Reduction of oxygenation and blood flow in pedicled bowel segments in the rat and its consequences for anastomotic healing.

PURPOSE: Experimental studies indicate that perioperative hypoperfusion impairs anastomotic healing. In bowel surgery, the part of bowel that will be anastomosed is often pedicled, leaving the blood supply dependent on the marginal artery only. Little is known about the blood supply in such a segment, and whether anastomotic strength is affected when flow would be reduced. This study describes oxygenation and blood flow in pedicled bowel segments in the rat and investigates whether early anastomotic strength changes with variations in blood flow. METHODS: In rats, pedicled segments were created in ileum and colon by successive ligation of the feeding arteries. Oxygenation and blood flow were measured in the distal part of this segment by use of near-infrared spectroscopy with indocyanine green as an intravascular tracer. In a second experiment, a short pedicled colonic segment was created and, after flow measurements, an anastomosis was constructed. Wound strength and hydroxyproline content were analyzed 2 and 5 days after operation. RESULTS: After creation of a pedicled segment, the concentration of oxygenated hemoglobin decreased significantly. Blood flow also significantly decreased to even less than 10% of baseline. A very large variation was observed between animals, in particular, after ligation of the first arteries. The strength of colonic anastomoses was not significantly correlated with the blood flow in the pedicled segment before anastomotic construction. CONCLUSIONS: The creation of a pedicled bowel segment greatly reduces tissue oxygenation and blood flow to its distal part. Such impaired perioperative flow does not significantly affect early wound strength after anastomotic construction.

Thrombogenicity and related biological properties of heparin bonded collagen coated polyester and human umbilical vein prosthetic vascular grafts.

BACKGROUND: Multiple factors contribute to the process of prosthetic graft failure. Some of them are specifically related to the biological behavior of the used materials. To pursue the ideal substitute for the autologous vein graft, many materials have been taken into consideration. Of these, polyester (Dacron) and human umbilical vein (HUV, Dardik) bypass grafts have gained much attention in vascular surgical practice over the years. This study compares the results of both in vivo and in vitro investigations on graft thrombogenicity and neo-intimal formation in collagen-coated heparin bonded Dacron and in HUV bypass grafts. It is an adjunct to our clinical comparison of graft materials in infrainguinal arterial reconstruction. METHODS: In 12 adult Beagle dogs, a patch was sewn onto the abdominal aorta (Dacron, n = 6; HUV, n = 6). At defined interval times, thrombocyte aggregation was measured with nuclear imaging of 99mTechnetium labeled platelets. Post-mortem histological analysis of the interface between the native vessel wall and the patch was performed in all animals. RESULTS: At 4 h (2.67, SD = 0.77) and after 2 weeks (2.21, SD = 0.28) after implantation, significantly higher thrombogenicity was measured in the HUV grafts compared to Dacron grafts (1.98, SD = 0.10 and 1.98, SD = 0.11, P = 0.02 and 0.025, respectively). At 4 weeks, no significant difference could be found (HUV, 2.26; SD = 0.29; Dacron, 2.11; SD = 0.16; P = 0.23). Measurement of 'neo-intimal' thickness after explantation of the patch at 28 days after the initial procedure showed a significant difference: in HUV grafts the mean thickness of the inner lining was 0.76 mm (SD = 0.50), compared to 0.16 mm (SD = 0.10) in the Dacron grafts (P = 0.013). CONCLUSION: HUV grafts showed a higher thrombogenicity at 4 h and 2 weeks after insertion of the graft compared to Dacron grafts. At 4 weeks this difference is not present. After 28 days the inner ('neo-intimal') lining is significantly more pronounced in HUV grafts than in Dacron grafts.

Intracellular localization of ornithine decarboxylase and its regulatory protein, antizyme-1.

