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Brillouin Light Scattering (BLS) spectroscopy is a non-invasive, non-contact, label-free optical technique that can provide information on the mechanical properties of a material on the sub-micron scale. Over the last decade it has seen increased applications in the life sciences, driven by the observed significance of mechanical properties in biological processes, the realization of more sensitive BLS spectrometers and its extension to an imaging modality. As with other spectroscopic techniques, BLS measurements not only detect signals characteristic of the investigated sample, but also of the experimental apparatus, and can be significantly affected by measurement conditions. The aim of this consensus statement is to improve the comparability of BLS studies by providing reporting recommendations for the measured parameters and detailing common artifacts. Given that most BLS studies of biological matter are still at proof-of-concept stages and use different--often self-built--spectrometers, a consensus statement is particularly timely to assure unified advancement.

Background: The early and specific detection of abiotic and biotic stresses, particularly their combinations, is a major challenge for maintaining and increasing plant productivity in sustainable agriculture under changing environmental conditions. Optical imaging techniques enable cost-efficient and non-destructive quantification of plant stress states. Monomodal detection of certain stressors is usually based on non-specific/indirect features and therefore is commonly limited in their cross-specificity to other stressors. The fusion of multi-domain sensor systems can provide more potentially discriminative features for machine learning models and potentially provide synergistic information to increase cross-specificity in plant disease detection when image data are fused at the pixel level., Results: In this study, we demonstrate successful multi-modal image registration of RGB, hyperspectral (HSI) and chlorophyll fluorescence (ChlF) kinetics data at the pixel level for high-throughput phenotyping of A. thaliana grown in Multi-well plates and an assay with detached leaf discs of Rosa × hybrida inoculated with the black spot disease-inducing fungus Diplocarpon rosae. Here, we showcase the effects of (i) selection of reference image selection, (ii) different registrations methods and (iii) frame selection on the performance of image registration via affine transform. In addition, we developed a combined approach for registration methods through NCC-based selection for each file, resulting in a robust and accurate approach that sacrifices computational time. Since image data encompass multiple objects, the initial coarse image registration using a global transformation matrix exhibited heterogeneity across different image regions. By employing an additional fine registration on the object-separated image data, we achieved a high overlap ratio. Specifically, for the A. thaliana test set, the overlap ratios (OR Convex ) were 98.0 ± 2.3% for RGB-to-ChlF and 96.6 ± 4.2% for HSI-to-ChlF. For the Rosa × hybrida test set, the values were 98.9 ± 0.5% for RGB-to-ChlF and 98.3 ± 1.3% for HSI-to-ChlF., Conclusion: The presented multi-modal imaging pipeline enables high-throughput, high-dimensional phenotyping of different plant species with respect to various biotic or abiotic stressors. This paves the way for in-depth studies investigating the correlative relationships of the multi-domain data or the performance enhancement of machine learning models via multi modal image fusion., Competing Interests: Declarations Ethics approval and consent to participate Not applicable. Competing interests The authors declare no competing interests., (© 2024. The Author(s).)

