Andrzej Gryglewski

Homological methods for extraction and analysis of linear features in multidimensional images

We show that the problem of extracting linear features from a noisy image and counting the number of branching points may be successfully solved by homological methods applied directly to the image without the need of skeletonization and the analysis of the resulting graph. The method is based on the superimposition of a mask set over the original image and works even when the homology of the feature is trivial and in arbitrary dimension. We tested the method on computer-generated data, 2D images of blood vessels, 2D satellite images and 3D images of collagen fibers.

Cross-reactivity of TNP immune effector T cells that mediate contact hypersensitivity and inflammatory bowel disease in the mouse.

Background: Experiments were aimed to test the cross-reactivity of immune Th1 cells that mediate contact hypersensitivity (CHS) or inflammatory bowel disease (IBD) to TNP in the mouse. Methods: CBA/J mice were immunized either epicutaneously or intrarectally with TNP and after appropriate time intervals were challenged with antigen in a crossed manner. The CHS reaction was measured by the ear swelling test. IBD was quantified by increase of colon weight and myeloperoxidase level. Both reactions were confirmed histologically. In passive-transfer experiments, mesenteric lymph node cells of animals sensitized intrarectally and peripheral lymph node and spleen cells of mice immunized epicutaneously were used. In some experiments, before being immunized mice were made either unresponsive to the TNP hapten by induction of suppressor T cells, or resistant to suppression after induction of upregulatory T cells. Results: Irrespective of the mode of sensitization upon appropriate challenge with antigen all mice developed a good CHS reaction as well as significant IBD. This cross-reactivity could be passively transferred by immune cells. In mice in which antigen-specific down- or upregulatory cells were induced before sensitization both CHS and IBD to TNP were modulated accordingly. Conclusion: TNP hapten deposited on skin or on mucosal surfaces induces effector cells that recognize antigen independent of its tissue localization, and produce a local inflammatory reaction. TNP-specific up- and downregulatory cells, shown before to regulate the CHS reaction, similarly modulate the generation and development of hapten-induced IBD.

Deficiency of contrasuppressor lymphocytes in alloxan-diabetic mice

Ly 1 immune cells of alloxan diabetic mice are inferior to cells of normoglycemic PCl sensitized animals in transferring adoptive responses into recipients. A new regulatory activity, contrasuppression, that prevents suppressor cells from influencing activity of immune cells, has been recently described. Two types of Ly 1 contrasuppressor (Tcs) cells modulate contact sensitivity reactions in mice. A non-specific Tcs cell, which by itself has no immune activity, helps Ly 1 immune effector cells in adoptive transfer to bypass, in the recipient, the suppressor cell barrier. The antigen-specific Tcs cell induced by immune complexes makes Ly 1 effector cells resistant to specific suppression. Both Tcs cell, in contrast to Ly 1 effector cells, adhere to Vicia villosa lectin and can easily be separated (VV+ and VV-, respectively). Our experiments show that diabetic mice are deficient in nonspecific Tcs cells. The most important finding was that when immune Ly 1 cells of diabetic mice, which otherwise transfer little immunity, were injected together with Ly 1 VV+ cells of normoglycemic animals (these cells have no ability to transfer immunity whatsoever), the adoptive transfer was significantly augmented. We also demonstrate that diabetic mice are unable, upon appropriate immunization, to produce antigen-specific Tcs cells. Since a hypoinsulinemic environment abolishes the function of promiscuous Tcs cells and prevents the development of antigen-specific Tcs cells, this may suggest that contrasuppressor cells have insulin receptors which make them particularly sensitive to insulin deficiency.

