Lack of obvious influence of PLLA nanofibers on the gene expression of BMP-2 and VEGF during growth and differentiation of human mesenchymal stem cells.

Growth factors like bone morphogenetic protein 2 (BMP-2) and vascular endothelial growth factor (VEGF) play an important role in bone remodeling and fracture repair. Therefore, with respect to tissue engineering, an artificial graft should have no negative impact on the expression of these factors. In this context, the aim of this study was to analyze the impact of poly(L-lactic acid) (PLLA) nanofibers on VEGF and BMP-2 gene expression during the time course of human mesenchymal stem cell (hMSC) differentiation towards osteoblasts. PLLA matrices were seeded with hMSCs and cultivated over a period of 22 days under growth and osteoinductive conditions, and analyzed during the course of culture, with respect to gene expression of VEGF and BMP-2. Furthermore, BMP-2-enwoven PLLA nanofibers were used in order to elucidate whether initial down-regulation of growth factor expression could be compensated. Although there was a great interpatient variability with respect to the expression of VEGF and BMP-2, PLLA nanofibers tend to result in a down-regulation in BMP-2 expression during the early phase of cultivation. This effect was diminished in the case of VEGF gene expression. The initial down-regulation was overcome when BMP-2 was directly incorporated into the PLLA nanofibers by electrospinning. Furthermore, the incorporation of BMP-2 into the PLLA nanofibers resulted in an increase in VEGF gene expression. Summarized, the results indicate that the PLLA nanofibers have little effect on growth factor production. An enhancement in gene expression of BMP-2 and VEGF can be achieved by an incorporation of BMP-2 into the PLLA nanofibers.

Chemoimmunotherapy for melanoma with dacarbazine and 2,4-dinitrochlorobenzene: results from a murine tumour model.

An empirically established chemoimmunotherapy that combines the epifocal application of the contact sensitizer dinitrochlorobenzene (DNCB) to cutaneous metastases with the systemic administration of dacarbazine (DTIC) yields high response rates and results in prolonged survival. However, despite the fact that this therapy has been in clinical use for several years, the mode of action still remains elusive. In order to overcome this limitation we established a murine model system. B16 melanoma cells were implanted subcutaneously in syngeneic C57BL/6 mice and treatment was started 7 days after. In a first set of experiments mice received intraperitoneal injections of DTIC followed by epifocal applications of DNCB 24 h later. Treatment significantly decreased tumour growth. In contrast, no significant effect was induced by DTIC or DNCB alone. Using this regimen, with varying doses of either DTIC or DNCB, we demonstrated that the therapeutic effect is dose dependent. Furthermore, the treatment of subcutaneous tumours with DTIC and DNCB influenced the course of visceral metastases: the growth of pulmonary metastases was significantly inhibited if subcutaneous tumours were treated as described. In conclusion, we have established a model system that seems to be appropriate for both the optimization of this therapeutic regimen and the characterization of effector mechanisms.

[Percutaneous transluminal angioplasty (PTA) of isolated crural arterial stenoses in critical arterial occlusive disease]. / Perkutane transluminale Angioplastie (PTA) isolierter Unterschenkelarterienstenosen bei kritischer arterieller Verschlusskrankheit.

PURPOSE: Retrospective analysis of the results after infrapopliteal PTA of isolated crural limb artery stenoses in patients with critical crural limb ischaemia. PATIENTS AND METHODS: Between 1989 and 1994 70 infrapopliteal dilatations of isolated crural limb artery stenoses in 44 patients (47 PTA procedures) were done with small diameter balloon catheters. 45 patients were stage IV according to Fontaine's classification, two patients were stage III. No patient had a relevant obstruction up to the popliteal artery. Follow up ranged from 1-50 months (mean 13.3 months). RESULTS: A technical success with a residual stenosis below 30% compared to the original vessel diameter was achieved in 80% of patients (n = 56). The cumulative limb-salvage rate was 76.6% after 6 to 36 months after PTA. RESULTS: In patients with chronical critical crural limb ischaemia PTA of isolated crural limb artery stenoses is an efficient therapy modality for limb-salvage. In many cases PTA is the last alternative method to amputation surgery if there is no sufficient distal vessel for a bypass.

