Time course and importance of neoadventitial formation in arterial remodeling following balloon angioplasty of porcine coronary arteries. (33/7861)

OBJECTIVES: Arterial remodeling has been suggested as the predominant factor in restenosis. However, the time course and morphometric factors that determine whether remodeling occurs remain unclear. We hypothesized that arterial remodeling does not occur in all arteries following balloon injury and is dependent on neoadventitial formation. METHODS: Using single (SI) and double (DI) balloon injury of Yorkshire porcine coronary arteries we examined changes in morphometry 3, 7, 14, 28 days following balloon injury. RESULTS: In both SI and DI arteries, the neoadventitia (NAD) area expanded by day 3 and was the first compartment to increase following injury. In SI arteries lumen area (LA) decreased between day 3 and 14 while in DI arteries, there was significantly less loss in LA. In SI arteries, contracture of the area circumscribed by the external elastic lamina (EEL), which occurred predominantly between day 7 and 14, accounted for 67% of the loss of LA. CONCLUSIONS: Accumulation of NAD appears to be the earliest change in the vessel wall following balloon injury of normal or previously injured arteries and precedes the growth of the I + M (intima and media). The predominant mechanism for lumenal narrowing following single balloon injury of a normal artery is remodeling. In contrast, remodeling does not occur in DI arteries, possibly due to differences in the degree of adventitial fibrosis of normal and injured arteries.  (+info)

A quantitative assessment of the healing of intramembranous and endochondral autogenous bone grafts. (34/7861)

The aim of the study was to assess quantitatively the amount of new bone formed in the early stages of healing of intramembranous and endochondral autogenous bone grafts so as to gain further insight into their integration with host bone. Eighteen critical size defects were created in the parietal bone of nine New Zealand White rabbits. In the experimental group (five rabbits), each rabbit was grafted with intramembranous bone in one defect and with endochondral bone in the other. In the control group (four rabbits), one defect was left empty (passive control) and the other was grafted with rabbit skin collagen (active control). After 14 days, the rabbits were killed and the defects were prepared for histological analysis. Serial sections were made across the whole defect. Each defect was divided into five regions spaced 1500 microns apart. Two sections were randomly drawn from each region. Quantitative analysis was performed on 100 sections using an image analyser computer software system to assess the amount of new bone formed in each defect. No bone was detected across the defect in either the active or passive controls. One-hundred-and-sixty-six per cent more new bone was formed in defects grafted with intramembranous bone than those grafted with endochondral bone. This represented an extremely significant difference (P < 0.0001, unpaired t-test) between the two groups. The results show that intramembranous autogenous bone produced more bone than the endochondral bone when grafted in the skull. Clinically, it is recommended that intramembranous bone is used to replace lost membranous bone in the oral cavity, as well as in skull defects, whenever possible.  (+info)

Interactions between the foot and bud patterning systems in Hydra vulgaris. (35/7861)

In the freshwater coelenterate, hydra, asexual reproduction via budding occurs at the base of the gastric region about two-thirds of the distance from the head to the foot. Developmental gradients of head and foot activation and inhibition originating from these organizing centers have long been assumed to control budding in hydra. Much has been learned over the years about these developmental gradients and axial pattern formation, and in particular, the inhibitory influence of the head on budding is well documented. However, understanding of the role of the foot and potential interactions between the foot, bud, and head patterning systems is lacking. The purpose of this study was to investigate the role of the foot in the initiation of new axis formation during budding by manipulating the foot and monitoring effects on the onset of first bud evagination and the time necessary to reach the 50% budding point. Several experimental situations were examined: the lower peduncle and foot (PF) were injured or removed, a second PF was laterally grafted onto animals either basally (below the budding zone) or apically (above the budding zone), or both the head and PF were removed simultaneously. When the PF was injured or removed, the onset of first bud evagination was delayed and/or the time until the 50% budding point was reached was longer. The effects were more pronounced when the manipulation was performed closer to the anticipated onset of budding. When PF tissue was doubled, precocious bud evagination was induced, regardless of graft location. Removal of the PF at the same time as decapitation reduced the inductive effect of decapitation on bud evagination. These results are discussed in light of potential signals from the foot or interactions between the foot and head patterning systems that might influence bud axis initiation.  (+info)

