Repair of abdominal aortic aneurysms with aorto-uni-iliac stentgraft and femoro-femoral bypass.

Endovascular repair (EVAR) is accepted as effective treatment for abdominal aortic aneurysms (AAAs) and has become the standard of care in many instances. The standard bifurcated stentgraft (BFG) is often not possible in patients with unfavourable aneurysm morphology. The aorto-uni-iliac (AUI) graft configuration with femoro-femoral bypass (FFBP) is a promising alternative which may extend the scope of EVAR for AAAs. The aim of this study was to evaluate the feasibility, efficacy and durability of AUI with FFBP. Design. The results of a single institution and a single surgeon were prospectively collected from January 2002 to August 2010. All patients were followed up at 1, 3, 6 and 12 months and then annually. Results. There were 33 patients (27 males) with a mean age of 71.7 years (range 46 - 84). Open surgery posed an unacceptably high risk to all patients owing to advanced age and/or American Society of Anesthesiologists (ASA) classification 3/4. Ineligibility for BFG was due to unfavourable anatomy or a combination of factors in most cases (31 patients). Two patients had anastomotic aneurysms after previous open surgery. The technical success rate was 100%. One severe intra-operative complication occurred (perforated iliac artery). Two patients (ASA 4) died within 30 days (peri-operative mortality rate 6.1%). Seven patients (21.1%) developed postoperative wound complications. Eight patients died during follow-up of non-aneurysm-related conditions. Twenty-three patients are alive, with mean follow-up of 24.4 months and a survival rate of 69.7%. Two complications occurred during long-term follow-up, namely 1 case of graft sepsis and 1 of FFBP occlusion. Conclusion. AUI with FFBP is a safe, effective and durable alternative in high-risk patients with AAAs where standard open repair is contraindicated and BFG repair is not possible owing to unfavourable aneurysm morphology.

Comparison of preserved vascular allografts using glycerol and University of Wisconsin solution in a goat carotid artery transplantation model.

BACKGROUND: Prosthetic grafts have poor patency rates in peripheral arterial reconstructions. Glycerol (GL)-preserved grafts are an alternative. The aim of this study was to examine patency, graft morphology and function of GL-preserved allografts in a goat carotid artery animal model. METHODS: The first group (n = 7) underwent bilateral replacement of the carotid artery by a carotid allograft that was preserved in GL for 1 week. In the second group (n = 5), a carotid artery allograft that was preserved in University of Wisconsin solution (UW) for 48 h was used. In the third group (n = 5), the jugular vein (autologous vein, AU) was used. The follow-up was 3 months. RESULTS: One UW graft and 1 GL graft occluded in the first 24 h postoperatively. Three-month primary patency rates for GL, UW and AU grafts were 93, 100 and 80%, respectively (p = 0.39). Graft diameter was increased in UW allografts (p < 0.005), whereas GL allografts remained unchanged. After explantation, GL allografts demonstrated contraction and relaxation capacity and lower intimal thickness (p < 0.001). CONCLUSION: GL preservation has proven to be a feasible method for arterial allograft transplantation in a large animal model with decreased intimal hyperplasia and renewed functional capability.

The effects of hyperosmosis or high pH on a dual-species biofilm of Enterococcus faecalis and Pseudomonas aeruginosa: an in vitro study.

AIM: To investigate the effect of hyperosmotic hyperosmosis or alkaline stress on a dual-species biofilm of Enterococcus faecalis and Pseudomonas aeruginosa. METHODOLOGY: Biofilms were grown on glass cover slips suspended in bacterial inoculate for 96 h, after which the cover slips with attached biofilms were immersed in brain heart infusion broth (BHI-broth) with 6 mol L(-1) sodium chloride (NaCl) representing the hyperosmotic group or Ca(OH)(2), pH 12.1, representing the alkaline group. Two per cent sodium hypochlorite and BHI- broth served as positive and negative controls, respectively. After treatment, the biofilms were washed, harvested and plated on blood-agar plates after serial dilution. The bactericidal effect was assessed by determining the colony-forming units (CFU). The effect on the biofilm mass was imaged with confocal laser scanning microscopy (CLSM). RESULTS: Hyperosmosis reduced the CFU of both species significantly after 72 h (P < 0.0001). After 168 h, P. aeruginosa was eradicated and the E. faecalis reduction was more than 99%. High pH could not induce a significant bacterial reduction. CLSM revealed dense flocculation of the biofilms incubated in alkaline broth. CONCLUSION: Hyperosmosis effectively reduced a dual-species biofilm of E. faecalis and P. aeruginosa, whilst high pH had limited bactericidal effect in this model.

