Stefan M. Kröber

Lymphatic endothelial progenitor cells contribute to de novo lymphangiogenesis in human renal transplants.

De novo lymphangiogenesis influences the course of different human diseases as diverse as chronic renal transplant rejection and tumor metastasis. The cellular mechanisms of lymphangiogenesis in human diseases are currently unknown, and could involve division of local preexisting endothelial cells or incorporation of circulating progenitors. We analyzed renal tissues of individuals with gender-mismatched transplants who had transplant rejection and high rates of overall lymphatic endothelial proliferation as well as massive chronic inflammation. Donor-derived cells were detected by in situ hybridization of the Y chromosome. We compared these tissues with biopsies of essentially normal skin and intestine, and two rare carcinomas with low rates of lymphatic endothelial proliferation that were derived from individuals with gender-mismatched bone marrow transplants. Here, we provide evidence for the participation of recipient-derived lymphatic progenitor cells in renal transplants. In contrast, lymphatic vessels of normal tissues and those around post-transplant carcinomas did not incorporate donor-derived progenitors. This indicates a stepwise mechanism of inflammation-associated de novo lymphangiogenesis, implying that potential lymphatic progenitor cells derive from the circulation, transmigrate through the connective tissue stroma, presumably in the form of macrophages, and finally incorporate into the growing lymphatic vessel.

High Cardiorespiratory Fitness is an independent Predictor of the Reduction in Liver Fat during a Lifestyle Intervention in Non-Alcoholic Fatty Liver Disease

Objective: Lifestyle intervention with diet modification and increase in physical activity is effective for reducing hepatic steatosis in patients with non-alcoholic fatty liver disease (NAFLD). However, for a similar weight loss, there is a large variability in the change in liver fat. We hypothesised that cardiorespiratory fitness may predict the response to the intervention. Design: Longitudinal study with increase in physical activity and diet modification. Setting: University teaching hospital. Patients: 50 adults with NAFLD and 120 controls at risk for metabolic diseases. Main outcome measures: Total-, subcutaneous abdominal- and visceral adipose tissue by magnetic resonance tomography, liver fat by 1HMR spectroscopy and cardiorespiratory fitness (VO2,max) by a maximal cycle exercise test at baseline and after 9 months of follow-up. Results: In all subjects total-, subcutaneous abdominal- and visceral adipose tissue decreased and fitness increased (all p<0.0001) during the intervention. The most pronounced changes were found for liver fat (−31%, p<0.0001). Among the parameters predicting the change in liver fat, fitness at baseline emerged as the strongest factor, independently of total- and visceral adipose tissue as well as exercise intensity (p = 0.005). In the group of subjects with NAFLD at baseline, a resolution of NAFLD was found in 20 individuals. For 1 standard deviation increase in VO2,max at baseline the odds ratio for resolution of NAFLD was 2.79 (95% confidence interval, 1.43–6.33). Conclusions: Cardiorespiratory fitness, independently of total adiposity, body fat distribution and exercise intensity, determines liver fat content in humans, suggesting that fitness and liver fat are causally related to each other. Moreover, measurement of fitness at baseline predicts the effectiveness of a lifestyle intervention in reducing hepatic steatosis in patients with NAFLD.

Bipolar radiofrequency ablation using internally cooled electrodes in ex vivo bovine liver: prediction of coagulation volume from applied energy.

Objective: We sought to evaluate the relationship between parameters of bipolar radiofrequency (RF) ablation using internally cooled electrodes. Materials and Methods: Bipolar RF ablations (n = 24) were performed in ex vivo bovine liver using an internally cooled applicator with 2 electrodes located on the same shaft. The power-output was systematically varied (20–75 W). On the basis of our experimental data, mathematical functions were fitted and the goodness-of-fit was assessed by the parameter R2. Results: The duration to induce an increase of tissue resistance and the amount of applied energy increased with a decreased power-output. The maximum short-axis was 4.5 cm (20 W) and required an application of 64 kilojoules (kJ). The volume of coagulation can be determined as a function of the duration of energy application (R2 = 0.954) and the amount of applied energy (R2 = 0.945). Conclusion: The amount of applied energy and the duration of energy application can predict the volume of induced coagulation and may be useful to control internally cooled bipolar RF ablation.

