Quantitative Image Analysis of Fibrillar Collagens Reveals Novel Diagnostic and Prognostic Biomarkers and Histotype-Dependent Aberrant Mechanobiology in Lung Cancer.

Fibrillar collagens are the most abundant extracellular matrix components in non-small cell lung cancer (NSCLC). However, the potential of collagen fiber descriptors as a source of clinically relevant biomarkers in NSCLC is largely unknown. Similarly, our understanding of the aberrant collagen organization and associated tumor-promoting effects is very scarce. To address these limitations, we identified a digital pathology approach that can be easily implemented in pathology units based on CT-FIRE software (version 2; https://loci.wisc.edu/software/ctfire) analysis of Picrosirius red (PSR) stains of fibrillar collagens imaged with polarized light (PL). CT-FIRE settings were pre-optimized to assess a panel of collagen fiber descriptors in PSR-PL images of tissue microarrays from surgical NSCLC patients (106 adenocarcinomas [ADC] and 89 squamous cell carcinomas [SCC]). Using this approach, we identified straightness as the single high-accuracy diagnostic collagen fiber descriptor (average area under the curve = 0.92) and fiber density as the single descriptor consistently associated with a poor prognosis in both ADC and SCC independently of the gold standard based on the TNM staging (hazard ratio, 2.69; 95% CI, 1.55-4.66; P < .001). Moreover, we found that collagen fibers were markedly straighter, longer, and more aligned in tumor samples compared to paired samples from uninvolved pulmonary tissue, particularly in ADC, which is indicative of increased tumor stiffening. Consistently, we observed an increase in a panel of stiffness-associated processes in the high collagen fiber density patient group selectively in ADC, including venous/lymphatic invasion, fibroblast activation (α-smooth muscle actin), and immune evasion (programmed death-ligand 1). Similarly, a transcriptional correlation analysis supported the potential involvement of the major YAP/TAZ pathway in ADC. Our results provide a proof-of-principle to use CT-FIRE analysis of PSR-PL images to assess new collagen fiber-based diagnostic and prognostic biomarkers in pathology units, which may improve the clinical management of patients with surgical NSCLC. Our findings also unveil an aberrant stiff microenvironment in lung ADC that may foster immune evasion and dissemination, encouraging future work to identify therapeutic opportunities.

Biomechanical Properties of the Periaortic Abdominal Tissue: It is Not as Fragile as It Seems.

BACKGROUND: The perivascular adipose tissue has been studied as a critical element that could influence physiological and disease processes of the vessel covered by it. In terms of anatomy, during the abdominal aorta's dissection, it is possible to identify the periaortic adipose tissue and the periaortic parietal peritoneum lying over it, sealing the retroperitoneal space. They seem to be fragile layers, with apparently no biomechanical role in the abdomen. However, it is well known that most cases of ruptured abdominal aortic aneurysms (AAAs) that reach the emergency department still alive present retroperitoneal bleeding contained by the previously mentioned two-layer combination, eventually allowing time for surgical treatment. In previous studies about aortic wall stress, tension, and AAA rupture prediction, only information concerning the vessel wall itself is highlighted. Therefore, the present work aims to study the biomechanical and histological properties of the periaortic tissue, comparing them to the same variables measured in aortic wall samples described in the medical literature. MATERIALS AND METHODS: Samples of periaortic tissue were harvested from 27 individuals during necropsy. Smoking status and the presence of AAAs were observed. Biomechanical uniaxial destructive tests were performed up to samples' rupture. Values of failure stress, tension, and strain were obtained. Samples were also harvested for histological analysis. RESULTS: Periaortic tissue presented less amount of collagen in smokers than in nonsmokers (P = 0.017). The periaortic tissue seems to be more elastic than aortic walls described in the literature (strain: 0.75 ± 0.37). Analyzing periaortic tissue failure stress (56.8 ± 101.26 N/cm2) and tension (7.65 ± 4.99 N/cm), it has at least 52% and 55%, respectively, of the stress and tension described in the medical literature for AAA walls. CONCLUSIONS: The periaortic tissue presents less collagen fibers in smokers than in nonsmokers. The periaortic tissue seemed very delicate during an autopsy, but the study of its biomechanical properties showed that it presents more than half of the resistance of an AAA wall. This information suggests this tissue might have a mechanical protective role against massive bleeding when it comes to an aortic rupture. Therefore this tissue's biomechanical information should be included in computational models on enlargement and rupture prediction of AAAs.