Determination of the scattering anisotropy with optical coherence tomography.

In this work we demonstrate measurements with optical coherence tomography (OCT) of the scattering phase function in the backward direction and the scattering anisotropy parameter g. Measurements of the OCT attenuation coefficient and the backscattering amplitude are performed on calibrated polystyrene microspheres with a time-domain OCT system. From these measurements the phase function in the backward direction is determined. The measurements are described by the single scattering model and match Mie calculations very well. Measurements on Intralipid demonstrate the ability to determine the g of polydisperse samples and, for Intralipid, g = 0.35 ± 0.03 is measured, which is well in agreement with g from literature. These measurements are validated using the Intralipid particle size distribution determined from TEM measurements. Measurements of g and the scattering phase function in the backward direction can be used to monitor changes in backscattering, which can indicate morphological changes of the sample or act as contrast enhancement mechanism.

[Myocarditis and cardiomyopathy: underestimated complications resulting from clozapine therapy]. / Myocarditis en cardiomyopathie; ernstige complicaties van clozapinetherapie.

BACKGROUND: Treatment with clozapine can affect the heart, leading to serious complications such as myocarditis and cardiomyopathy. When in their early stages both illnesses are difficult to diagnose; this can have serious consequences. Recent analyses of clozapine data suggest that particularly myocarditis is possibly more common than has been assumed hitherto. AIM: To determine the frequency of these complications and to find out what diagnostic tests are available and whether it is necessary or possible to adjust current guidelines on these complications. METHOD: The relevant literature was consulted via PubMed, Embase Psychiatry and Psycinfo on the basis of the keywords 'clozapine' and 'myocarditis', 'cardiomyopathy' and 'heart failure'. RESULTS: Studies showed that the incidence of myocarditis varied from 0.015 to 1.3%. Cardiomyopathy was the subject of fewer studies, one study reported an incidence of 0.022%. More than 50% of the cases of myocarditis developed during the first few weeks of treatment, the average time being about 15 days. For an early diagnosis it is important to monitor the patient's symptoms carefully, especially during the first four weeks following the start of medication. Monitoring should include laboratory tests and electrocardiography. Echocardiography and MRI can be useful additions to the diagnostic process. CONCLUSIONS: Early diagnosis of myocarditis is important because it is a serious condition. Timely recognition of subclinical myocarditis could possibly prevent later complications such as cardiomyopathy. Clinical guidelines are proposed on the basis of the literature.

HIV-occlusive vascular disease.

OBJECTIVES: To evaluate peripheral arterial occlusive disease in HIV-infected patients regarding clinical presentation and outcome of surgical intervention. DESIGN: Prospective clinical survey. PATIENTS AND METHODS: Routine voluntary testing for HIV/AIDS was performed in all patients presenting to our vascular unit. HIV+ patients were enrolled in a registry and followed up prospectively. RESULTS: We identified 154 HIV+ patients, of whom 91 (59%) presented with occlusive disease. There were 71 males and 20 females with a mean age of 44.2 years. The usual risk factors for atherosclerosis were present, but the incidence was less than reported in the classic atherosclerosis population. More than 90% of the patients presented with advanced stage vascular disease (Fontaine III/IV), which explains the high rate (31.9%) of primary amputation. Eighty-seven patients presented with lower-limb ischaemia, 2 patients with upper-limb ischaemia and 2 patients with symptomatic carotid artery stenosis. Seventy-eight procedures were performed on 72 patients, with a perioperative mortality of 6.95%. The limb salvage rate for femoro-popliteal bypass procedures was poor (36.1%), resulting in a high incidence of secondary amputations and prolonged hospital stay. Long-term mortality for the operated patients was 20% over a mean follow-up period of 15.4 months. Hypo-albuminaemia was found to be an important predictor of outcome. CONCLUSION: Patients presenting with HIV-associated peripheral arterial disease should be carefully selected for intervention, taking into consideration nutritional and immune status, stage of the vascular disease and selecting the appropriate procedure.

Autosomal recessive ichthyosis with hypotrichosis syndrome: further delineation of the phenotype.