Decellularized extracellular matrix (dECM) is an excellent natural source for 3D bioprinting materials due to its inherent cell compatibility. In vat photopolymerization, the use of dECM-based bioresins is just emerging, and extensive research is needed to fully exploit their potential. In this study, two distinct methacryloyl-functionalized, photocrosslinkable dECM-based bioresins were prepared from digested porcine liver dECM through functionalization with glycidyl methacrylate (GMA) or conventional methacrylic anhydride (MA) under mild conditions for systematic comparison. Although the chemical modifications did not significantly affect the structural integrity of the dECM proteins, mammalian cells encapsulated in the respective hydrogels performed differently in long-term culture. In either case, photocrosslinking during 3D (bio)printing resulted in transparent, highly swollen, and soft hydrogels with good shape fidelity, excellent biomimetic properties and tunable mechanical properties (~ 0.2-2.5 kPa). Interestingly, at a similar degree of functionalization (DOF ~ 81.5-83.5 %), the dECM-GMA resin showed faster photocrosslinking kinetics in photorheology resulting in lower final stiffness and faster enzymatic biodegradation compared to the dECM-MA gels, yet comparable network homogeneity as assessed via Brillouin imaging. While human hepatic HepaRG cells exhibited comparable cell viability directly after 3D bioprinting within both materials, cell proliferation and spreading were clearly enhanced in the softer dECM-GMA hydrogels at a comparable degree of crosslinking. These differences were attributed to the additional hydrophilicity introduced to dECM via methacryloylation through GMA compared to MA. Due to its excellent printability and cytocompatibility, the functional porcine liver dECM-GMA biomaterial enables the advanced biofabrication of soft 3D tissue analogs using vat photopolymerization-based bioprinting., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Marie Weinhart reports financial support was provided by German Research Foundation. Sebastian Seiffert reports financial support was provided by German Research Foundation. Beate Koksch reports financial support was provided by German Research Foundation. Igor Maximilian Sauer reports financial support was provided by German Research Foundation. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

With the development of 3D vision techniques, RGB-D cameras are increasingly used to allow easier and cheaper access to the third dimension. In this paper, we focus on testing the potential of the Kinect Azure RGB-D camera in the 3D reconstruction of indoor scenes. First, a series of investigations of the hardware was performed to evaluate its accuracy and precision. The results show that the measurements made with the Azure could be exploited for close-range survey applications. Second, we performed a methodological workflow for indoor reconstruction based on the Open3D framework, which was applied to two different indoor scenes. Based on the results, we can state that the quality of 3D reconstruction significantly depends on the architecture of the captured scene. This was supported by a comparison of the point cloud from the Kinect Azure with that from a terrestrial laser scanner and another from a mobile laser scanner. The results show that the average differences do not exceed 8 mm, which confirms that the Kinect Azure can be considered a 3D measurement system at least as reliable as a mobile laser scanner.

Developments in the field of artificial intelligence have made great strides in the field of automatic semantic segmentation, both in the 2D (image) and 3D spaces. Within the context of 3D recording technology it has also seen application in several areas, most notably in creating semantically rich point clouds which is usually performed manually. In this paper, we propose the introduction of deep learning-based semantic image segmentation into the photogrammetric 3D reconstruction and classification workflow. The main objective is to be able to introduce semantic classification at the beginning of the classical photogrammetric workflow in order to automatically create classified dense point clouds by the end of the said workflow. In this regard, automatic image masking depending on pre-determined classes were performed using a previously trained neural network. The image masks were then employed during dense image matching in order to constraint the process into the respective classes, thus automatically creating semantically classified point clouds as the final output. Results show that the developed method is promising, with automation of the whole process feasible from input (images) to output (labelled point clouds). Quantitative assessment gave good results for specific classes e.g., building facades and windows, with IoU scores of 0.79 and 0.77 respectively.