[Percutaneous balloon dilatation of isolated lesions of the calf arteries in critical ischemia of the leg]. / Perkutane Ballondilatation bei isolierten Läsionen der Unterschenkelarterien mit kritischer Beinischämie.

Between 1990 and 1993 we performed 42 percutaneous transluminal balloon angioplasties (PTA) in 30 patients with isolated lesions of crural arteries and limb threatening ischaemia. The average age of the patients was 70.5 years, 90% were diabetics. With low-profile balloon catheters between 2 and 4 mm we dilatated 15 tibioperoneal trunks, 12 anterior tibial arteries, 3 posterior tibial arteries and 12 peroneal arteries. Initial success was achieved in 83% of the dilatations with an average increase of ankle-brachial index of 0.18. After PTA two groin haematomes as the only complications were observed. In 22 cases healing of the acral lesions under local surgical treatment was seen. Two of the clinical unsuccessful patients required popliteopedal bypass surgery and 5 below-knee amputation because of lacking reconstructive possibilities. The follow-up period varied from 1 to 35 months (mean 10.3 months). Life table analysis showed a cumulative limb salvage rate of 82% after one and two years. The PTA of infrapopliteal artery stenoses and occlusions is considered as an effective and safe therapy modality to avoid below-knee amputation in patients with limb threatening ischaemia.

[The diagnostic value of angioscopy in venous thrombectomy]. / Diagnostischer Stellenwert der Angioskopie bei der venösen Thrombektomie.

Since 1983 angioscopy was applied as a control method in 187 venous thrombectomies to improve the treatment of acute iliofemoral thrombosis. In a retrospective study we tried to show the impact of angioscopy intraoperatively and the influence on long-term results. Thrombectomy was performed in 97 patients affected at three levels, in 50 cases with pelvic-femoral, in 35 with pelvic and in 43 with femoro-tibial thrombosis. The average clinical age of the thrombosis was 5 days, 66% of the patients (age 39 years) were female. The endoscopic findings were compared with phlebological results after one year using a phleboscore between 0 points (occlusion) and 5 points (normal). The phlebographies were analyzed so that the functional status of the vein was represented. After venous thrombectomy 42.8% of the cases were endoscopically classified complete but in 57.2% residual clots were observed. It was possible to completely (24.6%) or partly (18.7%) remove these clots by further thrombectomy maneuvers, non removable remnants were found in 7.5% and a venous spur in 6.4%. The statistical analysis with Kruskal-Wallace test showed significant differences in venous morphology between the endoscopically complete thrombectomies and those with residual clots. After a follow-up period of 30 months (12-64) the clinical results were very good. In 58% we observed normal findings, a cvi grade I in 35%, grade II in 4%. Crural ulcers had developed in only 3%. From our data we conclude that endoscopy is an excellent method for intraoperative quality-control in venous thrombectomy.

Tibioperoneal arterial lesions and critical foot ischaemia: successful management by the use of short vein grafts and percutaneous transluminal angioplasty.

BACKGROUND: In a substantial number of mainly diabetic patients isolated crural arterial lesions are found to be the underlying cause for severe ischaemic foot lesions. Without revascularisation, patients with this specific occlusion pattern will inevitably face major amputation. To attain limb salvage in this setting, since the early eighties short vein grafts were used to bypass the occluded infrapopliteal arteries. More recently, percutaneous transluminal angioplasty (PTA) was also attempted to avoid limb loss in selected patients. PATIENTS AND METHODS: Since May 1986 in 125 patients 130 autologous bypass grafts from the BK-popliteal artery or the proximal tibioperoneal arteries to malleolar vessels were performed in the presence of extended crural arterial occlusions and critical foot ischaemia (rest pain 3, tissue loss 127). In another series in 89 limbs (rest pain 5, tissue loss 84) of 84 patients PTA was done to treat 168 focal stenoses of > 50% diameter reduction and 11 short occlusions in a total of 135 crural arteries. RESULTS: Using life-table analysis, primary and secondary cumulative patency rates for short vein grafts with distal graft origin were 90% and 98% at 30 days, 76% and 83% at one year and 46% and 49% at seven years, respectively. The corresponding limb salvage rates amounted to 95%, 80% and 63%. Initial complete or partial technical success after PTA of crural arteries could be obtained in 93%: The limb salvage rates achieved were 95% at 30 days, 82% at one year and 63% at six years. CONCLUSION: Our results suggest that--depending on the extent of lesions--both short vein grafts as well as PTA are successful complementary treatment modalities to avoid limb loss in predominantly diabetic patients with infrapopliteal artery disease and critical ischaemia.

