Search PubMed⌕ Search

Biomedical subjects

R Fischer

Publications and source records attributed to R Fischer.

At least 217 records · Page 12Linked to original sources
PubMed1997

Fluorescence in-situ hybridization (FISH) reveals that in chronic myelogenous leukaemia (CML) following interferon-alpha therapy, normalization of megakaryocyte size is associated with the loss of bcr/abl translocation.

AIMS: In addition to predominant granulocytic proliferation, bone marrow morphology in Philadelphia chromosome positive (Ph1+) CML is characterized by atypical dwarf or microforms of megakaryocytes. However, following therapy with interferon-alpha 2b (IFN), these micromegakaryocytes occur less frequently. The purpose of this study was to elucidate whether the reappearance of normal megakaryocytes may be associated also with a reduction of the bcr/abl-positive cell clone. METHODS AND RESULTS: Fluorescence in-situ hybridization (FISH) technique in combination with immunomorphometry (CD61) was performed on trephine biopsies. A total of 311 CD61-positive megakaryocytes, including precursors and atypical microforms, were evaluated in pre-treatment specimens derived from 11 patients with Ph1+ CML. A specific fusion site marking the bcr/abl translocation was found in 87% of megakaryocytes which showed a size of 169 +/- 35 microns2. In untreated patients, atypical microforms (size 200 microns2) were observed in 66% of the total megakaryocytic population. Following IFN therapy 369 megakaryocytes could be analysed in sequential examinations and were found to display a significant decrease (63%) in positive fusion signals. In addition there was also a significant enhancement in average size (252 +/- 66 microns2) reflecting a reduction in the number of micromegakaryocytes (43%). These findings were particularly conspicuous in three patients with a major to complete cytogenetic remission. CONCLUSIONS: A normalization of megakaryocyte size following IFN therapy in CML is significantly associated with a loss of the bcr/abl translocation site and therefore indicates a (partial) recovery of normal haematopoiesis.

Fusion Proteins, bcr-abl↗
PubMed1997

Incidence of apoptosis in HIV-myelopathy, myelodysplastic syndromes and non-specific inflammatory lesions of the bone marrow.

Myelodysplastic syndromes, AIDS-related myelopathy and non-specific inflammatory reactions (mostly rheumatoid myelitis) are characterized by normo- to hypercellular bone marrow, but frequently display cytopenias in the peripheral blood. In the current study we have addressed the question whether this situation reflects an increased programmed cell death in haemopoiesis. For this purpose, the in situ end-labelling technique was applied to formalin-fixed and paraffin-embedded trephine biopsies derived from patients and a control group without any haematological disorder. Results were evaluated by morphometry. Significantly more apoptotic cell death was observed in the haemopoietic marrow of patients with either disease. Using double-immunohistochemistry with the monoclonal antibody PG-MI (CD68), we were able to demonstrate that approximately one third of the apoptotic cells were ingested by macrophages. Our findings are in keeping with previously published data that postulated increased frequencies of macrophages in these disorders as well as raised serum levels of TNF-alpha.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Nuclear traffic in fungal hyphae: in vivo study of nuclear migration and positioning in Aspergillus nidulans.

Nuclear migration and nuclear positioning are fundamental processes in all eukaryotic cells. They are easily monitored during hyphal growth of filamentous fungi. We expressed the green fluorescent protein (GFP) as a fusion protein with the putative nuclear localization domain of the transcriptional activator stuA in nuclei of Aspergillus nidulans and visualized these organelles in living cells. Nuclear staining was observed in interphase nuclei but not during mitosis. Nuclear division, nuclear migration, septum formation and branching were analysed with time-lapse video microscopy during hyphal extension. Hyphae elongated at 0.1-1.2 microm min(-1) and nuclei moved with similar speeds towards the hyphal tip until they had reached a defined position. An individual regulation of nuclear mobility in a given hyphal compartment was observed. Some representative movies are available on the Internet (http://www.blacksci.co.uk/products/journals/molextra.htm). Nuclear positioning was also studied at the molecular level. The ApsA protein, which regulates nuclear migration, was localized at the cytoplasmic membrane in germlings and hyphae by immunofluorescence and GFP tagging. A model of nuclear migration, nuclear positioning and the role of ApsA is presented.

Aspergillus nidulans↗
PubMed1997

Reduced incidence of ovarian hyperstimulation syndrome by prophylactic infusion of hydroxyaethyl starch solution in an in-vitro fertilization programme.

