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Biomedical subjects

J Fischer

Publications and source records attributed to J Fischer.

At least 37 records · Page 2Linked to original sources
PubMed1999

Selective modulation of phosphatidylserine exposure on subpopulations of human peripheral blood lymphocytes by a plant lectin, Viscum album agglutinin (VAA)-I and its recombinant form (rVAA) in vitro.

Growing evidence suggests that lectin-carbohydrate interactions are involved in the regulation of the balance between cell growth and programmed cell death. Viscum album agglutinin (VAA)-I is a galactoside-specific, type II ribosome-inactivating plant lectin. At concentrations less than 10 ng/ml, VAA-I has been shown to induce gene expression and secretion of proinflammatory cytokines as well as apoptosis in cultures of human peripheral blood mononuclear cells (PBMC). This study analyzes the effects of VAA-I and its recombinant nonglycosylated form (rVAA) on alterations of cell membrane permeability of cultured human peripheral lymphocytes (PBL) and on membrane exposure of phosphatidylserine characteristic of apoptosis. Analyses were performed by flow cytometry after staining with propidium iodide (PI) and/or with FITC-Annexin V/PI. After 24 h incubation of PBMC with 100 ng/ml VAA-I and rVAA, staining with supravital concentration of PI (20 microg/ml) for 1 h revealed no differences in percentages of PI-positive cells induced by the two forms of lectin (32.3% and 29.4%), but the exposure to 5 microg/ml PI for 15 min resulted in a significant difference: 35.1% and 8.0% after VAA-I and rVAA treatment, respectively. Kinetic analysis of membrane alterations showed mainly Annexin V positivity after 24 h, whereas after 48 h and 72 h incubation with 100 ng/ml VAA-I or rVAA loss of membrane integrity occurred, as demonstrated by PI staining. Similar to VAA-I, rVAA showed a higher binding affinity for monocytes and granulocytes than for lymphocytes. In cultures of PBL, the binding rank order of both lectins to lymphocyte subsets was NK, CD19+ > CD8+ > CD4+. The amount of Annexin/PI staining of PBL subsets corresponds to the degree of their binding capacity. In conclusion, present results demonstrate that VAA-I and its nonglycosylated recombinant form rVAA exhibit comparable effects on cell membrane alterations in the subsets of human PBLs.

Annexins↗
PubMed1999

Toward standardization of CD34+ cell enumeration: an international study. Biomedial Excellence for Safer Transfusion Working Party.

BACKGROUND: An international multicenter study, involving six sites in North America and six sites in Europe, was undertaken to assess the performance of standardized methods for the enumeration of CD34+ cells in peripheral blood over the dynamic range from 200 cells per microL to zero. Two commercially available techniques were studied, a flow cytometry method and a microvolume fluorimetry method. STUDY DESIGN AND METHODS: Coded samples were centrally prepared and sent to test sites by overnight mail. Samples included internal replicates, linear dilutions, and specimens at the lower limit of detection. In addition, commercially available reagent positive control cells were sent to a subset of laboratories. RESULTS: Over the sample range studied, the intersite precision among different laboratories was good with coefficients of variation ranging from 14 percent to 24 percent for microvolume fluorimetry and from 20 percent to 31 percent for flow cytometry. Intrasite precision ranged from 7 percent to 21 percent. Test linearity was excellent with sites demonstrating a mean r2 = 0.992 for microvolume fluorimetry and r2 = 0.984 for flow cytometry. The lower limit of detection was 5 CD34+ cells per microL for both commercial assays. Over the range of 5 to 50 CD34+ cells per microL, the microvolume fluorimetry assay reported slightly higher values than the flow cytometry assay. Preliminary analysis of reagent positive control cells showed very good precision and accuracy. CONCLUSIONS: Standardization of CD34+ cells enumeration is improving and commercially available assays provide accurate and precise methods. More investigation of reagent positive control cells is warranted.

Antigens, CD34↗
PubMed1999

Duplications of DNA sequences between loci D20S478 and D20S206 at 20q11.2 and between loci D20S902 and D20S480 at 20q13.2 mark new tumor genes in papillary renal cell carcinoma.

