Quantitation of microcomputed tomography-imaged ocular microvasculature

PURPOSE

To quantitatively assess microvascular dimensions in the eyes of neonatal wild-type and VEGF(120)-tg mice, using a novel combination of techniques which permit three-dimensional (3D) image reconstruction.

METHODS

A novel combination of techniques was developed for the accurate 3D imaging of the microvasculature and demonstrated on the hyaloid vasculature of the neonatal mouse eye. Vascular corrosion casting is used to create a stable replica of the vascular network and X-ray microcomputed tomography (muCT) to obtain the 3D images. In-house computer-aided image analysis techniques were then used to perform a quantitative morphological analysis of the images.

RESULTS

With the use of these methods, differences in the numbers of vessel segments, their diameter, and volume of vessels in the vitreous compartment were quantitated in wild-type neonatal mice or littermates over-expressing a labile (nonheparin binding) isoform of vascular endothelial growth factor (VEGF(120)) from the developing lens. This methodology was instructive in demonstrating that hyaloid vascular networks in VEGFA(120) over-expressing mice have a 10-fold increase in blind-ended, a six-fold increase in connected vessel segments, in addition to a sixfold increase (0.0314 versus 0.0051 mm(3)) in total vitreous vessel volume compared with wild type. These parameters are not readily quantified via histological, ultrastructural, or stereological analysis.

CONCLUSION

The combination of techniques described here provides the first 3D quantitative characterization of vasculature in an organ system; i.e., the neonatal murine intra-ocular vasculature in both wild-type mice and a transgenic model of lens-specific over-expression of VEGF.

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.

Synchrotron X-ray microtomography for assessment of bone tissue scaffolds

X-ray microtomography (microCT) is a popular tool for imaging scaffolds designed for tissue engineering applications. The ability of synchrotron microCT to monitor tissue response and changes in a bioactive glass scaffold ex vivo were assessed. It was possible to observe the morphology of the bone; soft tissue ingrowth and the calcium distribution within the scaffold. A second aim was to use two newly developed compression rigs, one designed for use inside a laboratory based microCT machine for continual monitoring of the pore structure and crack formation and another designed for use in the synchrotron facility. Both rigs allowed imaging of the failure mechanism while obtaining stress-strain data. Failure mechanisms of the bioactive glass scaffolds were found not to follow classical predictions for the failure of brittle foams. Compression strengths were found to be 4.5-6 MPa while maintaining an interconnected pore network suitable for tissue engineering applications.

Impact of combinatory growth factor application on rabbit Achilles tendon injury with operative versus conservative treatment: a pilot study

Acute Achilles tendon (AT) rupture is a common injury with a comparatively high complication rate. Presently, surgical treatments compete with nonoperative treatment modalities. The aim of this study was to elucidate the possible beneficial effects of short-term combinatory application of growth factors on tendon healing during operative or conservative treatment. In this controlled laboratory study, the left ATs of 40 adult New Zealand White rabbits were transected and either sutured or treated conservatively. Half of the animals from each treatment modality group repetitively received a mixture of VEGF165, bFGF, and rPDGF which was administered peritendineally. The left legs were immobilized with external fixateurs for 6 weeks. The ATs were harvested 3 months after intervention. Tensile strength tests revealed no significant differences between operative and conservative treatments. Compared to the normal right ATs, 60% of the average breaking strength was reached 3 months after surgery. Growth factor application did not result in significant improvements. Only a tendency towards higher blood vessel densities was noted in the groups treated with the factors. Collagen type I/III ratios also displayed no significant differences. This study indicates that there is no difference in the biomechanical outcome of conservative versus operative AT rupture treatment and only a marginal impact of short-term combinatory growth and angiogenesis factor application.

Blood flow patterns spatially associated with platelet aggregates in murine colitis

In the normal murine mucosal plexus, blood flow is generally smooth and continuous. In inflammatory conditions, such as chemically-induced murine colitis, the mucosal plexus demonstrates markedly abnormal flow patterns. The inflamed mucosal plexus is associated with widely variable blood flow velocity as well as discontinuous and even bidirectional flow. To investigate the mechanisms responsible for these blood flow patterns, we used intravital microscopic examination of blood flow within the murine mucosal plexus during dextran sodium sulphate-and trinitrobenzenesulfonic acid-induced colitis. The blood flow patterns within the mucosal plexus demonstrated flow exclusion in 18% of the vessel segments (P < 0.01). Associated with these segmental exclusions was significant variation in neighboring flow velocities. Intravascular injection of fluorescent platelets demonstrated platelet incorporation into both fixed and rolling platelet aggregates. Rolling platelet aggregates (mean velocity 113 microm/sec; range, 14-186 microm/sec) were associated with reversible occlusions and flow variations within the mucosal plexus. Gene expression profiles of microdissected mucosal plexus demonstrated enhanced expression of genes for CCL3, CXCL1, CCL2, CXCL5, CCL7, CCL8, and Il-1b (P < 0.01), and decreased expression of CCL6 (P < 0.01). These results suggest that platelet aggregation, activated by the inflammatory mileau, contributes to the complex flow dynamics observed in acute murine colitis.