Autosomal recessive ichthyosis with hypotrichosis (ARIH) syndrome, which is characterized by congenital ichthyosis, abnormal hair and corneal involvement, has recently been shown in one consanguineous Israeli Arab family to be caused by a mutation in the ST14 gene, which encodes serine protease matriptase. No other families have so far been described since the original report. In this current report we describe a female patient from a second family with ARIH syndrome who carries a homozygous novel mutation, p.M1I. The patient has congenital ichthyosis, light brown, curly, sparse hair, improving with age, and sparse body hair, eyebrows and eyelashes. She does not suffer from photophobia, but has blepharitis. The phenotype of this patient closely resembles that of the affected individuals in the previously reported family, although she does not have tooth abnormalities and the ichthyosis is milder.

Interactions between colon cancer cells and hepatocytes in rats in relation to metastasis.

Adhesion of cancer cells to endothelium is considered an essential step in metastasis. However, we have shown in a previous study that when rat colon cancer cells are administered to the vena portae, they get stuck mechanically in liver sinusoids. Then, endothelial cells retract rapidly and cancer cells bind to hepatocytes. We investigated the molecular nature of these interactions between colon cancer cells and hepatocytes. Cancer cells in coculture with hepatocytes became rapidly activated with distinct morphological changes. Cancer cells formed long cytoplasmic protrusions towards hepatocytes in their close vicinity and these protrusions attached to microvilli of hepatocytes. Then, adhering membrane areas were formed by both cell types. Integrin subunits alphav, alpha6 and beta1 but not alphaL, beta2, beta3 and CD44 and CD44v6 were expressed on the cancer cells. In conclusion, colon cancer cells show an active behaviour to bind to hepatocytes, likely involving the integrin subunits alphav, alpha6 and beta1, indicating that early events in colon cancer metastasis in liver are distinctly different than assumed thus far.

Surgical intervention for HIV related vascular disease.

OBJECTIVES: To determine the outcome of surgical intervention in patients with HIV associated vascular disease. DESIGN: Prospective clinical survey. MATERIALS AND METHODS: Routine voluntary testing for HIV/AIDS was performed in patients who presented to our unit with peripheral vascular disease. One hundred and nine patients (5.7%) were prospectively identified over a 5-year period (2001-2006). RESULTS: 24 patients presented with aneurysmal disease whilst occlusive disease was present in 66 patients. There was not much difference between patients with aneurysmal disease and patients with occlusive disease as to age, CD4 count and other risk factors for vascular disease. The peri-operative mortality for aneurysmal disease was 10.6% versus 3.6% for occlusive disease (p=0.264). Long-term mortality was significantly worse (p=0.049) for patients with aneurysmal disease. The results of revascularization in occlusive disease were poor with a limb salvage rate of 31.6%. There was no significant difference in CD4 T-cell counts between primary amputation and revascularization groups (p=0.058). CONCLUSION: Patients with aneurysmal disease have a high peri-operative and long-term mortality and it appears that surgical intervention should be reserved for life-threatening aneurysms only. Patients with occlusive disease have a better survival rate but limb salvage is poor. Primary amputation may be preferable to bypass surgery in patients with critical limb ischaemia.

A prospective comparison of secondary interventions and mortality in open and endovascular infrarenal abdominal aortic aneurysm repair.

Endovascular aneurysm repair (EVAR) has provided a safe and effective alternative to the standard open repair of abdominal aortic aneurysms (AAAs). It has, however, been associated with a high requirement for secondary interventions. This prompted us to compare the two procedures with regard to secondary interventions and mortalities. The sample size was 278 patients, of whom 156 had undergone the open operation and 122 had undergone EVAR. The perioperative morbidity and mortality, as well as the major and minor secondary intervention rates, were obtained for these patients. The results suggest that there is no significant difference in secondary interventions and mortality between the two groups, despite the EVAR group being at significantly higher risk.

Cerebral monitoring during carotid endarterectomy--a comparison between electroencephalography, transcranial cerebral oximetry and carotid stump pressure.

