Endothelialization of Cardiac Valve Bioprostheses

The main disadvantage of implanted xenograft valves used in cardiac surgery is their poor clinical long-term result, due to early tissue degeneration. In order to improve the performance of such glutaraldehyde fixed bioprostheses, a biological coating with viable endothelial cells was suggested. Therefore, glutaraldehyde preserved bovine pericard patches, as well as commercially available xenograft valves, were lined using human venous endothelial cells or microvascular cells from the subcutaneous fat tissue. Before cells were transplanted into their new environment, grafts were treated with an amino acid solution in order to neutralize the cytotoxic effect of free aldehydes, and precoated with fibronectinheparin and basic fibroblast growth factor (bFGF) or endothelial cell growth supplement (ECGS) in order to enhance cell proliferation. Coated specimens were kept in culture conditions for a further seven days. Proliferation of transplanted cells was verified by an increase of activation following 3H-thymidine incorporation, while the maintained metabolic cell activity was demonstrated via Prostacycline (PGI2) measurement. Morphology was evaluated by means of scanning electron microscopy (SEM). As evaluated by the β-Counter, 7 ng/ml bFGF (288,727 ± 39,668 counts on day 4) substantially enhanced cell proliferation after seeding, opposed to the stimulation with 30,000 ng/ml ECGS (91,924 ± 1129 counts on day 4), (p<0.001). The PGI2 release of transplanted cells was stimulated with 25 μM Na arachidonic acid by the factor 2.6 ± 0.3 and inhibited with 5 mM acetylsalecylic acid by the factor 0.7 + 0.2 on day 4 when compared with the basic level. After seven days of cultivation, SEM observation revealed that specimens stimulated with bFGF showed areas of confluent coated leaflets with an even distribution of cell layer. We therefore conclude that proliferation of transplanted cells is most favorable when stimulated with bFGF and that a special treatment of GA preserved cardiac valve bioprostheses allows a vital biological coating with human endothelial cells.

Phosphatidylcholine does not protect rats against 5-fluorouracil/folinic acid-induced damage of the intestinal luminal mucosa

PURPOSE

The study was performed to evaluate the ability of phosphatidylcholine (PPC) to modulate the toxicity of 5-fluorouracil/folinic acid (5-FU/FA) in rats.

METHODS

Twenty-eight female Wistar rats were divided into four series, each consisting of 6--8 animals and administered 0.5 ml isotonic solution i.v. once a day. The series were as follows: 1) saline; 2) 20 mg 5-FU + 4 mg FA; 3) 30 mg 5-FU + 6 mg FA; 4) 2 weeks daily orally 50 mg PPC/kg body weight (b.w.), on day 12, 30 mg 5-FU + 6 mg FA. As an indicator of membrane luminal impairment, 72 h after an i.v. administration, peptidase activities were measured by using an in situ perfusion model.

RESULTS

The i.v. application of 5-FU/FA causes a clear reduction of enzyme activities in comparison to the control group.

CONCLUSIONS

In investigations with rats, we have shown that a low concentration of oral PPC (50 mg/kg b.w.) cannot protect the luminal mucosa membrane from being injured by the enterotoxic action of 5-FU/FA.

Low detection rate of p53 antibodies in sera of soft tissue sarcoma patients

Accumulation of the p53 gene product can lead to its immunogenic appearance and the generation of p53 serum antibodies (p53ab). In different cancer types the occurrence of detectable p53ab has an independent prognostic impact. In spite of the known p53 protein overexpression rate in soft tissue sarcomas (STS), up to 70%, there have been no investigations done on p53ab in serum in STS patients. In this prospective study of 50 STS patients, we investigated the presence of serum p53ab using an enzyme-linked immunosorbent assay system and the presence of p53 overexpression in the appropriate tissue specimen immunohistochemically. Using Kruskal-Wallis chi(2) and Kaplan-Meier tests the results were then correlated to histopathological and clinical data. Six of the 50 patients (12%) showed p53ab detectable in the serum, and 56% (28/50) of the tumors were p53 immunohistochemically positive. Four of the six p53ab positives (66%) had immunohistochemically p53 positive and two (33%) had negative tumors. Altogether four of the 50 patients (8%) were positive for p53ab in serum as well as for p53 immunohistochemistry in tumor tissue specimens. Twenty patients (40%) were negative for both. All of the p53ab positive patients had stage I or II tumors. Excluding tumor stage there was no p53ab correlation to histopathological, clinical or prognostic parameters. We conclude that in STS patients, p53ab also occurs but in contrast to other tumor types at a relatively low frequency. According to our results, the clinical value of p53ab seems to be limited in STS patients.

Protective effect of oral phosphatidylcholine on radiation-induced release of intestinal peptidases in rats

PURPOSE

To investigate whether phosphatidylcholine (PPC) has a protective effect on mucosa-irradiated rats.

METHODS

The rats were orally fed with 25, 50, and 100 mg PPC/kg body weight (b.w.), respectively, for 3 weeks before irradiation. After administering the medication and 1 day after irradiation, a 20 cm segment of the proximal jejunum was perfused in situ and peptidase activities, as well as the concentrations of the membrane components, were assayed.

RESULTS

We have shown that the application of a low dose of 25 mg PPC/kg b.w. daily for 21 days can prevent damage to membranes induced by 2.0 Gy as represented in the peptidase release profiles during the perfusion of the proximal jejunum of rats. Higher dose levels did not increase the protective effect.