The enzyme ornithine decarboxylase (ODC) and its regulatory protein antizyme-1 (AZ1) are key regulators in the homeostasis of polyamines. To gain more insight into the exact intracellular distribution of ODC and AZ1, we performed immunocytochemical and Green Fluorescent Protein-fluorocytochemical studies in cultured human cervix carcinoma and human prostatic carcinoma (PC-346C) cells. ODC localization patterns varied from predominantly cytoplasmic to both cytoplasmic and nuclear staining, whereas AZ1 was mostly found in the nucleus. In cells that were synchronized in the mitotic phase, localization of both ODC and AZ1 changed from perinuclear at the beginning of mitosis into nucleoplasmic at close proximity to the chromosomes during meta-, ana- and telophase. Upon completion of mitosis, localization of ODC and AZ1 was reverted back to the cytoplasm, i.e., predominantly perinuclear immediately after cytokinesis. When PC-346C cells were treated with polyamines to induce AZ1-regulated ODC degradation, ODC was predominantly found in the nucleus and colocalized with immunoreactive AZ1. A comparable accumulation of ODC and AZ1 in the nucleus was found in PC-346C cells treated with the polyamine analog SL-11093. The present study suggests that AZ1 is involved in nucleocytoplasmic shuttling of ODC, which may be a prerequisite for ODC regulation and/or function.

Increased expression of matrix metalloproteinases in the murine zymosan-induced multiple organ dysfunction syndrome.

Matrix metalloproteinases (MMPs) have been implicated as mediators of tissue damage in several inflammatory diseases. Since the multiple organ dysfunction syndrome (MODS) is thought to result from systemic inflammation, overactivation of MMPs could contribute to the organ damage observed. The expression and activity of several MMPs were studied in a murine model for MODS. Sixty mice were given an aseptic intraperitoneal injection of lipopolysaccharide, followed, after 6 days, by zymosan. At days 2, 5, 8, 12, and 16 after the injection of zymosan, the liver, lungs, spleen, and kidneys were collected from groups of mice for either RNA extraction, gelatinase zymography and collagenase (MMP-1 and -13) assays (six mice per time point), or immunohistochemistry (three mice per time point). A group of nine mice did not receive zymosan and acted as controls. The expression of MMP-2 mRNA in zymosan-treated mice was strongly up-regulated in liver tissue only. For MMP-9, this was the case in all organs examined. Quantitative gelatin zymography demonstrated the near complete absence of any gelatinase activity in tissues from control mice. However, in the liver, lungs, and especially the spleen of zymosan-treated animals, significantly increased activity of proform and active MMP-2 and -9 was observed with time. Overall, MMP-1 and -13 activities were very low in all samples from the liver and lungs. In the spleen, however, high levels of MMP-1 and -13 were observed in zymosan-treated animals. Immunohistochemical staining for MMP-2 was detected in the liver and spleen, but not in lung and kidney tissue of zymosan-treated animals. Staining for MMP-9 could be detected in liver, lung, and spleen tissues of zymosan-treated mice. For both MMPs, staining appeared to be limited to phagocytes. In conclusion, the data suggest a role for MMPs, especially MMP-9, in the pathogenesis of MODS.

Doxycycline improves wound strength after intestinal anastomosis in the rat.

BACKGROUND: The strength of intestinal anastomoses is relatively low in the first days after operation, possibly as a result of localized degradation of the supporting matrix by enzymes from the matrix metalloproteinase (MMP) family. The aim of this study was to examine whether doxycycline, a drug known to inhibit MMP activity, could enhance anastomotic strength. METHODS: Male Wistar rats received anastomoses in both ileum and colon. From the day before operation onwards, animals were treated daily with doxycycline (orally or subcutaneously) in a dose of 10 mg/day or with saline only. Rats were killed 1, 3, or 5 days after operation, and anastomotic bursting pressure and breaking strength were measured. At day 3, anastomotic hydroxyproline levels were measured, MMP (gelatinase) activity was analyzed by gelatin zymography, and anastomotic histology was examined. RESULTS: Doxycycline enhanced wound strength, but only at day 3, when it was at its lowest. Subcutaneous administration of 10 mg/day increased median colonic and ileal breaking strength by 27% (P =.0019) and 104% (P =.0376), respectively. Colonic bursting pressure was increased by 93% (P =.0002). Wound histology was similar in experimental and control groups. CONCLUSIONS: Administration of doxycycline enhances anastomotic strength and should be investigated further as a means to preserve anastomotic integrity.

Distribution patterns of ornithine decarboxylase in cells and tissues: facts, problems, and postulates.

Ornithine decarboxylase (ODC) is a key enzyme in polyamine biosynthesis. Increased polyamine levels are required for growth, differentiation, and transformation of cells. In situ detection of ODC in cells and tissues has been performed with biochemical, enzyme cytochemical, immunocytochemical, and in situ hybridization techniques. Different localization patterns at the cellular level have been described, depending on the type of cells or tissues studied. These patterns varied from exclusively cytoplasmic to both cytoplasmic and nuclear. These discrepancies can be partially explained by the (lack of) sensitivity and/or specificity of the methods used, but it is more likely that (sub)cellular localization of ODC is cell type-specific and/or depends on the physiological status (growth, differentiation, malignant transformation, apoptosis) of cells. Intracellular translocation of ODC may be a prerequisite for its regulation and function.