Avoiding damage of the endothelial cells, especially in thin corneas, remains a challenge in corneal collagen crosslinking (CXL). Knowledge of the riboflavin gradients and the UV absorption characteristics after topical application of riboflavin in concentrations ranging from 0.1% to 0.5% could optimize the treatment. In this study, we present a model to calculate the UV-intensity depending on the corneal thickness. Ten groups of de-epithelialized porcine corneas were divided into 2 subgroups. Five groups received an imbibition of 10 min and the other five groups for 30 min. The applied riboflavin concentrations were 0.1%, 0.2%, 0.3%, 0.4% and 0.5% diluted in a 15% dextran solution for each subgroup. After the imbibition process, two-photon fluorescence microscopy was used to determine fluorescence intensity, which was compared to samples after saturation, yielding the absolute riboflavin concentration gradient of the cornea. The extinction coefficient of riboflavin solutions was measured using a spectrophotometer. Combining the obtained riboflavin concentrations and the extinction coefficients, a depth-dependent UV-intensity profile was calculated for each group. With increasing corneal depth, the riboflavin concentration decreased for all imbibition solutions and application times. The diffusion coefficients of 10 min imbibition time were higher than for 30 min. A higher RF concentration and a longer imbibition time resulted in higher UV-absorption and a lower UV-intensity in the depth of the cornea. Calculated UV-transmission was 6 percentage points lower compared to the measured transmission. By increasing the riboflavin concentration of the imbibition solution, a substantially higher UV-absorption inside the cornea is achieved. This offers a simple treatment option to control the depth of crosslinking e.g. in thin corneas, resulting in a lower risk of endothelial damage., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Two-photon absorption (TPA) and other nonlinear interactions of molecules with time-frequency-entangled photon pairs have been predicted to display a variety of fascinating effects. Therefore, their potential use in practical quantum-enhanced molecular spectroscopy requires close examination. This Tutorial presents a detailed theoretical study of one- and two-photon absorption by molecules, focusing on how to treat the quantum nature of light. We review some basic quantum optics theory and then we review the density-matrix (Liouville) derivation of molecular optical response, emphasizing how to incorporate quantum states of light into the treatment. For illustration, we treat in detail the TPA of photon pairs created by spontaneous parametric down conversion, with an emphasis on how quantum light TPA differs from that with classical light. In particular, we treat the question of how much enhancement of the TPA rate can be achieved using entangled states. This Tutorial includes a review of known theoretical methods and results as well as some extensions, especially the comparison of TPA processes that occur via far-off-resonant intermediate states only and those that involve off-resonant intermediate states by virtue of dephasing processes. A brief discussion of the main challenges facing experimental studies of entangled two-photon absorption is also given.

When a low flux of time-frequency-entangled photon pairs (EPP) illuminates a two-photon transition, the rate of two-photon absorption (TPA) can be enhanced considerably by the quantum nature of photon number correlations and frequency correlations. We use a quantum-theoretic derivation of entangled TPA (ETPA) and calculate an upper bound on the amount of quantum enhancement that is possible in such systems. The derived bounds indicate that in order to observe ETPA the experiments would need to operate at a combination of significantly higher rates of EPP illumination, molecular concentrations, and conventional TPA cross sections than are achieved in typical experiments.

Fluorescence-detected Fourier transform (FT) spectroscopy is a technique in which the relative paths of an optical interferometer are controlled to excite a material sample, and the ensuing fluorescence is detected as a function of the interferometer path delay and relative phase. A common approach to enhance the signal-to-noise ratio in these experiments is to apply a continuous phase sweep to the relative optical path, and to detect the resulting modulated fluorescence using a phase-sensitive lock-in amplifier. In many important situations, the fluorescence signal is too weak to be measured using a lock-in amplifier, so that photon counting techniques are preferred. Here we introduce an approach to low-signal fluorescence-detected FT spectroscopy, in which individual photon counts are assigned to a modulated interferometer phase ('phase-tagged photon counting,' or PTPC), and the resulting data are processed to construct optical spectra. We studied the fluorescence signals of a molecular sample excited resonantly by a pulsed coherent laser over a range of photon flux and visibility levels. We compare the performance of PTPC to standard lock-in detection methods and establish the range of signal parameters over which meaningful measurements can be carried out. We find that PTPC generally outperforms the lock-in detection method, with the dominant source of measurement uncertainty being associated with the statistics of the finite number of samples of the photon detection rate.

Surveying fields from geosciences to infrastructure monitoring make use of a wide range of instruments for accurate 3D geometry acquisition. In many cases, the Terrestrial Laser Scanner (TLS) tends to become an optimal alternative to total station measurements thanks to the high point acquisition rate it offers, but also to ever deeper data processing software functionalities. Nevertheless, traditional surveying techniques are valuable in some kinds of projects. Nowadays, a few modern total stations combine their conventional capabilities with those of a laser scanner in a unique device. The recent Trimble SX10 scanning total station is a survey instrument merging high-speed 3D scanning and the capabilities of an image-assisted total station. In this paper this new instrument is introduced and first compared to state-of-the-art image-assisted total stations. The paper also addresses the topic of various laser scanning projects and the delivered point clouds are compared with those of other TLS. Directly and indirectly georeferenced projects have been carried out and are investigated in this paper, and a polygonal traverse is performed through a building. Comparisons with the results delivered by well-established survey instruments show the reliability of the Trimble SX10 for geodetic work as well as for scanning projects.