The "central vein sign" in inflammatory demyelination: The role of fibrillar collagen type I.

Accumulating evidence corroborates the role of the "central vein sign" in the radiological diagnosis of multiple sclerosis (MS). Here, we report human magnetic resonance imaging (MRI) and corresponding pathological data that inflammation-dependent intracerebral remodeling of the vessel wall is directly associated with the prominence of intralesional veins on susceptibility-based MRI. In adult marmosets with experimental autoimmune encephalomyelitis, vessel-wall fibrosis was detected early in the demyelinating process, even in lesions <2 weeks old, though fibrosis was more evident after 6 weeks. Vascular remodeling consisted of both luminal enlargement and eccentric thickening of the perivascular space (fibrillar collagen type I deposition) and affected almost exclusively white matter, but not subpial cortical, lesions. The long-term effect of vessel remodeling in MS lesions is currently unknown, but it might potentially affect tissue repair. ANN NEUROL 2019;85:934-942.

Molecular insights into prolyl and lysyl hydroxylation of fibrillar collagens in health and disease.

Collagen is a macromolecule that has versatile roles in physiology, ranging from structural support to mediating cell signaling. Formation of mature collagen fibrils out of procollagen α-chains requires a variety of enzymes and chaperones in a complex process spanning both intracellular and extracellular post-translational modifications. These processes include modifications of amino acids, folding of procollagen α-chains into a triple-helical configuration and subsequent stabilization, facilitation of transportation out of the cell, cleavage of propeptides, aggregation, cross-link formation, and finally the formation of mature fibrils. Disruption of any of the proteins involved in these biosynthesis steps potentially result in a variety of connective tissue diseases because of a destabilized extracellular matrix. In this review, we give a revised overview of the enzymes and chaperones currently known to be relevant to the conversion of lysine and proline into hydroxyproline and hydroxylysine, respectively, and the O-glycosylation of hydroxylysine and give insights into the consequences when these steps are disrupted.

The dating of thrombus organization in cases of pulmonary embolism: an autopsy study.

BACKGROUND: Pulmonary embolism (PE) is associated to high mortality rate worldwide. However, the diagnosis of PE often results inaccurate. Many cases of PE are incorrectly diagnosed or missed and they are often associated to sudden unexpected death (SUD). In forensic practice, it is important to establish the time of thrombus formation in order to determine the precise moment of death. The autopsy remains the gold standard method for the identification of death cause allowing the determination of discrepancies between clinical and autopsy diagnoses. The aim of our study was to verify the morphological and histological criteria of fatal cases of PE and evaluate the dating of thrombus formation considering 5 ranges of time. METHODS: Pulmonary vessels sections were collected from January 2010 to December 2017. Sections of thrombus sampling were stained with hematoxylin and eosin. The content of infiltrated cells, fibroblasts and collagen fibers were scored using a semi-quantitative three-point scale of range values. RESULTS: The 30 autopsies included 19 males (63.3%) and 11 females (36.7%) with an average age of 64.5 ± 12.3 years. The time intervals were as follows: early (≤1 h), recent (> 1 h to 24 h), recent-medium (> 24 h to 48 h), medium (> 48 h to 72 h) and old (> 72 h). In the first hour, we histologically observed the presence of platelet aggregation by immunofluorescence method for factor VIII and fibrinogen. The presence of lymphocytes has been identified from recent thrombus (> 1 h to 24 h) and the fibroblast cells were peripherally located in vascular tissue between 48 and 72 h, whereas they resulted central and copious after 72 h. CONCLUSIONS: After a macroscopic observation and a good sampling traditional histology, it is important to identify the time of thrombus formation. We identified histologically a range of time in the physiopathology of the thrombus (early, recent, recent-medium, medium, old), allowing to determine the dating of thrombus formation and the exact time of death. CLINICAL TRIAL NUMBER: NCT03887819. TRIAL REGISTRATION: The trial registry is Cliniclatrials.gov, with the unique identifying number NCT03887819. The date of registration was 03/23/2019 and it was "Retrospectively registered".

