Late Dissection of Pulmonary Autograft Treated by Valve-Sparing Aortic Root Replacement

Abstract   Dissection of the pulmonary autograft is an extremely rare complication requiring emergent treatment as there is a chance of rupture and proximal aortic involvement. The autograft dissection can involve the aortic annulus, causing separation of leaflets from the annulus in addition to causing annular dilatation, thereby precluding resuspension of leaflets. The usual treatment in such cases is to perform the Bentall procedure, which involves placing a valved conduit (usually mechanical valve) and thereby necessitating anticoagulation. This report describes a case of successful valve-sparing aortic root replacement following the Ross procedure with dissection of autograft.     

Effects of Volatile Anesthetics on Glutamate Transporter, Excitatory Amino Acid Transporter Type 3: The Role of Protein Kinase C

Background: Glutamate transporters play an important role in maintaining extracellular glutamate homeostasis. The authors studied the effects of volatile anesthetics on one type of glutamate transporters, excitatory amino acid transporter type 3 (EAAT3), and the role of protein kinase C in mediating these effects.

Methods: Excitatory amino acid transporter type 3 was expressed in Xenopus oocytes by injection of EAAT3 mRNA. Using two-electrode voltage clamp, membrane currents were recorded before, during, and after application of l-glutamate. Responses were quantified by integrating the current trace and are reported as microcoulombs. Data are mean +/- SEM.

Results: l-Glutamate-induced responses were increased gradually with the increased concentrations of isoflurane, a volatile anesthetic. At 0.52 and 0.70 mm isoflurane, the inward current was significantly increased compared with control. Isoflurane (0.70 mm) significantly increased Vmax (maximum velocity) (3.6 +/- 0.4 to 5.1 +/- 0.4 [mu]C;P < 0.05) but not Km (Michoelis-Menten Constant) (55.4 +/- 17.0 vs. 61.7 +/- 13.6 [mu]m;P > 0.05) of EAAT3 for glutamate compared with control. Treatment of the oocytes with phorbol-12-myrisate-13-acetate, a protein kinase C activator, caused a significant increase in transporter current (1.7 +/- 0.2 to 2.5 +/- 0.2 [mu]C;P < 0.05). Responses in the presence of the combination of phorbol-12-myrisate-13-acetate and volatile anesthetics (isoflurane, halothane, or sevoflurane) were not greater than those when volatile anesthetic was present alone. Oocytes pretreated with any of the three protein kinase C inhibitors alone (chelerythrine, staurosporine, or calphostin C) did not affect basal transporter current. Although chelerythrine did not change the anesthetic effects on the activity of EAAT3, staurosporine or calphostin C abolished the anesthetic-induced increase of EAAT3 activity.     

Angio-immunoblastic lymphadenopathy: a clinical, immunological and molecular study

Twenty four patients with angio-immunoblastic lymphadenopathy (AILD) presenting between 1974 and 1985 have been reviewed. Clinical features at presentation included rash, fever, lymphadenopathy and hepatosplenomegaly in 75% of patients. Polyclonal hypergammaglobulinaemia was seen in 19/20 patients; 5 had normal immunoglobulin levels. Combination chemotherapy with MVPP was the optimal treatment with 6/7 patients achieving complete remission. Duration of remission ranged from 9 months to 4 years and was significantly longer in patients achieving complete as opposed to partial remission. In 6 patients phenotype studies were performed on single cell suspensions and immunoperoxidase studies on frozen sections of 7 lymph nodes. There was a reversal of the normal T suppressor/helper cell ratio with a predominance of T suppressor cells. Loss of normal B follicles was observed histologically in all except one lymph node. Germline configuration of the beta B-chain of the T cell receptor was observed in lymph nodes of 4 patients with AILD, and a rearranged T cell receptor was observed in 1 patient in whom a second lymph node biopsy had shown alteration of the histological picture to that of T-zone lymphoma. Frozen sera of 15 patients were screened for antibodies to HTLV I and III and were found to be negative.     

Novel porous aortic elastin and collagen scaffolds for tissue engineering

Decellularized vascular matrices are used as scaffolds in cardiovascular tissue engineering because they retain their natural biological composition and three-dimensional (3-D) architecture suitable for cell adhesion and proliferation. However, cell infiltration and subsequent repopulation of these scaffolds was shown to be unsatisfactory due to their dense collagen and elastic fiber networks. In an attempt to create more porous structures for cell repopulation, we selectively removed matrix components from decellularized porcine aorta to obtain two types of scaffolds, namely elastin and collagen scaffolds. Histology and scanning electron microscopy examination of the two scaffolds revealed a well-oriented porous decellularized structure that maintained natural architecture of the aorta. Quantitative DNA analysis confirmed that both scaffolds were completely decellularized. Stress-strain analysis demonstrated adequate mechanical properties for both elastin and collagen scaffolds. In vitro enzyme digestion of the scaffolds suggested that they were highly biodegradable. Furthermore, the biodegradability of collagen scaffolds could be controlled by crosslinking with carbodiimides. Cell culture studies showed that fibroblasts adhered to and proliferated on the scaffold surfaces with excellent cell viability. Fibroblasts infiltrated about 120 microm into elastin scaffolds and about 40 microm into collagen scaffolds after 4 weeks of rotary cell culture. These results indicated that our novel aortic elastin and collagen matrices have the potential to serve as scaffolds for cardiovascular tissue engineering.     

Demineralization and ion binding action of polycarboxylate cement liquid on human dental enamel

The demineralization and ion binding effects on dental tissues due to poly(acrylic) acid attack under different dilution conditions of the latter are studied by scanning electron microscope (SEM) and infrared (IR) spectroscopy. The results indicate that in addition to the general demineralization effects such as preferential prism core attack, prism periphery attack, and protruding prism rods, competing ion binding effects also occur. Using optimum dilution conditions, the microstructural effects of demineralization and ion binding are shown and the effects are related to IR spectral observations.