Showed Tissue Necrosis Research Articles

Real-Time Monitoring of Oxygen-Consumption Rate in Mouse Liver Slices Incubated in Organ-on-a-Chip Devices.

We developed an organ-on-a-chip (OOC) based on precision-cut liver slices to assess liver function in real-time, both in health and disease, in a controlled and noninvasive manner. We achieved this by integrating fiber-optic-based oxygen sensors before and after the microchamber in which a liver slice was incubated under flow, to measure oxygen concentrations in the medium in real time. We first demonstrated that the basal oxygen consumption rate (OCR) of liver slices is a reliable indicator of liver slice viability. By monitoring basal OCR (2.9-5.7 pmol O2/min/μg protein) in incubation medium, we found that it correlated well to cellular adenosine triphosphate (ATP) content (3.0-7.9 pmol/μg protein) (r = 0.82, p < 0.0001). Second, we induced a diseased state in liver slices by targeting the mitochondria, as they play a critical role in liver function and disease. We exposed the liver slices to succinate in abundance (40 mM) for short periods (1 h) to rapidly boost mitochondrial OCR. Two successive treatments of succinate increased the OCR of liver slices by 1.5 pmol/min/μg each time. However, between treatments, the liver slice OCR did not return to its basal OCR, instead decreasing drastically by 60-70%, suggesting succinate toxicity. We confirmed this with ATP analysis (1.0 pmol/μg protein) and hematoxylin and eosin staining, which showed tissue necrosis and apoptosis. Our system could be an advantageous model for future studies assessing liver (patho)physiology in response to potentially toxic drugs or lifestyle-related liver diseases.

S2284 Black Esophagus as Cause of UGIB After a Complicated Urologic Procedure

Introduction: We report a case of upper endoscopy performed for a patient with coffee-ground emesis after a complicated urologic procedure. It showed diffuse black discoloration in mid-distal esophagus consistent with acute esophageal necrosis (AEN). Case Description/Methods: This is a 68-year-old male with diabetes mellitus (DM), chronic kidney disease, hypertension (HTN) and bladder cancer. He was admitted to intensive care after transurethral resection of bladder tumor (TURBT) was complicated by bladder perforation that required open laparotomy and bladder repair. Patient remained intubated for 48 hours. During the postoperative period, he developed ileus with nausea, vomiting and abdominal distention. He subsequently developed coffee-ground emesis and chest pain. He was not on acid suppressing medication. Upper endoscopy was performed to investigate etiology of upper gastrointestinal bleeding (UGIB), which showed diffuse areas of black discoloration in mid-distal esophagus suggestive for esophageal necrosis (Figure). Pathology showed tissue necrosis consistent with AEN. Patient was promptly treated with a proton-pump inhibitor and sucralfate. Symptoms rapidly improved without recurrence of bleeding or complication. Discussion: AEN, also known as “black esophagus” or necrotizing esophagitis, is a rare syndrome characterized by circumferential black mucosa at the distal esophagus and stops at the gastroesophageal junction. The prevalence is about 0.2% and 4 times more likely in men than women. Risk factors include DM, malignancy, HTN, alcohol abuse and coronary artery disease. The etiology is likely esophageal ischemia from a low-flow state followed by a backflow injury from chemical contents of gastric secretions. Majority of patients present with UGIB, followed by dysphagia and epigastric/chest pain. Symptoms can develop rapidly following an inciting event. With adequate resuscitation and medical therapy (proton pump inhibitors and sucralfate), patients can recover rapidly. Complications may include stricture, perforation, mediastinitis, and death. Prognosis is poor due to underlying critical illness, but mortality specific to AEN is much lower. Endoscopic appearance is suggestive, but biopsy is recommended to establish the diagnosis and exclude other diagnoses (e.g. melanoma and acanthosis nigricans). Repeat endoscopic evaluation is important to assess mucosal healing and determine duration of antacid therapy. Endoscopic balloon dilation may be necessary for stricture from AEN.Figure 1.: Diffuse circumferential black discoloration in lower esophagus.

Histological Studies of Cassava (Manihot esculenta Crantz) Root Infection Using Aspergillus niger Rhizopus stolonifer, Aspergillus niger, Aspergillus flavus, Botryodiplodia theobromae and Trichoderma viride

Histological studies were carried out to investigate the impact of some pathogenic organisms on infected cassava root after different periods of incubation. Cassava roots inoculated with Aspergillus niger, Rhizopus stolonifer, Aspergillus flavus, and Trichoderma viride showed progressive depletion of the starch grains in the cells and tissue maceration of the cassava root as the period of incubation increased. Cassava root inoculated with A. flavus showed tissue necrosis and slight fragmentation of the starch grains whereas, cassava tissues infected with A. niger showed tissue necrosis and general maceration of the starch grains within the tissue thereby creating empty spaces within the cells with no clear arrangement of the starch grains. Inoculation of the cassava tissues with R. stolonifer resulted in rapid loss of the starch grains and erosion of surrounding cell boundaries. Cassava tissue colonized by T. viride showed tissue necrosis and maceration of the starch grains. Healthy (uninoculated) cassava root tissue showed intact cells packed with large starch grains suggesting that in the host-parasite relationship, the pathogens established themselves inter and intracellularly in the parenchymatous cells of the cortex of the cassava root clearing them of starch grains, and resulting to poor yield and nutritional value of cassava and also economic loss.

