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Biomedical subjects

K Brockbank

Publications and source records attributed to K Brockbank.

9 recordsLinked to original sources
PubMed2005

Enhanced tissue strength in cryopreserved, collagen-based blood vessel constructs.

Traditional cryopreservation methods do not adequately preserve complex natural or engineered multicellular tissues due to the ice formation in the extracellular matrices. Vitrification is an alternate ice-free method for cryopreservation. This study compares the effects of vitrification and conventional cryopreservation on an engineered blood vessel construct. Collagen-based vascular constructs were used as models in this study. Tubular constructs were cut into rings and distributed into fresh, frozen, and vitrified groups for evaluation of mechanical properties and cell viability. Passive mechanical tests revealed enhanced tissue strength after both freezing and vitrification. Cryosubstitution studies of frozen and vitrified constructs revealed negligible ice in the vitrified specimens and extensive ice formation in the extracellular matrix of frozen specimens. Morphological changes associated with ice formation were visible within tissues preserved using traditional cryopreservation but not in tissue preserved using vitrification. The metabolic assay results indicated that vitrified tissue had similar viability to fresh controls. These results suggest that the increased tissue strength after cryopreservation may relate to thermal property change during preservation that cross-link collagen in tissue-engineered blood vessels. Further development of this cryopreservation method is necessary to minimize the alteration in material property and maintain cell viability of the constructs.

Animals↗
PubMed2001

Patient-controlled analgesia and postoperative nausea and vomiting: efficacy of a continuous infusion of ondansetron.

A continuous infusion of ondansetron was compared with a placebo infusion in 80 patients undergoing major breast reconstructive surgery. All patients received a standard anaesthetic and a bolus dose of ondansetron after induction. They were then randomly allocated to receive an intravenous infusion of ondansetron or a placebo infusion for 24 h in a double-blind fashion. Postoperative analgesia was provided by patient-controlled subcutaneous diamorphine. In the ondansetron group, the severity of nausea, measured by a 10-point verbal rating scale, was reduced (p = 0.01) and fewer patients stated at postoperative interview that nausea and vomiting was a problem (p = 0.01).

Adolescent↗
PubMed1999

Remodeling of an acellular collagen graft into a physiologically responsive neovessel.

Surgical treatment of vascular disease has become common, creating the need for a readily available, small-diameter vascular graft. However, the use of synthetic materials is limited to grafts larger than 5-6 mm because of the frequency of occlusion observed with smaller-diameter prosthetics. An alternative to synthetic materials would be a biomaterial that could be used in the design of a tissue-engineered graft. We demonstrate that a small-diameter (4 mm) graft constructed from a collagen biomaterial derived from the submucosa of the small intestine and type I bovine collagen has the potential to integrate into the host tissue and provide a scaffold for remodeling into a functional blood vessel. The results obtained using a rabbit arterial bypass model have shown excellent hemostasis and patency. Furthermore, within three months after implantation, the collagen grafts were remodeled into cellularized vessels that exhibited physiological activity in response to vasoactive agents.

Animals↗
PubMed1999

Improving patients' postoperative sleep: a randomized control study comparing subcutaneous with intravenous patient-controlled analgesia.

One hundred female patients undergoing major reconstructive plastic or gynaecological surgery were randomized to either receive subcutaneous patient-controlled analgesia (PCA) (bolus dose 2.5 mg diamorphine in 1 ml with a 20-minute lockout) or intravenous PCA (bolus dose 0.5 mg diamorphine in 1 ml with a 5-minute lockout). Data were collected by questionnaire and interview to evaluate the intervention on pain scores, quality of sleep on the first postoperative night, postoperative nausea and vomiting (PONV) and overall patient acceptability. The subcutaneous PCA group experienced less 'worse pain' (P < 0.01) and less sleep disturbance due to pain (P < 0.001). Subcutaneous PCA would appear to offer patients a safe and effective means of analgesia and may offer significant advantages over the intravenous route of administration.

