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F Berger

Publications and source records attributed to F Berger.

At least 181 records · Page 10Linked to original sources
PubMed1998

Position dependent control of cell fate in the Fucus embryo: role of intercellular communication.

The early embryo of the brown alga Fucus comprises two cell types, i. e. rhizoid and thallus which are morphogically and cytologically distinguishable. Previous work has pointed to the cell wall as a source of position-dependent information required for polarisation and fate determination in the zygote and 2-celled embryo. In this study we have analysed the mechanism(s) of cell fate control and pattern formation at later embryonic stages using a combination of laser microsurgery and microinjection. The results indicate that the cell wall is required for maintenance of pre-existing polarity in isolated intact cells. However, all cell types ultimately have the capacity to re-differentiate or regenerate rhizoid cells in response to ablation of neighbouring cells. This regeneration is regulated in a position-dependent manner and is strongly influenced by intercellular communication, probably involving transport or diffusion of inhibitory signals which appear to be essential for regulation of cell fate decisions. This type of cell-to-cell communication does not involve symplastic transport or direct cell-cell contact inhibition. Apoplastic diffusible gradients appear to be involved in pattern formation in the multicellular embryo.

Body Patterning↗
PubMed1998

Cell fate in plants. Lessons from the Arabidopsis root.

Classical studies in plant development have indicated that the fate of plant cells is fixed late, after cell division has ceased. Earlier commitment events are therefore considered reversible. To gain a mechanisatic understanding of the processes involved in specification and fixation of cell fate in plants, we are using the Arabidopsis root epidermis as a model system. The Arabidopsis root epidermis is composed of two cell types whose pattern of differentiation is directed by positional cues during development. Examination of mutations has identified genes involved in the establishment of cell fate specification in this tissue. TRANSPARENT TESTA GLABRA (TTG) and GLABRA2 (GL2) are positive regulators of non-hair fate and are active during the early differentiation of the epidermis in the meristem. GL2 encodes a homeobox protein which is expressed in non-hair cells in the meristem and is positively regulated by TTG. Mutations in genes involved in the regulation of ethylene biosynthesis and signal transduction indicate that ethylene is a positive regulator of hair cell fate. Treatment of ttg and gl2 plants with modulators of ethylene biosynthesis indicate that ethylene acts down stream of TTG and GL2 during the fate specification process. The relationship between meristem organisation and the mechanism underpinning the establishment of cell fate in other systems is also discussed.

Arabidopsis↗
PubMed1998

Signals involved in control of polarity, cell fate and developmental pattern in plants.

The plant extracellular matrix has multiple roles in determining pattern during plant development. These include provision of anchorage sites for focal adhesion-like structures which may play a direct signalling role and provide a reference for cytoskeletal elements involved in nuclear rotation and orientation of the cell division plane. The activity of mechanosensitive ion channels in the plasma membrane can also be regulated by the mechanical properties of the cell wall. Moreover, there is increasing evidence from a variety of systems suggesting that the cell wall may be a direct source of factors which specify cell fate in response to position. These may be inserted into the wall by differentiating cells and may act by providing signals to adjacent cells or by providing positive feedback to the protoplast contained therein, maintaining its fate according to its position.

Cell Differentiation↗
PubMed1998

Pyothorax-associated lymphoma: relationship with Epstein-Barr virus, human herpes virus-8 and body cavity-based high grade lymphomas.

Pyothorax-associated lymphoma (PAL) is a newly-described entity developing several decades after artificial pneumothorax treatment for pulmonary or pleural tuberculosis. It is known to be associated with Epstein-Barr virus (EBV) with constant expression of the two latent membrane proteins: latent membrane protein (LMP)-1 and EBV-associated nuclear antigen (EBNA)-2. We are reporting three new cases of PAL. All of the tumours were of B-cell lineage and classified as large-cell diffuse lymphomas according to the International Working Formulation for the Classification of Lymphomas. The EBV genome was detected in two of the cases with LMP-1 and EBNA-2 expression. No EBV could be detected in the third case suggesting that different mechanisms may be involved in the pathogenesis of the disease. Body cavity-based high grade lymphomas (BCBL) represent a new disease, developing mainly in human immunodeficiency virus (HIV) infected patients: the tumoural cells often contain both human herpes virus (HHV)-8 (or Kaposi's sarcoma herpes virus) and EBV genomes, suggesting that these viruses might co-operate in the pathogenesis of the disease. The pleural location and the association of EBV have led to speculation that PAL could also be related to HHV-8 infection. However, no HHV-8 genome could be detected in any of the 14 tested cases already reported in the literature nor in the two cases we studied (one EBV-positive and one EBV-negative), suggesting that PAL and BCBL are two different entities.

