Endothelial cell seeding of small-caliber synthetic grafts in the baboon.

Endothelial cell (EC) seeding has been proposed as a method to improve the performance of small-caliber synthetic vascular prostheses. Seeding experiments to date have all been carried out in the dog. This study investigates EC seeding of small-caliber Dacron carotid interposition grafts compared with contralateral control grafts in the baboon. Surface thrombogenicity was assessed at 24 hours, 2 weeks, and 4 weeks after implantation with indium 111-labeled autologous platelets. Morphologic and immunohistochemical techniques were used to assess the identity and homogeneity of the EC inoculum before seeding and to identify cell types on the harvested grafts. There was no significant difference in patency rates between seeded and control grafts at 5 weeks. Platelet accumulation on seeded grafts was significantly less (p less than 0.05) than on paired controls at 2 and 4 weeks after implantation. The luminal lining of seeded grafts had more cellular ingrowth, less adherent thrombus, and more surface cells with the morphologic and histochemical characteristics of EC than did the lining of controls. EC seeding reduces the platelet reactivity and accelerates EC coverage of small-caliber grafts in the baboon.

Evaluation of arterial prostheses in a baboon ex vivo shunt: the effect of graft material and flow on platelet deposition.

Surface thrombogenicity is recognized as an important factor in the failure of small caliber vascular prostheses. The baboon ex vivo shunt was developed to study small caliber grafts under controlled conditions at different flow rates. The shunt was created by percutaneous insertion of catheters into the baboon femoral artery and vein. Platelet-graft interactions were studied using autogenous indium 111 labeled platelets. Two graft materials were placed in series and exposed to blood flow for 2 1/2 hours at flow rates of 25 and 200 ml/min. At the end of this period, the grafts were removed for morphologic examination. Platelet adhesion to the grafts, especially with the less thrombogenic materials (PTFE and HUV), was found to be independent of flow rate. PTFE was found to be the least platelet-reactive material, HUV was intermediate, and knitted Dacron was the most thrombogenic surface. Platelet deposition on the flow surface was confirmed by light microscopy and scanning electron microscopy.

The isolation and characterization of Ca++-accumulating subcellular membrane fractions from cerebral arteries.

A study was undertaken using differential centrifugation methods to isolate from rabbit cerebral arteries the subcellular microsomal protein fractions capable of actively sequestering Ca++. One isolated protein fraction displayed a relatively large adenosine triphosphate (ATP)-dependent Ca++-accumulating capacity that was completely inhibited by NaN3, and was therefore designated the "mitochondrial fraction." Electron microscopy confirmed that this fraction consisted of numerous mitochondrial elements. Another isolated membrane fraction possessed a Ca++-accumulating capacity dependent on ATP and oxalate and only partially sensitive to NaN3. In the presence of mersalyl acid or the Ca++ ionophore, A23187, Ca++ uptake by this fraction was inhibited 98.0% and 87.4%, respectively. Electron microscopy revealed that this fraction consisted of numerous membrane vesicles, and measurements of Na+-K+-ATPase (adenosine triphosphatase) activity indicated minimal plasma membrane contamination. It was concluded that this microsomal fraction consisted primarily of sarcoplasmic reticulum. At physiological free [Ca++] levels, Ca++ uptake by this fraction was inhibited by norepinephrine through a process sensitive to tolazoline but not propranolol. The effects on Ca++ uptake of added cyclic adenosine monophosphate (cAMP) alone or with rabbit or bovine protein kinase were inconclusive. The organic Ca++ channel blockers, nifedipine and verapamil, significantly inhibited Ca++ uptake by sarcoplasmic reticulum.

Cell-surface carbohydrates in proliferative epidermal lesions. Distribution of A, B, and H blood group antigens in benign and malignant lesions.

The distribution of A, B, and H blood group antigens was studied by means of peroxidase-antiperoxidase technique in normal skin and in lesions of carcinomas in situ (solar keratoses, Bowen's disease), squamous cell carcinoma, keratoacanthomas, and verrucae. In normal skin, the epidermis of persons of blood group O showed H antigens throughout the epidermis; of blood group A, H and A antigens; and of blood group B, H and B antigens. In lesions of solar keratoses, there were no antigens of blood groups in the irregular downward proliferations. In five of 11 cases of Bowen's disease, there were no antigens of blood groups in the epidermis. In eight out of 10 cases of squamous cell carcinoma, no antigens of blood groups were found in the islands of the neoplastic process, but in two cases they were present in a patchy distribution. In the benign lesions examined, the antigens of A, B, and H blood groups were always present, although in verrucae the staining was confined to the upper layers of the epidermis only.

Nephrogenic adenoma and embryonic kidney tubules share PNA receptor sites.

Nephrogenic adenoma a rare bladder, ureter, or urethral lesion, is of disputed pathogenesis, metaplastic and congenital etiologies both being implicated in its development. Since light and electron microscopy have been unable to fully resolve the lesion's pathogenesis, the authors used biotinylated lectins as probes and avidin-biotin peroxidase complex (ABC) as a visualant to study cases of nephrogenic adenomas and compared their lectin binding patterns with those of normal transitional epithelium, human embryonic kidneys, and cases of cystitis cystica and glandularis and squamous metaplasia of the bladder in an effort to clarify this issue. Only the epithelial lining of the luminal surface and tubuli in nephrogenic adenoma and tubules in embryonic kidney exhibited free PNA receptor sites. The striking staining similarities between the epithelial components of nephrogenic adenomas and mesonephric and metanephric tubules complement previous findings concerning the origin of nephrogenic adenoma.

Villous adenoma of the urinary bladder: a morphologic or biologic entity?

Villous adenomas in the urinary bladder are rare neoplasms whose malignant potential is unclear. A case of a morphologically benign non-invasive mucin producing papillary neoplasm of the urinary bladder associated with cystitis glandularis is presented. Absence of A tissue isoantigen from the neoplastic and metaplastic cells and the presence of H tissue isoantigen in both neoplastic and metaplastic cells is observed in a patient whose blood type is A, indicating incomplete maturation of surface coat constituents. The histologically benign appearance of this lesion may belie a malignant potential.