Development of Novel Animal Model for Studying Scoliosis Using a Noninvasive Method and Its Validation through Gene-Expression Analysis.

Study DesignTo induce scoliosis in young female Wistar rats using a noninvasive method and to validate this model.PurposeTo induce scoliosis in a rat model noninvasively by bracing and to study the corresponding gene-expression profile in the spine and different organs.Overview of LiteratureScoliosis involves abnormal lateral curvature of the spine, the causes of which remain unclear. In the literature, it is suggested that scoliosis is genetically heterogeneous, as there are multiple factors involved directly or indirectly in its pathogenesis. Clinical and experimental studies were conducted to understand the etiology of anatomical alterations in the spine and internal organs, as the findings could help clinicians to establish new treatment approaches.MethodsTwelve female Wistar rats aged 21 days were chosen for this study. Customized braces and real-time polymerase chain reaction (RT-PCR) primers for rats were designed using Primer 3 software. Radiological analysis (X-rays), histopathological studies, SYBR green, and RT-PCR analysis were performed.ResultsThe spines of six rats were braced in a deformed position, which resulted in a permanent structural deformity as confirmed by X-ray studies. The remaining rats were used as controls. Quantitative studies of the expression of various genes (osteocalcin, pleiotrophins, matrix metalloproteinase-2 [MMP2] and MMP9, TIMP, interleukins 1 and 6, tumor necrosis factor-α) showed their differential expression and significant upregulation (p<0.05) in different organs of scoliotic rats in comparison to those in control rats. Histopathological findings showed tissue necrosis and fibrosis in the brain, retina, pancreas, kidney, liver, and disc of scoliotic rats.ConclusionsBracing is a noninvasive method for inducing scoliosis in an animal model with 100% reliability and with corresponding changes in gene expression. Scoliosis does not just involve a spine deformity, but can be referred to as a systemic disease on the basis of the pathological changes observed in various internal organs.

PGE&lt;sub&gt;2&lt;/sub&gt; Generation in Myocardium from Isolated Rat Atrium under Hypoxia and Reoxygenation Conditions. Effect of Anti-&lt;i&gt;β&lt;/i&gt;&lt;sub&gt;1&lt;/sub&gt; IgG from Patients with Chronic Severe Periodontitis

Background: Hypoxia is one of the most frequently encountered stresses in health and disease. Methods: We compared the effects of an anti-β1 periodontal IgG (pIgG) and an authentic β1 adrenergic agonist, xamoterol, on isolated myocardium from rat atria contractility. We used an ELISA assay to measure the generation of PGE2 in vitro after the addition of either the antibody or the adrenergic agonist. We analyzed the myocardium histopathologically in the presence of both the antibody and/or the adrenergic agonist drug during normoxia, hypoxia and reperfusion conditions. Results: PGE2 generation increased during the hypoxia and was unchanged during reoxygenation period compared with the production of this prostanoid in atria during normoxia condition. A β1 specific adrenoceptor antagonist atenolol and the β1 synthetic peptide abrogated the increment of the prostanoid in the presence of pIgG but only atenolol due to it in the presence of xamoterol. The increment of PGE2 was dependent on the activation of cox-1 and cox-2 isoforms. Moreover, cox-2 was more active and produced more increments in the production of PGE2 in the presence of the pIgG than cox-1 activation. Histopathologically, studies of myocardium specimens during these different periods of the experimental protocol: basal (B), hypoxia (H) and reoxygenation (R), were also performed and showed tissue necrosis and edematization at the myocardium level. Conclusion: The phenomenon studied here supports the notion that PGE2 may be responsible for tissue edematization. PGE2 maybe acts as a beneficial modulator in the myocardium and prevents a major injury of it. The inflammation damage to the heart organ and cardiomyocytes caused by the actions of the antibodies in the course of heart lesions provoked by cardiovascular autoimmune disease, explains some of these results obtained in the present experiments. Further studies will be needed to establish the real role of PGE2 during hypoxia injury of the heart in the course of autoimmune diseases.