Development of Tissue-Engineered Ligaments: Elastin Promotes Regeneration of the Rabbit Medial Collateral Ligament.

When ligaments are injured, reconstructive surgery is sometimes required to restore function. Methods of reconstructive surgery include transplantation of an artificial ligament and autotransplantation of a tendon. However, these methods have limitations related to the strength of the bone-ligament insertion and biocompatibility of the transplanted tissue after surgery. Therefore, it is necessary to develop new reconstruction methods and pursue the development of artificial ligaments. Elastin is a major component of elastic fibers and ligaments. However, the role of elastin in ligament regeneration has not been described. Here, we developed a rabbit model of a medial collateral ligament (MCL) rupture and treated animal knees with exogenous elastin [100 µg/(0.5 mL·week)] for 6 or 12 weeks. Elastin treatment increased gene expression and protein content of collagen and elastin (gene expression, 6-fold and 42-fold, respectively; protein content, 1.6-fold and 1.9-fold, respectively), and also increased the elastic modulus of MCL increased with elastin treatment (2-fold) compared with the controls. Our data suggest that elastin is involved in the regeneration of damaged ligaments.

Label-free detection of fibrillar collagen deposition associated with vascular elements in glioblastoma multiforme by using multiphoton microscopy.

Glioblastoma multiforme (GBM-WHO grade IV) is the most common and the most aggressive form of brain tumors in adults with the median survival of 10-12 months. The diagnostic detection of extracellular matrix (ECM) component in the tumour microenvironment is of prognostic value. In this paper, the fibrillar collagen deposition associated with vascular elements in GBM were investigated in the fresh specimens and unstained histological slices by using multiphoton microscopy (MPM) based on two-photon excited fluorescence (TPEF) and second harmonic generation (SHG). Our study revealed the existence of fibrillar collagen deposition in the adventitia of remodelled large blood vessels and in glomeruloid vascular structures in GBM. The degree of fibrillar collagen deposition can be quantitatively evaluated by measuring the adventitial thickness of blood vessels or calculating the ratio of SHG pixel to the whole pixel of glomeruloid vascular structure in MPM images. These results indicated that MPM can not only be employed to perform a retrospective study in unstained histological slices but also has the potential to apply for in vivo brain imaging to understand correlations between malignancy of gliomas and fibrillar collagen deposition.

Polarized Microscopy in Lesions With Altered Dermal Collagen.

Alterations in dermal collagen are noted in dermatofibroma, dermatofibrosarcoma protuberans, morphea, lichen sclerosus et atrophicus, hypertrophic scars, and keloids. The authors sought to determine whether variations in birefringence of collagen by polarized microscopy could be of help in diagnosing such conditions. Representative hematoxylin and eosin sections of 400 cases, including dermatofibroma, dermatofibrosarcoma protuberans, hypertrophic scars, keloid, morphea, and lichen sclerosus, were examined under polarized microscopy. Distinct patterns of birefringence of collagen for each disease were noted under polarized microscopy. This study highlights the use of polarized microscopy as adjunctive tool in differentiating different diseases with collagen alteration.

Identifying distinct nanoscopic features of native collagen fibrils towards early diagnosis of pelvic organ prolapse.

