Although autologous connective tissue grafts (ACTG) are an ideal vascular substitute, they have not yet been used as small diameter vascular grafts because of thrombogenicity. We reported on ACTGs in which mesh tubes were fabricated from ultra-fine polyester fibers (UFPF) and used as a framework. Antithrombogenicity was established using an original heparinization method, with a 50% patency 1 month postimplantation. Early failure of these grafts was caused mainly by loss of antithrombogenicity before development of endothelialization on the inner surface. In this study, higher concentrations of heparin were used for in situ heparinization of the grafts before implantation in combination with antiplatelet therapy (cilostazol, OPC-13013 for the first month after substitution for canine carotid arteries. As a result, more complete healing of the grafts was attained, with a patency rate of 63% at 1 month, when small doses of antiplatelet agents were used. More intensive antiplatelet therapy resulted in impairment of graft healing, causing hematomas around the grafts. Thus, optimal doses of antiplatelet agents remain uncertain.

Animals↗

PubMedDate not supplied

Development of ultrafine polyester fiber vascular grafts with high endothelialization capability. Angiogenesis by ultrafine polyester fibers.

The authors previously showed that a vascular prosthesis made of ultrafine polyester fibers (UFPF) had high healing ability even when of low porosity. In this study, new highly porous vascular grafts fabricated from UFPF (water porosity: 3,600 ml/min/cm2, 8 mm in inner diameter and 5 cm in length), were developed and implanted in the thoracic descending aorta of dogs to evaluate their endothelialization capability. Two weeks after implantation, many colonies of endothelial cells with openings of capillary blood vessels were noted, even in the middle portion of the grafts. Numerous fibroblasts and capillary blood vessels were also observed in the synthetic walls. These results suggest that UFPF vascular grafts provide a suitable microenvironment for infiltration and proliferation of fibroblasts, which are accompanied by the capillary formation as nutrient supply; these capillaries provide multiple sources of endothelial coverage on the luminal surface. It is expected that the new, highly porous vascular grafts may have rich endothelialization capability and stable healing properties in humans.

Animals↗

PubMedDate not supplied

Two-dimensional orientational response of smooth muscle cells to cyclic stretching.

It was hypothesized that an orientated cellular tissue for incorporation into vital, functioning hybrid artificial organs can be prepared by periodically applying mechanical stresses on a hybrid tissue. Therefore, the effect of cyclic stretching on the two-dimensional (2-D) orientation response of arterial smooth muscle cells (SMCs) was studied. Smooth muscle cells derived from bovine aortas were seeded onto transparent elastomeric membranes made of polyurethane, and subjected to periodical stretching with various amplitudes from 5-20% at frequencies of 15 to 120 RPM for up to 24 hours. Phase-contrast microscopic views of SMCs were time-lapse video recorded. The orientation angle to the direction of stretching (OA) and cellular longitudinal length (CLL) of individual cells were analyzed by a computerized image processor. After several hours, SMCs subjected to the stress exhibited orientation responses perpendicular to the direction of stretching, evidenced by a significant increase in OA. The responses were more rapid under operating conditions with higher amplitudes and frequencies of stretching. Meanwhile, little significant change in CLL was observed. These findings indicate that an applied mechanical stress induces a significant orientation response, without morphologic alteration of SMCs. The mechanically induced orientation response provides a fundamental basis for more structured hybrid organs and tissue engineering.

Animals↗

PubMedDate not supplied

Development of a vascular prosthesis for a growing child. A graft expandable in vivo.

Specially designed vascular prostheses that can be dilated after implantation using a percutaneous transluminal angioplasty (PTA) balloon catheter have been developed. The grafts are made of woven polyester fiber fabrics, the circumferential yarns of which consist of two different types of polyester fiber bundles: One is a straight weak bundle, the other is a strong bundle wound around the former. The graft with an initial diameter of 6 mm could be dilated to 9 mm by luminal inflation of the balloon four to five times at 10 atmospheres (atm) in vitro. After disrupting the weak bundle by the dilatation procedure, the strong bundles were straightened, which maintained the enlarged diameter of the new caliber. Grafts of 6 mm in initial diameter implanted into the thoracic aortas of mongrel dogs for 3 months also could be dilated in vivo by inflating the PTA four to five times at 15 atm, as found in the vitro study. Macroscopic observation revealed that, around the dilated grafts, only a tiny hematoma was formed and nominal subsequent bleeding was observed, which indicated that the dilatation procedure was performed safely. The graft, which enables adaptation of the hydrodynamic property of the graft to the increased blood flow by PTA after implantation, is applicable in a growing child.

