Regeneration in pig livers by compensatory hyperplasia induces high levels of telomerase activity.

BACKGROUND: Several highly proliferative human cells transiently activate telomerase, a ribonucleoprotein with reverse transcriptase activity, to counterbalance replication-associated telomere erosion and to increase stress resistance. Quiescent human hepatocytes exhibit very low or undetectable levels of telomerase activity. However, hepatocytes display a remarkable proliferative capability following liver injury. To investigate whether liver regeneration by compensatory hyperplasia is associated with telomerase activation, we measured telomerase activity in pig livers after 70 to 80% partial hepatectomy using a fully quantitative real-time telomeric repeat amplification protocol. In contrast to commonly studied inbred laboratory mouse strains, telomere length and telomerase activity in porcine tissues are comparable to humans. RESULTS: Following partial hepatectomy, histology revealed mitotic hepatocytes as marker for compensatory hyperplasia. As expected, there was no induction of inflammation. Telomerase activity increased significantly showing the highest levels (5-fold upregulation) in pigs treated with partial hepatectomy and hepatic decompression. Moreover, telomerase activity significantly correlated to the number of mitotic hepatocytes. CONCLUSION: Our data demonstrate telomerase activation in liver regeneration by compensatory hyperplasia in a large animal model with telomere biology comparable to humans. Telomerase activation may constitute a mechanism to protect proliferating liver cells against telomere shortening and oxidative stress.

Limitations in molecular detection of lymph node micrometastasis from colorectal cancer.

Colorectal cancer patients with lymph node metastasis have a shorter survival and may require adjuvant therapy after surgery of the primary tumor. It is supposed that a more reliable diagnosis can be achieved using tumor-specific DNA mutations for the detection of metastasizing cells. To design a practical approach for a molecular diagnosis of micrometastasis, we applied direct DNA sequencing to screen 48 early stage colorectal carcinomas for the most frequent mutations of the KRAS, P53, and APC tumor genes. KRAS mutations were detected as frequently as described earlier. In contrast, the frequency of P53 and APC hot spot mutations was unexpectedly low, compared with previous studies using other screening methods or including advanced tumor stages. Not more than 31% of early stage tumors showed a mutation in at least 1 of the selected hot spot codons. Applying mutant-enriched polymerase chain reaction (PCR), the mutation of the primary tumor was detected in lymph node DNA from 2 of the KRAS-positive patients. In 1 patient, the result was not verified by subtractive iterative PCR, a principally different molecular method with high sensitivity and specificity. Our data suggest that screening for suitable markers for a molecular detection of occult lymph node metastasis cannot be restricted to small-sized hot spot regions of a few tumor genes and possibly must include tumor-specific epigenetic changes. Furthermore, restriction enzyme-based methods such as mutant-enriched PCR are not suitable to detect any mutation with equal efficiency and they should be carefully controlled to avoid false-positive detection of marker mutations in lymph node DNA.

Myeloperoxidase enhances nitric oxide catabolism during myocardial ischemia and reperfusion.

Impaired microvascular function during myocardial ischemia and reperfusion is associated with recruitment of polymorphonuclear neutrophils (PMN) and has been attributed to decreased bioavailability of nitric oxide (NO). Whereas myeloperoxidase (MPO), a highly abundant, PMN-derived heme protein facilitates oxidative NO consumption and impairs vascular function in animal models of acute inflammation, its capacity to function in this regard during human myocardial ischemia and reperfusion remains unknown. Plasma samples from 30 consecutive patients (61 +/- 14 years, 80% male) presenting with acute myocardial infarction were collected 9 +/- 4 h after vessel recanalization and compared to plasma from healthy control subjects (n = 12). Plasma levels of MPO were higher in patients than in control subjects (1.4 +/- 0.9 vs 0.3 +/- 0.2 ng/mg protein, respectively, p < 0.0001). The addition of hydrogen peroxide to patient plasma resulted in accelerated rates of NO consumption compared to control subjects (0.53 +/- 0.25 vs 0.068 +/- 0.039 nM/s/mg protein, respectively, p < 0.0001). Myocardial tissue from patients with the same pathology revealed intense recruitment of MPO-positive PMN localized along infarct-related vessels as well as diffuse endothelial distribution of non-PMN-associated MPO immunoreactivity. Endothelium-dependent microvascular function, as assessed by an acetylcholine-dependent increase in forearm blood flow in 75 patients with symptomatic coronary artery disease, inversely correlated with MPO plasma levels (r = -0.75, p < 0.005). Plasma from patients undergoing myocardial reperfusion contained increased levels of MPO, which catalytically consumed NO in the presence of H(2)O(2). Given the correlation between intravascular MPO levels and forearm vasomotor function in patients with coronary artery disease, MPO appears to be an important modulator of vasomotor function in inflammatory vascular disease and a potential therapeutic target for treatment.