Purpose: The diagnosis of cancer, the symptoms of the illness and its treatment have an influence on how patients and their caregivers experience distress. However, data focusing on caregivers and their cancer-related distress in the outpatient setting is sparse. This study aimed to compare cancer-related distress of caregivers and patients and to derive implications for the system of outpatient psycho-oncological care., Methods: One hundred thirty-eight patients and 102 caregivers receiving psycho-oncological counseling completed a standardized interview based on a self-assessment questionnaire (Questionnaire on Stress in Cancer Patients, FBK)., Results: Group comparisons for cancer-related distress revealed one statistically significant difference for the subscale 'Fear' of the FBK, Z = 2.308, p = .021, and d = .44. Caregivers showed higher cancer-related fear (M = 2.76, SD = 1.14) than patients (M = 2.41, SD = 1.29). There were no differences in 'psychosomatic complaints', 'information deficit', 'restrictions in everyday life', 'social strains', or the total score of the FBK., Conclusions: Caregivers seem to experience cancer-related distress equal to or even more severely than patients themselves. Results suggest that there is a need for more low-threshold offers of outpatient psycho-oncological counseling for caregivers.

Background: Previous studies have reported changes in nutrition-related behaviors in alcohol-dependent patients after alcohol detoxification, but prospective studies assessing the effects of these changes on maintaining abstinence are lacking., Objectives: To assess changes in craving and consumption of chocolate and other sweets over time up to six months after outpatient alcohol detoxification treatment and to detect differences in abstinent versus nonabstinent patients., Methods: One hundred and fifty alcohol-dependent patients were included in this prospective observational study. Participants completed self-report questionnaires on nutrition-related behaviors and craving before detoxification treatment (baseline, t1), one week (t2), one month (t3), and six months later (t4)., Results: Significant changes in craving for and consumption of chocolate as well as in craving for other sweets were observed over time. Increases were most prominent within the first month. Patients who remained abstinent until t3 consumed three times more chocolate than nonabstainers. One quarter of the patients switched from being rare (t1) to frequent (t3) chocolate eaters, and 84% of these remained abstinent until t3. No significant correlations were found between craving for alcohol and craving for or consumption of chocolate or other sweets., Conclusions/importance: In the first month after outpatient alcohol detoxification treatment, significant changes in nutrition-related behaviors were observed. These changes were not associated with alcohol craving. For a subgroup, increasing the frequency of chocolate consumption might be a temporary protective factor with respect to alcohol relapse.