OBJECTIVE: Various modalities are used for cerebral monitoring during carotid endarterectomy (CEA). The aim of this study was to evaluate whether transcranial cerebral oximetry (TCO) and carotid stump pressure (SP) are as accurate as electroencephalography (EEG) for monitoring cerebral ischaemia during carotid cross-clamping. METHODS: One hundred consecutive patients who underwent CEA were studied with continuous and simultaneous EEG and TCO. SP was measured for each patient. The percentage decrease of oxygenation on TCO was calculated during cross-clamping and surgery. EEG findings were used as the benchmark to detect cerebral ischaemia and were the indication for insertion of a temporary shunt. The relationship with TCO was observed in terms of percentage decrease in oxygenation. RESULTS: A total of 6 patients were shunted on the basis of their EEG changes. TCO changed more than 20% in these 6 patients, but an additional 12 patients had TCO changes with a normal EEG. This correlated with a decrease in blood pressure (BP) and was corrected by increasing the BP. The positive predictive values (PPVs) and negative predictive values (NPVs) for shunting based on TCO (as compared with EEG) were 33% and 100% respectively. Thirty-four patients had SP <50 mmHg, of whom 4 were shunted based on EEG changes. Two of 66 patients with SP >50 mmHg were shunted based on EEG changes. If a shunting policy had been based on a SP of 50 mmHg, 30 patients would have been shunted unnecessarily (PPV 12%), whereas the non-requirement for a shunt was predicted correctly in 64 of 66 patients (NPV 97%). There were 2 major strokes: 1 contralateral on day 3 in a patient with bilateral severe stenoses, and 1 ipsilateral in a nonshunted patient with normal EEG, TCO and SP >50 mmHg. CONCLUSION: Compared with EEG, TCO is a practical and non-invasive monitoring system with a high sensitivity (100%) but a low specificity. TCO is more sensitive to a drop in BP and responds earlier to these changes than EEG. SP should not be used as the sole predictor for shunting during CEA.

Emergency endovascular repair for ruptured abdominal aneurysms--a feasibility study and report of 10 cases.

BACKGROUND: Endovascular aneurysm repair (EVAR) has been proved to be effective and safe in the elective management of abdominal aortic aneurysms (AAAs). Initial reports concerning endovascular management of ruptured aneurysms have been promising. OBJECTIVE: To determine the outcome of endovascular repair of ruptured aneurysms in the local setting. Materials and methods. Patients who presented with ruptured AAAs were considered for endovascular repair if they were haemodynamically stable and had suitable aneurysm morphology for EVAR. RESULTS: Ten patients (9 males, 1 female) with a mean age of 74.9 years were treated. All aneurysms were successfully excluded using aorta uni-iliac stent grafts in 7 patients and bifurcated stent grafts in 2 patients. In 1 patient who had had a previous EVAR, a proximal extension device was used. Two patients died in the peri-operative period (30-day mortality of 20%) and 1 patient died after 2 months. Seven patients are still alive. No endo-leaks occurred in any of the survivors. CONCLUSION: Endovascular repair of ruptured AAAs is feasible with acceptable peri-operative mortality and short- to medium-term results.

Lichen planus is associated with human herpesvirus type 7 replication and infiltration of plasmacytoid dendritic cells.

BACKGROUND: Lichen planus (LP) is a common inflammatory skin disease of unknown aetiology. Viral causes have been suggested. OBJECTIVES: To find candidate viruses associated with LP. METHODS: Lesional and nonlesional skin samples, peripheral blood mononuclear cells and serum were obtained from patients with LP. Ultrastructural, viral DNA, immunohistochemical and serological analyses were performed, and comparisons were made with psoriatic and normal skin. RESULTS: Electron microscopy revealed typical 120-200-nm enveloped particles with a 100-nm nucleus resembling human herpesvirus (HHV) virions both in dermis and in epidermis of lesional LP tissue. HHV-7 DNA was found in 11 of 18 lesional LP samples, as opposed to only one of 11 nonlesional LP samples (P =0.06), two of 11 lesional psoriasis samples (P = 0.05) and none of four normal skin samples. No relation was found between LP skin and DNA of other known HHVs (HHV-1-6 and 8). With immunohistochemistry, significantly more HHV-7+ cells were found in lesional LP epidermis than in normal epidermis. Lesional LP dermis contained significantly more HHV-7+ cells than nonlesional LP, psoriatic or normal dermis. Moreover, LP skin contained overwhelmingly and consistently more plasmacytoid dendritic cells (upregulated in virally induced conditions) than nonlesional LP samples. CONCLUSIONS: We conclude that HHV-7 replicates in LP lesions, but not in psoriasis, another inflammatory skin condition. HHV-7 is possibly involved in the pathogenesis of LP. These preliminary data make further research on this topic of interest.