Aged↗
PubMed1998

Cell ablation studies in plant development.

As an alternative and complementary approach to genetic targeted ablation, laser ablation has been applied to a variety of plant systems to investigate the basics of development in plants. The recent relevant literature is reviewed and provides concrete examples of how root development in Arabidopsis and cell polarization in Fucus have been studied using laser microsurgery. Guidelines are proposed for researchers who would like to apply laser ablation techniques to a given developmental problem.

Arabidopsis↗
PubMed1998

[Pseudotumor amylosis of the bladder. Apropos of a case].

A 57 year-old patient with localized pseudo-tumoral amyloidosis of bladder is described. There was no past medical history. Hematuria was the main symptom. The treatment consisted in transurethral resection. Two recurrences occurred at 4 and at 6 years which were also treated by resections. Clinical and biological evaluation was normal. Localized pseudo-tumoral amyloidosis of the urinary tract is a rare affection of good prognosis. Lesions present as pseudo-tumoral masses which can be biopsied without any risk of hematuria. Investigations are required to eliminate a generalized amyloidosis or a malignant lymphoproliferation. Treatment should be as conservative as possible.

Amyloidosis↗
PubMed1997

[Is transcatheter occlusion of a persistent foramen ovale a possibility for the avoidance of a paradoxical embolism?].

BACKGROUND AND OBJECTIVE: Cerebral embolism may have different causes with sometimes serious consequences. If no specific reason can be found, paradoxical embolization through a persistent foramen ovale (PFO) is increasingly as a cause of the cerebral ischaemia. This study was undertaken to ascertain whether in patients with cerebral embolism occlusion of a PFO with a transcatheter technique can prevent further cerebral emboli. PATIENTS AND METHODS: Indications for transcatheter occlusion were based on neurological signs (ischaemic stroke), cardiovascular diagnosis, and coagulation tests. Between August 1991 and July 1996, transcatheter occlusion of a PFO was performed in 28 fully anticoagulated patients (median age 37.8 [15.4-65.4] years). The mean PFO diameter was 9.5 mm (3-17), mean duration of fluoroscopy 18.3 (8.7-43.1) min. The Rashkind device was implanted in three patients, the Sideris buttoned device in 25. During the follow-up period (2-64 months; mean 13 months) renewed neurological symptoms occurred in only one patient. Transoesophageal echocardiography excluded thrombi on the implanted device or in the left atrium, and a residual PFO. The cause of the one neurological episode is therefore not clear. All other patients have remained free of symptoms and recurrence without anticoagulation after placement of the device. CONCLUSIONS: Transcatheter occlusion of a PFO is a relatively simple and safe procedure. Our results suggest that it can at least lower the incidence of further cerebral embolizations. The clinical value of the method in comparison with anticoagulation requires further study.

Adolescent↗
PubMed1997

Primary anaplastic large-cell lymphoma in adults: clinical presentation, immunophenotype, and outcome.

Anaplastic, CD30+, large-cell lymphoma is now a well-recognized pathologic entity that accounts for 2% to 8% of all lymphomas. Recent progress has been made in the understanding of certain biologic features found in anaplastic large-cell lymphoma, but information about its clinical behavior, in comparison to other large-cell lymphomas, is limited. The pathologic review of a large multicenter study of the treatment of aggressive lymphoma identified 146 cases of anaplastic large-cell lymphoma (ALCL) on the basis of morphology and CD30 expression. We compared initial presentation, immunophenotype, and clinical outcome of these cases with those of the 1,695 nonanaplastic diffuse large-cell lymphomas (non-ALCL) included in the same trial. Patients with ALCL were more likely to be male (P = .018) and were younger (P < .0001) than those with non-ALCL. B symptoms were more frequent in ALCL (P = .006). Skin (P < .0001) and lung (P < .05) involvement was also more frequent in ALCL, but frequency of bone marrow involvement was identical (P = . 5). Tumor cell phenotype was B in 56 cases (38%), T in 49 cases (34%), and null in 33 cases (22%). Response to chemotherapy (P = . 001), event-free survival (P = .006), and overall survival (P = . 0004) were better for ALCL than for non-ALCL. Multivariate analyses identified anaplastic character as an independent factor that predicted a longer survival. Tumor cell phenotype did not influence event-free survival (P = .72) or overall survival (P = .83). ALCL in adults is a clinicopathologic entity which, independent of its phenotypic characteristics, has a better outcome than other diffuse large-cell lymphomas.