Homological Methods in Feature Extraction of Multidimensional Images

We show that the newly developed homology al- gorithms are helpful in imaging problems on the example of an algorithm extracting one dimensional features from a noisy image. We indicate that in some situations the global nature of this algorithm may become advantageous when compared with the standard algorithms based on skeletonization and pruning. The algorithm works in every dimension. I. INTRODUCTION The topological technique commonly used in image seg- mentation is the extraction of connected components of a black and white image. In the language of homology theory (1) this may be viewed as constructing the zeroth homology group of the image. Higher homology groups, which measure the presence of cycles, tunnels, and cavities in the image, are also used in computer vision and image processing (2), (1), (3), (4), (5), (6) but so far their usage is limited in part because the cycles, tunnels and cavities are not so frequent in images and in part because the classical algorithm for higher homology groups has cubical complexity which is in contrast to the linear time needed to construct connected components (7). In this paper we show that higher homology groups are useful in image analysis even if the image itself and/or the features to be extracted contain no tunnels or holes. This is because holes may appear when the image is superimposed over some pattern (mask) and the appearance (or lack of appearance) of holes may be used to test certain features of the image via the study of homology generators. Moreover, image analysis based on higher homology groups may be performed quickly due to the recently developed reduction homology algorithms (8), (9), (10), which offer speed comparable to the speed of the algorithms constructing connected components. The first four authors supported by Polish MNSzW, Grant N201 037 31/3151. The implementations of these algorithms are available from (11) (see also (12), (13)). To present the method we discuss a sample problem, which consists in the extraction of linear structures from the image under the presence of other features and noise. We became interested in the problem when studying two concrete issues: the analysis of 2D colonoscope images of blood vessels in colon mucosa (14), (15) and the analysis of 3D reconstituted confocal microscopy images of type I collagen fibrils (16). Similar issues are studied in the analysis of blood vessel images in various other settings (17), (18), (19)), as well as in the detection of roads on satellite images ((20), (21)) and many other problems.

The Effect of Surgical Stress on Postoperative Tαβ and Tγδ Cell Distribution

ABSTRACT Background: It was previously shown that appropriate distribution of immune cells between different tissues and organs of the body is required for proper function of the immune system. Our previous experiments demonstrated that surgical trauma in mice induces Tγδ lymphocyte migration from peripheral blood to peritoneal lymphoid organs. Tγδ cells have regulatory activity as they suppress the cell-mediated immune response in vitro via TGF-β. In the current study, we aim to evaluate the influence of surgery on both Taβ and Tγδ lymphocyte distribution in patients that underwent operation. Materials and Methods: We investigated the percentage of Tαβ and Tγδ cells in peripheral blood of patients undergoing standard surgical procedures (gastric resection, colorectal resection, cholecystectomy, and strumectomy) before and 3 days after operation. The percentage of Tαβ and Tγδ cells was evaluated by FACS Canto II cytofluorimeter. Results: We showed that only major surgery located in the peritoneal cavity (gastric and colorectal surgery) decreases the percentage of Tγδ cells in peripheral blood as opposed to less traumatic surgery (strumectomy and cholecystectomy) which does not have such effect. However, significant reduction of Tγδ cells after operation was only observed in a group of patients that underwent gastrectomy. Additionally, we found that gastrectomy results in significant reduction of cumulative Tγδ CD4 and Tγδ CD25 lymphocyte counts. Conclusion: Surgery results in decreased percentage of Tγδ lymphocytes in peripheral human blood, and this correlates with the severity and location of the surgical trauma. This observation may help to predict postoperative recovery after gastroabdominal surgery.

Sensitivity and Specificity of Fractal Analysis to Distinguish Between Healthy and Pathologic Rectal Mucosa Microvasculature Seen During Colonoscopy.

Purpose: Conventional endoscopy is limited by human capability to recognize and to differentiate pathology. Fractal analysis of blood vessels has been used in other organs, such as the retina, but never before to supplement colonoscopy. The aim of this study was to assess whether it is possible to differentiate between healthy and pathologic rectal mucosa using fractal analysis of the mucosal microvascular architecture seen during colonoscopic examination (Supplemental Digital Content 1, http://links.lww.com/SLE/A145). Methods: A total of 300 consecutive patients, 133 females and 167 males with a mean age of 49.1 (±11.3) years, undergoing endoscopy were included in the prospective cohort study. Colonoscopy of the sigmorectal region was performed, and then analyzed with computer-assisted image fractal analysis. Results: Fractal analysis of mucosal vasculature allowed for differentiation between healthy and pathologic rectal mucosa, as well as different pathologies (P<0.0001). The sensitivity of fractal analysis to diagnose rectal neoplasia was 92.8% to 96.4%, while the specificity was 91.9% to 98.5% depending on the fractal parameter. The sensitivity of fractal analysis to diagnose rectal colitis was 84.2% to 92.1%, while the specificity was 95.0% to 96.0%, depending on the fractal parameter. Conclusions: Computer-assisted fractal analysis allows for differentiation between healthy and pathologic rectal mucosa, as well as between different mucosal pathologies, seen during colonoscopy. Fractal analysis improves the sensitivity and specificity of colonoscopy to aid in the diagnosis of neoplasia or colitis, and should be included in the screening and surveillance of these pathologies.