Pelvic organ prolapse (POP) is characterized by weakening of the connective tissues and loss of support for the pelvic organs. Collagen is the predominant, load-bearing protein within pelvic floor connective tissues. In this study, we examined the nanoscopic structures and biomechanics of native collagen fibrils in surgical, vaginal wall connective tissues from healthy women and POP patients. Compared to controls, collagen fibrils in POP samples were bulkier, more uneven in width and stiffer with aberrant D-period. Additionally, the ratio of collagen I (COLI) and collagen III (COLIII) is doubled in POP with a concomitant reduction of the amount of total collagen. Thus, POP is characterized by abnormal biochemical composition and biophysical characteristics of collagen fibrils that form a loose and fragile fiber network accountable for the weak load-bearing capability. The study identifies nanoscale alterations in collagen as diagnostic markers that could enable pre-symptomatic or early diagnosis of POP. FROM THE CLINICAL EDITOR: Pelvic organ prolapse (POP) occurs due to abnormalities of the supporting connective tissues. The underlying alterations of collagen fibers in the connective tissues have not been studied extensively. In this article, the authors showed that collagen fibrils in POP patients were much different from normal controls. The findings may provide a framework for the diagnosis of other connective diseases.

Comparison of Aortic Collagen Fiber Angle Distribution in Mouse Models of Atherosclerosis Using Second-Harmonic Generation (SHG) Microscopy.

Characterization of collagen fiber angle distribution throughout the blood vessel wall provides insight into the mechanical behavior of healthy and diseased arteries and their capacity to remodel. Atherosclerotic plaque contributes to the overall mechanical behavior, yet little is known experimentally about how collagen fiber orientation is influenced by atherogenesis. We hypothesized that atherosclerotic lesion development, and the factors contributing to lesion development, leads to a shift in collagen fiber angles within the aorta. Second-harmonic generation microscopy was used to visualize the three-dimensional organization of collagen throughout the aortic wall and to examine structural differences in mice maintained on high-fat Western diet versus age-matched chow diet mice in a model of atherosclerosis. Image analysis was performed on thoracic and abdominal sections of the aorta from each mouse to determine fiber orientation, with the circumferential (0°) and blood flow directions (axial ±90°) as the two reference points. All measurements were used in a multiple regression analysis to determine the factors having a significant influence on mean collagen fiber angle. We found that mean absolute angle of collagen fibers is 43° lower in Western diet mice compared with chow diet mice. Mice on a chow diet have a mean collagen fiber angle of ±63°, whereas mice on a Western diet have a more circumferential fiber orientation (~20°). This apparent shift in absolute angle coincides with the development of extensive aortic atherosclerosis, suggesting that atherosclerotic factors contribute to collagen fiber angle orientation.

The failing human heart is characterized by decreased numbers of telocytes as result of apoptosis and altered extracellular matrix composition.

Telocytes (TCs) are a novel type of interstitial cells only recently described. This study aimed at characterizing and quantifying TCs and telopodes (Tps) in normal and diseased hearts. We have been suggested that TCs are influenced by the extracellular matrix (ECM) composition. We used transmission electron microscopy and c-kit immunolabelling to identify and quantify TCs in explanted human hearts with heart failure (HF) because of dilated, ischemic or inflammatory cardiomyopathy. LV myectomy samples from patients with aortic stenosis with preserved ejection fraction and samples from donor hearts which could not be used for transplantation served as controls. Quantitative immunoconfocal analysis revealed that 1 mm(2) of the normal myocardium contains 14.9 ± 3.4 TCs and 41.6 ± 5.9 Tps. As compared with the control group, the number of TCs and Tps in HF decreased more than twofold. There were no differences between HF and control in the number of Ki67-positive TCs. In contrast, terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling-positive TCs increased threefold in diseased hearts as compared to control. Significant inverse correlations were found between the amount of mature fibrillar collagen type I and the number of TCs (r = -0.84; P < 0.01) and Tps (r = -0.85; P < 0.01). The levels of degraded collagens showed a significant positive relationship with the TCs numbers. It is concluded that in HF the number of TCs are decreased because of higher rates of TCs apoptosis. Moreover, our results indicate that a close relationship exists between TCs and the ECM protein composition such that the number of TCs and Tps correlates negatively with the amount of mature fibrillar collagens and correlates positively with degraded collagens.