Angioplasty, Balloon↗

PubMedDate not supplied

Highly oriented, tubular hybrid vascular tissue for a low pressure circulatory system.

A hierarchically structured hybrid vascular tissue was prepared from vascular cells and collagen. First a hybrid medial tissue was prepared by pouring a cold mixed solution of bovine aortic smooth muscle cells (SMCs) and Type I collagen into a tubular glass mold composed of a mandrel and a sheath (inner diameter, 1.5 mm; outer diameter, 7 mm; length, 7 cm). An SMC incorporating collagenous gel was formed with incubation at 37 degrees C. After the sheath of the mold was removed, the resulting fragile tissue cultured in the medium shrank in a time dependent manner to form an opaque, dense tissue. Seeding at a higher cell density and a lower concentration of collagen resulted in rapid and prominent shrinkage. Morphologic investigation showed that with time, bipolarly elongated SMCs and collagen fiber bundles became positioned around the mandrel. When the mandrel was removed, a tubular hybrid medial tissue was formed. A hybrid vascular tissue with a hierarchical structure was constructed by seeding endothelial cells onto the inner surface of the hybrid medial tissue. Prepared tissues tolerated luminal pressures as great as 100 mmHg and mechanical stress applied during the anastomotic procedure. This method allowed the authors to prepare hybrid medial tissues of predetermined size (specifically inner diameter, wall thickness, and length) and mechanical property, which all depend on the mold design, SMC seeding density, initial collagen concentration, and incubation period. Hybrid vascular tissues may provide physiologic functions such as antithrombogenicity and regulation of vasomotor tone when implanted into a venous system.

Animals↗

PubMedDate not supplied

A new microporous polyurethane vascular graft prepared by an excimer laser ablation technique.

Three types of polyurethane (PU) based tubes (internal diameter, 2 mm; wall thickness, 100 microns) with micropores of well controlled size and arrangement were fabricated using an excimer laser (KrF) ablation technique. The pore size (100 microns) and the longitudinal pore-to-pore distance (200 microns) were constant, and the circumferential pore-to-pore intervals were 60 degrees (type 1), 30 degrees (type 2), and 15 degrees (type 3). The surface of the fabricated tube was photochemically modified with photoreactive gelatin. Scanning electron microscopy showed that pore size and arrangement were precisely controlled as designed, and that a gelatinous layer thoroughly covered the luminal surface. The stiffness parameter (beta), inversely related to compliance, was determined from the change in external diameter against intraluminal pressure. An increase in the number of pores around the circumference decreased the beta value. The type 1 tubes implanted preliminarily in rats for 4 weeks showed good patency (80%). The combination of excimer laser-directed microporing and photochemical surface processing techniques enabled the development of a novel compliant small caliber vascular graft, which is expected to show enhanced transmural tissue ingrowth in vivo.

Animals↗

PubMedDate not supplied

Impregnation of basic fibroblast growth factor on a microporous small caliber graft enhances vascularization.

The incorporation of a cellular adhesive extracellular matrix and a growth factor into a designed concept for a vital, functioning artificial vascular graft may accelerate tissue regeneration, including endothelialization. Microporous polyurethane grafts (inner diameter, 1.5 mm; wall thickness, 100 microns; length, 20 mm; pore size, 100 microns), fabricated using an excimer laser ablation technique, were coated with a mixed solution of photoreactive gelatin, basic fibroblast growth factor (bFGF), and heparin, and were subsequently photocured by ultraviolet irradiation. Control grafts were treated only with photoreactive gelatin. Both bFGF/heparin impregnated grafts (n = 6) and control grafts (n = 9) were implanted in aortas of rats for 4 weeks. All the implanted grafts were patent when harvested. Endothelialization mainly proceeded from anastomotic sites for both groups. The endothelial coverage in the bFGF/heparin impregnated groups was greater than that in the control animals. At the midportion of the grafts, regenerated endothelial and subendothelial layers were seen for the bFGF/heparin groups, but only fibrin layers were seen for the controls. Thus, coimmobilization of bFGF and heparin significantly enhanced neoarterial wall regeneration through perianastomotic as well as transmural tissue ingrowth. The former was more extensive than the latter.

Animals↗

PubMedDate not supplied

Pedunculated bronchogenic cyst mimicking pleural lesion.