Anatomical aspect of nerve-preserving surgery for rectal cancer.

The outcome after resection for rectal cancers has improved following standardization of the surgical technique and the introduction of total mesorectal excision (TME) (1-4). In particular the TME technique has resulted in better local control and survival (5). The existence of nodal metastases has been the most important overall prognostic factor in determining long-term survival rates (6). Adequate lymphadenectomy measured by analysis of at least 15 lymph nodes, correlates with improved survival, independent of stage, patient demographics, and tumor characteristics (7). However, surgical resection of the rectum with TME performed for rectal cancer has been connected with a high risk of loss of sexual function due to autonomic nerve damage. It is a common complication and may occur after radical pelvic sur gery of all types: radical prostatectomy, radical cystoprostatectomy, anterior rectal resection and abdominoperineal rectal resection. The pathophysiology of sexual dysfunction after pelvic surgery is unique because it can be a result of vascular or neurogenic factors alone, or a combination of both. Age, sex, type of surgery, and presence of malignant disease have all been shown to be associated with an increased risk of postoperative sexual dysfunction (8). In 1982, Walsh and Donker demonstrated that impotence following radical prostatectomy often occurred secondary to injury to the branches of the pelvic plexus that innervates the cavernous bodies of the penis, and they proposed minor modifications in the surgical procedure to avoid this complication (9). Later, these modifications were widely implemented during surgical procedures involving radical prostatectomy (10) and cystoprostatectomy (11). The sphincter-saving procedures also diminished the risk of postoperative sexual dysfunctions in abdomino-perineal resection (APR). The impotence rates after APR reported in the literature vary from 15% to 92%, and sexual dysfunction rates after all rectal cancer surgeries range between 10% and 60% (12). Most surgeons are currently perform ing TME with preserva tion of the neurovascular bundles, a technique which has been shown to be effective in reducing postoperative sexual dysfunction rates. In 1997 Enker et al. reported that APR performed in accordance with the principles of TME and autonomic nerve preservation results in preserving both sexual and urinary functions (13). Their study showed that 57% of patients undergoing APR and 85% undergoing sphincter preserving operations maintained their urinary and sexual functions (14). With the increasing popu larity of laparoscopy some surgeons perform laparoscopic assisted TME. Quah reported that sexual dysfunction rates in men were higher after laparoscopic surgery than after open surgery, while the rates of sexual dysfunctions in women stayed the same for both techniques (15). However, owing to the paucity of reports

Differential Effect of Experimental Diabetes on the Early and Late Phase of Contact Sensitivity Reaction in Mice

Contact sensitization induces two different kinds of T cells (both Ly 1) that act in sequence to produce upon challenge with antigen a classical 24-hour local skin swelling reaction. One of these cells produces an antigen-specific factor. It has been suggested that it sensitizes mast cells, similar to IgE antibody, and causes them to release vasoactive amines in the presence of antigen. This results in an early (2-hour) swelling reaction. Increased vascular permeability facilitates the entry of the second, lymphokine-producing Ly 1 cell into the site of reaction to elicit the classical 24-hour delayed-type hypersensitivity reaction. In alloxan diabetic mice, contact sensitivity reactions are reduced significantly, and our experiments show that insulin deficiency affects only the activity of the late acting, lymphokine-producing cell and leaves the factor-producing cell responsible for the early swelling reaction unaffected. Our experiments demonstrate that insulin deficiency has different effects on distinct subpopulations of T lymphocytes.