3D Raman mapping of the collagen fibril orientation in human osteonal lamellae.

Chemical composition and fibrillar organization are the major determinants of osteonal bone mechanics. However, prominent methodologies commonly applied to investigate mechanical properties of bone on the micro scale are usually not able to concurrently describe both factors. In this study, we used polarized Raman spectroscopy (PRS) to simultaneously analyze structural and chemical information of collagen fibrils in human osteonal bone in a single experiment. Specifically, the three-dimensional arrangement of collagen fibrils in osteonal lamellae was assessed. By analyzing the anisotropic intensity of the amide I Raman band of collagen as a function of the orientation of the incident laser polarization, different parameters related to the orientation of the collagen fibrils and the degree of alignment of the fibrils were derived. Based on the analysis of several osteons, two major fibrillar organization patterns were identified, one with a monotonic and another with a periodically changing twist direction. These results confirm earlier reported twisted and oscillating plywood arrangements, respectively. Furthermore, indicators of the degree of alignment suggested the presence of disordered collagen within the lamellar organization of the osteon. The results show the versatility of the analytical PRS approach and demonstrate its capability in providing not only compositional, but also 3D structural information in a complex hierarchically structured biological material. The concurrent assessment of chemical and structural features may contribute to a comprehensive characterization of the microstructure of bone and other collagen-based tissues.

Histologic, histochemical, and biomechanical properties of fragments isolated from the anterior wall of abdominal aortic aneurysms.

OBJECTIVE: To analyze biomechanical, histologic, and histochemical properties of anterior fragments of abdominal aortic aneurysms (AAA) and to correlate them with the maximum transverse diameter (MTD) and symptoms associated to the aneurysms. METHODS: Fragments of the anterior aneurysm wall were obtained from 90 patients submitted to open repair of AAA of degenerative etiology from 2004 to 2009 in the Clinics Hospital of São Paulo University Medical School. Two specimens were produced from the fragments: one for histologic analysis for quantification of collagen fibers, elastic fibers, smooth muscle cells, and degree of inflammatory activity and the other for uniaxial tensile test to assess biomechanical failure properties of the material, such as strength, tension, and stress. Cases were classified according to symptoms and to the AAA MTD. RESULTS: Fragments from AAA with MTD < 5.5 cm showed higher values for biomechanical failure properties than those of AAA with MTD < 5.5 cm (strength, 5.32 ± 2.07 × 4.1 ± 2.41 N; tension, 13.83 ± 5.58 × 10.82 ± 6.48 N/cm; stress, 103.02 × 77.03 N/cm(2); P < .05). No differences were observed between the groups in relation to failure strain (0.41 ± 0.12 × 0.37 ± 0.14; P = .260) and thickness of the fragments (1.58 ± 0.41 × 1.53 ± 0.42 mm; P = .662). The average values of fiber compositions of all the fragments were as follows: collagen fibers, 44.34 ± 0.48% and 61.85 ± 10.14% (Masson trichrome staining and Picrosirius red staining, respectively); smooth muscle cells, 3.46 ± 2.23% (immunohistochemistry/alpha-actin); and elastic fibers, less than 1% (traces) (Verhoeff-van Gieson staining). No differences in fiber percentages (collagen, elastic, and smooth muscle) were observed in fragments from AAA with MTD <5.5 cm and <5.5 cm, but more intense inflammatory activity was seen in larger AAA (grade 3; 70% × 28.6%; P = .011). Compared with asymptomatic aneurysms, symptomatic aneurysms showed no differences in the biomechanical failure properties (strength, 5.32 ± 2.36 × 4.65 ± 2.05 N; P = .155; tension, 14.08 ± 6.11 × 12.81 ± 5.77 N/cm; P = .154; stress, 103.02 × 84.76 N/cm(2); P = .144), strain (0.38 ± 0.12 × 0.41 ± 0.13; P = .287), thickness of the fragments (1.56 ± 0.41 × 1.57 ± 0.41 mm; P = .848), and histologic composition (collagen fibers, 44.67 ± 11.17 × 44.02 ± 13.79%; P = .808; smooth muscle fibers, 2.52 × 2.35%; P = .751; elastic fibers, <1%) CONCLUSIONS: Fragments of the anterior wall from larger aneurysms were more resistant than those from smaller AAA, with no tissue properties that could explain this phenomenon in the histologic or histochemical analyses utilized. CLINICAL RELEVANCE: The fragments of the anterior midsection from larger aneurysms were more resistant than those from smaller abdominal aortic aneurysms, with no tissue properties that could explain this phenomenon in the histologic or histochemical analyses. Larger aneurysms, at least in this place may be stronger than smaller aneurysms. It could point toward regional differences (heterogeneity, localized pathologies) as an important player in aneurysm rupture. Uniaxial strain tests are an important tool for the comprehension of a complex behavior such as that from an aneurysmal aortic wall. However, these tests still have limitations in providing information that would allow the calculation of the risk of rupture for abdominal aortic aneurysms.