Prophylactic infusion of human serum albumin can reduce or mitigate severe ovarian hyperstimulation syndrome (OHSS) in patients at high risk. Recently, concern has been expressed in the lay press regarding the potential viral transmissions with blood constituents. Hence, we looked for a safe non-biological substitute with comparable physical properties in order to cope with this concern. One hundred patients of our in-vitro fertilization (IVF) programme with oestradiol serum concentrations > or = 11010 pmol/l on the day of human chorionic gonadotrophin injection and/or > or = 20 oocytes retrieved and/or previous severe OHSS were infused with 1000 ml 6% hydroxyaethyl starch solution at the time of oocyte collection and 500 ml 48 h later. A total of 82 IVF patients at risk without prophylactic infusions during the preceding years served as controls. Both groups were identical according to patient's age, body mass index, androgen concentrations, peak oestradiol concentrations, number of retrieved oocytes, fertilization and pregnancy rates. There were seven cases of severe OHSS in untreated patients and two cases in the treatment group (P = 0.08). In moderate OHSS a significant difference became obvious with only ten cases in the treatment group and 32 cases in the control group (P < 0.00001). Hydroxyaethyl starch solution seems to be an effective and economic alternative in reducing severe and moderate OHSS during IVF treatment.

Adult↗
PubMed1997

Mapping of the RNA-binding domain of the cucumber mosaic virus movement protein.

A series of in-frame deletion mutants was used to identify a domain within the 3a protein of cucumber mosaic virus (CMV) that is required for RNA-binding activity. Deletions in the 3a gene were generated by PCR and restriction digestion, and the resulting mutated 3a sequences were cloned either in pT7-7 or in pGEX-5X3 expression vectors. The mutated 3a proteins or fusions with glutathione S-transferase (GST) were expressed in E. coli, purified, and their nucleic acid-binding activities analysed by photochemical UV cross-linking assays using digoxigenin-UTP-labelled RNA probes. Comparative analyses of seven mutated 3a proteins obtained from inclusion bodies and eight GST fusion proteins revealed that there is an RNA-binding domain located between amino acids 174 and 233. This RNA-binding domain is able to bind single-stranded RNA out of the context of the complete 3a movement protein and is highly conserved within both subgroups of CMV.

Amino Acid Sequence↗
PubMed1997

Antimitochondrial antibody profiles in primary biliary cirrhosis distinguish at early stages between a benign and a progressive course: a prospective study on 200 patients followed for 10 years.

In recent retrospective studies, it was shown that subtypes of antimitochondrial antibodies (AMA) can help to discriminate between a benign [only anti-M9 and/or anti-M2 positive by enzyme-linked immunosorbent assay (ELISA)] and a rather progressive course (anti-M2, -M4 and/or -M8 positive). According to different constellations of these AMA subspecificities in ELISA and complement fixation test (CFT), four AMA profiles (A-D) were defined. In 1984 we started a prospective study based on 200 PBC patients with known AMA profiles in order to correlate the antibody pattern with the clinical outcome. Progression was defined primarily as the necessity of liver transplantation and death due to hepatic failure or variceal bleeding. At entry, 18 (9%) of the 200 patients had AMA profile A (only anti-M9), 57 (29%) profile B (only anti-M2 with or without anti-M9), 74 (37%) profile C (anti-M2 in association with anti-M4/-M8 by ELISA), and 51 (26%) profile D (anti-M2/-M4/-M8 by ELISA and CFT). At the beginning of the study, 177 patients had PBC stage I/II. During the observation period of ten years, ten patients died and in 18 orthotopic liver transplantation (OLT) was performed; all these patients belonged to profile C/D. Furthermore, 44% of the patients with profile C and 31% of the patients with profile D progressed to late stages, as defined by histology and clinical manifestations such as portal hypertension and increase of bilirubin, while only one of the patients with profile B and none of the profile A-patients developed late stage PBC. A significant increase of bilirubin was observed only in C/D-patients. AMA profiles did not change during the follow-up. In conclusion, AMA profiles discriminate between a benign and a progressive course of PBC already at early stages.

Adult↗
PubMed1997

Apoptosis (programmed cell death) in idiopathic (primary) osteo-/myelofibrosis: naked nuclei in megakaryopoiesis reveal features of para-apoptosis.

