Structural elements influencing von Willebrand factor (vWF) binding affinity for platelet glycoprotein Ib within a dispase-digested vWF fragment

We investigated the structural elements in human von Willebrand factor (vWF) that influence binding affinity for platelet glycoprotein (GP) Ib using a dispase-digested vWF fragment as a prototype (residues Leu480/Val481-Gly718 of the vWF subunit; Andrews et al, Biochemistry 28:8326, 1989). The major structural features of this fragment are a large A1-loop formed by an intrachain disulfide bond between Cys509 and Cys695 and six O-linked sugar chains. The fragment was chemically modified by (1) reduction and S-carboxyamido-methylation (R/A), (2) desialylation (DS), or (3) a combination of both (R/A-DS). The GPIb binding affinity of these fragments was basically evaluated by competitive binding assay with anti-GPIb monoclonal antibody (LJ-Ib1), a receptor blocker for vWF (Sugimoto et al, Biochemistry 30:5202, 1991). Both the prototype and the R/A fragments were also assessed for their function in shear-induced platelet aggregation. Results unambiguously demonstrated that the presence of a disulfide bridge (Cys509-Cys695) within this domain downregulates the affinity of vWF to GPIb. In addition, it was also demonstrated that the terminal sialic acids attached to six o-linked sugar chains within this domain contribute to optimal functional modulation by the antibiotic ristocetin, but not by snake venom botrocetin.     

Right axillary arterial perfusion for a ruptured type B aortic dissection: Report of a case

The results of surgical treatment for a ruptured type B aortic dissection remain far from satisfactory. It is believed that additional perfusion from the right axillary artery might be more beneficial than perfusion from only the femoral artery during surgery for a ruptured thoracic aneurysm. The right axillary perfusion is more likely to perfuse the vital organs proximal to the ruptured area, and thus avoid retrograde emboli. In addition, if the open proximal method is performed, then the right axillary perfusion is able to facilitate the evacuation of air from the aortic lumen. We present herein the case of a patient in whom a ruptured type B acute aortic dissection was successfully treated by applying right axillary perfusion through a left thoracotomy.     

Is left ventricular regional wall motion after CABG influenced by cardioplegic protection?]

This clinical study was conducted to determine whether different techniques of cardioplegic protection reflected left ventricular regional wall motion after CABG. A total of 43 patients with more than 90% stenosis of the LAD (seg 6 and/or 7) before CABG, who had patent grafts were allocated to two groups: namely, the crystalloid group, comprised of 23 patients given cold crystalloid cardioplegia and topical ice slush, and the blood group, comprised of 20 patients given tepid blood cardioplegia delivered intermittently antegrade. Each group was divided into two subgroups according to whether the left ventricular regional wall motion showed no change or deterioration after CABG. We also examined the relationship between the grading of the collateral artery before CABG and the postoperative ventricular regional wall motion. The number of patients who showed deterioration after CABG was higher in the crystalloid group than in the blood group (p = 0.008). Moreover, patients in the crystalloid group whose collateral artery had been graded as 0 before CABG tended to show deterioration of left ventricular local wall motion after CABG (p = 0.07). Whereas those patients in the blood group did not. In conclusion, the incidence of deterioration after CABG was higher in the crystalloid group than in the blood group.     

Tricuspid valve replacement in a patient with idiopathic tricuspid regurgitation]

Tricuspid regurgitation is often seen but is rarely categorized as "idiopathic". A 66-year-old man suspected of idiopathic tricuspid regurgitation underwent tricuspid valve replacement. With right heart failure over twenty years, his CTR increased to eighty six (86) per cent. During operation, no abnormal findings were observed except for the dilated tricuspid valve ring. Then a stented porcine xenograft (Carpentier-Edwards 33 mm) was inserted in the tricuspid valve annulus. Seven years after replacement, he died. Autopsy demonstrated myocardial hypertrophy of the right ventricle and dilatation of the right heart, supporting the diagnosis of idiopathic tricuspid regurgitation.     

Ruptured aneurysm of a posterior inferior cerebellar artery communicating artery. Case report and histological findings

A hypertensive 60-year-old man presented with a rare aneurysm arising from the posterior inferior cerebellar artery (PICA) communicating artery, manifesting as subarachnoid hemorrhage with intraventricular hemorrhage. Angiography showed a small aneurysm arising from a fine and tortuous artery interconnecting the bilateral vermian branches of distal PICAs. The right PICA was absent and its vermian territory was supplied by the left PICA through this communicating artery. The right anterior inferior cerebellar artery was also connected to the vermian branch of the right PICA. At surgery, a reddish and apparent fusiform aneurysm was noted at the top of the arterial loop under the cerebellar vermis. Microsurgical trapping and removal of the aneurysm was performed without complication. Histological examination demonstrated typical findings of a true aneurysm. Only four previous cases of aneurysm of the communicating artery between the bilateral distal PICAs have been reported. In all five reported cases including ours, the PICA communicating artery contributed to the collateral blood supply of the contralateral vermian territory based on vascular anomalies. Hemodynamic stress and congenital vulnerability may have caused this aneurysm. Trapping is suitable to treat this precarious aneurysm if other collateral vessels supply the contralateral vermian territory.     