Mechanisms of biliary stent clogging: confocal laser scanning and scanning electron microscopy.

BACKGROUND AND STUDY AIMS: Endoscopic insertion of plastic biliary endoprostheses is a well-established treatment for obstructive jaundice. The major limitation of this technique is late stent occlusion. In order to compare events involved in biliary stent clogging and identify the distribution of bacteria in unblocked stents, confocal laser scanning (CLS) and scanning electron microscopy (SEM) were carried out on two different stent materials - polyethylene (PE) and hydrophilic polymer-coated polyurethane (HCPC). PATIENTS AND METHODS: Ten consecutive patients with postoperative benign biliary strictures were included in the study. Two 10-Fr stents 9 cm in length, one made of PE and the other of HCPC, were inserted. The stents were electively exchanged after 3 months and examined using CLS and SEM. RESULTS: No differences were seen between the two types of stent. The inner stent surface was covered with a uniform amorphous layer. On top of this layer, a biofilm of living and dead bacteria was found, which in most cases was unstructured. The lumen was filled with free-floating colonies of bacteria and crystals, surrounded by mobile laminar structures of mucus. An open network of large dietary fibers was seen in all of the stents. CONCLUSIONS: The same clogging events occurred in both PE and HCPC stents. The most remarkable observation was the identification of networks of large dietary fibers, resulting from duodenal reflux, acting as a filter. The build-up of this intraluminal framework of dietary fibers appears to be a major factor contributing to the multifactorial process of stent clogging.

The effect of the antimicrobial peptide, Dhvar-5, on gentamicin release from a polymethyl methacrylate bone cement.

The objective of this study was to investigate the release mechanism and kinetics of the antimicrobial peptide, Dhvar-5, both alone and in combination with gentamicin, from a standard commercial polymethyl methacrylate (PMMA) bone cement. Different amounts of Dhvar-5 were mixed with the bone cement powders of Osteopal and the gentamicin-containing Osteopal G bone cement and their release kinetics from the polymerized cement were investigated. Additionally, the internal structure of the bone cements were analysed by scanning electron microscopy (SEM) of the fracture surfaces. Secondly, porosity was investigated with the mercury intrusion method and related to the observed release profiles. In order to obtain an insight into the mechanical characteristics of the bone cement mixtures, the compressive strength of Osteopal and Osteopal G with Dhvar-5 was also investigated. The total Dhvar-5 release reached 96% in the 100 mg Dhvar-5/g Osteopal cement, whereas total gentamicin release from Osteopal G reached only 18%. Total gentamicin release increased significantly to 67% with the addition of 50mg Dhvar-5/g, but the Dhvar-5 release was not influenced. SEM showed an increase of dissolved gentamicin crystals with the addition of Dhvar-5. The mercury intrusion results suggested an increase of small pores (< 0.1 microm) with the addition of Dhvar-5. Compressive strength of Osteopal was reduced by the addition of Dhvar-5 and gentamicin, but still remained above the limit prescribed by the ISO standard for clinical bone cements. We therefore conclude that the antimicrobial peptide, Dhvar-5, was released in high amounts from PMMA bone cement. When used together with gentamicin sulphate, Dhvar-5 made the gentamicin crystals accessible for the release medium presumably through increased micro-porosity (< 0.1 microm) resulting in a fourfold increase of gentamicin release.

Mechanistic study of the photodynamic inactivation of Candida albicans by a cationic porphyrin.

The growing resistance against antifungal agents has renewed the search for alternative treatment modalities, and antimicrobial photodynamic inactivation (PDI) is a potential candidate. The cationic porphyrin 5-phenyl-10,15,20-Tris(N-methyl-4-pyridyl)porphyrin chloride (TriP[4]) is a photosensitizer that in combination with light can inactivate bacteria, fungi, and viruses. For future improvement of the efficacy of PDI of clinically relevant fungi such as Candida albicans, we sought to understand the working mechanism by following the response of C. albicans exposed to PDI using fluorescence confocal microscopy and freeze-fracture electron microscopy. The following events were observed under dark conditions: TriP[4] binds to the cell envelope of C. albicans, and none or very little TriP[4] enters the cell. Upon illumination the cell membrane is damaged and eventually becomes permeable for TriP[4]. After lethal membrane damage, a massive influx of TriP[4] into the cell occurs. Only the vacuole membrane is resistant to PDI-induced damage once TriP[4] passes the plasma membrane. Increasing the incubation time of C. albicans with TriP[4] prior to illumination did not increase the influx of TriP[4] into the cell or the efficacy of PDI. After the replacement of 100% phosphate-buffered saline (PBS) by 10% PBS as the medium, C. albicans became permeable for TriP[4] during dark incubation and the efficacy of PDI increased dramatically. In conclusion, C. albicans can be successfully inactivated by the cationic porphyrin TriP[4], and the cytoplasmic membrane is the target organelle. TriP[4] influx occurred only after cell death.