Cardiolipin is a mitochondrion-specific phospholipid that stabilizes the assembly of respiratory chain complexes, favoring full-yield operation. It also mediates key steps in apoptosis. In Barth syndrome, an X chromosome-linked cardiomyopathy caused by tafazzin mutations, cardiolipins display acyl chain modifications and are present at abnormally low concentrations, whereas monolysocardiolipin accumulates. Using immortalized lymphoblasts from Barth syndrome patients, we showed that the production of abnormal cardiolipin led to mitochondrial alterations. Indeed, the lack of normal cardiolipin led to changes in electron transport chain stability, resulting in cellular defects. We found a destabilization of the supercomplex (respirasome) I+III2+IVn but also decreased amounts of individual complexes I and IV and supercomplexes I+III and III+IV. No changes were observed in the amounts of individual complex III and complex II. We also found decreased levels of complex V. This complex is not part of the supercomplex suggesting that cardiolipin is required not only for the association/stabilization of the complexes into supercomplexes but also for the modulation of the amount of individual respiratory chain complexes. However, these alterations were compensated by an increase in mitochondrial mass, as demonstrated by electron microscopy and measurements of citrate synthase activity. We suggest that this compensatory increase in mitochondrial content prevents a decrease in mitochondrial respiration and ATP synthesis in the cells. We also show, by extensive flow cytometry analysis, that the type II apoptosis pathway was blocked at the mitochondrial level and that the mitochondria of patients with Barth syndrome cannot bind active caspase-8. Signal transduction is thus blocked before any mitochondrial event can occur. Remarkably, basal levels of superoxide anion production were slightly higher in patients' cells than in control cells as previously evidenced via an increased protein carbonylation in the taz1Δ mutant in the yeast. This may be deleterious to cells in the long term. The consequences of mitochondrial dysfunction and alterations to apoptosis signal transduction are considered in light of the potential for the development of future treatments., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Mitochondria continually fuse and divide to yield a dynamic interconnected network throughout the cell. During apoptosis, concomitantly with permeabilization of the mitochondrial outer membrane (MOMP) and cytochrome c release, mitochondria undergo massive fission. This results in the formation of small, round organelles that tend to aggregate around the nucleus. Under some circumstances, preceding their fission, mitochondria tend to elongate and to hyperfuse, a process that is interpreted as a cell defense mechanism. Since many years, there is a controversy surrounding the physiological relevance of mitochondrial fragmentation in apoptosis. In this review, we present recent advances in this field, describe the mechanisms that underlie this process, and discuss how they could cooperate with Bax to trigger MOMP and cytochrome c release. This article is part of a Special Issue entitled Mitochondria: the deadly organelle., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Unlabelled: Round opacities in the lungs found in the course of a neoplastic disorder or during the initial tumor staging are most often regarded as metastases without histological studies to prove their nature. These presumed metastases are, however, very often diagnosed later as benign lesions or primary malignant pulmonary tumors., Aim: To investigate the histological substrate of solitary pulmonary nodules in patients with a history of neoplastic condition and study the role of video-assisted thoracoscopy in their diagnosing and treatment., Method: The study included 22 patients with solitary pulmonary nodules and history of previous malignant tumors who underwent video-assisted thoracoscopic surgery at the Clinic of Vascular and Thoracic Surgery, University Hospital Aschersleben, Germany between 01.01.2006 and 31.12.2009. Pulmonary wedge resection was performed and it was followed by histological verification., Results: A diagnosis of pulmonary metastasis was confirmed in only 8 of the patients (36.4%). In another 8 of them (36.4%) the solitary pulmonary nodule proved to be a primary lung cancer, i.e. a second malignant tumor. The bronchial carcinoma was synchronous with the primary tumor in four of these patients, and metachronous in the rest. In the other 6 patients (27.2%) the lesions proved to be benign., Conclusions: Not all solitary pulmonary nodules in patients with preceding malignant formations are metastases. In order to define their nature more precisely they should be resected by video-assisted thoracoscopy, if possible. In benign lesions video-assisted thoracoscopic resection is the definitive medical procedure too.

Mitochondrial morphology varies according to cell type and cellular context from an interconnected filamentous network to isolated dots. This morphological plasticity depends on mitochondrial dynamics, a balance between antagonistic forces of fission and fusion. DRP1 and FIS1 control mitochondrial outer membrane fission and Mitofusins its fusion. This review focuses on OPA1, one of the few known actors of inner membrane dynamics, whose mutations provoke an optic neuropathy. Since its first identification in 2000 the characterization of the functions of OPA1 has made rapid progress thus providing numerous clues to unravel the pathogenetic mechanisms of ADOA-1., (Copyright 2009 Elsevier Ltd. All rights reserved.)

