External Stenting with a New Polyester Mesh Reduces Neointimal Hyperplasia of Vein Grafts in a Sheep Model

Objective

External stents placed around vein grafts have demonstrated effectiveness in reducing neointimal hyperplasia by preventing distension of the thin-walled vein grafts when exposed to arterial pressure. However, the ideal stent material has yet to be defined. The following study investigates the short- and long-term effects of an innovative polyester mesh stent designed with optimized adaptation of circumferential compliance.

Methods

Following in vitro definition of the ideal macro-porous polyester stent material, a total of 12 sheep underwent implantation of bilateral carotid artery vein graft bypasses. In six sheep, the short-term outcome (four weeks of implantation) was investigated by comparing the newly-designed stent to native veins, micro-porous PTFE stent grafts and metallic Biocompound® stents (BCGs). Flow volume and graft diameter were measured prior to explantation. Grafts were evaluated histologically with respect to morphometry and immunoassaying. In the long-term group (6-month implantation time), the polyester stent was compared to native veins.

Results

All stents effectively prevented dilatation of the graft. Perfused vessel diameters of the polyester veins were 8.3±0.6 mm. BCG as well as PTFE veins showed diameter reduction to 7.4±0.7mm (p<0.05) and 7.8±0.4 mm (p<0.05), respectively. Both in the short and long terms, the new polyester stent led to significantly higher reduction of neointimal hyperplasia and luminal encroachment compared to the native vessel. It proved superior to PTFE stenting, while the Biocompound® material failed to prove efficacy.

Conclusions

It was demonstrated that the new macro-porous polyester mesh stent reduced neointimal hyperplasia more effectively than other commercially available stents.

The interference of distal humeral plating with the medial and lateral collateral ligaments of the elbow

INTRODUCTION

The aim of the present study was to determine the anatomical relationship and evaluate the potential interference of today's common distal humerus plates with the medial and lateral collateral ligaments of the elbow.

MATERIALS AND METHODS

The elbow joints of 23 embalmed upper extremities were dissected. Three different brands of distal humerus double-plating systems were applied in a standardized fashion. We used a caliper to measure the amount of absolute overlap of the plates on the corresponding collateral ligaments.

RESULTS

The data show contact and overlap with the medial and lateral collateral ligaments in all tested medial and lateral plates. The posterolateral and posteromedial plates showed no contact with the ligaments, yet they did contact the posterior joint capsules. The medial plates showed less contact/overlap when compared with the lateral and extended medial plates.

CONCLUSION

Based on the present data, we conclude that distal humerus plating using the perpendicular technique with standard-sized medial plates shows the least amount of overlap over the medial and lateral collateral ligaments. The extent of the overlap of the ligaments by the humeral plates is clearly shown in the present study.

Finger injuries caused by power-operated windows of motor vehicles: an experimental cadaver study

The aim of this experimental cadaver study was to investigate which kinds of lesions could occur in jam events between the glass and seal entry of power-operated motor vehicle side door windows at two different closing forces. Ten hands of fresh cadaver specimens were used. Three different hand positions chosen to simulate real events in which a finger is jammed between the glass and seal entry of the window of a current motor vehicle were examined. The index, middle, ring, and little finger of each hand were separately jammed both at the proximal and distal interphalangeal joint at closing forces of 300 and 500 N with a constant window glass closing speed of 10 cm/s. Macroscopically visible injuries were documented and radiographs of all fingers were obtained in two standard planes. At a closing force of 300 N, contusion marks of the skin, palmar joint instabilities and superficial skin lesions occurred, whilst at 500 N superficial skin lesions, superficial and deep open crush injuries, and fractures were observed. The results of this study experimentally demonstrate the kinds of finger injuries that could be expected in real jam events between the glass and seal entry in automatic power-operated windows.

Entrapment of adult fingers between window glass and seal entry of a motor vehicle side door: an experimental study for investigation of the force at the subjective pain threshold

In modern motor vehicles with automatic power windows, a potential hazard exists for jam events of fingers between the window glass and seal entry. This study determined entrapment forces acting on adult fingers at the subjective maximum pain threshold during entrapment in such windows. The length and the girth of the proximal and distal interphalangeal joints of the triphalangeal fingers of the right hands of 109 participants (60 men, 49 women) were measured; the diameter was calculated from girth, which was assumed to be circular. The automatic power window system of a motor vehicle side door was changed to a mechanical system. During entrapment the force distributed across the four proximal interphalangeal joints (PIPs), and separately on the proximal interphalangeal (iPIP) and then the distal interphalangeal (iDIP) joints of the index finger was measured using a customized force sensor. The maximum bearable entrapment force was 97.2 ± 51.8 N for the PIPs, 43.4 ± 19.9 N for the iPIP, and 36.9 ± 17.8 N for the iDIP. The positive correlation between finger diameter and maximum entrapment force was significant. Particularly with regard to the risk to children's fingers, the 100 N statutory boundary value for closing force of electronic power windows should be reduced.

Antitumor effect of the vascular-disrupting agent ZD6126 in a murine renal cell carcinoma model

ZD6126 is a vascular-disrupting agent that affects the endothelial tubulin cytoskeleton causing selective occlusion of tumor vasculature and extensive tumor cell necrosis. The present study evaluated the antitumor and antivascular activities of ZD6126 in the clinically relevant murine renal cell carcinoma (RENCA) model and also evaluated biological response to therapy using color Doppler imaging as biomarker. Mice were implanted with RENCA tumor cells (day 0) and established tumors were treated with ZD6126 (100 mg/kg i.p.) or vehicle with repeated intermittent doses on day 10, 14 and 18. ZD6126 treatment led to a significant reduction in tumor size and was associated with extensive tumor necrosis and a reduction in tumor blood flow versus controls. MVD increased with intermittent treatment (day 10, 14 and 18). In an additional study, animals were treated at day 19 and quantitative three-dimensional microvascular corrosion casting was performed to enable detailed assessment of the tumor vascular architecture. Corrosion casting showed that tumor vessel architecture is affected by treatment, whereas pre-existing vessels in control tissues are practically not affected. Inter-vessel and inter-branch distances as well as vessel diameters are influenced by treatment. In conclusion, ZD6126 showed potent antitumor efficacy in the RENCA model and our data suggest that decrease in tumor blood flow may be a useful surrogate marker of treatment effect.