Trisomy of chromosome 20 is associated with the progression of papillary renal cell carcinomas (RCC). To define the gene loci, we have analyzed 40 tumors by applying 18 polymorphic microsatellite markers. An allelic imbalance at all informative loci was seen in 14 cases. Partial duplications of chromosome 20 in 14 tumors delineated four nonsyntenic regions: region A at chromosome 20p12-p13, regions B and C at chromosome 20q11.2, and region D at chromosome 20q13.2. Region B was bracketed by loci D20S206 and D20S478, both mapped to 54 cM and both excluded. The smallest overlapping duplication at region D was scaled down to the region between loci D20S480 and D29S902 marking approximately 100-kb genomic sequences. Allelic duplication in papillary RCC was confirmed by fluorescence in situ hybridisation analysis by using BAC clones 441o14 and 354n14 positive for the flanking loci at region B. Altogether 70% of papillary RCC showed genetic changes at least at one of the four regions, but coalteration of two or more regions was seen in most cases.

Alleles↗
PubMed1999

Mapping the papillary renal cell carcinoma gene between loci D17S787 and D17S1799 on chromosome 17q21.32.

Trisomy of chromosome 17 is associated with the development of papillary renal cell tumors (RCT). We have analyzed 37 papillary RCT by applying 25 polymorphic microsatellite markers and found an overlapping duplication including loci D17S1795 and D17S1306 on chromosome 17q21. This region was then analyzed in additional 118 sporadic and hereditary papillary RCT. Overlapping partial duplications at the chromosome 17q21.32 region localized the papillary RCT gene to an approximately 300 kb genomic sequences flanked by loci D17S787 and D17S1799. Altogether, 92% of the 100 papillary RCT showed allelic duplication at this region. We did not find mutation in coding sequences or altered expression of the hepatic leukemia factor gene, which is mapped the smallest duplicated interval, in any type of RCT. Therefore, another gene within the 300 kb region might be responsible for the development of papillary RCT.

Base Sequence↗
PubMed1999

Lectin histochemistry of pathological bones.

Our present knowledge of the structure and function of glycoproteins in bone tissue is very limited. The introduction of lectins into histology offered principally a new approach for studying the presence and chemical structure of glycoproteins in tissue sections. In this paper these highly specific carbohydrate binding molecules have been used to characterize glycoproteins in the cellular elements of normal bone and benign bone lesions. We retrospectively examined 35 benign bone lesions (7 fibrous dysplasias, 5 foreign body granulomas, 5 epulis, 8 osteoid osteomas, 10 giant cell tumors) together with 25 normal bone samples. In normal bone samples and all cases of benign bone lesions, two characteristic types of PNA binding were found after neuraminidase digestion in osteoclasts. In osteoclasts which did not adhere to bone surface, diffuse intracytoplasmic PNA binding was seen, and following the adherence to the bone surface, it disappeared, and the resorption zone became stainable. We assume that this PNA binding glycoprotein is formed in the cytoplasm of osteoclasts, then, after the activation of osteoclasts, the glycoprotein gets accumulated at the resorption zone of the cytomembrane where it plays a significant role in the bone resorption.

Bone Diseases↗
PubMed1998

Moesin becomes linked to the plasma membrane in attached neutrophil granulocytes.

Following 35 min of adhesion to a plastic surface, an 80-kDa F-actin-binding protein was shown to be enriched in the plasma membrane fractions of porcine neutrophils by protein blotting with labeled F-actin. This protein was almost undetectable in membrane fractions of free floating neutrophils, while it was present in total cell samples. The 80-kDa protein appeared to be a major high molecular mass component of the isolated actin-cytoskeleton of both control and attached cells. The studied F-actin-binding protein was recognized by anti-moesin antibodies. Our results suggest that moesin is translocated to the plasma membrane upon adhesion of neutrophils to the extracellular surface.

Actins↗
PubMed1998

NPY upregulates genes containing cyclic AMP response element in human neuroblastoma cell lines bearing Y1 and Y2 receptors: involvement of CREB.