Morphological and functional alterations in glycerol preserved rat aortic allografts.

Glycerol preservation is an effective method for long-term preservation of skin allografts and has a potential use in preserving arterial allografts. We evaluated the effect of glycerol concentration and incubation period on vessel-wall integrity of rat aortic allografts. No significant differences were measured in breaking strength (2.3 +/- 0.3 N) and bursting pressure (223 +/- 32 kPa) between standard glycerolized and control segments (1.7 +/- 0.3 N, 226 +/- 17 kPa). Isometric tension measurements showed complete lack of functional contraction and relaxation capacity in allograft segments prepared according to all preservation protocols. Morphologically, thickness of the vessel-wall media diminished after preservation using low (30/50/75%) or high (70/85/98%) concentrations of glycerol, as compared to control segments (i.e. 81 +/- 2.4 microm, 95 +/- 5.6 microm and 125 +/- 3.5 microm, respectively). Confocal microscopy and Fourier analysis demonstrated that vascular collagen and elastin bundle orientation had remained unaltered. Electron microscopy showed defragmentation of luminal endothelial cells. In conclusion, glycerol preservation of rat aorta resulted in an acellular tissue matrix, which maintained biomechanical integrity and extracellular matrix characteristics. The next step in the investigation will be to test the concept of glycerol preservation of arterial allografts in a vascular transplantation model.

Light scattering of human lens vesicles in vitro.

In passing through the lens, light crosses thousands of cell membranes. To explore the possible contribution of lipids to the scattering properties of the lens, we have carried out in vitro studies with lipids extracted from human lenses 1-90 years of age. Sphingomyelin and human lens lipids were extruded into large unilamellar vesicles (LUVs). The intensity of light scattered by human lens LUVs increased with age and lipid hydrocarbon chain order. Hydrocarbon chain order also correlated with light scattering intensity by sphingomyelin LUVs. Light scattered by LUVs composed of sphingomyelin (1-30 mg ml(-1)) was 20 to 100 times more intense than that scattered by the same concentration of alpha-crystallin in aqueous media. Increased lipid hydrocarbon chain order as well as variations in the headgroup and interfacial region of bilayers resulting from lipid compositional changes can influence membrane light scattering properties. In vitro measurements suggest that the contribution to light scattering by lipids may be significant and should not be disregarded in the investigation of factors and components that lead to the increase in light scattering by human lenses with age and cataract.

Effects of hypergravity on the morphological properties of the vestibular sensory epithelium. II. Life-long exposure of rats including embryogenesis.

Rats were exposed to a hypergravity (HG) level of 2.5 x g from conception until the age of 14 weeks. The vestibular epithelia of four of these animals and four control animals were immunohistochemically labeled for actin and tubulin. The apical cross-sectional area of epithelial cells of HG exposed rats appeared to be larger in all end organs. Area increase was 7.0% in the utricle (p<0.005) and 8.2% in the crista (p<<0.001). Hair cells and supporting cells appeared to be intact. The cellular arrangement and the proportion of different cell types within the epithelia was normal.

Histatin 5 and derivatives. Their localization and effects on the ultra-structural level.

Histatins, a family of cationic peptides present in saliva, are active against the opportunistic yeast Candida albicans. The mechanism of action is still unclear. Histatin 5 and more potent synthetic variants, dhvar4 and dhvar5, were used to study localization and effects on morphology on the ultra-structural level. Although all peptides induced leakage, no association with the plasma membrane, indicative for permanent pores, was observed with immuno-gold-labeling. Freeze-fracturing showed severe changes of the plasma membrane. Together with, for the dhvars, the loss of intracellular integrity, this suggests that leakage may be a secondary effect rather than an effect of formation of permanent pores.