Forces and deformations of the abdominal wall--a mechanical and geometrical approach to the linea alba

Force-elongation responses of the human abdominal wall in the linea alba region were determined by tensile tests in which the linea alba was seen to exhibit a nonlinear elastic, anisotropic behavior as is frequently observed in soft biological tissues. In addition, the geometry of the abdominal wall was determined, based on MRI data. The geometry can be specified by principal radii of curvature in longitudinal of approximately 470 mm and in the transverse direction of about 200 mm. The determined radii agree with values found in other studies. Mechanical stresses, deformations and abdominal pressures for load cases above 6% elongation can be related using Laplace's formula and our constitutive and geometrical findings. Results from uni- and biaxial tensile tests can thus be compared using this model. Calculations confirm that abdominal pressures of approximately 20 kPa correspond to related biaxial forces of about 3.4N/mm in the transverse and 1.5 N/mm in the longitudinal direction. Young's moduli can be calculated with respect to the uniaxial as well as the biaxial loading. At these physiological loadings, a compliance ratio of about 2:1 between the longitudinal and transversal directions is found. Young's moduli of about 50 kPa occur in transversal direction and of about 20 kPa in longitudinal direction at transverse and longitudinal strains both in the order of 6%. These findings coincide with results from other investigations in which the properties of the abdominal wall have been examined.

Lengths, girths, and diameters of children's fingers from 3 to 10 years of age

We obtained data on the lengths, girths, and diameters of the fingers of children from 3 to 10 years of age. A total of 160 children (78 girls, 82 boys) were examined in a cross-sectional investigation. The length of each finger of the right hand of every child was measured, as were the girths of the proximal, middle, and distal phalanges, and of the proximal and distal interphalangeal joint. The average length of the thumb was 49 (35-65) mm. The index and ring fingers both averaged 69 (index, 50-88; ring, 42-96) mm in length, while the middle and little fingers averaged 72 (57-100) and 56 (40-74) mm, respectively. Average diameter, calculated from the girth measurement, was 16 (11-22) mm for the thumb, 15 mm for both the index (9-22) and middle (10-21) fingers, 14 (10-20) and 13 (8-19) mm for the ring and little fingers, respectively. The average length of each finger increased by 37% from 3 to 10 years of age, average girth by 24%, and diameter increased by 20%. We observed no differences in length, girth, and diameter between the sexes. The dimensions of children's fingers are relevant to injuries from automatic, power-operated window lifters of motor vehicles because risk of injury to a finger jammed between an ascending window and the seal entry depends upon the diameter of the finger. Additionally, short fingers of young children can be jammed over almost their entire length in the oblique design of a car window seal entry.

Three-dimensional analysis of tumour vascular corrosion casts using stereoimaging and micro-computed tomography

OBJECTIVE

In order to perform effective translational research for cancer therapy, we need to employ pre-clinical models which reflect the clinical situation. The purpose of this study was to quantitatively compare the vascular architecture of human colorectal cancer and experimental tumour models to determine the suitability of animal models for vascular studies and antivascular therapy.

METHODS

In this study we investigated the three-dimensional properties of colonic tumour vasculature in both human clinical tissues (normal mucosa control [n=20], carcinoma [n=20] and adenoma [n=6]) and murine colorectal xenografts (LS147T [n=6] and SW1222 [n=6]). Scanning Electron Microscope Stereoimaging (SEM) and X-ray Micro-Computed Tomography (Micro-CT) methods were employed for 3D analyses of the vascular corrosion casts from these tissues.

RESULTS

Morphological measurements showed that there were significant differences in the underlying morphology in the different tissues. Of the studied xenografts, LS147T is more consistently similar to the vascular architecture of the human carcinoma than SW1222. The only reversal of this is for the inter-vessel distance.

CONCLUSION

While SEM stereoimaging provided better surface detailed resolution of the corrosion casts, it was complimented by the fully 3D micro-CT method. Comparison made between the xenografts and clinical tumours showed that the LS147T xenografts shared many similarities with the clinical tumour vasculature. This study provides insight into how to select the most suitable pre-clinical models for translational studies of clinical cancer therapy.

Dimensions of the myopectineal orifice: a human cadaver study

BACKGROUND

In mesh implantations, there needs to be a balance between mass and the size of the meshes. However, the mesh size should allow for adequate prevention of hernia recurrence by sufficient coverage of the entire myopectineal orifice (MPO).

AIM AND OBJECTIVE

The aim was to determine the MPO dimensions and several pelvic parameters.

METHODS

Thirty-two inguinal regions were assessed in 16 embalmed cadavers.

RESULTS

The MPO averaged 7.8 cm (+/-3.0) in width and 6.5 cm (+/-1.9) in height. The weak inguinal area cranially to the inguinal ligament was 4.5 cm (+/-1.7) high. We found significant gender differences: MPOs in males showed the same width and height (7.6 x 7.6 cm), whereas in females, the MPO width was greater than its height (8.1 x 5.3 cm). Noticeable correlations of the MPO parameters to constitutional parameters were found for body size versus the height of the MPO (r = 0.5005) and interspinous distance versus the height of the MPO (r = 0.7653).

CONCLUSIONS

A mesh measuring 10 x 8 cm is suitable for both genders: in females, it will cover the whole MPO, including the infraligamental part, whereas in males, the weak inguinal area is preferentially covered.

Angiogenesis and vascular network of teratocarcinoma from embryonic stem cell transplant into seminiferous tubules

BACKGROUND

Carcinoma in situ (CIS) of the testis is considered to be a precancerous germinal cell lesion, but the precise cellular and molecular mechanisms underlying transformation of CIS into invasive pluripotent cancer cells remain to be elucidated. Moreover, a satisfactory animal model for the experimental study of germinal tumours has not been developed to date.

METHODS

We have developed a tumour model that involves the microinjection of green fluorescent protein-labelled embryonic stem (ES) cells (which are functionally equivalent to CIS cells) into syngenic mouse seminiferous tubules, a unique cell microenvironment in which germinal cells mature and CIS arise. To characterise the vascularisation of teratocarcinomas, which arise after cell transplant, we used immunohistochemistry, together with a qualitative and quantitative analysis of scanning electron microscopy images of corrosion casting samples.

RESULTS

Embryonic stem cells transplanted into seminiferous tubules did not differentiate into germinal cells, but rather they behaved as invasive embryonal carcinoma (EC) stem cells. The vascular pattern of the experimental teratocarcinomas showed a highly disorganised architecture, and some of the neoplastic capillaries were derived, at least in part, from the original transplanted ES cells.

CONCLUSION

The transplantation of pluripotent ES cells into seminiferous tubules efficiently recapitulates the early stages of development of teratocarcinomas. Consequently, this method constitutes a novel in vivo model to study the mechanisms of invasion and progression of experimental germinal tumours.

[Microvessel visualisation: applications and limitations]

Vessel systems and the microvascular unit may be studied by a variety of morphological techniques which enable improved structure-function analyses. Two-dimensional light and electron microscopic sectioning techniques with and without specific markers are complemented by 3D vascularisation and perfusion study techniques. Static ex vivo modalities still prevail, however, the future will be dominated by intravital high-resolution techniques.

Angiogenese-Gentherapie mit AdVEGF165- Eine Art „Delay“ für Lappenplastiken?