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.

Medial wall of the cavernous sinus: microanatomical diaphanoscopic and episcopic investigation

PURPOSE

To elucidate the question whether expansion of pituitary adenomas into the cavernous sinus (CS) has to be regarded as focal penetration rather than invasion, a microanatomical study of the medial wall (MW) of the CS was performed.

METHOD

Fourteen sellar hemiblocks underwent microsurgical dissection from lateral and medial approach. The thickness of the MW of the CS was examined by diaphanoscopy.

FINDINGS

The internal carotid artery (ICA) was adherent to the MW in five cases. In five specimens the lateral wall of the sella turcica consisted of a single layer without perforations. In nine cases this wall had two layers. There was no perforation of both layers in any case. Diaphanoscopy revealed thin MW in the lateral border of the sella (n = 13), below the horizontal segment of the ICA (n = 10), and antero-inferiorly to the carotid syphon (n = 9).

CONCLUSIONS

Expansion into the CS may be facilitated by low anatomical resistance against chronic tumor growth.

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.

Vascular microarchitecture of murine colitis-associated lymphoid angiogenesis

In permissive tissues, such as the gut and synovium, chronic inflammation can result in the ectopic development of anatomic structures that resemble lymph nodes. These inflammation-induced structures, termed lymphoid neogenesis or tertiary lymphoid organs, may reflect differential stromal responsiveness to the process of lymphoid neogenesis. To investigate the structural reorganization of the microcirculation involved in colonic lymphoid neogenesis, we studied a murine model of dextran sodium sulfate (DSS)-induced colitis. Standard 2-dimensional histology demonstrated both submucosal and intramucosal lymphoid structures in DSS-induced colitis. A spatial frequency analysis of serial histologic sections suggested that most intramucosal lymphoid aggregates developed de novo. Intravital microscopy of intravascular tracers confirmed that the developing intramucosal aggregates were supplied by capillaries arising from the quasi-polygonal mucosal plexus. Confocal optical sections and whole mount morphometry demonstrated capillary networks (185 +/- 46 microm diameter) involving six to ten capillaries with a luminal diameter of 6.8 +/- 1.1 microm. Microdissection and angiogenesis PCR array analysis demonstrated enhanced expression of multiple angiogenic genes including CCL2, CXCL2, CXCL5, Il-1b, MMP9, and TNF within the mucosal plexus. Intravital microscopy of tracer particle flow velocities demonstrated a marked decrease in flow velocity from 808 +/- 901 microm/sec within the feeding mucosal plexus to 491 +/- 155 microm/sec within the capillary structures. We conclude that the development of ectopic lymphoid tissue requires significant structural remodeling of the stromal microcirculation. A feature of permissive tissues may be the capacity for lymphoid angiogenesis.

Spatial calibration of structured illumination fluorescence microscopy using capillary tissue phantoms

Quantitative assessment of microvascular structure is relevant to the investigations of ischemic injury, reparative angiogenesis and tumor revascularization. In light microscopy applications, thick tissue specimens are necessary to characterize microvascular networks; however, thick tissue leads to image distortions due to out-of-focus light. Structured illumination confocal microscopy is an optical sectioning technique that improves contrast and resolution by using a grid pattern to identify the plane-of-focus within the specimen. Because structured illumination can be applied to wide-field (nonscanning) microscopes, the microcirculation can be studied by sequential intravital and confocal microscopy. To assess the application of structured illumination confocal microscopy to microvessel imaging, we studied cell-sized microspheres and fused silica microcapillary tissue phantoms. As expected, structured illumination produced highly accurate images in the lateral (X-Y) plane, but demonstrated a loss of resolution in the Z-Y plane. Because the magnitude of Z-axis distortion was variable in complex tissues, the silica microcapillaries were used as spatial calibration standards. Morphometric parameters, such as shape factor, were used to empirically optimize Z-axis software compression. We conclude that the silica microcapillaries provide a useful tissue phantom for in vitro studies as well as spatial calibration standard for in vivo morphometry of the microcirculation.