We report a rare case of a bronchogenic cyst presenting as a pleural nodule. CT and MRI demonstrated a well circumscribed, homogeneous lesion located on the pleural surface apart from the mediastinum. It was proven to be a bronchogenic cyst localized between the parietal and visceral pleurae and connected with the mediastinum only through fibrous tissue. Radiologists should be aware that a mediastinal bronchogenic cyst may be located apart from the mediastinum.

Bronchogenic Cyst↗

PubMedDate not supplied

Mechanisms and mediators of psychological stress-induced rise in core temperature.

OBJECTIVE: Despite numerous case reports on "psychogenic fever," it remains uncertain how psychological stress raises core temperature and whether the rise in core temperature is a real fever or a hyperthermia. This article reviews studies on the psychological stress-induced rise in core temperature (PSRCT) in animals with the aim to facilitate studies on the mechanisms of so-called psychogenic fever in humans. METHODS: To address this question, we reviewed the mechanisms and mediators of the PSRCT and classic conditioning of the fever response in animals. RESULTS: The PSRCT is not due to the increased locomotor activity during stress, and the magnitude of the PSRCT is the same in warm and cold environments, indicating that it is a centrally regulated rise in temperature due to an elevated thermoregulatory "set point." The PSRCT caused by conventional psychological stress models, such as open-field stress, is attenuated by cyclooxygenase inhibitors, which block prostaglandin synthesis. On the other hand, the PSRCT elicited by an "anticipatory anxiety stress" is not inhibited by cyclooxygenase inhibitors but by benzodiazepines and serotonin Type 1A receptor agonists. The febrile response can be conditioned to neutral stimuli after paired presentation with unconditioned stimuli such as injection of lipopolysaccharide, a typical pyrogen. CONCLUSIONS: Most findings indicate that the PSRCT is a fever, a rise in the thermoregulatory set point. The PSRCT may occur through prostaglandin E2-dependent mechanisms and prostaglandin E2-independent, 5-HT-mediated mechanisms. The febrile response can be conditioned. Thus, these mechanisms might be involved in psychogenic fever in humans.

Animals↗

PubMedDate not supplied

Diagnosis and physiopathology of laryngeal deposits in autoimmune disease.

We report the clinical features and pathology of a previously unreported form of vocal fold disease seen in 4 patients, 3 of whom were diagnosed as autoimmune disease. The characteristic features of these lesions were found as bilateral transverse lesions in the mid portion of the vocal folds. The patients had dysphonia and diplophonia. Stroboscopic examinations showed 180-degree phase shifts between the anterior and posterior portion of the vocal folds. Case 1 had systemic lupus erythematosus, case 2 had Hashimoto's thyroiditis, and case 3 had progressive systemic sclerosis. Prior to the onset of hoarseness, autoimmune antibody titers were increased. These cases need differential diagnosis from vocal fold nodules and cysts. Two cases were recurrent after endoscopic surgery, 1 recurring 3 times. Glucocorticoid was effective in preventing the recurrence in the early phase. Recurrence may have occurred because the surgical strategy was the same as that used for vocal fold nodules or cysts.

Adult↗

PubMedDate not supplied

Intracerebroventricular injection of tumor necrosis factor-alpha induces thermal hyperalgesia in rats.

To investigate the role of tumor necrosis factor-alpha (TNF-alpha) in the brain in nociception, we injected recombinant human TNF-alpha (rhTNF-alpha; 1 pg-10 ng/rat) into the lateral cerebroventricle (LVC) in rats and observed the changes in paw withdrawal latency to radiant heat by using the plantar test for 90 min after injection. LCV injections of TNF-alpha at doses of 10 pg, 100 pg and 1 ng reduced paw withdrawal latency, showing a maximal response at a dose of 10 pg which peaked 60 min after injection. TNF-alpha at doses of 1 pg and 10 ng had no effect on nociception during the test period. The TNF-alpha (10 pg)-induced reduction in paw withdrawal latency was blocked by simultaneous injection of diclofenac (1 ng), a cyclooxygenase inhibitor, or interleukin-1 receptor antagonist (IL-1 ra, 10 ng). LCV injection of neither diclofenac (1 ng) nor IL-1 ra (10 ng) had any effect on nociception by itself. The results suggest that TNF-alpha in the brain induces thermal hyperalgesia and that the brain TNF-alpha-induced hyperalgesia is mediated by the central action of interleukin-1 and activation of the cyclooxygenase pathway of the arachidonate.

Animals↗