Interaction of quinolones with the theophylline metabolism in man: investigations with lomefloxacin and pipemidic acid.

The single-dose pharmacokinetics of theophylline alone and at the end of a five-day treatment period with a new difluorinated quinolone antibacterial, lomefloxacin (400 mg/d) and pipemidic acid (400 mg b.i.d.) were investigated in 12 healthy male volunteers. Concentration of theophylline and its metabolites 1-methylxanthine, 1-methyluric acid, 1.3-dimethyluric acid and 3-methylxanthine were determined in plasma, and (except 1-methyluric acid) in urine by HPLC separation. The elimination half-life of theophylline before quinolone treatment was 5.7 +/- 2.0 h and did not change significantly under coadministration of lomefloxacin (6.2 +/- 2.0 h), whereas with pipemidic acid a marked prolongation (10.8 +/- 2.3 h) occurred. Results without and during coadministration of lomefloxacin showed no detectable 1-methylxanthine in plasma. With pipemidic acid, 1-methylxanthine was observed in the plasma and 1-methyluric acid and 3-methylxanthine were not detected. Lomefloxacin showed only a slight alteration in the metabolite formation of theophylline, whereas pipemidic acid induced marked changes. In contrast to pipemidic acid, no metabolic interaction would be expected under concomitant use of lomefloxacin and theophylline within the recommended dose range for both drugs.

[Early and late results of transperitoneal thrombectomy in thrombosis of the inferior vena cava]. / Früh- und Spätergebnisse nach transperitonealer Thrombektomie bei Thrombose der Vena cava inferior.

Acute inferior vena cava thrombosis is a rare clinical feature with unknown incidence. A clear evidence about the best treatment does not exist. Especially the indications for surgical therapy and their clinical results are published only in a few reports. So the aim of this study was to take a look to our experience and make an evaluation of the combined transcaval and transfemoral venous thrombectomy. In a retrospective study of the past 12 years 19 patients with a mean age of 28.5 years, 15 women and 4 men, showing ascension of a iliofemoral clot to the vena cava were treated by transperitoneal and transfemoral thrombectomy. The mean thrombus age was 7 days, 2 patients had bilateral iliofemoral thrombosis. Simultaneously a transfemoral thrombectomy and transcaval thrombectomy were performed after exposure of the vena cava inferior via transabdominal approach. In all cases a venous patency could be achieved, 3 times a re-thrombectomy within 1 week was necessary. One intraabdominal hematoma was revised surgically. One patient died on the first postoperative day because of a fulminant lung embolism. After a mean follow-up of 6 years 3 patients did not have any symptoms of post-thrombotic sequelae, 13 had mild and only one patient moderate post-thrombotic syndrome. The combined transperitoneal and transfemoral venous thrombectomy of the vena cava inferior represents a safe and effective treatment of the acute thrombosis of the vena cava inferior. Severe post-thrombotic sequelae especially in young women may be avoided.

[Intraoperative quality control in carotid surgery]. / Intraoperative Qualitätskontrolle in der Carotis-Chirurgie.

The intraoperative quality control in carotid surgery is performed by different methods: angiography, duplex-ultrasonography, transcranial Doppler ultrasonography, cw-Doppler, B-mode ultrasonography, pulsed Doppler with spectral analysis, angioscopy and flow-measurements. In Germany these measures are used only in one third of the carotid reconstructions. Especially with angiography and duplex-ultrasonography technical defects can be detected and differentiated if they were without clinical relevance like low-grade stenoses, small intima-flaps and residual plaques or needed to be reexplored. These are high-grade stenoses, acute thrombus-formations of the endarterectomised area and large intima-flaps. Abnormalities were detected in a mean of 17% of all carotid reconstructions by intraoperative control methods. In 5% severe irregularities lead to an immediate revision. Despite that there does not exist clear evidence whether the use of quality control methods reduces the perioperative neurological complication rate. It is not necessary to perform intraoperative quality control if meticulous operative technique with shunting and patch angioplasty is applied and a low perioperative complication rate is reached. For the documentation of the surgical result angiography can be recommended.