There is general agreement that apoptosis (programmed/physiological cell death) plays an important role in regulating normal hematopoiesis and that so-called naked nuclei (NN) present end stages of megakaryopoiesis. Using in situ end-labeling techniques (ISEL), a morphometric analysis was performed on bone marrow trephine biopsies repeatedly derived from patients with idiopathic (primary) osteo-/myelofibrosis (IMF). The purpose of this study was to quantify apoptosis and to elucidate its relationship with NN of megakaryopoiesis. Moreover, evolution of this phenomenon during progression of myelofibrosis (assessed by morphometry of silver-stained sequential biopsies) and its predictive value were investigated. In IMF, morphometric measurements revealed a rate of ISEL-positive cells that was significantly higher than previously published data on the normal bone marrow and in patients with acute myeloblastic leukemia, but lower than in the myelodysplastic syndromes. However, NN with their tightly packed (nuclear) lobules and condensed chromatin were not reactive. Statistical evaluation failed to show a significant correlation between incidence of apoptotic cells and fiber density or an increase in this feature associated with progression of fibro-osteosclerotic marrow changes and prognosis. The failure of NN to react in ISEL implicates an absence of DNA fragmentation characteristic of apoptosis. For this reason our findings are in keeping with the assumption that NN are compatible with para-apoptosis.

Apoptosis↗
PubMed1997

Clinicopathological impact of the interaction between megakaryocytes and myeloid stroma in chronic myeloproliferative disorders: a concise update.

In this report an attempt has been made to discuss some of the issues pertinent to myelofibrosis complicating chronic myeloproliferative disorders (CMPDs) that are significantly associated with megakaryocyte function. In this context, biochemical, clinical and particularly morphological features were reviewed. Morphological findings based on elaborate techniques were in keeping with the assumption that in chronic myeloid leukemia (1) the number of CD61-positive megakaryocytes, and in particular their precursors were the parameters most closely associated with myelofibrosis (2) an increased content of reticulin fibers in follow-up biopsies significantly correlated with laboratory data indicative of a high tumor burden (anemia, peripheral blasts, hepatosplenomegaly) and thus a more advanced stage of the disease process (3) even a slight increase in reticulin, i.e. doubling of the normal fiber density was associated with a worse prognosis independent of therapeutic regimens given (4) Dynamics of myelofibrosis was significantly influenced by treatment. In this context, calculation of the myelofibrosis progression index (MPI) revealed a higher score following interferon therapy compared with busulfan. In addition, in idiopathic myelofibrosis (5) the evolution of myelofibrosis was unpredictable and according to the MPI, progression occurred at a relatively low rate (6) proliferation and dilatation of sinusoids accompanying intravascular hematopoiesis and collagen type IV deposits were predominant features in later (fibro-osteosclerotic) stages in the course of disease (7) transmural migration of megakaryocytes demonstrated by three dimensional reconstruction revealed a mole-like tunneling through the thickened sinusoidal wall. A very careful assessment of the numerous correlations between bone marrow features and laboratory data will allow clinicians and pathologists to gain a better insight into the mutual relationships between hematological and morphological findings in CMPDs.

Cell Communication↗
PubMed1997

Lymphocyte-predominant Hodgkin's disease. An immunohistochemical analysis of 208 reviewed Hodgkin's disease cases from the German Hodgkin Study Group.

There is wide consensus that lymphocyte predominance Hodgkin's disease (LPHD) represents a distinct clinicopathological entity of B-cell origin. However, inconsistent results of immunophenotyping studies and low confirmation rates among multi-center trials pose the question of whether LPHD really expresses heterogeneous marker profiles or whether it represents a mixture of morphologically similar entities. Among 2,836 cases reviewed by the German Hodgkin Study Group, immunophenotyping was performed on 1) cases classified or confirmed as LPHD by the reference panel (n = 104) or 2) cases not confirmed as LPHD but classified as classical HD (cHD) within the reference study trial (n = 104). In most cases, immunohistochemistry revealed a phenotype either LPHD-like (CD20+, CD15-, CD30-, CD45+) or cHD-like (CD15+, CD30+, CD20-, CD45-). In 27 cases, the immunophenotype was not fully conclusive. Additional markers for Epstein-Barr virus and CD57 and in situ hybridization for mRNA light chains allowed for a more clear-cut distinction between LPHD and cHD. However, in 25 of 104 cases, immunohistochemistry disproved the morphological diagnosis of LPHD of the panel experts, whereas 13 cases originally not confirmed as LPHD showed a LPHD-like immunopattern. Immunohistochemically confirmed LPHD cases showed a significantly better freedom from treatment failure (P = 0.033) than cHD; this was not observed in the original study classification based only on morphology (P > 0.05). Significantly better survival for LPHD cases improved from P = 0.047 (original study classification) to P = 0.0071 when classified by immunohistochemistry. Our results show that LPHD is a more immunohistochemical rather than a purely morphological diagnosis. Immunophenotyping of HD biopsies suspected of being LPHD is mandatory when a modified therapy protocol, that is, one different from those used in cHD, is discussed.