Normal human colonic subepithelial myofibroblasts enhance epithelial migration (restitution) via TGF-beta3. (36/7861)

After injury and loss of epithelial cells, intestinal barrier function is reestablished by migration of viable epithelial cells from the wound edge (restitution). Myofibroblasts are located close to the basal surface of epithelial cells. This study aimed to investigate the role of human colonic subepithelial myofibroblasts in epithelial restitution. Primary cultures of subepithelial myofibroblasts were established. Monolayers of the epithelial cell lines IEC-6 and T84 were "wounded" in a standard manner to create an in vitro model of restitution. Migration of epithelial cells across the wound edge was assessed following culture in myofibroblast-conditioned medium. Myofibroblast expression of transforming growth factor (TGF)-beta isoforms was examined using RT-PCR, and TGF-beta isoform bioactivity was assessed using Mv 1 Lu bioassay. Myofibroblast-conditioned medium, via a TGF-beta-dependent pathway, significantly enhanced migration of epithelial cells across the wound edge and significantly inhibited cell proliferation in wounded monolayers. Messenger RNA for TGF-beta1, -beta2, and -beta3 was detected in the myofibroblasts, and Mv 1 Lu bioassay showed the presence of predominantly bioactive TGF-beta3. This study shows that human colonic subepithelial myofibroblasts secrete predominantly bioactive TGF-beta3 and enhance restitution in wounded epithelial monolayers via a TGF-beta-dependent pathway.  (+info)

Healing of diabetic neuropathic foot ulcers receiving standard treatment. A meta-analysis. (37/7861)

OBJECTIVE: The aim of the study was to determine the percentage of individuals with neuropathic diabetic foot ulcers receiving good wound care who heal within a defined period of time. RESEARCH DESIGN AND METHODS: We conducted a systematic review of the control groups of clinical trials that evaluated a treatment for diabetic neuropathic foot ulcers. The meta-analytic techniques used include an estimation of the weighted mean percentage healed by end point, an evaluation of the homogeneity of trials, and an estimate of the 95% CI of the grouped data. Grouped-data univariate and multivariate logistic regression was conducted to assess the impact of mean age, ulcer size, and duration on the percentage of ulcers healed at end point. RESULTS: We found a total of 10 control groups meeting our criteria. Six control groups used 20 weeks as the end point for healing or nonhealing. For the six control arms with a 20-week end point, we found a weighted mean healing rate of 30.9% (95% CI 26.6-35.1). A similar analysis for the four 12-week arms found a mean healing rate of 24.2% (19.5-28.8). We failed to detect any statistically significant heterogeneity for either the 20-week or the 12-week trials. CONCLUSIONS: After 20 weeks of good wound care, approximately 31% of diabetic neuropathic ulcers heal. Similarly, after 12 weeks of good care, approximately 24% of neuropathic ulcers attain complete healing. Further patient-level analyses are necessary to definitively determine the associations of age, wound size, and wound duration with likelihood of healing.  (+info)

Transcutaneous oxygen tension and toe blood pressure as predictors for outcome of diabetic foot ulcers. (38/7861)