Xanthogranulomatous cholecystitis resembling carcinoma with extensive tumorous infiltration of the liver and colon

BackgroundXanthogranulomatous cholecystitis is a macrophage-rich inflammatory condition of the gallbladder that occasionally presents with tumorlike appearance.Case presentationIn the present case the inflammation involved all the layers of the gallbladder, the surrounding connective tissue, and part of the right lobe of the liver and right transverse colon. The clinical and radiological findings were suggestive of advanced carcinoma of the gallbladder. However, intraoperative frozen section investigation revealed xanthogranulomatous cholecystitis, for which simple cholecystectomy is the treatment of choice.ConclusionsThe original cause of the condition is unclear in most cases. In the present case it is possible that rupture of the gallbladder in association with the patients known history of trauma have initiated the process

Genetic Ablation of cGMP-Dependent Protein Kinase Type I Causes Liver Inflammation and Fasting Hyperglycemia

OBJECTIVE The nitric oxide/cGMP/cGMP-dependent protein kinase type I (cGKI) signaling pathway regulates cell functions that play a pivotal role in the pathogenesis of type 2 diabetes. However, the impact of a dysfunction of this pathway for glucose metabolism in vivo is unknown. RESEARCH DESIGN AND METHODS The expression of cGKI in tissues relevant to insulin action was analyzed by immunohistochemistry. The metabolic consequences of a genetic deletion of cGKI were studied in mice that express cGKI selectively in smooth muscle but not in other cell types (cGKI-SM mice). RESULTS In wild-type mice, cGKI protein was detected in hepatic stellate cells, but not in hepatocytes, skeletal muscle, fat cells, or pancreatic β-cells. Compared with control animals, cGKI-SM mice had higher energy expenditure in the light phase associated with lower body weight and fat mass and increased insulin sensitivity. Mutant mice also showed higher fasting glucose levels, whereas insulin levels and intraperitoneal glucose tolerance test results were similar to those in control animals. Interleukin (IL)-6 signaling was strongly activated in the liver of cGKI-SM mice as demonstrated by increased levels of IL-6, phospho-signal transducer and activator of transcription 3 (Tyr 705), suppressor of cytokine signaling-3, and serum amyloid A2. Insulin-stimulated tyrosine phosphorylation of the insulin receptor in the liver was impaired in cGKI-SM mice. The fraction of Mac-2–positive macrophages in the liver was significantly higher in cGKI-SM mice than in control mice. In contrast with cGKI-SM mice, conditional knockout mice lacking cGKI only in the nervous system were normal with respect to body weight, energy expenditure, fasting glucose, IL-6, and insulin action in the liver. CONCLUSIONS Genetic deletion of cGKI in non-neuronal cells results in a complex metabolic phenotype, including liver inflammation and fasting hyperglycemia. Loss of cGKI in hepatic stellate cells may affect liver metabolism via a paracrine mechanism that involves enhanced macrophage infiltration and IL-6 signaling.

Mastocytosis: reactive or neoplastic?

Mast cells are now known to derive from CD34+ haemopoietic stem cells in the bone marrow. However, it has not yet been established whether the various types of mastocytosis, which involve tumour-like proliferation of mast cells, are true neoplastic disorders or reactive/hyperplastic conditions. In this study, tissue specimens (five bone marrow, two spleen, one skin) from female patients with histologically confirmed mastocytosis were investigated with a recently developed polymerase chain reaction assay for the determination of clonality of female cells using the human androgen receptor gene (HU-MARA). Mast cells purified to near homogeneity from hysterectomy specimens served as a control. The findings in bone marrow and skin either were not reproducible, or indicated polyclonality. However, both spleen specimens exhibited monoclonality. In addition, DNA analysis by flow cytometry was performed and revealed a diploid chromosome content with proliferation indices of under 8% in all the specimens. This is the first molecular biological study to indicate that mastocytosis is indeed neoplastic in nature.

Complete Remission of Third Recurrence of Acute Myeloid Leukemia after Treatment with Imatinib (STI-571)

We report the case of a 76-year old patient with third relapse of AML who was successfully treated with Imatinib. The decision to try Imatinib was guided by bright expression of c-kit on the patients blasts. Treatment was well tolerated but the dose was reduced for pancytopenia and later stopped completely because of pneumonia. The patient recovered with i.v. antibiotics, antimycotics and s.c. G-CSF. Reevaluation of the bone marrow after the end of treatment demonstrated the absence of malignant blasts. Treatment with Imatinib was started again with the intention to prolong remission duration. During the following months peripheral blood counts stabilized in the normal range indicating that a fourth complete remission has been achieved in this patient. This is the first report demonstrating that Imatinib can induce complete remission in relapsed c-kit positive AML in an elderly patient. Prolonged cytopenia remains a considerable problem indicating that normal haematopoiesis is not completely independent of the signalling cascades inhibited by Imatinib. Nevertheless our report supports further study of this drug in c-kit positive AML.