How to optimize autonomic nerve preservation in total mesorectal excision: clinical topography and morphology of pelvic nerves and fasciae

BACKGROUND

Urogenital dysfunction after rectal and pelvic surgery was significantly decreased with the introduction of nerve-preserving dissection and total mesorectal excision (TME). Profound topographic knowledge of the pelvic connective tissue spaces is indispensable for identification and preservation of autonomic pelvic nerves. The purpose of this cadaver study was to highlight the course of important autonomous nerve structures and to identify potential injury sites.

METHODS

Eleven cadavers were dissected according to TME with subsequent preparation of the pelvic nerves. The pelves of further three cadavers were sliced horizontally and cubed. Specimens were harvested and processed for light microscopy and immunohistochemistry to analyze both fascia and the types of nerves and their localization.

RESULTS

The neurovascular bundle, arising from the inferior pelvic plexus, shows the highest nerve density. At the lateral edge of Denonvilliers' fascia, it pierces the parietal pelvic fascia. Several fine nerve branches spread into the loose periprostatic tissue up to the prostate or pass the prostate toward the urinary bladder. En route, we consistently find perikarya of autonomic nerves. Within the mesorectum, nerve fibers are distributed heterogeneously with laterally high densities, ventrally and dorsally low densities.

CONCLUSION

The highest risk for pelvic nerve damage-apart from lesions of the superior hypogastric plexus itself-is anterolaterally of the rectum where the neurovascular bundle releases from the pelvic sidewall. Careful dissection helps to identify and protect these nerve structures. The retroprostatic Denonvilliers' fascia contains no important nerve structures.

Non-viral VEGF(165) gene therapy--magnetofection of acoustically active magnetic lipospheres ('magnetobubbles') increases tissue survival in an oversized skin flap model

Adenoviral transduction of the VEGF gene in an oversized skin flap increases flap survival and perfusion. In this study, we investigated the potential of magnetofection of magnetic lipospheres containing VEGF₁₆₅-cDNA on survival and perfusion of ischemic skin flaps and evaluated the method with respect to the significance of applied magnetic field and ultrasound. We prepared perfluoropropane-filled magnetic lipospheres (‘magnetobubbles’) from Tween60-coated magnetic nanoparticles, Metafectene, soybean-oil and cDNA and studied the effect in an oversized random-pattern-flap model in the rats (n= 46). VEGF-cDNA-magnetobubbles were administered under a magnetic field with simultaneously applied ultrasound, under magnetic field alone and with applied ultrasound alone. Therapy was conducted 7 days pre-operative. Flap survival and necrosis were measured 7 days post-operatively. Flap perfusion, VEGF-protein concentration in target and surrounding tissue, formation and appearance of new vessels were analysed additionally. Magnetofection with VEGF-cDNA-magnetobubbles presented an increased flap survival of 50% and increased flap perfusion (P < 0.05). Without ultrasound and without magnetic field, the effect is weakened. VEGF concentration in target tissue was elevated (P < 0.05), while underlying muscle was not affected. Our results demonstrate the successful VEGF gene therapy by means of magnetobubble magnetofection. Here, the method of magnetofection of magnetic lipospheres is equally efficient as adenoviral transduction, but has a presumable superior safety profile.

Effect of intraluminal pillars on particle motion in bifurcated microchannels

A central feature of intussusceptive angiogenesis is the development of an intravascular pillar that bridges the opposing sides of the microvessel lumen. In this report, we created polydimethyl siloxane (PDMS) microchannels with geometric proportions based on corrosion casts of the colon microcirculation. The structure of the PDMS microchannels was a bifurcated channel with an intraluminal pillar in the geometric center of the bifurcation. The effect of the intraluminal pillar on particle flow paths was investigated using an in vitro perfusion system. The microchannels were perfused with fluorescent particles, and the particle movements were recorded using fluorescence videomicroscopy. We found that the presence of an intravascular pillar significantly decreased particle velocity in the bifurcation system (p < 0.05). In addition, the pillar altered the trajectory of particles in the center line of the flow stream. The particle trajectory resulted in prolonged pillar contact as well as increased residence time within the bifurcation system (p < 0.001). Our results suggest that the intravascular pillar not only provides a mechanism of increasing resistance to blood flow but may also participate in spatial redistribution of cells within the flow stream.

Morphology of the dorsal and lateral calcaneocuboid ligaments

BACKGROUND

The dorsolateral calcaneocuboid ligaments have different configurations. In the literature they are only described as either the dorsal or lateral calcaneocuboid ligament. However, recent reconstructive surgical techniques may benefit from a better understanding of the anatomy. The aims of this study were to classify the morphology and attachments of the dorso-lateral calcaneocuboid ligaments and to determine their dimensions.