CONCLUSIONS

These findings suggest that a low dosage of exogenous PPC is capable of hindering the impairment of membranes induced by a small dose of radiation.

A low dose of ionizing radiation increases luminal release of intestinal peptidases in rats

PURPOSE

Mucosal inflammation in the small intestine is a potentially hazardous side effect of abdominal irradiation. In an effort to develop a quantitative method of evaluating mucosal damage, the luminal release of brush border enzymes in response to ionizing radiation was examined using two investigational strategies.

METHODS

First, a 20 cm segment of the proximal jejunum was perfused in situ and enzymatic activities within the perfusates were evaluated. In a second approach, enzymatic activities were directly evaluated in isolated brush border membranes from the jejunal mucosa.

RESULTS

Most of the peptidase activities measured were increased in the perfusates 1 day after irradiation and had returned to control levels at 4 days. In the brush border membranes, some enzyme activities decreased at 1 day and were, with the exception of leucineaminopeptidase (LAP), similar to control levels at 4 days.

CONCLUSIONS

LAP is more strongly affected by radiation than the transmembranously bounded enzymes.

Detection of p53 autoantibodies in sera of gastric cancer patients and their prognostic relevance

BACKGROUND

Changes in the p53 gene product can be immunogenic and enable the formation of p53 serum antibodies (p53ab), detectable in patients with different cancer types. So far, there have been no reports describing the detectability of p53ab in gastric cancer patients.

METHODS

We investigated the presence of p53ab and their clinical relevance in a cohort of 74 gastric cancer patients, using an enzyme-linked immunosorbent assay system.

RESULTS

In our investigation 20.3% of all patients (15 of 74) and 46.9% of the patients with immunohistochemically (IHC) p53-positive tumors (15 of 32) showed detectable p53ab in serum. All p53ab-positive patients had IHC p53-positive tumors. We have found a significant correlation of p53ab with a higher tumor stage (P = 0.002) and also with a poor prognosis of survival (P = 0.04).

CONCLUSION

We have shown that in gastric cancer patients p53ab are also detectable and that p53ab positivity is a predictor of an unfavorable prognosis.

Absence of p53 autoantibodies in sera from glioma patients

Alteration of the tumor suppressor gene p53 is the most frequent genetic feature of human cancer and leads to over-expression and loss of function of the p53 protein in affected cells. Patients with many types of cancer, including breast, lung, and colon carcinoma, were shown to develop auto-immune response against the overexpressed protein and to produce autoantibodies directed to immunodominant epitopes common for both wild type and mutants. The presence of p53 autoantibodies (p53-aAb) seems to be, at least in patients with breast and bronchial tumors, related to an unfavorable prognosis. The present study aimed to investigate the presence of p53-aAb in patients with malignant glioma. Sera from 70 consecutive patients with gliomas graded WHO G III and IV were collected and assayed together with sera from 30 controls. A new photometric sandwich-ELISA was used for semiquantitative analysis of p53-aAb titers. p53 gene and its protein product were examined in formalin-fixed and fresh-frozen tumor tissues using immunohistochemistry, PCR-single-strand conformational polymorphism, and sequencing. Sixty percent of the glioma cases showed immunohistochemically positive cells, thus indicating intracellular accumulation of p53. Sequencing of the hot-spot exons 5-8 revealed mutations in 39% of the tumor cases. In contrast to results in other types of malignant tumors, where up to 40% of patients have high serum titers of p53-aAb, no such antibodies were found in patients with malignant cerebral glioma despite the presence of mutated or alterated p53 protein in the primary tumors. None of the non-cancer control patients had detectable titers of p53-aAb, although sera from five of six lung cancer patients had medium to high titers. The presented data suggest that glial tumors are unusual in the absence of serum antibodies to p53. It is hypothesized that impaired function of most immunocompetent cells invading brain tumors could be the cause for the absence of an autoimmune response.

Endothelialization of cardiac valve bioprostheses

The main disadvantage of implanted xenograft valves used in cardiac surgery is their poor clinical long-term result, due to early tissue degeneration. In order to improve the performance of such glutaraldehyde fixed bioprostheses, a biological coating with viable endothelial cells was suggested. Therefore, glutaraldehyde preserved bovine pericard patches, as well as commercially available xenograft valves, were lined using human venous endothelial cells or microvascular cells from the subcutaneous fat tissue. Before cells were transplanted into their new environment, grafts were treated with an amino acid solution in order to neutralize the cytotoxic effect of free aldehydes, and precoated with fibronectin-heparin and basic fibroblast growth factor (bFGF) or endothelial cell growth supplement (ECGS) in order to enhance cell proliferation. Coated specimens were kept in culture conditions for a further seven days. Proliferation of transplanted cells was verified by an increase of activation following 3H-thymidine incorporation, while the maintained metabolic cell activity was demonstrated via Prostacycline (PGI2) measurement. Morphology was evaluated by means of scanning electron microscopy (SEM). As evaluated by the beta-Counter, 7 ng/ml bFGF (288,727 +/- 39,668 counts on day 4) substantially enhanced cell proliferation after seeding, opposed to the stimulation with 30,000 ng/ml ECGS (91,924 +/- 1129 counts on day 4), (p < 0.001). The PGI2 release of transplanted cells was stimulated with 25 microM Na arachidonic acid by the factor 2.6 +/- 0.3 and inhibited with 5 mM acetylsalicylic acid by the factor 0.7 +/- 0.2 on day 4 when compared with the basic level.(ABSTRACT TRUNCATED AT 250 WORDS)