Multicontrast-weighted magnetic resonance imaging of atherosclerotic plaques at 3.0 and 1.5 Tesla: ex-vivo comparison with histopathologic correlation.

The purpose was to analyze magnetic resonance (MR) plaque imaging at 3.0 Tesla and 1.5 Tesla in correlation with histopathology. MR imaging (MRI) of the abdominal aorta and femoral artery was performed on seven corpses using T1-weighted, T2-weighted, and PD-weighted sequences at 3.0 and 1.5 Tesla. Cross-sectional images at the branching of the inferior mesenteric artery and the profunda femoris were rated with respect to image quality. Corresponding cross sections of the imaged vessels were obtained at autopsy. The atherosclerotic plaques in the histological slides and MR images were classified according to the American Heart Association (AHA) and analyzed for differences. MRI at 3.0 Tesla offered superior depiction of arterial wall composition in all contrast weightings, rated best for T2-weighted images. Comparing for field strength, the highest differences were observed in T1-weighted and T2-weighted techniques (both P< or =0.001), with still significant differences in PD-weighted sequence (P< or =0.005). The majority of plaques were histologically classified as calcified plaques. In up to 21% of the cases, MRI at both field strengths detected signal loss characteristic of calcification although calcified plaque was absent in histology. MRI at 3.0 Tesla offers superior plaque imaging quality compared with 1.5 Tesla, but further work is necessary to determine whether this translates in superior diagnostic accuracy.

Improvement of impaired microcirculation and tissue oxygenation by hemodilution with hydroxyethyl starch plus cell-free hemoglobin in acute porcine pancreatitis.

AIMS: To avoid the progression from mild edematous acute pancreatitis (AP) to the severe necrotizing form, one therapeutic option is to improve pancreatic microcirculation and tissue oxygenation. The aim of the study was to evaluate the influence of improved rheology (isovolemic hemodilution) plus enhanced oxygen supply (bovine hemoglobin HBOC-301) on pancreatic microcirculation, tissue oxygenation and survival in severe acute experimental pancreatitis. METHODS: Severe AP was induced in 39 pigs (25-30 kg BW) by stimulation with intravenous administration of cerulein plus a pressure- and volume-controlled 10-min intraductal infusion of glycodeoxycholic acid. Seventy-five minutes after induction of AP, animals were randomized and hemodiluted isovolemically (PAOP constant) with either 10% hydroxyethyl starch (HES) 200,000/0.5 plus HBOC-301 (+0.6 g/dl plasmatic hemoglobin; Oxyglobin, Biopure, Cambridge, Mass., USA), or 10% HES 200,000/0.5, or Ringer's solution to a hematocrit of 15%. Hemodynamics, oxygen transport parameters, pancreatic microcirculation and tissue oxygen tension were evaluated over 6 h. Then the abdomen was closed, animals were extubated and observed for 6 days. After that, the surviving animals were sacrificed and specimens were taken from the pancreas. The histopathologic findings were scored by two blinded pathologists who quantified acinar necrosis, fat necrosis, inflammation and edema. RESULTS: Isovolemic hemodilution with HES plus HBOC-301 reduced mortality and preserved pancreatic microcirculation compared with Ringer's solution, but was not significantly different from hemodilution with HES alone. Only treatment with HES plus HBOC-301 normalized pancreatic tissue oxygen tension compared with IHD with HES or Ringer's solution alone. CONCLUSIONS: IHD with HES plus HBOC-301 as a combination of rheologic and O(2)-delivering therapy may represent a novel therapeutic option for treatment of AP.