MATERIALS AND METHODS

The dorso-lateral aspects of the calcaneocuboid joint of 30 cadaver feet were dissected to expose the associated ligaments. Further, we evaluated possible bony landmarks of the calcaneus that could imply which shape or course the ligament would have in a specific individual.

RESULTS

Our findings showed a wide variety of configurations in shape, number, and attachment sites. A constant dorsal ligament and an additional narrower lateral ligament was detectable in half of the cases. The majority of the dorso-lateral calcaneocuboid ligament-complex had an upward course and fanning out from proximal to distal. No bony predictor for the ligaments' shape or course was found.

CONCLUSION

The dorso-lateral ligament-complex of the calcaneocuboid joint revealed a wide variety of configurations.

CLINICAL RELEVANCE

Better understanding of the anatomy of these ligaments may aid in the anatomic reconstruction of these ligaments.

Bridging mucosal vessels associated with rhythmically oscillating blood flow in murine colitis

Oscillatory blood flow in the microcirculation is generally considered to be the result of cardiopulmonary influences or active vasomotion. In this report, we describe rhythmically oscillating blood flow in the bridging vessels of the mouse colon that appeared to be independent of known biological control mechanisms. Corrosion casting and scanning electron microscopy of the mouse colon demonstrated highly branched bridging vessels that connected the submucosal vessels with the mucosal plexus. Because of similar morphometric characteristics (19 +/- 11 microm vs. 28 +/- 16 microm), bridging arterioles and venules were distinguished by tracking fluorescent nanoparticles through the microcirculation using intravital fluorescence videomicroscopy. In control mice, the blood flow through the bridging vessels was typically continuous and unidirectional. In contrast, two models of chemically induced inflammation (trinitrobenzenesulfonic acid and dextran sodium sulfate) were associated with a twofold reduction in flow velocity and the prominence of rhythmically oscillating blood flow. The blood oscillation was characterized by tracking the bidirectional displacement of fluorescent nanoparticles. Space-time plots and particle tracking of the oscillating segments demonstrated an oscillation frequency between 0.2 and 5.1 cycles per second. Discrete Fourier transforms demonstrated a power spectrum composed of several base frequencies. These observations suggest that inflammation-inducible changes in blood flow patterns in the murine colon resulted in both reduced blood flow velocity and rhythmic oscillations within the bridging vessels of the mouse colon.

Microvessel density and VEGF/VEGF receptor status and their role in sarcomas of the pulmonary artery

Neoangiogenesis, driven by a variety of angiogenic factors, plays an essential role during development and progression of malignant tumors. Vascular endothelial growth factor (VEGF) and its receptors have been designated a central part in the angiogenic process during malignancy. We studied the vascular parameters by means of morphology and morphometry in 7 sarcomas of the pulmonary artery (SPA) and 10 poorly differentiated leiomyosarcomas of soft tissue. Immunohistochemical analysis of VEGF and VEGFR was related to survival and prognosis. The microvessel density (MVD) and intervascular distances (IVD) differed significantly only at sites of necrosis compared to non-necrotic areas in SPA but not for soft tissue leiomyosarcomas. MVD, IVD and vascular surface area (VSA) revealed no difference between SPA and leiomyosarcomas of different origin. We found a more pronounced expression of VEGF in most tumors at sites of necrosis. The receptors were present in a subset of tumor vessels mostly at the tumor border. VEGFR-2 expression was also seen in a subset of tumor cells whereas VEGFR-1 showed only weak expression in some tumors. Local hypoxia seems to induce a higher MVD and a lower IVD at sites of necrosis compared to those areas without necrosis. The presence of necrosis in both sarcoma groups was correlated with the presence of VEGF due to local tumor hypoxia and subsequent up-regulation of VEGFR-2 and VEGFR-1 in tumor vessels as well as tumor cells. Overall and relapse-free survival showed no difference concerning all examined parameters. Thus, microvessel density does not seem to be a prognostic factor in SPA and other sarcomas.

Murine microvideo endoscopy of the colonic microcirculation

Natural orifice endoscopy in small animal models has been limited in the past by instrument size and optical performance. In this report, we investigate the feasibility of using a recently developed microvideo endoscopy system to evaluate the colon microcirculation. Using a murine model of acute colitis, microvideo endoscopy was useful in mapping the topography of inflammation as well as identifying relevant structures in the microcirculation. We conclude that natural orifice endoscopy is a useful method for the minimally invasive longitudinal assessment of the colonic mucosal microcirculation.