Four NPY receptor subtypes have been cloned, and shown to be coupled to both Ca2+ and cAMP. However, very little is known about the downstream elements mediating NPY actions. It has recently been demonstrated in our laboratory that intrahypothalamic (i.h.t.) administration of NPY induces hypothalamic CaM kinase activity, cyclic AMP response element binding protein (CREB) phosphorylation and cyclic AMP response element (CRE) binding activity in rat hypothalamic nuclear proteins. In the present study, we have investigated whether these changes in CRE binding transcriptional factors activated by NPY results in gene regulation using a human neuroblastoma cell line (SK-N-BE2). This cell line which expresses the Y2 subtype of NPY receptors was transfected with a fusion gene containing 1.305 kb of human CRF 5' flanking region with a perfect palindromic CRE site linked to firefly luciferase gene. NPY treatment increased CaM kinase II activity, CREB phosphorylation and CRE binding in these cells. In transfected cells, luciferase activity was also increased by NPY (1.8-4-fold) within 4 h of treatment. Moreover, forskolin (7-30-fold), which stimulates cAMP production, and thapsigargin (6-8-fold), which mobilizes intracellular calcium, also increased luciferase activity within 4 h of treatment. PMA (phorbol-12-myristate-13-acetate), an activator of protein kinase-C, induced luciferase activity by 1.8-fold. NPY augmented forskolin-stimulated luciferase activity from 11- to 15-fold, but had no significant effect on thapsigargin-induced luciferase activity. These findings suggest that activation of protein kinase A (PKA) or CaM kinase leads to the induction of fusion gene. NPY treatment upregulated fusion gene expression through Ca2+ pathway in SK-N-BE2 cell line. Pretreatment with CREB antisense, but not the sense oligodeoxynucleotides, inhibited forskolin-, thapsigargin- and NPY-stimulated luciferase activity. However, CREB sense or antisense oligodeoxynucleotide treatment had no effect on PMA-stimulated luciferase activity. Furthermore, NPY induced CRE binding activity and the expression of CRE containing Y1 receptor gene in SK-N-MC cell line. These findings suggest that NPY can upregulate CRE containing reporter gene including Y1 receptor gene and NPY-induced reporter gene regulation in SK-N-BE2 cells is mediated by intracellular Ca2+ and CREB protein.

Animals↗
PubMed1998

Beta-amyloid (1-42) peptide impairs blood-brain barrier function after intracarotid infusion in rats.

The effects of intracarotid infusions of beta-amyloid (1-42) peptide was studied on the permeability of brain vessels. Using a quantitative Evans blue method a dose-dependent increase of brain tissue albumin content was established following intracarotid injections of the peptide. Cerebral vessels of increased permeability were also demonstrated with a vital 'staining' technique. Lectin histochemistry revealed an almost complete abolition of specific lectin binding sites of affected endothelial cells. The findings indicate a significant deterioration by beta-amyloid (1-42) peptide of blood-brain barrier function and suggest that this may result from endothelial damage. It is assumed that altered permeability of cerebral vessels may be involved in the development of brain pathologies associated with Alzheimer's disease.

Amyloid beta-Peptides↗
PubMed1998

Duplication and overexpression of the mutant allele of the MET proto-oncogene in multiple hereditary papillary renal cell tumours.

Previous karyotyping showed a combined trisomy of chromosome 7 and 17 in sporadic and hereditary papillary renal cell tumours (RCT). A recent molecular analysis revealed a mutation in the MET tyrosine kinase (chromosome 7q31) in the germline of four out of seven families with hereditary papillary RCT (HPRCT). We have analysed germline cells as well as multiple tumours obtained from HPRCT families and sporadic cases for alteration of the MET tyrosine kinase and for allelic duplication at chromosome 7 and 17. We have detected a germ line mutation in the MET tyrosine kinase in one of the two families with HPRCTs and also found the same mutation in the germ line of one patient with clinically recognized multiple, bilateral papillary RCTs but without family history. The mutant MET allele is consequently duplicated and overexpressed in tumour cells indicating that duplication of the mutant MET allele is necessary before cells enter the tumorigenic pathway. The lack of germline mutation in two members of another HPRT family and duplication of the same parental allele of chromosome 7 in multiple tumours suggests that a germ line event other than mutation of MET tyrosine kinase is involved in the development of these tumours. Duplication of different alleles of chromosome 7 in sporadic and of chromosome 17 in both types of tumours excludes a germline mutation at these chromosomal sites.

Adenoma↗
PubMed1998

Lysosomal glycosaminoglycan storage as induced by dicationic amphiphilic drugs: investigation into the mechanisms underlying the slow reversibility.