A regular tissue functioning requires the adequate supply of oxygen and nutrient via blood vessels. The sequences of formation and maturation of vessels are initiated and maintained by different growth factors. The VEGF growth factor plays an exceptional role in these mechanisms. The creation of sublethal ischemia as an angiogenic stimulus known as "Delay" is a well established procedure in plastic surgery, although the underlying molecular biological mechanisms still remain unknown. The important role of VEGF and its regulation depending on oxygen pressure suggest a strong connection between this growth factor and the delay phenomenon. The VEGF concentration in skin and underlying muscle was measured in overdimensioned random pattern flaps on 32 male Sprague-Dawley rats after either VEGF gene therapy or circumcision without elevation of the flap and compared to controls. Additional random pattern flaps were raised seven days post gene therapy or delay. The effect on the flap perfusion was measured postoperatively using Indocyanine green Laser Fluoroscopy and the size of the surviving and necrotic areas of the flaps were analysed. The skin of the random pattern flaps showed both in the Delay group and in the VEGF gene therapy group a significantly elevated VEGF concentration compared to the controls. The underlying rectus abdominis muscle showed no significant differences in VEGF concentration between the groups. The flap perfusion postoperatively was significantly increased solely in the VEGF gene therapy group. The analysis of the surviving area of the flaps showed a significant increase over the controls in the gene therapy group. The Delay procedure results in a significantly and locally raised concentration of the VEGF growth factor. The gene therapeutical use of this growth factor allows us to raise flap perfusion and to reduce necrosis. Both VEGF gene therapy and Delay seem to promote similar mechanisms whereas the gene therapy produced superior results in this setting.

Protecting the Endothelial Integrity of Internal Thoracic Arteries

BACKGROUND

Previous functional studies on human internal thoracic arteries, comparing the effect of the traditional harvesting method (occlusion with a clip) with a method leaving the artery perfused, revealed considerably impaired endothelial function associated with enhanced contractility after clipping. We have now investigated whether these observations could be correlated (1) with plasma markers of endothelial dysfunction, and (2) with structural changes in the endothelial layer.

METHODS

32 patients were randomly distributed into groups of clipped and perfused arteries. Arterial blood samples were obtained from both the artery and extracorporeal circulation to determine sP-selectin, sE-selectin, sL-selectin, and thrombomodulin using enzyme-linked immunosorbent assay. Arteries from three patients were examined by scanning electron microscopy.

RESULTS

Concentrations of sP-selectin and thrombomodulin were significantly higher in plasma from clipped arteries compared to perfused arteries, whereas sE-selectin and sL-selectin concentrations were similar within the groups. Scanning electron microscopy revealed significant structural changes and loss of endothelial cells in clipped arteries.

CONCLUSION

Biochemical and structural results support our findings that leaving the internal thoracic artery perfused preserves endothelial function in the arterial graft.

The VEGF receptor tyrosine kinase inhibitor, ZD6474, inhibits angiogenesis and affects microvascular architecture within an orthotopically implanted renal cell carcinoma

The proangiogenic vascular endothelial growth factor-A (VEGF) is essential for the development of new tumor vessels. ZD6474 is a novel inhibitor of VEGF receptor-2 (VEGFR-2) tyrosine kinase activity, which also has additional activity against epidermal growth factor (EGF) receptor tyrosine kinase. The antitumor activity of different schedules of ZD6474 in a clinically relevant, metastasizing, murine renal cell carcinoma (RENCA) model was evaluated in this study. RENCA cells were inoculated into the left kidney of 24 mice (day 0). Daily ZD6474 (50 mg/kg p.o.) treatment was initiated 1 day or 10 days after tumor cell inoculation and continued until day 21. Following treatment, kidney weight and volume were assessed and blood vessel density determined by CD31 staining. Visible metastases in the lungs, spleen, and lymph nodes were quantified using a dissection microscope. In an additional study, animals were treated according to the same regimen and quantitative three-dimensional microvascular corrosion casting was performed to enable detailed assessment of the tumor vascular architecture. Therapy initiated on day 1 or day 10 resulted in a 79% and 59% reduction in primary tumor volume, a 79% and 60% reduction in the number of lung metastases, and a 58% and 59% reduction in vessel density of primary tumors compared with the control group, respectively. Corrosion casting proved a 5.4- and 3.2-fold lower vascular volume compared with untreated tumors, observations that paralleled with significant architectural alterations. In this RENCA model, ZD6474 was a highly active inhibitor of tumor angiogenesis, primary tumor growth and tumor metastasis.

Microenvironmental adaptation of experimental tumours to chronic vs acute hypoxia

This study investigated long-term microenvironmental responses (oxygenation, perfusion, metabolic status, proliferation, vascular endothelial growth factor (VEGF) expression and vascularisation) to chronic hypoxia in experimental tumours. Experiments were performed using s.c.-implanted DS-sarcomas in rats. In order to induce more pronounced tumour hypoxia, one group of animals was housed in a hypoxic atmosphere (8% O₂) for the whole period of tumour growth (chronic hypoxia). A second group was acutely exposed to inspiratory hypoxia for only 20 min prior to the measurements (acute hypoxia), whereas animals housed under normal atmospheric conditions served as controls. Acute hypoxia reduced the median oxygen partial pressure (pO₂) dramatically (1 vs 10 mmHg in controls), whereas in chronically hypoxic tumours the pO₂ was significantly improved (median pO₂=4 mmHg), however not reaching the control level. These findings reflect the changes in tumour perfusion where acutely hypoxic tumours show a dramatic reduction of perfused tumour vessels (maybe the result of a simultaneous reduction in arterial blood pressure). In animals under chronic inspiratory hypoxia, the number of perfused vessels increased (compared to acute hypoxia), although the perfusion pattern found in control tumours was not reached. In the chronically hypoxic animals, tumour cell proliferation and tumour growth were significantly reduced, whereas no differences in VEGF expression and vascular density between these groups were observed. These results suggest that long-term adaptation of tumours to chronic hypoxia in vivo, while not affecting vascularity, does influence the functional status of the microvessels in favour of a more homogeneous perfusion.

AdVEGF165gene transfer increases survival in overdimensioned skin flaps

BACKGROUND

Vascular endothelial growth factor (VEGF) is a key regulator of angiogenesis. VEGF A also plays an important role in wound healing of the skin by promoting angiogenesis and by stimulating blood vessel growth. Therefore we tested the hypothesis that flap survival could be increased by the preoperative injection of AdVEGF(165).

METHODS

We studied the effect of AdVEGF(165) in an overdimensioned ischemic random-pattern-flap model in the rat (n = 50) with a length-to-width ratio of 4 : 1. VEGF cDNA was administered in two concentrations of 5 x 10(8) plaque-forming units (pfU) and 1 x 10(9) pfU using a recombinant adenoviral vector. Recombinant virus was injected subdermally 7, 3 or 0 days prior to flap harvest for the lower concentration and 7 days prior for the higher concentration. Flap survival and necrosis were observed at day 7, the day the animals were sacrificed.