Venom of Indian monocellate cobra and Russell's viper show anticancer activity in experimental models

Indian monocellate cobra ( Naja kaouthia) and Russell's viper ( Vipera russelli) are common snakes of the East Indian sub-peninsula. The anticarcinogenic activities of their crude venoms were studied on carcinoma, sarcoma and leukemia models. Sub-lethal doses of venoms showed cytotoxicity on Ehrlich ascites carcinoma (EAC) cells in vivo. The venoms increased lifespan of EAC mice and strengthened the impaired host antioxidant system. Sarcoma formation in mice (3-methylcholanthrene induced) after venom treatment was significantly less ( p < 0.005). Histopathological examination of tumors showed tissue necrosis. The venoms displayed potent cytotoxic and apoptogenic effect on human leukemic cells (U937/K562). The venoms reduced cell proliferation rate ( p < 0.005) and produced morphological alterations indicative of apoptosis induction. Different degree and nature of anticarcinogenic property of cobra and viper venoms may be attributed to the difference in their constituents.

ACUTE SKIN GRAFT REJECTION INDUCED BY β2 MICROGLOBULIN- ASSOCIATED MINOR TRANSPLANTATION ANTIGENS: CHARACTERISATION IN β2 MICROGLOBULIN-DEFICIENT MICE.

142 Minor transplantation antigens are constituted by the association of an MHC class I or class II molecule with a peptide derived from a protein which displays allotypic differences between the donor and the recipient. Previous experiments have shown that β2 microglobulin (β2m) peptides are constitutively present in the MHC class I and II molecules. These antigenic complexes are minor transplantation antigens in mice as indicated by the rejection of β2m-positive grafts by genetically β2m deficient mice. The aim of our study is to investigate the effector pathways responsible for the rejection induced by minor transplantation antigens. We performed skin grafts from wild-type C57BL/6 (β2m+/+) mice on C57BL/6 β2m deficient (β2m−/−) mice. 93% of β2m−/− mice (N=21) rejected their graft within 20 days after transplantation. β2m−/− mice depleted in vivo of CD4 (N=10) or CD8 (N=10) cells by mAb administration did not reject β2m+/+ skins, indicating the requirement for both CD4 and CD8 T cells in this process. CTL assays performed with T cells isolated from lymph nodes draining the rejected grafts showed that β2m−/− mice displayed significant cytotoxicity against β2m+/+ targets. Histological examination of rejected grafts showed tissue necrosis and infiltration by numerous eosinophils (number of eosinophils/0,0025 mm2: 36 vs 2 in syngeneic grafts, P<0,0001). This led us to search for the presence of Interleukin-5, the major eosinophil growth and differentiation factor. In vitro, lymph node T cells from β2m−/− sensitized mice produced large amounts of IL-5 when stimulated with β2m +/+ cells. Furthermore, IL-5 mRNA was detected by RT-PCR within rejected β2m+/+, but not in syngeneic skins. In conclusion, CD4 as well as CD8 T cells are required for the acute rejection induced by β2m-associated minor transplantation antigens. Both CTL activity and an IL-5/eosinophil pathway appear to be involved in the rejection process. Their respective roles are under current investigation.

Internal Sclerostomy With a Mechanical Trephine Versus the Neodymium:YAG Laser in Dogs

To experimentally compare and contrast the internal sclerostomy produced using a mechanical trephine with that made by an Nd:YAG laser, and to evaluate the healing patterns, efficacy, and technical advantages of each method. Four healthy dogs with normal eyes were used in this study. The left eye of each dog had an internal sclerostomy performed with an automated mechanical trephine. The right eye of each dog had an internal sclerostomy performed with an Nd:YAG laser. Postoperatively, the intraocular pressure of each eye was measured at regular intervals. The dogs were euthanized successively at 1, 2, 3, and 4 weeks postoperatively, and the morphology of the surgical sites was studied. The Nd:YAG laser was easier to manipulate and technically less demanding than the mechanical trephine. However, the Nd:YAG laser induced more prominent corneal edema and conjunctival hyperemia compared with the automated trephine. Morphology of the tissue response showed tissue necrosis and greater inflammation with the Nd:YAG laser than with the automated trephine. These two techniques demonstrate differences in technical demands and tissue response. Both are characterized by minimal reactive fibrosis of the episcleral and Tenon's capsule fibroblast.