Several dicationic amphiphilic compounds, such as the immunomodulator tilorone and analogues, impair the lysosomal catabolism of sulphated glycosaminoglycans (GAGs). Thereby they cause lysosomal GAG storage in rats and in cultured fibroblasts of several species including man. The GAG storage is rather slowly reversible in vivo; it persists for months after discontinuance of drug treatment. In the present study, we investigated the mechanisms underlying the slow reversibility. Cultured bovine corneal fibroblasts were pretreated for 4 days with tilorone (5 and 20 microM) or with compound CL-90.100 (3 and 10 microM) and further cultured in drug-free medium for periods up to 11 days. The intracellular GAG storage was analysed biochemically and demonstrated histochemically. The subcellular drug distribution (CL-90.100) was demonstrated by fluorescence microscopy. Dermatan sulphate (DS) provided the predominant contribution towards the GAG storage. After pretreatments with the low, as well as the high concentrations of either drug, the storage of DS was irreversible during the period of observation, whereas the minor storage of heparan sulphate was resolved. The enhanced secretion of the lysosomal enzyme beta-hexosaminidase (E.C. 3.2.1.52) caused by pretreatment with the high concentration of tilorone was also readily reversible. Thus, enzyme deprivation could not be the explanation for the sustained DS storage. The localization of the drug-related fluorescence within perinuclear cell organelles, presumably lysosomes, resembled that of the stored GAGs as visualized by histochemical staining. Both, the fluorescence and the positive GAG staining persisted with unchanged intracellular distribution throughout the recovery period. The present results suggest that the persistence of the DS storage is due to the formation of long-lived, non-degradable DS-drug complexes within the lysosomes.

Acridines↗
PubMed1998

Safety and cost effectiveness of a 10 x 10(9)/L trigger for prophylactic platelet transfusions compared with the traditional 20 x 10(9)/L trigger: a prospective comparative trial in 105 patients with acute myeloid leukemia.

In 105 consecutive patients with de novo acute myeloid leukemia (French-American-British M3 excluded), we compared prospectively the risk of bleeding complications, the number of platelet and red blood cell transfusions administered, and the costs of transfusions using two different prophylactic platelet transfusion protocols. Two hundred sixteen cycles of induction or consolidation chemotherapy and 3,843 days of thrombocytopenia less than 25 x 10(9)/L were evaluated. At the start of the study, each of the 17 participating centers decided whether they would use a 10 x 10(9)/L prophylactic platelet transfusion trigger (group A/8 centers) or a 20 x 10(9)/L trigger (group B/9 centers). Bleeding complications (World Health Organization grade 2-4) during treatment cycles were comparable in the two groups: 20 of 110 (18%) in group A and 18 of 106 (17%) in group B (P = .8). Serious bleeding events (grade 3-4) were generally not related to the patient's platelet count but were the consequence of local lesions and plasma coagulation factor deficiencies due to sepsis. Eighty-six percent of the serious bleeding episodes occurred during induction chemotherapy. No patient died of a bleeding complication. There were no significant differences in the number of red blood cell transfusions administered between the two groups, but there were significant differences in the number of platelet transfusions administered per treatment cycle: pooled random donor platelet concentrates averaged 15.4 versus 25.4 (P < .01) and apheresis platelets averaged 3.0 versus 4.8 (P < .05) for group A versus group B, respectively. This resulted in the cost of platelet therapy being one third lower in group A compared with group B without any associated increase in bleeding risk.

Acute Disease↗
PubMed1998

Barbary macaques categorize shrill barks into two call types.

In response to disturbances in their surroundings, Barbary macaques, Macaca sylvanus, utter a distinctive call, the 'shrill bark'. Differences within this call type correlate with the stimulus eliciting the calling. I tested whether monkeys categorized calls according to the eliciting stimulus and whether their perception of calls coincided with the classification derived from the acoustic analysis. Different playback designs using the habituation-dishabituation paradigm were created in which calls exhibiting varying degrees of acoustic difference were paired. I conducted experiments in two populations of semi-free ranging Barbary macaques. The results suggest that subjects categorized calls according to the eliciting stimulus. In addition, subjects from the population in which the recordings were made were significantly better than subjects from the other population at discriminating between calls with small acoustic differences. The results suggest that call categorization is influenced by experience, mediated by individual knowledge of the caller or common call characteristics within the population. Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1998

Local variation in Barbary macaque shrill barks.

We examined vocalizations of Barbary macaques, Macaca sylvanus, given in response to a dog, in two populations, at Rocamadour, France, and Salem, Germany. Calls were recorded from 16 individuals in Rocamadour and 23 individuals in Salem. Despite an overall similarity, an acoustic analysis revealed significant differences in the call structure between populations. To test the perceptual salience of these acoustic differences, we conducted playback experiments in both populations in which calls from the own or the other population were broadcast. The overall response pattern did not differ significantly between the populations with regard to the origin of the call. However, subjects responded slightly, but significantly longer after playback of calls from the other group. Although call function apparently determined the general response of subjects, they none the less discriminated between calls from different origins. These results suggest a small but possibly meaningful plasticity in call production. Copyright 1998 The Association for the Study of Animal Behaviour.

Journal Article↗