Adult↗
PubMed1997

Surgical management of complicated colonic diverticulitis.

BACKGROUND: Improvements in surgical techniques, advances in intensive care medicine and progress in the management of peritoneal sepsis have recently favoured colonic resection with primary anastomosis in the treatment of complicated diverticulitis. METHODS: Some 224 patients with complicated diverticulitis who had undergone surgery in the preceding 22 years were reviewed. Complications present on admission included acute phlegmon without pus formation (92 patients), paracolic abscess and/or localized peritonitis (99), diffuse purulent peritonitis (33), complete obstruction of the sigmoid colon (eight) and paracolic abscess complicated by fistula (27). RESULTS: The overall mortality rate was two (1 per cent) of 183 for resection with primary anastomosis, seven of 31 for Hartmann's operation and four of ten for the delayed three-stage procedure. The anastomosis was made by instruments employing the double-stapled technique in 130 patients and hand-sutured in 94. Reversal of Hartmann's operation was undertaken in only 31 per cent compared with 89 per cent for closure of the protective colostomy in patients with primary anastomosis. CONCLUSION: The Hartmann operation may be the most popular at present, but resection with primary anastomosis is the safest procedure for all stages of complicated diverticulitis, and reduces costs. There is no longer any clinical indication for the three-stage operation.

Adult↗
PubMed1997

Characterization of the hypo-osmolarity-induced Ca2+ response in cultured rat astrocytes.

The influence of astrocyte swelling on the cytosolic free calcium concentration [Ca2+]i was studied at the single cell level. Sudden exposure of normo-osmotically (305 mosmol/l) cultured astrocytes to hypo-osmotic medium induced a biphasic increase in cytosolic calcium with an initial peak followed by a sustained plateau. The response was osmolarity dependent and was maximal at 205 mosmol/l with respect to [Ca2+]i and the percentage of responding cells. Other modes of astrocyte swelling [gradual adjustment of hypo-osmolarity, normo-osmotic exposure of hyper-osmotic (405 mosmol/l) maintained cells] produced a much weaker [Ca2+]i response. Change from 405 to 205 mosmol/l, however, resulted in the entire peak and an increased plateau. Experiments with Ca(2+)-free medium and after pretreatment with BAPTA-AM, thapsigargin, phorbol myristate acetate, or nimodipine revealed that the peak mainly resulted from depletion of intracellular Ca2+ stores, whereas the plateau was probably due to capacitative Ca2+ entry and Ca2+ influx independent of store depletion including a nimodipin-sensitive component. Prior depletion of ryanodine-, bradykinin- or ATP-sensitive stores revealed that the initial hypo-osmolarity-induced Ca(2+)-release was from a Ca2+ pool also affected by ATP and bradykinin, but not by ryanodine. The recent finding, that the hypo-osmolarity-induced [Ca2+]i response was completely maintained if phospholipase C-mediated phosphatidylinositol hydrolysis was blocked, suggests that hypo-osmolarity may exert an inositol (1,4,5) triphosphate-independent access to these stores.

Adenosine Triphosphate↗
PubMed1997

Gastrointestinal lymphonodular hyperplasia and lymphoid polyps of the rectum--a rare coincidence.