Opa1 modulates mitochondrial fusion, cristae structure and apoptosis. The relationships between these functions and autosomal dominant optic atrophy, caused by mutations in Opa1, are poorly defined. We show that Bnip3 interacts with Opa1, leading to mitochondrial fragmentation and apoptosis. Fission is due to inhibition of Opa1-mediated fusion and is counteracted by Opa1 in an Mfn1-dependent manner. Bnip3-Opa1 interaction is necessary to trigger Opa1 complex disruption in a Bax- and/or Bak-dependent manner, ultimately leading to apoptosis. Our results uncover a direct link between Opa1 on the inner mitochondrial membrane and the apoptotic machinery on the outer membrane that modulates fusion and cristae structure by separate mechanisms. These findings might help to unravel optic atrophy aetiology as retinal ganglion cells are particularly prone to hypoxia, an inductor of Bnip3 expression.

Background Information: Human OPA1 (optic atrophy type 1) is a dynamin-related protein of the mitochondrial IMS (intermembrane space) involved in membrane fusion and remodelling. Similarly to its yeast orthologue Mgm1p that exists in two isoforms generated by the serine protease Pcp1p/Rbd1p, OPA1 exists in various isoforms generated by alternative splicing and processing. In the present paper, we focus on protease processing of OPA1., Results: We find that various mammalian cell types display a similar pattern of OPA1 isoforms [two L-OPA1 (long isoforms of OPA1) and three S-OPA1 (short isoforms of OPA1)] and that loss of the inner membrane potential, but not inhibition of oxidative phosphorylation or glycolysis, induces rapid and complete processing of L-OPA1 to S-OPA1. In isolated mitochondria, OPA1 processing was inhibited by heavy-metal chelators, pointing to processing by a mitochondrial metalloprotease. The pattern of OPA1 isoforms and its processing kinetics were normal in mitochondria devoid of the serine protease PARL (presenilins-associated rhomboid-like protein) - the human orthologue of Pcp1/Rbd1 - and in cells from patients carrying homozygous mutations in SPG7 (spastic paraplegia type 7), a gene encoding the matrix-oriented metalloprotease paraplegin. In contrast, OPA1 processing kinetics were delayed upon knock-down of YME1L (human yme1-like protein), an IMS-oriented metalloprotease. OPA1 processing was also stimulated during apoptosis, but inhibition of this processing did not affect apoptotic release of OPA1 and cytochrome c. Finally, we show that all OPA1 isoforms interact with Mfn1 (mitofusin 1) and Mfn2 and that these interactions are not affected by dissipation of DeltaPsim (inner mitochondrial membrane potential) or OPA1 processing., Conclusions: Metalloprotease-mediated processing of OPA1 is modulated by the inner membrane potential and is likely to be mediated by the YME1L protease.

To characterize the molecular links between type-1 autosomal dominant optic atrophy (ADOA) and OPA1 dysfunctions, the effects of pathogenic alleles of this dynamin on mitochondrial morphology and apoptosis were analyzed, either in fibroblasts from affected individuals, or in HeLa cells transfected with similar mutants. The alleles were missense substitutions in the GTPase domain (OPA1(G300E) and OPA1(R290Q)) or deletion of the GTPase effector domain (OPA1(Delta58)). Fragmentation of mitochondria and apoptosis increased in OPA1(R290Q) fibroblasts and in OPA1(G300E) transfected HeLa cells. OPA1(Delta58) did not influence mitochondrial morphology, but increased the sensitivity to staurosporine of fibroblasts. In these cells, the amount of OPA1 protein was half of that in control fibroblasts. We conclude that GTPase mutants exert a dominant negative effect by competing with wild-type alleles to integrate into fusion-competent complexes, whereas C-terminal truncated alleles act by haplo-insufficiency. We present a model where antagonistic fusion and fission forces maintain the mitochondrial network, within morphological limits that are compatible with cellular functions. In the retinal ganglion cells (RGCs) of patients suffering from type-1 ADOA, OPA1-driven fusion cannot adequately oppose fission, thereby rendering them more sensitive to apoptotic stimuli and eventually leading to optic nerve degeneration., ((c) 2007 Wiley-Liss, Inc.)