Multiphoton tomography visualizes collagen fibers in the tumor microenvironment that maintain cancer-cell anchorage and shape.

Second harmonic generation (SHG) multiphoton imaging can visualize fibrillar collagen in tissues. SHG has previously shown that fibrillar collagen is altered in various types of cancer. In the present study, in vivo high resolution SHG multi-photon tomography in living mice was used to study the relationship between cancer cells and intratumor collagen fibrils. Using green fluorescent protein (GFP) to visualize cancer cells and SHG to image collagen, we demonstrated that collagen fibrils provide a scaffold for cancer cells to align themselves and acquire optimal shape. These results suggest a new paradigm for a stromal element of tumors: their role in maintaining anchorage and shape of cancer cells that may enable them to proliferate.

Proteomics analysis of ancient food vessel stitching reveals >4000-year-old milk protein.

RATIONALE: The 19th century excavation of an exceptionally well-preserved Early Bronze Age high status log-coffin burial from northern England, dated to 2200-2020 BC, yielded a 'food residue' collected from the inside of an accompanying bark vessel. This residue contained fibrous stitching that was used to hold the bark walls of the vessel together, first described as animal sinews, although the surviving material clearly contains animal hairs. Protein sequencing by soft ionisation mass spectrometry should identify the proteins that constitute the material, as well as the animal species from which they derive. METHODS: Peptide mass fingerprinting (PMF) by MALDI-TOF-MS combined with liquid chromatography-ESI-LTQ-MS/MS was used to identify low-abundance proteins as well as the dominant proteins in the sample. RESULTS: These proteomics techniques revealed the dominant proteins as deriving from the fibrous keratins (both types 1 and 2) and collagens (types 1 and 3), specifically those indicative of a bovine source. However, several peptide sequences diagnostic of bovine α-S1-casein were also observed, indicating that traces of milk had been preserved within the >4000-year-old fibrous residue. CONCLUSIONS: The presence of this food vessel that once contained milk within a burial of high status is suggestive of the importance placed on these secondary products. It is perhaps more remarkable that this information was retrieved not only from material of such antiquity, but also from an excavation that occurred nearly 200 years ago.

Effectiveness of correction of bleomycin-induced lung injury by early and late administration of surfactant-BL.

Rats were exposed to inhalation of surfactant-BL starting from the first or eighth day after intratracheal administration of bleomycin. At the early stages, the preparation effectively attenuated damage to ultrastructural components of the lung tissue and reduced the severity and extent of subsequent pulmonary pathology.