Reactive and neoplastic lymphocytes in human bone marrow: morphological, immunohistological, and molecular biological investigations on biopsy specimens.

BACKGROUND: Slight, diffuse or focal lymphocyte proliferation is relatively common in bone marrow biopsy specimens. It may be impossible to determine whether this represents a reactive lymphocytosis or low grade non-Hodgkin lymphoma (NHL) on the basis of routine investigations alone. AIM: To investigate the supplementary use of molecular biological techniques in this situation. METHODS: 529 formalin fixed, paraffin embedded bone marrow biopsy specimens from the iliac crest were subjected to histological and immunohistochemical staining to determine the number and nature of the lymphocytes present. The cases were divided into three groups according to the lymphocyte count: normal (< 10% of nucleated bone marrow cells), slightly increased (10-30%), and markedly increased (> 30%). All of the last group could be diagnosed as NHL from the morphological findings alone. The clonality of rearrangements of the IgH and TCR gamma genes was investigated by polymerase chain reaction (PCR). RESULTS: Monoclonality was observed in 7.5% of the 372 cases with a normal lymphocyte count, in 50% of the cases with a modest increase in lymphocyte numbers (suggesting a diagnosis of low grade NHL not detected by immunostaining), and in 77% of the cases with markedly increased lymphocyte numbers. CONCLUSIONS: If PCR is used in addition to the immunohistochemical investigation of bone marrow biopsies, considerably more cases of NHL can be identified, making this of particular use in staging and detection of recurrences.

Granulosa cell tumor of the ovary. Immunohistochemical evidence of low proliferative activity and virtual absence of mutation of the p53 tumor-suppressor gene.

Background and Methods: Because the use of immunohistochemistry in the diagnosis of granulosa cell tumor (GCT) has not been fully explored, routinely processed (formalin-fixed, paraffin-embedded) tissue from 11 GCT, adult type, was investigated immunohistochemically (ABC method) with a broad spectrum of antibodies against various markers, including p53 and Ki-67. All of the tumors exhibited typical morphology, were limited to the ovary (stage I), and 7 cases followed a benign clinical course. Results: All the tumors exhibited strong expression of vimentin, but most other antigens (including smooth muscle actin) were expressed infrequently by a minority of tumor cells or not at all. Tumor cells in 9 GCT expressed inhibin A. All the tumors exhibited very low proliferative activity, fewer than 10% of the tumor cell nuclei being stained by the antibody MIB-1 (Ki-67 antigen). The antibody D07 revealed marked overexpression of p53 protein in only one tumor. Clinical outcome was not found to be related to immunophenotypic differences. Conclusions: The diagnosis of GCT should be based primarily on the typical morphology revealed by conventional stains, but additional immunohistochemical staining with a small panel of selected antibodies (for example, against keratin, vimentin, and inhibin A) may be helpful in a few cases. The very low proliferative activity and the lack of overexpression of p53 protein are consistent with the benign clinical behavior of the majority of GCT.

Intracranial inflammatory tumors: A survey of their various etiologies by presentation of 5 cases

Due to similar clinical and neuroradiological features, intracranial inflammatory tumors (IITs) are frequently mis-diagnosed as brain neoplasms, from which they notably differ in respect to therapy and prognosis. In this article, five cases of such tumors are presented. Three of the patients with brain tumors (cases 3, 4 and 5) presented a history of ‘pararheumatic’ syndromes but no diagnosis of defined immunopathies. On the basis of radiological findings, all processes were classified as genuine brain neoplasms, but histology showed reactive inflammatory features. The possible etiologies of these ‘tumors’ are discussed on the basis of all clinical and histological data of the patients. The spectrum of diseases potentially leading to the manifestation of an IIT is reviewed. Additionally, the presentation of case 5, who developed a highly malignant B-cell-lymphoma 6 months after the removal of an IIT without any histological signs of atypia, shows that this differential diagnosis always has to be kept in mind.