RESULTS

Adenoviral gene transfer with VEGF(165) 3 and 7 days before flap harvest showed a significantly increased flap survival of 50% together with a significantly reduced necrosis (p < 0.01). Injection using a titer of 1 x 10(9) pfU 7 days prior to surgery increased flap survival even more, though failing to reach statistical significance compared to the lower concentration. VEGF protein concentration in the injected skin was significantly higher than in controls (p < 0.01). Flap perfusion was increased as well, demonstrated by indocyanine green (ICG) fluoroscopy (p < 0.001).

CONCLUSIONS

Our results confirm the important role of VEGF(165) on angiogenesis in ischemic flaps. Indeed by injecting VEGF(165) at 3 to 7 days preoperatively in a concentration of 1 x 10(9) pfU our data show that length-to-width ratio for random-pattern-flaps could be increased from 2 : 1 to 3 : 1 and therefore may allow a wider range of applications of this simple flap technique.

Fungal polysaccharopeptide inhibits tumor angiogenesis and tumor growth in mice

Angiogenesis is crucial to tumor growth and metastasis, and interruption of this process is a prime avenue for therapeutic intervention of tumor proliferation. The present study has made use of the S180 tumor-bearing mouse model to investigate the polysaccharopeptide, PSP, isolated from the edible mushroom Coriolus versicolor, a herbal medicine known for its anti-angiogenesis properties. Quantitative analysis of microcorrosion casting of the tumor tissue showed more angiogenic features such as dense sinusoids and hot spots, in control (untreated) than in PSP-treated animals. Immunostaining of tumor tissues with antibody against the endothelial cell marker (Factor VIII) demonstrated a positive correlation in that both the vascular density and tumor weight were lower in mice treated with PSP. Morphometric analysis of corrosion casts revealed that, even though the total amount of new vessel production was reduced, the basic tumor type-specific vascular architecture was retained. However, the expression of vascular endothelial cell growth factor (VEGF) in these tumors was suppressed. In conclusion, anti-angiogenesis should be one of the pathways through which PSP mediated its anti-tumor activity.

Inguinal hernia: measurement of the biomechanics of the lower abdominal wall and the inguinal canal

BACKGROUND

The stability of the lower abdominal wall may play a considerable role in the development of inguinal hernia. Therefore, the strength of the individual wall layers needs to be quantified. Despite numerous advances in hernia repair, comparatively few systematic biomechanic and morphometric analyses have been performed. Our aim was to establish and apply a standardised procedure for testing the abdominal wall layers' stability.

METHODS

After dissecting the abdominal walls of 16 cadavers into separate layers, we used a spherical punch and a force transducer to investigate the forces necessary to foraminate the layer. In addition, maximum tensile-strength and suction tests and histologic morphometry were performed.

RESULTS

The transversalis fascia was torn up on an average of 10.5 N, the peritoneum including pre- and subperitoneal tissue on 46.6 N, the aponeurosis of obliquus internus abdominis muscle on 51.7 N, and the aponeurosis of obliquus externus abdominis muscle on 92.6 N. Tensile tests of tissue strips obtained from defined areas showed comparable results. In contrast, surgical mesh revealed values between 60 and 150 N in punching tests. Left-right comparisons, as well as comparisons of the individual areas, revealed considerable intra- and inter-individual differences.

CONCLUSIONS

Biological hernia repair should focus on a reinforcement of the tissue layers with the highest biomechanic stability. Reinforcement of the transversal fascia must be questioned according to our results of poor mechanical resistance.

[Endovascular aneurysm treatment: Radiological and macropathological findings of the endoluminal surface of modular stent grafts]

PURPOSE

Characterization of the endoluminal surface of a modular stent graft and correlation of macropathological findings with results of radiological methods.

METHODS

Aneurysms of the infrarenal aorta were created in 36 mongrel FBI dogs using autologous material. Endovascular treatment was performed with modular stent grafts using two polyester-covered nitinol stents connected with overlap within the aneurysm. Follow-up was 1 and 6 weeks, and 6 months for 12 animals, respectively. Results were documented using sonography, intravascular ultrasound (IVUS), spiral CT, MRI, and digital subtraction angiography (DSA). After fixation, the aorta was prepared and incised lengthwise. Before histopathological work-up, the different segments were macropathologically characterized and correlated with the respective findings of the radiological methods.

RESULTS

4 cases showed high grade stenosis within the stent grafts and graft occlusion occurred in two cases. The connection sites of these modular stent grafts showed steps and partial separation of the graft components was causative in 5 of these cases. Migration of graft components occurred in three cases, one of them with complete disconnection of the modular device. Irregulartities and deposits on the endoluminal surface were systematically underestimated with all radiological techniques used. IVUS showed moderate concordance concerning deployment and unfolding of the stent graft, however, irregularities of the endoluminal surface were systematically underestimated. Concordance of MRI, sonography, and CT was worse. Contrast-enhanced T1-w MRI detected endoluminal deposits with moderate concordance. However, the thickness of deposits was underestimated. DSA, IVUS, and CT showed only poor concordance with macropathological findings.

CONCLUSIONS

The connection site of modular stent grafts predisposes to stenosis, occlusion, and disconnection of the modular device. Stent deployment and unfolding of the membrane might be examined with IVUS. MRI is useful for detecting endoluminal deposits and stenosis. However, radiological methods will underrate irregularities and deposits of the endoluminal surface.

[Aortic valve structures as landmarks for determining coronary artery ostia in transthoracic echocardiography]

BACKGROUND

Occasionally, coronary arteries are recorded in transthoracal echocardiography. The question was if this modality could be used as non-invasive screening method of the coronaries. A prerequisite for this is an exact and reproducible measurement of the origin of the coronary arteries.

MATERIAL AND METHOD

The topography of the coronary ostia in relation to the aortic valve was examined morphometrically in the aortae of 20 embalmed cadavers and 50 patients of a cardiologist's practice who underwent transthoracal echocardiography.

RESULTS

In all cases, the coronary arterial orifices were located eccentrically in the coronary sinus, shifted to the non-coronary aortic sinus. The distance between left coronary orifice to the commissure of the left and the right semilunar valvula was 13.3 mm on average in the anatomical measurements, whereas in the echocardiography this distance was 14.3 mm. The distance between the left ostium and the attachment of the left and the posterior semilunar valvula 9.4 mm, corresponding to 11.6 mm in echocardiography. The distance between right coronary orifice and the attachment of the right and the left semilunar valvula was 18.0 and 17.3 mm respectively, and the distance between right coronary orifice and the commissure of the right and the posterior semilunar valvula accounted for 8.5 and 9.7 mm respectively. On the average, the ostia were located 3.9 mm below the level of the sinotubular junction. Multiple ostia occurred in 65%, 92% of these were in the right coronary aortic sinus, shifted from the main orifice to the attachment of the right and the left semilunar valvula.

CONCLUSION

In the cardiologist's routine, the attachments of the aortic leaflets proved to be very useful as landmarks. The coronary arterial orifices have been educible in nearly all cases. These results show that transthoracal echocardiography may be used in the screening for coronary artery disease.