The mitochondria are dynamic organelles that constantly fuse and divide. An equilibrium between fusion and fission controls the morphology of the mitochondria, which appear as dots or elongated tubules depending the prevailing force. Characterization of the components of the fission and fusion machineries has progressed considerably, and the emerging question now is what role mitochondrial dynamics play in mitochondrial and cellular functions. Its importance has been highlighted by the discovery that two human diseases are caused by mutations in the two mitochondrial pro-fusion genes, MFN2 and OPA1. This review will focus on data concerning the function of OPA1, mutations in which cause optic atrophy, with respect to the underlying pathophysiological processes.

A bovine collagen graft was implanted in 30 dogs for the replacement of the femoral vein, the iliac vein and the inferior vena cava. During the observation period up to 210 days six thromboses of the graft were observed. Histological results after 30 days: development of a "neo-intima" with collagen type III, originating from the anastomosis. After 90 to 210 days: Continuous endothelial layer of the graft with appearance of smooth muscle fibers in the neo-intima. From the graft bed there was found resorption of the bovine collagen and replacement by new collagen type III fibers.

A pedicled autologous jejunum transplant and a free bovine collagen prosthesis were tried for the treatment of short, benign stenoses of the bile duct in animal experiments. In both cases at follow-up periods of 6--18 months an unrestricted flow of bile was recorded in the plastically dilated bile duct macroscopically, radiologically and by the chemical laboratory. On the basis of these results in animal experiments, 3 patients were treated with a pedicled jejunum transplant for the correction of short benign stenosis of the bile duct following previous cholecystectomy. All the patients are free from complaints after observation periods of 6 months, 1 year and 2 1/2 years.

The use of a modified bovine collagen graft as a low-pressure conduit was investigated by implantation into the iliocaval system of dogs. In the 210 day observation period, a patency rate of 87.5% was achieved. Nearly all graft failures occured within the first 14 days following implantation; failure after that time did not seem to be dependent upon length of time of implantation. Progressive organization of the neointima was seen histologically. New smooth muscle fibers were observed in the neointima with electron microscopic evidence of reconstitution of the subendothelial membrane. Continuing resorption of graft collagen coincided with its replacement by newly developed collagen type III fibers in a surface-parallel orientation.

Simple end-to-end reconstruction of benign bile duct stenosis is possible only in a few cases. To preserve the function of papilla of Vater as the best anticholangitis therapy, we developed a method of bile duct expansion by a pedunculated jejunal patch-graft in animal experiments. After these successful experiments three patients with iatrogenic short bile duct stenosis were treated with this operation. These patients remain free of pathologic clinical and radiological findings 8-30 months after surgery.

Results of animal experiments are presented on the applicability in the low pressure system of a collagen prosthesis, which has been used successfully, for considerable time, in the arterial replacement in patients and dogs. Grafts of up to 7 cm in length were implanted into the suprarenal segment of the inferior vena cava (v. cava caudalis) in dogs and observed clinically over a period of more than 500 days. Histological investigations were made. With some limitations the results obtained are considered as good and point towards the applicability of the examined graft material in the low pressure system.

A pedunculate patch, obtained from a disconnected segment of jejunum, was implanted into the longitudinal incision of the ductus choledochus. Intra-operatively, the findings were based upon direct cholecystocholangiography; postoperatively, upon laboratory tests. After an observation period of 12 months a new cholangiography of the transplant was made along with a selective picture of the mesenteric arteries. The choledochus duct with the transplant was examined histologically. Three dogs died immediately postoperatively of peritonitis due to suture insufficiency. Five dogs died of invaginate ileus. These animals, as well as the remaining 8 dogs showed macroscopically and microscopically a smooth and uneventful healing of the transplant at the end of the observation period. Radiographies showed free flow of the biliary duct system. The selective mesenteric arteriographies evidenced beginning anastomosis between the transplant and the capillaries of the bile duct. Based on the results presented, the pedunculate jejunal graft can be considered well suited as an expansion graft for the bile duct.