On the anatomy and histology of the pubovisceral muscle enthesis in women.

AIMS: The origin of the pubovisceral muscle (PVM) from the pubic bone is known to be at elevated risk for injury during difficult vaginal births. We examined the anatomy and histology of its enthesial origin to classify its type and see if it differs from appendicular entheses. METHODS: Parasagittal sections of the pubic bone, PVM enthesis, myotendinous junction, and muscle proper were harvested from five female cadavers (51-98 years). Histological sections were prepared with hematoxylin and eosin, Masson's trichrome, and Verhoeff-Van Gieson stains. The type of enthesis was identified according to a published enthesial classification scheme. Quantitative imaging analysis was performed in sampling bands 2 mm apart along the enthesis to determine its cross-sectional area and composition. RESULTS: The PVM enthesis can be classified as a fibrous enthesis. The PVM muscle fibers terminated in collagenous fibers that insert tangentially onto the periosteum of the pubic bone for the most part. Sharpey's fibers were not observed. In a longitudinal cross-section, the area of the connective tissue and muscle becomes equal approximately 8 mm from the pubic bone. CONCLUSION: The PVM originates bilaterally from the pubic bone via fibrous entheses whose collagen fibers arise tangentially from the periosteum of the pubic bone.

Morphological and Histopathological Study of Autopsied Patients with Atherosclerosis and HIV.

BACKGROUND: Chronic infection by HIV evolves with a vascular inflammatory action causing endothelial dysfunction. The action of the virus, as well as the side effects of antiretroviral drugs, contribute to the progression of cardiovascular diseases. The present study aimed to evaluate the percentage of collagen fibers and the density of mast cells, chymase and tryptase, in aortas of patients with and without HIV, and also patients with and without atherosclerosis. METHODS: Aortic fragments were obtained from autopsied patients aged 22-69 years and selected regardless of the cause of death or underlying disease. The samples were divided into four groups, (1) Group with HIV and with atherosclerosis; (2) Group with HIV and without atherosclerosis; (3) Group without HIV and with atherosclerosis; (4) Group without HIV and without atherosclerosis (Control). The percentage of collagen fibers was analyzed in the intima-media layer and the density of mast cells was analyzed in all aortic layers. Graphpad Prism 5.0® software was used for statistical analysis. RESULTS: There were more collagen fibers in HIV patients, with or without atherosclerosis. The group with HIV and atherosclerosis presented a higher density of chymase and tryptase mast cells. The correlation between collagen fibers and age was negative in the non-HIV group and with atherosclerosis. CONCLUSION: The inflammatory process resulting from HIV infection may be relevant in the alteration of aortic collagen fibers and in triggering or accelerating atherosclerosis. The study is important because HIV patients have increased risks for the development of cardiovascular diseases, and follow-up is necessary to prevent such diseases.

Quantitative analysis of collagen fiber organization in injured tendons using Fourier transform-second harmonic generation imaging.

Fourier transform-second harmonic generation (FT-SHG) imaging is used as a technique for evaluating collagenase-induced injury in horse tendons. The differences in collagen fiber organization between normal and injured tendon are quantified. Results indicate that the organization of collagen fibers is regularly oriented in normal tendons and randomly organized in injured tendons. This is further supported through the use of additional metrics, in particular, the number of dark (no/minimal signal) and isotropic (no preferred fiber orientation) regions in the images, and the ratio of forward-to-backward second-harmonic intensity. FT-SHG microscopy is also compared with the conventional polarized light microscopy and is shown to be more sensitive to assessing injured tendons than the latter. Moreover, sample preparation artifacts that affect the quantitative evaluation of collagen fiber organization can be circumvented by using FT-SHG microscopy. The technique has potential as an assessment tool for evaluating the impact of various injuries that affect collagen fiber organization.