Focal topographic changes in inflammatory microcirculation associated with lymphocyte slowing and transmigration

Microcirculation is the primary mechanism for delivering lymphocytes to inflammatory tissues. Blood flow within microvessels ensures a supply of lymphocytes at the blood-endothelial interface. Whether the structure of the inflammatory microcirculation facilitates lymphocyte transmigration is less clear. To illuminate the microcirculatory changes associated with lymphocyte transmigration, we used intravital videomicroscopy to examine the dermal microcirculation after application of the epicutaneous antigen oxazolone. Intravascular injection of fluorescein-labeled dextran demonstrated focal topographic changes in the microcirculation. These focal changes had the appearance of loops or hairpin turns in the oxazolone-stimulated skin. Changes were maximal at 96 h and coincided with peak lymphocyte recruitment. To determine whether these changes were associated with lymphocyte transmigration, lymphocytes obtained from efferent lymph of draining lymph nodes at 96 h were fluorescently labeled and reinjected into inflammatory microcirculation. Epifuorescence intravital video microscopy demonstrated focal areas were associated with lymphocyte slowing and occasional transmigration. In contrast, focal loops and lymphocyte slowing were rarely observed in the contralateral control microcirculation. Results suggest that structural adaptations in inflammatory microcirculation represented by focal topographic changes may contribute to regulation of tissue entry by recirculating lymphocytes.

3D microvascular architecture of pre-cancerous lesions and invasive carcinomas of the colon

Despite the significance of tumour neoangiogenesis and the extensive knowledge on the molecular basis of blood vessel formation currently no quantitative data exist on the 3D microvascular architecture in human primary tumours and their precursor lesions. This prompted us to examine the 3D vascular network of normal colon mucosa, adenomas and invasive carcinomas by means of quantitative microvascular corrosion casting. Fresh hemicolectomy specimens from 20 patients undergoing cancer or polyposis coli surgery were used for corrosion casting, factor VIII and VEGF immunostaining. In addition, immunostaining was done on colorectal tissue from 33 patients with metastatic and non-metastatic carcinomas, polyposis coli and adenomas. This first quantitative analysis of intervessel and interbranching distances, branching angles and vessel diameters in human cancer specimens revealed distinct patterns of the microvascular unit in the tumour centre and periphery. Irrespective of the tumour localization and grading all individual tumours displayed qualitatively and quantitatively the same vascular architecture. This gives further evidence for the existence of a tumour type-specific vascular architecture as recently demonstrated for experimental tumours. Metastatic tumours displayed different vascular architectures only within hot spots, in terms of smaller intervascular distances than in non-metastatic tumours. Pre-cancerous lesions have in part virtually the same vascular architecture like invasive carcinomas. Comparison of VEGF immunostaining also suggests that angiogenesis sets in long before the progress towards invasive phenotypes and that the so-called angiogenic switch is more likely a sequence of events. © 2001 Cancer Research Campaign www.bjcancer.com

[Diagnosis of acute lung embolism with spiral CT and 3D reconstruction. Development of an animal model and technical probe in an ex-vivo experiment]

PURPOSE

To develop a model for simulation the CT morphologic situation of acute pulmonary embolism, to evaluate the accuracy of spiral CT and 3D reconstruction in the detection of artificial emboli and to investigate the influence of the orientation of emboli depending on z-axis orientation.

MATERIALS AND METHODS

Standardized artificial emboli made of wax and of defined size and shape were positioned into the pulmonary arteries of porcine lungs. Castings of the embolized pulmonary arterial trees were made by injection of a special opaque resin. After performance of spiral CT the data sets of the emboli and the pulmonary arteries were post-processed. The 3D segmentations were compared with the anatomic preparation to evaluate the accuracy of spiral CT/3D reconstruction-technique. Technical specimens simulating CT-morphology of acute embolized vessels underwent spiral CT in six different positions with respect to the z-axis. The CT data were reconstructed using a standardized and a contrastadapted method with interactive correction. The 3D emboli were analysed under qualitative aspects, and measurements of their extent were done.

RESULTS

In nearly 91%, there was complete agreement between CT and the corresponding findings at the anatomical preparation. Measurements of the 3D reconstructed technical specimens showed discrepancies of shape and size in dependence of the size of the original preparation, orientation and reconstruction technique. Overestimation up to 4 mm and underestimation to 2.2 mm were observed. Measurements of preparations with heights from 14 to 26 mm showed variances of +/- 1.5 mm (approximately 6-11%).

CONCLUSION

The presented models are suitable to simulate CT morphology of acute pulmonary embolism under ex-vivo conditions. Accuracy in the detection of artificial emboli using spiral CT/3D reconstruction is affected by localization, size and orientation of the emboli and the reconstruction technique.

Effects of thrombin and of the phospholipase C inhibitor, D609, on the vascularity of the chick chorioallantoic membrane

Microvascular corrosion casting was used to assess the effects of thrombin and D609, a phospholipase C inhibitor, on the vascularity of the chick embryo chorioallantoic membrane (CAM). Discs containing vehicle, thrombin or D609 were placed on the CAM of fertilized white Leghorn eggs on Day 9 of gestation and vascularity was assessed on Day 11. Thrombin caused significant increases in the numbers (43%), diameters (5%) and lengths (17%), of both pre- and postcapillaries (first-order vessels by centripetal ordering). Conversely, D609 caused a decrease in the numbers (27%), lengths (12%) and diameters (8%) of first-order vessels. D609 decreased the total vascular volume of first- to third-order vessels by 32%, whereas thrombin increased vascular volume by 27%. Additionally, thrombin increased capillary plexus density by 6%, whereas D609 decreased capillary plexus density by 3%. These findings provide a quantitative assessment of changing vascularity in the chick CAM--a model assay system in the development of pro- and antiangiogenic agents.

Inhibition of proteasome function induces programmed cell death in proliferating endothelial cells

Proteolysis mediated by the ubiquitin-proteasome system has been implicated in the regulation of programmed cell death. Here we investigated the differential effects of proteasomal inhibitors on the viability of proliferating and quiescent primary endothelial cells in vitro and in vivo. Subconfluent, proliferating cells underwent carbobenzoxy-L-isoleucyl-gamma-t-butyl-L-glutamyl-L-alanyl-L-leucinal (PSI) -induced apoptosis at low concentrations (EC(50)=24 nM), whereas at least 340-fold higher concentrations of PSI were necessary to obtain the same effect in confluent, contact-inhibited cells. PSI-mediated cell death could be blocked by a caspase-3 inhibitor (Ac-DEVD-H), but not by a caspase-1 inhibitor (Ac-YVAD-H), suggesting that a caspase-3-like enzyme is activated during PSI-induced apoptosis. When applied to the embryonic chick chorioallantoic membrane, a rapidly expanding tissue, PSI induced massive apoptosis also in vivo. PSI treatment of the CAM led to the formation of areas devoid of blood flow due to the induction of apoptosis in endothelial and other cells and to the collapse of capillaries and first order vessels. Our results demonstrate that proteasomal inhibitors such as PSI may prove effective as novel anti-angiogenic and anti-neoplastic substances.