Lymphoid polyps of the rectum are rare lesions. We report on an 8 1/2-year-old boy, who presented with hematochezia and abdominal pain. Flexible endoscopy revealed large sessile polyps of the rectum and lymphonodular hyperplasia of the duodenum, terminal ileum und descending colon. One rectal polyp was excised in toto, microscopically it revealed the typical features of a lymphoid polyp. Based on the distinct follicular architecture, the cytomorphology and the immunohistochemical findings of the lymphatic infiltrate we were able to distinguish this lesion from malignant lymphoma. The coincidence of lymphoid polyps and gastrointestinal lymphonodular hyperplasia gives evidence that both entities are different variations of the same benign lymphoproliferative process. Lymphoid polyps of the rectum should be treated by local excision for diagnostic purposes. Immunohistochemical staining of fresh, nonfixed tissue is a useful ancillary technique in distinguishing these benign lesions from lymphoma of mucosa associated lymphoid tissue (MALT-lymphoma).

Biopsy↗
PubMed1997

Classical Hodgkin's disease. Clinical impact of the immunophenotype.

Antibodies against CD15, -30, and -20 are often used to support morphological diagnosis of Hodgkin's Disease (HD). The classical HD, i.e., the non-lymphocyte-predominance types, are CD15+, CD30+, and CD20- in general. However, the results for CD15 are less clear-cut in many studies, showing up to 40% of classical HD that lack positivity for this maker. Little is currently known about the relevance of antigen expression in relation to clinical outcome in HD. Therefore, the three markers were analyzed in 1751 cases from the German Hodgkin Study Group, using micro-wave epitope retrieval to optimize staining sensitivity. Eighty-three percent of the cases showed a classical immunophenotype (CD15+, CD30+, CD20-), twelve percent lacked CD15 positivity (CD15-, CD30+, CD20-), and five percent showed other combinations. For 1286 cases, clinical follow-up was available, which revealed significant differences for freedom from treatment failure (P = 0.0022) and overall survival (P = 0.0001) between cases with classical immunophenotype and CD15 negativity (CD30+, CD20-). Multivariate Cox regression using the three markers, age, sex, histology, stage, B-symptoms (fever, sweats, weight loss > 10% of body weight), hemoglobin, and erythrocyte sedimentation rate as factors showed that lack of CD15 expression in classical HD is an independent negative prognostic factor for relapses (P = 0.022) and survival (P = 0.0035). In conclusion, immunohistochemistry is able to identify classical HD cases with unfavorable clinical outcome.

Adolescent↗
PubMed1997

Fractal analyses of HRV signals: a comparative study.

In this paper, we have investigated the scaling behavior of the heart rate variability signals using the power spectral density (PSD), the discrete wavelet transform (DWT), and dispersive analysis (DA), and the maximum likelihood estimator (MLE) method. Results suggested the lowest variance for the MLE method, greatest variance for the PSD methods, the other methods somewhere in between.

Fractals↗
PubMed1996

Calcium-dependent activation of Erk-1 and Erk-2 after hypo-osmotic astrocyte swelling.

The influence of hypo-osmotic cell swelling on the activity of the mitogen-activated protein (MAP) kinases Erk-1 and Erk-2 (where Erk stands for extracellular signal-regulated protein kinase) was studied in cultured rat astrocytes. Hypo-osmotic treatment led within 10 min to an increased activity of Erk-1 and Erk-2, which became maximal at 20 min and returned to the basal level within 60 min. Moreover, exposure to hypo-osmotic conditions induced a biphasic increase in cytosolic Ca2+ concentration ([Ca2+]i): a rapid peak-like increase was followed by a sustained plateau. The absence of extracellular Ca2+ completely abolished Erk activation as well as the plateau of the [Ca2+]i response after hypo-osmotic stimulation. Application of wortmannin and agents to elevate intracellular cAMP levels also completely blocked Erk activation but were without effect on the biphasic [Ca2+]i response to hypo-osmotic treatment of the cells, suggesting a role of PtdIns 3-kinase and the Ras/Raf pathway downstream of the calcium signal. Protein kinase C (PKC) and Ca2+/calmodulin (CaM)-dependent kinases are unlikely to play a role in the hypo-osmolarity-induced signalling towards MAP kinases, as revealed by the blockage of PKC and CaM kinases. Inhibition of tyrosine kinases, pertussis-toxin- or cholera-toxin-sensitive G-proteins and phospholipase C had no effect on the [Ca2+]i response; the Erk response to hypo-osmolarity was also largely unaltered. This is different from the swelling-induced MAP kinase activation in hepatocytes, which was shown to occur via a calcium-independent but G-protein- and tyrosine kinase-dependent mechanism. Thus osmo-signalling towards MAP kinases might exhibit cell-type-specific features.

Androstadienes↗