OBJECTIVE: The present study was undertaken to compare the predictive values of transcutaneous oxygen tension (TcPO2) and toe blood pressure (TBP) measurements for ulcer healing in patients with diabetes and chronic foot ulcers. RESEARCH DESIGN AND METHODS: Investigated prospectively were 50 diabetic patients (37 men) with chronic foot ulcers. The age was 61 +/- 12 (mean +/- SD), and the diabetes duration was 26 +/- 14 years. TBP (mmHg) was measured in dig I and TcPO2 (mmHg) at the dorsum of the foot. Ulcer healing was continuously evaluated by measuring the ulcer area every 4-6 weeks. After a follow-up time of 12 months, the patients were divided into three groups according to clinical outcome: healed with intact skin, improved ulcer healing, or impaired ulcer healing. RESULTS: Of the 13 patients who deteriorated, 11 had TcPO2 < 25 mmHg, while 34 of the 37 patients who improved had TcPO2 > or = 25 mmHg. The sensitivity and specificity for TcPO2 were 85 and 92%, respectively, when a cutoff level of 25 mmHg was used for determination of outcome of ulcer healing (healing or nonhealing). The corresponding values for TBP at 30 mmHg were 15 and 97%. Measurement of TcPO2 provided a higher positive predictive value (79%) than TBP (67%). CONCLUSIONS: The results indicate that TcPO2 is a better predictor for ulcer healing than TBP in diabetic patients with chronic foot ulcers, and that the probability of ulcer healing is low when TcPO2 is < 25 mmHg.  (+info)

Keratinocyte growth regulation in fibroblast cocultures via a double paracrine mechanism. (39/7861)

Epithelial-mesenchymal interactions play an important role in regulating tissue homeostasis and repair. For skin, the regulatory mechanisms of epidermal-dermal interactions were studied in cocultures of normal human epidermal keratinocytes (NEK) and dermal fibroblasts (HDF) rendered postmitotic by alpha-irradiation (HDFi). The expression kinetics of different cytokines and their receptors with presumed signalling function in skin were determined at the RNA and protein level in mono- and cocultured NEK and HDFi. In cocultured HDFi, mRNA and protein synthesis of keratinocyte growth factor (KGF) (FGF-7) was strongly enhanced, whereas in cocultured keratinocytes interleukin (IL)-1alpha and -1beta mRNA expression increased compared to monocultures. Thus we postulated that IL-1, which had no effect on keratinocyte proliferation, induced in fibroblasts the expression of factors stimulating keratinocyte proliferation, such as KGF. The functional significance of this reciprocal modulation was substantiated by blocking experiments. Both IL-1alpha and -1beta-neutralizing antibodies and IL-1 receptor antagonist significantly reduced keratinocyte proliferation supposedly through abrogation of KGF production, because IL-1 antibodies blocked the induced KGF production. These data indicate a regulation of keratinocyte growth by a double paracrine mechanism through release of IL-1 which induces KGF in cocultured fibroblasts. Thus IL-1, in addition to its proinflammatory function in skin, may play an essential role in regulating tissue homeostasis.  (+info)

Dietary phospholipids rich in long-chain polyunsaturated fatty acids improve the repair of small intestine in previously malnourished piglets. (40/7861)

Malnourished piglets were studied to establish how a diet containing long-chain polyunsaturated fatty acids (LC-PUFA) of the (n-6) and (n-3) series, esterified in the form of phospholipids, affects intestinal recovery after severe malnutrition. Piglets (7-d-old) were randomly assigned to two groups. One group was fed a piglet milk formula and the other was malnourished by protein-energy restriction for 30 d. Healthy and malnourished piglets were then divided into two subgroups fed for 10 d either an adapted milk formula (C and M) or the same diet supplemented with LC-PUFA phospholipids (C-P and M-P). The M-P group had greater protein, DNA, cholesterol and phospholipid levels and a lower triglyceride level in the jejunal segment than did the M group. The fatty acid composition of the jejunal mucosa and microsomes of the M-P piglets did not differ from that of healthy piglets (C). However, in jejunal mucosa, microsomes and phospholipids from malnourished piglets that did not receive LC-PUFA (group M) had significantly lower percentages of (n-6) LC-PUFA than those in healthy piglets (C). The (n-3) LC-PUFA percentages of jejunal mucosa were also lower in the M group than in the C group. The small intestine of piglets fed the LC-PUFA-supplemented formula recovered more completely from histologic lesions and biochemical alterations caused by the malnutrition process than the small intestine of piglets fed the control formula without LC-PUFA.  (+info)