Ischemia of the sternocleidomastoid muscle following occipital artery embolization for dural arteriovenous fistula

We report a case of localized ischemia of the sternocleidomastoid muscle (SCM) occurring after occipital artery embolization of a dural arteriovenous fistula (dAVF). A 45-year-old man presented intracerebral hemorrhage from a dAVF at the left transverse-sigmoid sinus. The dAVF had a high flow fistula from the left occipital artery (OA). Endovascular therapy was carried out one month later. Transarterial embolization of the OA was carried out prior to the transvenous approach to decrease the shunt flow. During obliteration of the proximal portion of the OA with fiber platinum coils and polyvinyl alcohol particles, the patient reported severe neck pain. The fistula was successfully embolized after transvenous packing of the left sigmoid sinus with detachable coils. The neck pain persisted for one week and disappeared after conservative treatment. T2-MR imaging 3 days after the embolization showed a hyperintensity in the left SCM. This ischemic lesion was probably induced by occlusion of the muscular branch of the OA. We discuss this common but rarely reported complication of OA embolization.     

Auxiliary heterotopic liver transplantation in the rat: A simplified model using cuff technique and application for congenitally hyperbilirubimemic Gunn rat

To study the immunological and metabolic effects of auxiliary liver transplantation (ALT), a simple ALT model in rats was developed using the cuff application. Effects of transient parking of normal liver were tested in congenitally hyperbilirubinemic Gunn rats. Serum bilirubin concentrations in Gunn rats, transplanted heterotopically with normal livers of Wistar rats, were dramatically reduced and maintained within normal levels. The graftectomy was performed safely 1 month after transplantation, but total bilirubin levels did not return to the preoperative value of the Gunn rats. It is possible that hepatic stem cells included in ALT liver migrated to the host liver and differentiated into cells capable of producing certain enzymes. © 1998 Wiley-Liss, Inc. MICROSURGERY 18:97-102 1998     

IL-12 inhibits TNF-α induced osteoclastogenesis via a T cell-independent mechanism in vivo

It has been reported that TNF-α plays an important role in bone resorption in pathological conditions. IL-12, which is a T cell mediator, is also an important inflammatory cytokine. We previously reported that IL-12 induces apoptosis in bone marrow cells treated with TNF-α in vitro via an interaction between TNF-α-induced Fas and IL-12-induced Fas ligand (FasL), and that, as a result, osteoclastogenesis is inhibited. The purpose of this study was to investigate the effects of IL-12 on TNF-α-mediated osteoclastogenesis in vivo. We administered TNF-α with and without IL-12 into the supracalvaria in mice. The numbers of osteoclasts in the sutures in the calvaria were higher in mice administered TNF-α than in control mice not administered TNF-α. The numbers of osteoclasts in mice administered both TNF-α and IL-12 were lower than those in mice administered only TNF-α. Next, we determined the levels of mRNAs for cathepsin K and tartrate-resistant acid phosphatase (TRAP). mRNA levels were increased in mice administered TNF-α compared with control mice, but not in mice administered both TNF-α and IL-12. We also evaluated the amounts of tartrate-resistant acid phosphatase 5b (TRACP 5b) in mouse sera. The levels of TRACP 5b in mice administered TNF-α were higher than those in control mice. On the other hand, in mice administered both TNF-α and IL-12, the levels were lower than those in mice administered TNF-α alone. Fas and FasL expression levels were analyzed by real-time RT-PCR. The levels of Fas mRNA were increased in the calvaria of mice administered TNF-α compared with control mice, while those of FasL mRNAs were increased in the calvaria of mice administered IL-12. In TdT-mediated dUTP-biotin nick end-labeling (TUNEL) assays, many apoptotic cells were found in the sutures in the calvaria of mice administered both TNF-α and IL-12. IL-12 also inhibited TNF-α-induced osteoclastogenesis in mice whose T cells were blocked by anti-CD4 and anti-CD8 antibodies. These results suggest that IL-12 inhibits TNF-α-mediated osteoclastogenesis and induces apoptotic changes through an interaction between TNF-α-induced Fas and IL-12-induced FasL, in vivo, via a T cell-independent mechanism.     

Reconstructive surgery for a fusiform common celiomesenteric trunk aneurysm and coexistent abdominal aortic aneurysm: Report of a case

A celiomesenteric trunk (CMT) accounts for fewer than 1% of all visceral artery anomalies. Aneurysms involving a CMT are exceptionally rare: our search of the literature found only eight cases reported. We treated a 73-year-old man with both a fusiform CMT aneurysm and an abdominal aortic aneurysm (AAA). The celiac artery and superior mesenteric artery were reconstructed by performing a retrograde prosthetic-graft bypass originating from the right limb of the bifurcated aortic graft used to repair the AAA. To our knowledge, this is the first report of successful surgical treatment of a CMT aneurysm and coexistent AAA.     

Basolateral Na+/H+ exchange maintains potassium secretion during diminished sodium transport in the rabbit cortical collecting duct

Stimulation of the basolateral Na(+)/K(+)-ATPase in the isolated perfused rabbit cortical collecting duct by raising either bath potassium or lumen sodium increases potassium secretion, sodium absorption and their apical conductances. Here we determined the effect of stimulating Na(+)/K(+)-ATPase on potassium secretion without luminal sodium transport. Acutely raising bath potassium concentrations from 2.5 to 8.5 mM, without luminal sodium, depolarized the basolateral membrane and transepithelial voltages while increasing the transepithelial, basolateral and apical membrane conductances of principal cells. Fractional apical membrane resistance and cell pH were elevated. Net potassium secretion was maintained albeit diminished and was still enhanced by raising bath potassium, but was reduced by basolateral ethylisopropylamiloride, an inhibitor of Na(+)/H(+) exchange. Luminal iberitoxin, a specific inhibitor of the calcium-activated big-conductance potassium (BK) channel, impaired potassium secretion both in the presence and absence of luminal sodium. In contrast, iberitoxin did not affect luminal sodium transport. We conclude that basolateral Na(+)/H(+) exchange in the cortical collecting duct plays an important role in maintaining potassium secretion during compromised sodium supplies and that BK channels contribute to potassium secretion.