Arterial wall regeneration in small-caliber vascular grafts in rats. Neoendothelial healing and prostacyclin production

Clinically available synthetic graft materials frequently fail when used as a small-caliber arterial substitute. Therefore, we developed a new type of graft material, prepared from a mixture of polyurethane and poly-L-lactic acid, to be used as a scaffold for the regeneration of the arterial wall. In this study microporous, compliant, biodegradable polyurethane/poly-L-lactic acid grafts (n = 16) and polytetrafluoroethylene grafts (n = 16) were implanted in the rat abdominal aorta and evaluated 3, 6, and 12 weeks after implantation. First, we evaluated the extent of neoendothelial healing (n = 8) by means of light microscopy and scanning electron microscopy. Next, we studied the ability of the neoendothelial cells to produce prostacyclin (n = 8) by means of bioassay for prostacyclin and radioimmunoassay for its stable hydrolysis product, 6-oxo-prostaglandin F1 alpha. There were no significant differences between the two graft types in the amount of prostacyclin production per unit graft area covered with neoendothelium, and this amount was the same as for normal endothelium. However, the polytetrafluoroethylene grafts showed incomplete neoendothelial healing, even after 12 weeks of implantation, in contrast to the polyurethane/poly-L-lactic acid grafts. The better healing characteristics of the polyurethane/poly-L-lactic acid grafts ensured the fast development of a complete neoarterial wall, possessing strength, compliance, and thromboresistance equivalent to normal arterial wall tissue. These results demonstrate that arterial wall tissue regeneration in polyurethane/poly-L-lactic acid grafts may open new perspectives in the field of arterial reconstructive surgery.     

The heterogeneity of follicular follicle center cell tumors. II. Clinical follow-up of 30 patients

The Kiel classification for the histology of malignant lymphomas distinguishes the group of follicular lymphomas as low-grade malignancies. Clinically, this proves to be a heterogeneous group. With the aim of establishing parameters giving indications for the prognosis of the patient, a retrospective analysis was made of 30 patients with a histologic diagnosis of follicular follicle center cell tumor (FCC). Neither the immunologic markers of the cells nor the stage of dissemination have prognostic significance for survival. On the basis of the predominating neoplastic cell type, a cytologic subdivision of the lymphomas was made, characterizing the following subgroups: SCC (small centrocytes with occasional centroblasts), CBCC/A (centrocytes with several centroblasts), and CBCC/B (centrocytes with many centroblasts), SLCC (small and large centrocytes), SLCB (small and large centroblasts). The actuarial survival of the total group of 30 patients was 66% after 5 years, but the survival in the cytologic subgroups ranged from 100% in group SCC to 0% in group SLCB. Comparing the groups SCC and CBCC/A with CBCC/B and SLCB gave a significantly worse prognosis for the groups with an increased number of centroblasts (i.e., CBCC/B and SLCB). Therefore it seems justified to treat patients with a predominance of centroblasts aggressively with the aim of reaching a complete remission.     

A clot-inducing wound covering with high vapor permeability: enhancing effects on epidermal wound healing in partial-thickness wounds in guinea pigs

Although the use of an occlusive wound covering accelerates the reepithelialization of a partial-thickness wound, it has the disadvantage of leading to wound exudate accumulation. The effect of an experimental polyetherurethane (PEU) wound covering with a high vapor permeability was compared with an occlusive wound covering (OpSite covering) and air exposure with respect to the rate of reepithelialization, eventual epidermal thickness, and scab thickness in 122 partial-thickness wounds in guinea pigs. The percentage of reepithelialization on day 2 was 85% in wounds covered with the permeable PEU membrane, whereas it was 66% and 35%, respectively, in wounds covered with the occlusive covering or exposed to air. The epidermal thickness did not differ among the three types of treatment. The scab thickness, however, was maximal in the uncovered air-exposed wounds. We conclude that epidermal wound healing is accelerated when the PEU wound covering is used. This wound-healing-promotion effect is apparently due to the high water vapor permeability of PEU, which induces clotting of the wound exudate, and subsequent jellifying of the clot layer.     

Influence of assay buffer on dissociation constants of drugs at beta-adrenoceptor subtypes

The present investigation has assessed the influence of assay buffer (Tris versus Krebs) on the abilities of several beta-adrenoceptor agonists and antagonists to displace the radioligand (-)-[125I]iodocyanopindolol [( 125I]CYP) from beta 1-(left atrial) and beta 2- (uterine) adrenoceptor sites. Saturation studies indicated that the dissociation constant (KD) for [125I]CYP at both beta-receptor sites was approximately 2-fold greater in Krebs as opposed to Tris buffer, and that the maximal density of binding sites (Bmax) in atria (but not uterus) was also reduced 2-fold. In general, the KD values for beta-adrenoceptor agonists were more influenced by the type of buffer used than were KD values for antagonists. Agonist KD values at beta 2-adrenoceptor sites were higher in Krebs than in Tris buffer, while at beta 1-adrenoceptor sites, variable changes resulted. The selective affinity of agonists at beta 1- and beta 2-adrenoceptor sites was therefore markedly influenced by the buffer used and could not be predicted from the established beta 1-/beta 2-adrenoceptor selectivity of the agonists as found in organ bath studies.     