Improved survival of TNF-deficient mice during the zymosan-induced multiple organ dysfunction syndrome.

The purpose of the study was to investigate the course of the zymosan-induced multiple organ dysfunction syndrome (MODS) in the absence of tumor necrosis factor (TNF) in a murine model. Tumor Necrosis Factor-alpha-lymphotoxin-a knockout (TNF/LT-/-) mice (n = 36) and wild-type (TNF/LT+/+) mice (n = 36) received 40 microg of lipopolysaccharide (LPS) intraperitoneally followed by zymosan at a dose of 1 mg/g body weight 6 days later (day 0). Animals were monitored daily for body weight and temperature and clinical symptoms. At day 22, most of the surviving mice were killed to examine organ weight and histology. A small number of animals were followed until day 48. In all animals, zymosan induced an acute sterile peritonitis phase followed by an apparent recovery. From day 8 onwards the TNF/LT+/+ mice entered a third-MODS-like-phase, characterized by loss of body weight, decreased body temperature, and significant mortality. At day 22, survival in the TNF/LT-/- mice (92%) was significantly (P = 0.01) higher than in the TNF/LT+/+ mice (60%). In addition, average body temperature and average relative (vs. weight at day 0) body weight were higher in the TNF/LT-/- mice than in the TNF/LT+/+ mice (35.9 degrees C and 100% vs. 33.3 degrees C and 84%, respectively). However, at this time point, surviving animals from both groups showed similar and significant organ damage, indicated by an increase in absolute and relative (vs body weight) weight of lung, spleen, and liver (liver only in the TNF/LT-/- mice). Moreover, histopathological examination of organs from the surviving animals showed a similar degree of microscopic damage in both groups. Interestingly, besides mononuclear cells, inflammatory infiltrates in lungs and livers of TNF/LT+/+ but not of TNF-/- mice contained neutrophils. In conclusion, TNF-deficient mice exhibit significantly improved morbidity and mortality during zymosan-induced MODS. However, the absence of TNF does not completely protect against MODS in this murine model.

Neurotensin-like Peptides in the CNS of Lampreys: Chromatographic Characterization and Immunohistochemical Localization with Reference to Aminergic Markers.

Neurotensin (NT)-like peptides in the CNS of the lamprey Lampetra fluviatilis were studied by radioimmunoassay (C-terminal specific NT antiserum), reverse-phase HPLC and immunohistochemistry. Multiple peaks of NT-immunoreactive (-ir) material were observed upon HPLC, of which a major peak eluted in the position of bovine NT. Immunofluorescence histochemistry showed that a monoclonal antibody recognizing the N-terminal (1 - 11) fragment of NT, as well as two polyclonal NT antisera labelled a large number of cell bodies in the periventricular area of hypothalamus, including the postinfundibular commissural nucleus and the ventral and dorsal hypothalamic nuclei. Additional groups of NT-ir cells were observed in the preoptic nucleus, the postoptic commissural nucleus, the mesencephalic tegmentum (L.fluviatilis), and in the spinal cord (L.fluviatilis and Ichtyomyzon unicuspis). Dense NT-ir fibre plexuses were present in the caudal hypothalamus, corpus striatum, ventral mesencephalon, and in the dorsal horn and lateral margin of the spinal cord. At the ultrastructural level the lateral spinal margin showed NT-ir terminal structures, which in most cases were not associated with synaptic specializations, although occasional synaptic contacts with unlabelled elements were found. The relation between NT-ir and monoamine-containing cells was examined with immunofluorescence double-staining, using antisera to tyrosine hydroxylase (TH), 5-hydroxytryptamine (5-HT), and histamine respectively. In the periventricular nuclei of hypothalamus numerous TH-, 5-HT-, as well as histamine-ir cells were located in close association with NT-ir cells, but none of the aminergic markers could be detected within NT-ir neurons. The chemical properties as well as the anatomical distribution of lamprey NT-like peptides show several similarities with those present in mammals, suggesting that NT-containing neuronal systems in the CNS developed early in vertebrate phylogeny.