Chemical consequences of relocation of the soft coral Lobophytum compactum and its placement in contact with the red alga Plocamium hamatum

Seven colonies of Lobophytum compactum Tixier-Durivault, 1956, which produce isolobophytolide as the major secondary metabolite, were selected from a fringing reef in the Pelorus Channel, Palm Island Group (18°34′S; 146°29′E), North Queensland, Australia. In September 1991, they were sectioned to afford two portions which were relocated to a grid, and a significant part of the parent colony which was left in place. The aim of the experiment was to determine the effect of relocation and contact with a toxic alga on the secondary metabolite content of a soft coral. A significant increase in the concentration of isolobophytolide was observed for all relocated colonies (n=14, p=0.001) compared to the non-relocated control colonies. This decreased after 2 mo, and was not significantly different from that of the non-relocated control colonies (n=14, p=0.881). After 1 mo, Plocamium hamatum J. Agardh plants were placed in direct contact with 50% of the relocated colonies. All soft-coral colonies in contact with the alga (n=7), showed tissue necrosis on the parts in direct contact with the alga after a further 2 wk. Tissues of the relocated control colonies (n=7), and those portions of treated colonies which were not in direct contact with the alga, were not affected. The parts of the colonies in contact with the alga showed a significant decrease in lipid content over time (n=7, p=0.001) and also a decrease in the concentration of the diterpene isolobophytolide (n=7, p=0.001). The effects of P. hamatum on the soft coral were essentially restricted to contract necrosis; chemical variations in the affected tissue were the outcomes of this necrosis. These results indicate that stress due to relocation is a more important factor in the variation of isolobophytolide levels in the soft coral L. compactum than is contact with the alga P. hamatum.

Failure of Local and Systemic Bacterial Clearance in Rats with Acute Pancreatitis

These studies were designed to investigate the ability of rats to clear subcutaneous bacterial abscesses following acute pancreatitis. Animals underwent subcutaneous injection of 1 x 10(9) Escherichia coli and Staphylococcus aureus and, 24 h later, were randomized into four groups to receive (A) an intravenous (i.v.) infusion of cerulein, (B) saline i.v., (C) ligation of the pancreatic head, or (D) sham ligation. After 12 h, abscess sizes were measured and blood was withdrawn for culture and assay amylase and endotoxin level assay. Animals were observed for an additional 12 h to record mortality. Both E. coli and S. aureus abscesses were larger in group C vs. group D, while only the E. coli lesion was larger in group A vs. group B. Bacteremia was detected in 60% of the animals in group A, 40% in groups B and D, and 100% in group C. Mortality was 80% in group C vs. 10% in all other groups. Amylase and endotoxin levels were higher in group C vs. all groups. In the second experiment rats were injected with bacteria as above. Four, twelve, and twenty-four hours later the abscesses were removed for quantitation of bacteria and histologic evaluation. At 24 h rats underwent procedure A, B, C, or D and the abscesses were excised 12 h later. Group C had a significantly higher number of viable bacteria inside the lesion compared to group D. Histology showed tissue necrosis and cellulitis not observed in group D. It is concluded that acute pancreatis causes failure of local and systemic bacterial clearance and that the incidence of bacteremia and mortality is proportional to the severity of the disease.

Metabolic changes in rabbit spinal cord after trauma: magnetic resonance spectroscopy studies.

Combined phosphorus and proton magnetic resonance spectroscopy (MRS), using double-tuned surface coils, was used to monitor certain metabolic changes in the L-3 spinal segment of anesthetized rabbits prior to and following experimental spinal cord trauma. Following severe trauma, resulting in spastic paraplegia, there was a delayed and progressive accumulation of lactic acid, a decline in intracellular pH, and a loss of high-energy phosphates. Maximal alterations occurred between 2 and 3 hours after the trauma, with little further change by 4 hours. Histological examination 2 weeks after trauma showed tissue necrosis and cavitation. These findings support the concept of secondary tissue injury after spinal cord trauma and suggest that early changes in metabolism, as shown by MRS, may predict irreversible tissue damage.

Pathology of spinal cord lesions caused by ossification of the posterior longitudinal ligament.

The pathologic changes in the spinal cord of three autopsied cases associated with ossification of the posterior longitudinal ligament ( OPLL ) are reported. Compression of the spinal cord was marked at the level of the intervertebral disc, and the spinal cord was strikingly flattened antero-posteriorly. Intensive damage was seen in the gray matter as compared to the white matter. The white matter showed demyelination and axon loss with status spongiosus, which was more marked in the postero-lateral than in the anterior columns. The most seriously damaged parts of the spinal cord showed tissue necrosis and cavity formation which extended from the central parts of the gray matter to the ventral parts of the posterior columns. Adventitial fibrous thickening of the vein, hyaline degeneration of the walls of the arterioles, and compression of the anterior spinal vein were observed in the damaged regions. It was evident that secondary circulatory disturbance due to the compression produced by the ossification was of significance in the pathogenesis of the spinal cord damage. A tangle of peripheral nerves, ectopic and reactive, with Schwann cell proliferation was present in the posterior median fissure and the postero-lateral columns in one case. The spinal nerve roots that showed marked demyelination and axon loss were damaged by ossification at the places where the anterior nerve roots emerged from the spinal cord and where the roots penetrate the dura. There was ossification of the dura mater in all cases examined.