The role of intraoperative digital subtraction angiography for quality control of standard carotid endarterectomy using patch angioplasty.

The absence of technical defects is considered to be of great importance during carotid endarterectomy (CEA). In this context, both safe surgical technique and intraoperative quality control may be a fundamental part of the operative procedure. We have therefore undertaken a prospective study to evaluate the possible benefits of completion angiography in standard CEA using patch angioplasty. The objectives were three-fold: (1) to identify the incidence of defects requiring prompt revision; (2) to assess the perioperative stroke rate as well as the number of residual stenosis after 6 weeks in angiographically controlled patients and (3) to compare these results with a control group. From 1 January to 30 September 1999 111 patients with 115 consecutive CEAs which had completion angiography (Group A) were prospectively entered into this study. The results in group A were compared with a series of again 111 patients (Group B) which had 116 CEAs without intraoperative quality control between January and September in the year before. Surgical technique was identical in both groups. In general, risk factors were distributed evenly among both group with the exception that in group A were significantly more high-grade ipsilateral ICA stenoses while group B had more patients with diabetes and ipsilateral CT-defects. In group A, angiographic irregularities prompted us to immediate re-exploration in five patients (dilatation of severe ICA spasm 1; re-exploration of distal ICA occlusion 1; reopening of occluded ECA 3). With a 30 day mortality of 0% each perioperative stroke rate was comparable with 3/115 in group A and 3/116 in group B (P=1.0). 2/3 patients with neurological deficits in group A had early postoperative carotid thrombosis--in spite of a normal completion study. Duplex examination after 6 weeks revealed one asymptomatic ICA occlusion in each group. The incidence of residual stenosis (> or =50%) was not significantly different being 3.7% in group A and 3.2% in group B (P=0.85). When applying a safe and simple operative technique for CEA, the incidence of abnormalities warranting immediate correction appears to be a rare event and, therefore, the necessity for obligatory quality control may be questionable. On the other hand, completion DSA allows a simple documentation of the adequacy of the surgical procedure.

[Diabetic foot--uncontrollable infections despite successful revascularization]. / Der diabetische Fuss--nicht beherrschbare Infektionen trotz erfolgreicher Revaskularisation.

We treated foot ulcerations in diabetics with limb-threatening ischemia using percutaneous balloon dilatation (44) and popliteodistal vein grafts (94). After revascularization, we observed in 12% an increase in the infection which necessitated major amputation despite open bypass or successful dilatation. A diabetic local immunodeficiency leads to cellular and humoral alterations which may cause severe tissue damage although the perfusion has been improved.

Lipid-induced insulin resistance in cultured hepatoma cells is associated with a decreased insulin receptor tyrosine kinase activity.

We have shown previously that experimental modifications of the cellular lipid composition of an insulin-sensitive rat hepatoma cell line (Zajdela Hepatoma Culture, ZHC) affect both binding and biological actions of insulin. Discrepancies between insulin binding and actions implied a postbinding defect, responsible for the observed insulin resistance in lipid-treated cells. To elucidate the mechanism for this defect, we have studied insulin binding and insulin receptor kinase activity in partially purified receptor preparations from ZHC cells grown either in normal medium or in medium supplemented with linoleic acid or 25-hydroxycholesterol. Insulin binding to the lectin-purified insulin receptor showed only a small alteration in receptor affinity for the preparations from lipid-treated cells. Insulin-stimulated autophosphorylation of the beta-subunit of the insulin receptor, as well as insulin-induced phosphorylation of the artificial substrate poly(Glu,Tyr)4:1, was significantly decreased in the preparations from lipid-modified cells. Although differences in basal levels were observed, the magnitude of the insulin-stimulated kinase activity was significantly decreased in receptor preparations from lipid-treated cells. These findings indicate that experimental modification of the lipids of cultured hepatoma cells can produce in insulin receptor kinase activity changes that are proportional to the reduced insulin action observed in these cells.