gentamicin concentration in the serum was 23.7 +/- 14.5 micrograms/mL immediately after the perfusion; it decreased below the desired trough level of 1 micrograms/mL between hours 4 and 8.

Resistance gene-dependent plant defense responses.

Abstract: Plants are constantly being challenged by aspiring pathogens, but disease is rare. Why? Broadly, there are three reasons for pathogen failure. Either (1) the plant is unable to support the niche requirements of a potential pathogen and is thus a non? host; or (2) the plant possesses preformed structural barriers or toxic compounds that confine successful infections to specialized pathogen species; or (3) upon recognition of the attacking pathogen, defense mechanisms are elaborated and the invasion remains localized. All three types of interaction are said to be incompatible, but only the latter resistance mech? anism depends on induced responses. Successful pathogen invasion and disease (compatibility) ensue if the preformed plant defenses are inappropriate, the plant does not detect the pathogen, or the activated defense responses are ineffective. In this review, we examine the essential prerequisites for patho? gen recognition and the induction of localized defense responses. Preformed defenses are considered elsewhere in this issue (see Osbourn, 1996, in this issue). Race-specific pathogen recognition is hypothesized to re? sult from the direct or indirect interaction of the product of a dominant or semidominant plant resistance (R) gene with a product derived from the corresponding dominant pathogen avirulence (Avr) gene (Keen, 1992; Staskawicz et al., 1995). Subsequent signal transduction events are assumed to coordinate the activation of an array of defense responses. This "simple" model appears to explain much but begs many questions. For example, R gene products are likely to provide key components for recognition, but how do the distinct classes of R proteins characterized to date (see Bent, 1996, in this is? sue) activate the defense response? Do different R gene classes activate distinct responses? The regulation of some components of defense mechanisms has been studied in plant cell cultures in response to non-race-specific elicitors, but to what extent do such studies provide a model for R gene func? tion? Plant resistance is often correlated with the activation of specific defense responses, but which (if any) are required to abolish or retard pathogen growth, and how? Which are pri? mary responses and which are secondary? Does the first response involve transcriptional regulation, the activation of preformed enzymes, and/or the opening of ion channels, or

A completely biological tissue-engineered human blood vessel

Abstract: Mechanically challenged tissue-engineered organs, such as blood vessels, traditionally relied on synthetic or modified biological materials for structural support. In this report, we present a novel approach to tissue-engineered blood vessel (TEBV) production that is based exclusively on the use of cultured human cells, i.e., without any synthetic or exogenous biomaterials. Human vascular smooth muscle cells (SMC) cultured with ascorbic acid produced a cohesive cellular sheet. This sheet was placed around a tubular support to produce the media of the vessel. A similar sheet of human fibroblasts was wrapped around the media to provide the adventitia. After maturation, the tubular support was removed and endothelial cells were seeded in the lumen. This TEBV featured a well-defined, three-layered organization and numerous extracellular matrix proteins, including elastin. In this environment, SMC reexpressed desmin, a differentiation marker known to be lost under standard culture conditions. The endothelium expressed von Willebrand factor, incorporated acetylated LDL, produced PGI2, and strongly inhibited platelet adhesion in vitro. The complete vessel had a burst strength over 2000 mmHg. This is the first completely biological TEBV to display a burst strength comparable to that of human vessels. Short-term grafting experiment in a canine model demonstrated good handling and suturability characteristics. Taken together, these results suggest that this novel technique can produce completely biological vessels fulfilling the fundamental requirements for grafting: high burst strength, positive surgical handling, and a functional endothelium.