The steroidogenic activity of isolated Leydig cells from mature rats depends on the isolation procedure

Three different collagenase dispersion techniques for isolation of Leydig cells from testes of mature rats have been compared with respect to the yield and quality of the isolated cells. No Leydig cells could be isolated after perfusion of the testis with collagenase (10 mg/ml) followed by incubation at 37°C without shaking, whereas Leydig cells were obtained after incubation of decapsulated testis tissue with collagenase (1 mg/ml) and shaking (80 cycles/min or 1500 cycles/min). Of the total phenylesterase activity, which is localized in the endoplasmic reticulum of interstitial cells, 50 and 85% was released after shaking at 80 and 1500 cycles/, respectively. After sedimentation of the cells 14 and 56% of the microsomal esterase activity was present in the supernatant, whilst 6 and 10% of the esterase activity could be recovered in Ficoll-purified cells. The high esterase activity in the supernatant and the low esterase activity in the purified cells indicated the presence of many broken cells. Testosterone production by cells prepared with the low shaking frequency could be stimulated 9-fold by LH, whereas cells prepared with the high shaking frequency did not respond to LH. Cell preparations which could be stimulated with LH could also be stimulated (3-fold) with NADPH, indicating the presence of damaged cells in addition to intact cells. The percentage of damaged cells in the preparations was estimated using an NADH-dependent histochemical test for mitochondrial diaphorase activity, which shows activity when cell membranes are damaged. Using this criterion, it was found that about 30% of ficoll-purified cells were damaged, whereas only 2% of cells which were pre-incubated and attached to plastic appeared to be damaged. In***     

Long-term survival of a patient with congenital short bowel and malrotation

Since 1969, reports of 16 patients presenting with the congenital short bowel and malrotation syndrome have been published. The prognosis of this malformation is poor; only two patients survived. We present the history of a third patient, successfully treated with long-term survival.     

Indications for laparoscopic colorectal surgery

Background: Between November 1991 and May 1995, a series of laparoscopic colectomies were performed in our hospital. Methods: Our main aim was to define more specifically the indications for laparoscopic colectomy. Results: A total of 69 patients underwent laparoscopic surgery for benign polypoid colorectal disease (n = 10), inflammatory bowel disease (n = 24), and colorectal malignancy (n = 35). Of the latter group, four patients underwent a palliative procedure. The conversion rate of the whole group was 29%. The main reason to convert was infiltrative growth in inflammatory disease or cancer. Respectively, seven (10%) and 12 (17%) patients sustained complications in the perioperative and early postoperative phase. Two patients died perioperatively (3%). The mean hospital stay was 12 days. On follow-up, 11 patients had developed a stenotic anastomosis, which was successfully dilated in all cases. After 3 years, the survival rate according to Kaplan-Meier is 86%, 66%, 68%, and 0% for Dukes' A, B, C, and D color carcinoma, respectively. In one patient with a Dukes B carcinoma, port site metastases were found. Conclusions: Justifiable indications for laparoscopic colorectal surgery include (a) a benign polyp 20–50 cm from the anal ring; (b) mobile, inflammatory large bowel disease; (c) palliation in case of malignant disease, preferably of the left hemicolon. It remains to be proven that laparoscopic colectomy is superior and not just equivalent to open colectomy. This is especially true for resections of colorectal carcinoma with curative intent. Therefore a cost/benefit analysis should be performed in a prospective, randomized setting. Received: 1 November 1996/Accepted: 1 July 1997     

Chromosomal analysis and the classification of soft tissue sarcomas

Seventeen soft tissue sarcomas were karyotyped and the chromosomal findings were compared with those in the literature. Some cases were easily classified (immuno)histologically, whereas others defied classification. In four cases with unequivocal histology, a "characteristic" chromosomal abnormality was found. In one case a diagnosis that was doubtful on histologic grounds was supported by the chromosomal findings, whereas in three other cases, the chromosomal pattern led to reconsideration of the histologic diagnosis. The remaining cases either showed chromosomal abnormalities with hitherto undescribed breakpoints or breakpoints described in tumors with different histology. The results extend the knowledge of chromosomal abnormalities in soft tissue sarcomas. Most importantly, the present approach demonstrates that close collaboration between the surgical pathologist and the cytogeneticist may improve the classification of soft tissue sarcomas.