Correlation of endoanal sonography with cross-sectional anatomy of the anal sphincter

BACKGROUND

Anal endosonography has become an important imaging method in the diagnosis of anorectal disorders. However, little information exists as to whether anal endosonography reliably defines pelvic floor structures. The aim of this study was to correlate endoanal sonography with cross-sectional anatomy and histology.

METHODS

Endosonographic tomograms were obtained from 9 human cadavers before fixation and cross-sectioning at identical levels. Muscular layers were defined by visual inspection, histology, immunohistology, and morphometry using three-dimensional sphincter reconstructions.

RESULTS

Endosonography visualized only two muscular layers, whereas anatomic sections always revealed three. Comparisons revealed identical findings with regard to internal sphincter volumes and asymmetries. However, due to its failure to identify the longitudinal muscle, endosonography largely overestimated external sphincter volumes. In contrast to current beliefs, anatomic studies failed to detect striated muscle fibers within the longitudinal muscle and did not show an intersphincteric space. However, anatomic cross sections demonstrated "anterior bands" as newly described anchoring mechanisms for the anal sphincters.

CONCLUSIONS

Anal endosonography supplies accurate information with regard to internal anal sphincter dimensions, but does not reliably outline deeper muscular layers. However, despite these drawbacks, comparisons of modern imaging techniques with cross-sectional anatomy may enhance our understanding of pelvic floor anatomy.

[Rectal carcinoma. Optimizing therapy by knowledge of anatomy with special reference to the mesorectum]

The connective tissue spaces of the pelvis and pelvic floor originate from an urogenital and perirectal mesenchymal cell complex, which can be clearly discerned. In the adult, the final compartments, which arise from these distinct tissue complexes, are still functionally separated. The perirectal tissue gives rise to the rectal fascia or rectal adventitia, also known as mesorectum. The connective tissue space between rectal and parietal pelvic fascia can be dissected as a plane free of vessels and nerves. Surgical dissection along this plane with complete mesorectum excision results in reliable excision of all relevant lymphatic pathways with extensive preservation of continence and sexual function.

Evidence for characteristic vascular patterns in solid tumours: quantitative studies using corrosion casts

The vascular architecture of four different tumour cell lines (CaX, CaNT, SaS, HEC-1B) transplanted subcutaneously in mice was examined by means of microvascular corrosion casting in order to determine whether there is a characteristic vascular pattern for different tumour types and whether it differs significantly from two normal tissues, muscle and gut. Three-dimensional reconstructed scanning electron microscope images were used for quantitative measurements. Vessel diameters, intervessel and interbranch distances showed large differences between tumour types, whereas the branching angles were similar. In all tumours, the variability of the vessel diameters was significantly higher than in normal tissue. The quantitative data provide strong evidence for a characteristic vascular network determined by the tumour cells themselves.

Angiogenesis inhibitors endostatin or TNP-470 reduce intimal neovascularization and plaque growth in apolipoprotein E-deficient mice

BACKGROUND

Neovascularization within the intima of human atherosclerotic lesions is well described, but its role in the progression of atherosclerosis is unknown. In this report, we first demonstrate that intimal vessels occur in advanced lesions of apolipoprotein E-deficient (apoE -/-) mice. To test the hypothesis that intimal vessels promote atherosclerosis, we investigated the effect of angiogenesis inhibitors on plaque growth in apoE -/- mice.

METHODS AND RESULTS

ApoE -/- mice were fed a 0.15% cholesterol diet. At age 20 weeks, mice were divided into 3 groups and treated for 16 weeks as follows: group 1, recombinant mouse endostatin, 20 mg. kg-1. d-1; group 2, fumagillin analogue TNP-470, 30 mg/kg every other day; and group 3, control animals that received a similar volume of buffer. Average cholesterol levels were similar in all groups. Plaque areas were quantified at the aortic origin. Median plaque area before treatment was 0.250 mm2 (range, 0.170 to 0.348; n=10). Median plaque areas were 0.321 (0.238 to 0.412; n=10), 0.402 (0.248 to 0.533; n=15), and 0.751 mm2 (0.503 to 0.838; n=12) for the endostatin, TNP-470, and control groups, respectively (P</=0.0001). Therefore, endostatin and TNP-470 inhibited plaque growth during the treatment period by 85% and 70%. Intimal smooth muscle cell contents of plaques from control and treated mice were similar.

CONCLUSIONS

Prolonged treatment with either angiogenesis inhibitor reduced plaque growth and intimal neovascularization in apoE -/- mice. Although the mechanism of plaque inhibition induced by these agents is not established, these results suggest that intimal neovascularization may promote plaque development.

Impact of the incubation medium on the endothelium of autologous vein grafts: damage scoring by scanning electron microscopy

The aim of this study was to examine the influence of different incubation media on the morphology of the endothelium of great saphenous vein grafts and establish a suitable scoring system for the evaluation of damage caused by these media. Fifty specimens of saphenous veins from ten patients during elective aorto-coronary bypass surgery were used. Ten specimens served as controls; the others were assigned to test groups and exposed to heparinized whole blood, Bretschneider's HTK, human albumin or Ringer's solution. Specimens exposed to heparinized blood showed only slight morphological alterations, whereas the other three mediums caused severe damage. Thus, heparinized blood seems to be most suitable as a rinsing and incubation medium. A widely accepted scoring system for the quantification of endothelial damage caused by the incubation media did not adequately reflect the morphology alterations in the cytoskeleton and membrane topology. The proposed scoring system, which is based on endothelial cell separation, endothelial cell loss, amount of deposits, endothelial cell surface homogeneity, in addition to the frequency of spikes and blebs, seems to be suitable for characterizing differences in endothelial morphology.

Impact of fibroblast growth factor-2 on tumor microvascular architecture. A tridimensional morphometric study

Three cell clones originated by transfection of human endometrial adenocarcinoma HEC-1-B cells with fibroblast growth factor-2 (FGF-2) cDNA and characterized by a different capacity to produce and secrete the growth factor were transplanted subcutaneously in nude mice. Corrosion casting of the tumor microvasculature of xenografts produced by injection of 2 x 10(6) or 10 x 10(6) FGF-2-B9 cells (which produce and secrete significant amounts of FGF-2), 10 x 10(6) FGF-2-A8 cells (which produce comparable amounts of FGF-2 but do not secrete it), or 10 x 10(6) control FGF-2-B8 cells (which produce only trace amounts of FGF-2) was performed after 14 days of growth. Interbranching distances, intervascular distances, branching angles, and vessel diameters were then determined using tridimensional stereo pairs of the casted tumor vascularity. When transplanted at the same concentration, FGF-2-B9 cells grew faster in nude mice compared with FGF-2-A8 and FGF-2-B8 clones. The total amount of new vessel formation was far higher in FGF-2-B9 tumors than in FGF-2-B8 or FGF-2-A8 tumors. Also, vessel courses were more irregular and blind-ending vessels and evasates were more frequent in FGF-2-B9 tumors. Moreover, FGF-2-B9 tumor microvasculature was characterized by a wider average vascular diameter and by an extreme variability of the diameter of each individual vessel along its course between two ramifications. No statistical differences were observed when the distribution curves of the values of intervascular distances, interbranching distances, and branching angles of the microvessel network were compared among the different experimental groups. The distinctive features of the microvasculature of FGF-2-B9 tumors were retained, at least in part, in the smaller lesions produced by injection of a limited number of cells. The data indicate that FGF-2 production and release confer to FGF-2-B9 cells the ability to stimulate the formation of new blood vessels with distinctive architectural features. Neovascularization of FGF-2-B9 lesions parallels the faster rate of growth of the neoplastic parenchyma. This does not affect the overall architecture of the microvessel network that appears to be primed by characteristics of the HEC-1-B tumor cell line and/or by the microenvironment of the host. To our knowledge, this work represents the first attempt to define the influence of a single, defined growth factor on the tridimensional tumor vascular pattern.