Adult↗
PubMed1990

Factors affecting patency of venous allografts in miniature swine.

In immunologically defined National Institutes of Health miniswine, a segment of internal jugular vein was anastomosed to the carotid artery as an interposition graft. Patency of swine major histocompatibility complex matched, one haplotype mismatched, and complete mismatched veins was 9.8, 6.3, and 3.0 weeks respectively (p = 0.009). More than 90% of mismatched and 20% of matched allografts developed a positive crossmatch before occlusion (p = 0.006). The mixed lymphocyte response did not predict graft occlusion. Treatment of 10 swine with cyclosporine (10 mg/kg/day) did not significantly improve patency for one haplotype mismatched grafts. In haplotype mismatched veins, cryopreserved grafts occluded more rapidly than noncryopreserved grafts: mean 2.4 versus 6.3 weeks, respectively (p = 0.002). In all cryopreserved vein grafts, alloantibody appeared at or after graft occlusion rather than before occlusion as seen with fresh allografts (p = 0.046). The mean patency of cryopreserved versus fresh autografts was 3.3 and greater than 32 weeks, respectively (p = 0.004). In summary, these results indicate that (1) allograft patency is related to the degree of swine major histocompatibility complex match and development of cytotoxic alloantibodies; (2) moderate-dose cyclosporine does not prolong allograft patency nor suppress development of antibody; (3) cryopreservation may accelerate graft occlusion through nonimmunologic mechanisms.

Animals↗
PubMed1989

Cryopreserved venous homografts as vascular conduits in canine carotid arteries.

In this study we evaluated the histologic condition, prostacyclin production, and compliance of morphologically intact cryopreserved venous homografts (CVH) and autografts 3, 6, and 9 months after arterial implantation. Eighteen external jugular veins were cryopreserved and implanted into the carotid arteries of mongrel dogs. All grafts were patent at the time of excision. Electron microscopy documented a disrupted endothelium in the homografts at 3 months that was intact at 9 months. The cellular infiltrate, suggestive of rejection, in the 3-month homografts resolved by 9 months. Prostacyclin production at 3 months was 8.7 +/- 3.2 pg/ml/cm2 compared with 24.1 +/- 9.6 pg/ml/cm2 (p less than 0.025) in the adjacent carotid artery. The prostacyclin production in the 6-month homografts was 21.7 +/- 12.4 pg/ml/cm2, not significantly different from the adjacent carotid artery. The return of prostacyclin paralleled the return of an intact endothelium. Compliance of fresh vein was diminished by cryopreservation, from 1.57 +/- 0.39% radial change/mm Hg (10(-2] to 0.79 +/- 0.21% radial change/mg Hg (10(-2] (p less than 0.02). The compliance of CVH at 3 months (1.7 +/- 1.0) and at 6 months (1.1 +/- 0.42) was not significantly different from cryopreserved veins. These data showed that CVH remained patent in dogs for 9 months, without loss of compliance for 6 months, and developed a morphologically intact and functional endothelium that paralleled the resolution of the inflammatory infiltrate.

Animals↗
PubMed1978

Alteration of myoblast phenotype by dimethyl sulfoxide.

Application of dimethyl sulfoxide to proliferating L8 myoblasts (an established cell line of rat skeletal muscle) for 72 hr completely prevented fusion and induction of creatine phosphokinase (EC 2.7.3.2) activity (an indicator of muscle differentiation). The growth pattern changed from the usual sheets of randomly oriented cells to flattened, whorled monolayers of elongated fibroblast-like cells. By electron microscopy, rough endoplasmic reticulum increased and extracellular material appeared that had the morphologic and staining characteristics of collagen. After 120 hr in dimethyl sulfoxide-containing medium, the cells secreted about 6 times more collagen than untreated controls. Dimethyl sulfoxide was ineffective when applied to L8 cells just prior to fusion, and effects of dimethyl sulfoxide were not readily reversible unless treated cells were subcultured at low density.

Animals↗
PubMedDate not supplied

Pain killers.

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Chronic Disease↗