Resection of the mesopancreas (RMP): a new surgical classification of a known anatomical space

Background

Prognosis after surgical therapy for pancreatic cancer is poor and has been attributed to early lymph node involvement as well as to a strong tendency of cancer cells to infiltrate into the retropancreatic tissue and to spread along the peripancreatic neural plexuses. The objective of our study was to classify the anatomical-surgical layer of the mesopancreas and to describe the surgical principles relevant for resection of the mesopancreas (RMP). Immunohistochemical investigation of the mesopancreatic-perineural lymphogenic structures was carried out with the purpose of identifying possible routes of metastatic spread.

Methods

Resection of the mesopancreas (RMP) was performed in fresh corpses. Pancreas and mesopancreas were separated from each other and the mesopancreas was immunohistochemically investigated.

Results

The mesopancreas strains itself dorsally of the mesenteric vessels as a whitish-firm, fatty tissue-like layer. Macroscopically, in the dissected en-bloc specimens of pancreas and mesopancreas nerve plexuses were found running from the dorsal site of the pancreatic head to the mesopancreas to establish a perineural plane. Immunohistochemical examinations revealed the lymphatic vessels localized in direct vicinity of the neuronal plexuses between pancreas and mesopancreas.

Conclusion

The mesopancreas as a perineural lymphatic layer located dorsally to the pancreas and reaching beyond the mesenteric vessels has not been classified in the anatomical or surgical literature before. The aim to ensure the greatest possible distance from the retropancreatic lymphatic tissue which drains the carcinomatous focus can be achieved in patients with pancreatic cancer only by complete resection of the mesopancreas (RMP).

Structural adaptations in the murine colon microcirculation associated with hapten-induced inflammation

BACKGROUND

Blood flowing across the vascular endothelium creates wall shear stress, dependent on velocity of flow and vessel geometry, that tends to disrupt lymphocyte-endothelial cell adhesion.

OBJECTIVE

The microcirculation in a murine model of acute colitis was investigated to identify structural adaptations during acute colitis that may facilitate transmigration.

METHODS

In 2,4,6-trinitrobenzenesulphonic acid-induced acute colitis, the infiltrating cells and colonic microcirculation was investigated by cellular topographic mapping, corrosion casting and three-dimensional scanning electron microscopy (SEM). Colonic blood velocimetry was performed using intravital microscopy.

RESULTS

Clinical and histological parameters suggested a peak inflammatory response at 96 h (p<0.001). The infiltrating cells were spatially related to the mucosal capillary plexus by three-dimensional topographic mapping (p<0.001). In normal mice, corrosion casting and three-dimensional SEM showed a polygonal mucosal plexus supplied by ascending arteries and descending veins. After 2,4,6-trinitrobenzenesulphonic acid stimulation, three-dimensional SEM showed preserved branch angles (p = 0.52) and nominal vessel lengths (p = 0.93), but a significantly dilated mucosal capillary plexus (p<0.001). Intravital microscopy of the mucosal plexus showed a greater than twofold decrease in the velocity of flow (p<0.001).

CONCLUSIONS

The demonstrable slowing of the velocity of flow despite an increase in volumetric flow suggests that these microvascular adaptations create conditions suitable for leucocyte adhesion and transmigration.

Periosteal repair of the dorsal calcaneocuboid ligament: a comparative biomechanical study

BACKGROUND

Isolated lateral calcaneocuboid joint instability rarely is described. Missed or delayed diagnosis resulting in inadequate treatment may lead to chronic instability, followed by sports inability and handicap in daily life. Besides arthrodesis, anatomic repair augmenting the elongated dorsal calcaneocuboid ligament with a local periosteal flap has recently been described for treatment.

METHODS

In a controlled laboratory study, eight isolated fresh-frozen human cadaver calcaneocuboid specimens were strained in a varus direction until failure of the dorsal calcaneocuboid ligaments. Then the dorsal calcaneocuboid ligaments were reconstructed with free periosteal flaps and tensile testing was repeated.

RESULTS

Compared to native dorsal calcaneocuboid ligaments, free single layer periosteal flap reconstructions were found to have inferior load to failure (-52%, p = 0,028), ultimate stress (-44%, p = 0.024), stiffness (-50%, p = 0.063), and strain energy density to failure (-37.5%, p = 0.111).

CONCLUSIONS

In vitro data demonstrate that isolated single-layer periosteal flap replacement offers inferior stability as compared to native dorsal calcaneocuboid ligaments. To obtain sufficient initial stability, the elongated native ligament should, therefore, be reefed and a single-layer periosteal flap augmentation should be added. This combined procedure can be recommended for stabilization of isolated chronic dorsolateral calcaneocuboid joint instability.