Russell body gastritis: an unusual, tumor-like lesion of the gastric mucosa.

The case of an 80-year-old woman who presented with epigastric symptoms is reported. Upper gastrointestinal endoscopy displayed Candida esophagitis and a localized swelling of the fundic mucosa. Histologic examination of the gastric biopsy showed a distinctive accumulation of numerous uniform plasma cells filled with so-called Russell bodies. On low-power view, the lesion resembled a neoplastic process due to the marked expansion of the lamina propria with distension of fundic glands. However, immunohistochemistry confirmed a polyclonal pattern of the plasma cells. This unusual reactive lesion of the gastric mucosa has only rarely been described and has been termed Russell body gastritis.

Histologic, immunohistochemical, and ultrastructural findings in human blast lung injury.

The objective of this autopsy-based study was to investigate the pathology of human blast lung injury using histology, Fat Red 7B staining, immunohistochemistry, and scanning electron microscopy on lung specimens from eight medicolegal autopsy cases of fatal close-range detonations of chemical explosives. The micromorphologic equivalents of human blast lung injury can be summarized as follows: diffuse alveolar overdistension, circumscribed interstitial hemorrhages showing a cufflike pattern around pulmonary vessels, venous air embolism, bone marrow embolism, and pulmonary fat embolism. Hemorrhages within the lung parenchyma that were present in this study in blast victims without coexisting blunt or penetrating chest trauma must be regarded as potentially life-threatening intrapulmonary bleeding sites in survivors. In addition, the potential clinical importance of the presence of massive pulmonary fat embolism, which has, to the best of our knowledge, not been described previously in human blast lung injury, must be emphasized because pulmonary fat embolism may be a leading cause of the rapid respiratory deterioration with progressive hypoxia and development of acute respiratory distress syndrome in blast victims who survive. Furthermore, this study provides evidence that air embolism presenting in blast victims is not a mere ventilation-induced artifact.

Expression of Maspin in non-muscle invasive bladder carcinoma: correlation with tumor angiogenesis and prognosis.

OBJECTIVES: Maspin is a member of the serpin (serine protease inhibitor) family and has been shown to be a suppressor of tumor growth and an inhibitor of angiogenesis as well as metastasis in several types of tumors. We studied expression patterns of Maspin in pTa/pT1 urothelial carcinoma of the bladder and compared them with microvessel density (MVD) for two vascular markers (CD34 and CD105) and correlated the findings with clinical outcome. MATERIAL AND METHODS: We investigated tumor samples of 110 patients undergoing transurethral resection for pTa/pT1 bladder carcinoma (pTa, n=84; pT1, n=26; grade 1, n= 22; grade 2, n= 81; grade 3, n=7). Immunohistochemical studies were performed using the monoclonal antibodies, anti-human Maspin (NCL Maspin), anti-CD34 Class II and anti-CD105. Maspin expression level was classified according to the staining intensity (- to +++). The blood vessels (CD34) and specifically proliferating blood vessels (CD105) were counted as vessels per field (microvessel density, MVD). RESULTS: Of the 110 tumors, 27 showed a negative immunostaining for Maspin, 46 tumors stained +, 29 stained ++, and 8 stained +++. Maspin expression correlated inversely with CD34 reactivity. In tumors with loss of or only weak Maspin expression, the MVD for CD34 was 21.7 vessels per field, and 4.2 vessels per field for proliferating vessels (CD105), whereas Maspin-positive tumors had an MVD of 17.7 vessels per field (CD34), and of 6.0 vessels per field (CD105). Complete follow-up data are available in 92 patients. After a median follow-up of 25 months, 18 of the 92 patients (19.6%) had tumor recurrences. Tumors with decreased Maspin expression (-/+) had a shorter disease-free interval (23 months) than patients with stronger Maspin (++/+++) expression (29 months), whereas a Kaplan-Meier analysis and the log-rank test showed no significant difference in disease-free survival between the patients. CONCLUSION: The clinical importance of Maspin has been mainly investigated regarding tumor progression or metastasis. We found a decreased Maspin expression in a large portion of pTa/pT1 bladder tumors. Even if patients with decreased Maspin expression have a slightly shorter disease-free survival Maspin does not appear to be a promising prognostic marker.