Liposuction-assisted nerve-sparing extended radical hysterectomy: oncologic rationale, surgical anatomy, and feasibility study

OBJECTIVE

Our purpose was to improve the therapeutic index of radical hysterectomy by extending the resection of parametrial tissue without further impairing pelvic autonomic nerve functions.

STUDY DESIGN

We studied the topographic anatomy of the parametrial tissue with high-resolution magnetic resonance imaging and by dissection of fresh human cadavers. We then performed a clinical feasibility study of the liposuction-assisted nerve-sparing extended radical hysterectomy.

RESULTS

Magnetic resonance imaging demonstrated that the perispinous adipose tissue is retained after type III radical hysterectomy and is a frequent site of tumor recurrence. The perispinous adipose tissue contains the pelvic plexus, the pelvic splanchnic nerves, small blood vessels, and lymphatic tissue. We developed the liposuction-assisted nerve-sparing extended radical hysterectomy and applied it to seven consecutive patients with cervical or vaginal cancer. No intraoperative or postoperative complications occurred. Postoperative magnetic resonance imaging assured us that perispinous adipose tissue was cleared in all cases. A metastatic lymph node was found in the perispinous adipose tissue removed by liposuction from one patient. Suprapubic cystostomies could be removed after a median period of 12 days.

CONCLUSION

The nerve-sparing removal of perispinous adipose tissue by liposuction is a feasible addition to wide en bloc parametrectomy in anatomically defined planes.

The vascular architecture of the chick chorioallantoic membrane: sequential quantitative evaluation using corrosion casting

Microvascular corrosion casting was used for evaluating qualitatively and quantitatively angiogenesis in the chick chorioallantoic membrane (CAM). Series of CAMs from day 8 to 18 were examined. The density of plexus capillaries increases rapidly until day 10 and then remains constant. The vessels connected to the plexus (first order vessels) increase in number and length between days 10 and 12. The vessels initiating from first-order vessels (second order) also increase in number but remain nearly the same in lengths and diameters. Compared to previous studies using stereomicroscopy, significant differences in vessel numbers and lengths exist, which can be explained by the low resolution and magnification resulting in too low vascular densities of the pre- and post-capillaries. The third-order vessels increase in number until day 12 when they reach a plateau, whereas higher-order vessels increase in number. These results give an insight into the vascular development of this organ, and provide the basis for assessing the targets and effects of angiogenic or antiagiogenic agents.

The vascular anatomy of the inner anterior abdominal wall with special reference to the transversus and rectus abdominis musculoperitoneal (TRAMP) composite flap for vaginal reconstruction

This study was designed to clarify the vascularization of the inner anterior abdominal wall with respect to the novel transversus and rectus abdominis musculoperitoneal (TRAMP) flap, which was introduced recently for vaginal reconstruction. A series of human cadavers was injected with a lead oxide-gelatine mixture by means of the deep inferior epigastric artery and subsequently dissected and examined by radiography. In all cases we found that the blood supply of the entire rectus abdominis muscle from the symphysis to the costal arch and that of the medial 10 to 15 cm of the transversus abdominis muscle, as well as the underlying peritoneum, was provided by several branches of the deep inferior epigastric artery. "Choke" arteries to the superior epigastric artery and also to the intercostal arteries (X, XI, and XII) have been shown to be common features. From the anatomic point of view, these observations offer the possibility of mobilizing large parts of the transversus abdominis muscle together with the rectus abdominis muscle for reconstructive surgery.

Impact of particulate contamination in crystalloid cardioplegic solutions: studies by scanning and transmission electron microscopy

The amount of particulate matter present in Bretschneider's cardioplegic solution (HTK) was assessed by laser-mediated particle counting. Permissible levels of contaminant particles with a distribution of diameters between 0.2 and 20 microns were found. A significant further increase in the particle count was observed when the fluid was administered for clinical use, which resulted in the additional release of particles from, for example, the infusion kit, which included an in-line filter with pores of 270 microns. Filtration of the HTK solution by a terminal inline filter (0.2 micron) significantly reduced the number of particles. In order to determine the chemical composition and the potential hazards of the particulate material we used scanning electron microscopy in combination with energy dispersive X-ray analysis and transmission electron microscopy to examine specimens taken from heart tissue obtained from Göttinger minipigs after cardioplegia and from humans undergoing mitral valve replacement after cardioplegia and reperfusion. Particles of various diameters were found either to be plugging coronary capillaries, to be adherent to the endothelial layer, or to be engulfed by polymorphonuclear (PMN) granulocytes, which appeared to be activated. Some of the PMN granulocytes were apparent in the endothelial layer. It is recommended, therefore, that a terminal in-line filter (0.2 micron) should be routinely used.

Does lung contusion affect both the traumatized and the noninjured lung parenchyma? A morphological and morphometric study in the pig

Isolated unilateral lung contusion (LC) was induced in 12 pigs to determine the pathophysiological role of LC in the high mortality after multiple injury. The Horovitz quotient, pulmonary vascular resistance, mean pulmonary artery pressure, mixed venous oxygen consumption, inspiratory pressure and compliance were significantly decreased in the LC group as compared to controls. The number of polymorphonuclear granulocytes, the microvascular permeability of albumine and the Wilhelmy balance as determined by bronchoalveolar lavage were significantly increased after lung contusion. As indicators of a systemic reaction we found elevated plasma levels of the terminal complement complex and decreased levels of the complement factor 3a after LC. The morphological assessment revealed changes such as those encountered during the early phase of adult respiratory distress syndrome, with granulocyte sticking, endothelial cell adhesion and transendothelial diapedesis. Morphometric analysis demonstrated a significant decrease in alveolar diameter in both the injured and the contralateral lung due to impaired surfactant surface activity. A distinct increase in septal diameter, related to edema and caused by increased microvascular permeability, was found in the injured lungs. These findings emphasize that LC leads to a generalized impairment of the entire lung, which may lead to progressive lung failure.

A simple and accurate method for 3-D measurements in microcorrosion casts illustrated with tumour vascularization

Microvascular corrosion casting is an established method to investigate vascular patterns of nearly all organs. Trying to evaluate these specimens quantitatively using native scanning electron microscope (SEM) pictures always implied a big error, because the information of depth cannot be taken into account. However, SEM stereo pairs allow for exact measurements. Tumour microcorrosion casts were used to demonstrate the feasibility of this 3-D quantification method. The information of depth was calculated for each measuring point using the parallax. From the resulting coordinates the intervascular distances, the interbranching distances as well as the interbranching angles were determined. We found significant differences between all investigated tumours. Reproducibility tests and tests for the greatest error possibilities resulted in a maximum deviation of 2.5% to be expected. Consequently this method is suitable for all application ranges of microvascular corrosion casting as a quantitative determination method.

[Myoperitoneal composite flaps: a new surgical principle for vaginal reconstruction]

In spite of the development of various techniques for the formation of a neovagina, the longterm results are often disappointing, especially if the simpler methods (dilation, ectopic pouch formation, epithelium transfer) have been applied. The more complex surgical techniques such as musculo/fasciocutaneous and colon flaps are associated with a significant risk of severe complications. For certain operative situations necessitating vaginal reconstruction, adequate procedures are still missing. Based on surgico-anatomic investigation of the vascular territories of the myoperitoneal anterior abdominal wall, we introduce the use of myoperitoneal composite flaps from the deep inferior epigastric artery angiosome as a novel surgical principle for vaginal reconstruction and report on the experience with the first two patients.

Endothelial damage of the venous graft in CABG. Influence of solutions used for storage and rinsing on endothelial function

A significant proportion of early graft occlusions after aortocoronary revascularization using autologous saphenous vein grafts (SVG) are due to mechanical and/or metabolic or biochemical endothelial lesions. The morphological examination of the endothelium, usually carried out using light microscopy or by various types of scanning electron microscopy (SEM), does not give any indication of the functioning of the endothelium (E). Functionally intact E is capable of producing endothelium-derived relaxing factor (EDRF); a practicable in vitro test is the relaxation of pre-contracted vein segments (VS) in response to acetylcholine (ACh) application. To study the effect of the solution used to rinse and store the SVG between removal and implantation on the functional characteristics of the E, we performed in vitro tests on macroscopically intact VS removed from the saphenous vein of 30 male patients who underwent elective CABG surgery. Isolated VS rings were incubated for 60 min in heparinized whole blood (HWB), Bretschneider's cardioplegic solution (HTK), human albumin solution (HAS), or Ringer's solution (RS) and compared with the results obtained immediately after the removal of untreated control samples (C) taken from the same patients. After equilibration in carbogen aerated Krebs-Henseleit solution and precontraction by 3 x 10(-7) M noradrenaline (NE), relaxation induced by 10(-6) M ACh was measured. Only the samples stored in HWB (13.4 +/- 0.4 mN) showed similar maximal contractions with NE to those in the control group (14.4 +/- 0.5 mN), i.e. all those segments which showed both contractions with NE and relaxation with ACh.(ABSTRACT TRUNCATED AT 250 WORDS)

Vascular patterns of tumors: scanning and transmission electron microscopic studies on human xenografts

The tumor vascular system plays a significant role both in tumor growth and metastasis as well as in therapy. However, there are comparatively few papers dealing with the morphology and architecture of tumor vascularity. This is inconceivable insofar as structural and architectural parameters determine tumor blood flow. Therefore, the vascular system of eight human tumor lines transplanted onto 121 thymus-aplastic nude mice was studied with light, scanning and transmission electron microscopy as well as microvascular corrosion casting. All tumors show a connective tissue-like capsule with a dense plexus of vessels forming a "vascular envelope". Particularly in early stages, these vessels follow a tortuous course with glomeruloidal arrangement and numerous indications of angiogenic activity. In the tumor centre regular arteries and veins are never to be seen. Instead, all vessels show a capillary wall construction with variations in height and electron densities of the endothelial cells. Changes in vessel diameter, lack of vascular hierarchy, blind ends as well as irregular sinusoidal systems originating from and draining to veins are common features. The vascular densities vary considerably within single tumors. Based on the vascular architecture and wall construction, necroses may occur even in areas with intervascular distances of only 15 microns. No significant differences in vascular architecture of the various cell lines could be observed.

Scanning electron microscopy of corrosion casting in medicine

The aims of this review are: 1. to provide a bibliography of the publications that have used the corrosion casting technique; 2. to describe the advantages and limitations of the methodology; 3. to illustrate possible applications in the field of medicine, and 4. to highlight the significance of this method in the teaching of medical students. Thus, this paper is primarily focused on the scanning electron microscopical examination of vascular corrosion casts. The unsurpassed three-dimensionality of the corrosion casting technique compared to any other means stands out in particular. This can be especially useful when complex vascular-anatomical relationships are present. This applies not only to the portrayal of the modes of branching and varying vascular densities but also to regulatory arrangements, such as sphincters and arteriovenous anastomoses. Between 1966 and 1990, a total of 549 publications were found in the Medline literature data bank, containing the key words "corrosion casting", "microvascular cast", or "vascular cast" (as of August, 1990). Of those publications, most dealt with applications to experimental animals. By contrast, only 142 reports were mainly or partially concerned with human investigational material. The normal vascular system of nearly all organs, insofar as this is of direct medical relevance, has been largely resolved. In our opinion, one of the most important potential applications of the corrosion casting technique lies in the investigation of gastrointestinal, renal or hepatic ailments, which coincide with the reconstruction or rarefication of the vascular bed, e.g., in ulcers, ileitis terminalis, colitis ulcerosa, cirrhosis or glomerulonephritis.

[The effect of topical heparin on histamine-induced wheals. A double-blind study]

Since it is difficult to demonstrate the effectiveness of heparin-containing ointments in the treatment of thrombophlebitis under clinical conditions, a double-blind experimental trial was performed in 18 volunteers. To produce a reproducible inflammation, ten drops of a histamine solution containing 10 mg histamine/100 ml, were applied to an area measuring 4 x 7 cm2 on both forearms of each test subject. Under each drop, the skin was pricked five times. Ten minutes after induction of inflammation, one forearm of each subject was treated in a double-blind randomized manner with an ointment containing heparin (50,000 IU heparin/100 g), the other arm being treated with the heparin-free ointment base. As a criterion of the effectiveness of the ointment, the course of the temperature of the forearms was measured using thermography. Ten minutes after application of the histamine solution, the temperature increased by a mean of about 3 degrees centigrade. After 30 minutes' treatment with heparin-containing ointment, the temperature then decreased by 1.77 degrees C, while that of the forearms treated with heparin-free ointment base decreased by only 1.14 degrees C. The difference was statistically significant (p less than 0.001). Sixty minutes after treatment the differences were still significant at p = 0.012. This study thus demonstrates the effectiveness of heparin-containing ointment in the treatment of histamine-induced inflammation.