Adult↗
PubMed1997

Unbalanced X;autosome translocation (X;18)(q13;p11) in a case of aggressive natural killer non-Hodgkin lymphoma.

Recent evidence has shown that rare cases of aggressive non-Hodgkin lymphomas (NHL) derive from cells belonging to the natural killer (NK) lymphocyte lineage and a new clinico pathologic entity has been proposed. Though well documented in B- and T-cell NHL, chromosome abnormalities are rare findings in NK-NHL and to date, no recurrent cytogenetic abnormality has been described. The present study reports the clinical data, cytogenetic and fluorescence in situ hybridization (FISH) analysis of a new case of typical NK-NHL characterized by a primary unbalanced translocation (X;18) (q13;p11). Recent data of X;autosome translocation in malignant lymphomas have proposed Xp22 and Xq28 as the location of NHL-related oncogenes. According to other published reports on the involvement of the Xq13 region in NHL and particularly in aggressive forms, we hypothesize the existence of additional putative lymphoma-associated oncogenes at the band Xq13.

Adult↗
PubMed1997

Prognosis of patients with advanced Hodgkin's disease: evaluation of four prognostic models using 344 patients included in the Group d'Etudes des Lymphomes de l'Adulte Study.

BACKGROUND: To determine whether a high risk group could be identified within a group of patients with advanced stage Hodgkin's disease (HD), the authors applied several prognostic models to patients treated according to the H89 protocol. METHODS: This study included 344 patients with Stage IIIB-IV HD who were treated with chemotherapy alone (8 cycles) or chemotherapy (6 cycles) plus radiation therapy. Four prognostic models were selected for this study: the numeric prognostic index of the Scotland and Newcastle Lymphoma Group, the Christie Hospital (Manchester)-St. Bartholomew's Hospital (London) model, the Memorial Sloan-Kettering Cancer Center (MSKCC) model, and the criteria used in the European Bone Marrow Transplant (EBMT)/Intergroup Trial. RESULTS: Univariate analysis of H89 protocol patients showed that 5 variables included in the models had prognostic significance: age > 45 years (P = 0.0001), anemia (hemoglobin < 12 g/dL for males and < 10 g/dL for females) (P = 0.0001), number of extranodal sites > or = 2 (P = 0.0013), serum lactic acid dehydrogenase greater than the normal value (P = 0.0018), and lymphocyte count < 0.75 x 10(9) L(-1) (P = 0.0063). All four models divided patients into prognostic subgroups. Significant differences among the subgroups were found by log rank analysis (chi-square test = 11-48; P = 0.01-0.0001). The worst prognostic group defined by the MSKCC model (> or = 3 adverse factors) had an overall survival rate of 59% at 3 years and an estimated 3-year event free survival rate of 43%. CONCLUSIONS: Patients with at least three adverse factors according to the MSKCC model or the EBMT criteria had a higher risk of failure with conventional treatment; however, based on survival rate, no very high risk group could be identified. Nonetheless, these prognostic models may be useful to recognize patients with good prognosis who can be cured with conventional therapy and for whom treatment morbidity and mortality can be minimized.

Adult↗
PubMed1997

Right ventricular function in patients treated with inhaled nitric oxide after cardiac surgery for congenital heart disease in newborns and children.

Measurement of right ventricular (RV) function is essential for complete assessment of the effects of inhaled nitric oxide in the postoperative cardiac patient; nitric oxide therapy can result in a decrease in pulmonary vascular resistance and improved echocardiographic RV ejection fraction without necessarily inducing a significant change in pulmonary artery pressure.

Child↗
PubMed1997

Primary hepatocellular carcinoma in workers exposed to vinyl chloride: a report of two cases.

BACKGROUND: Vinyl chloride (VC), an industrial toxic gas, has a dose-dependent carcinogenicity in rodents and has been responsible for multiple cases of liver angiosarcoma in humans. The aim of this study was to describe histopathologic liver alterations and to evaluate risk factors for hepatocellular carcinoma in two workers from the same plant, both of whom had primary nonangiosarcoma liver tumors and were exposed to VC. METHODS: Clinical, biochemical, serologic, and pathologic data were reviewed at the time of hepatic resection. Clinical and biologic follow-up were available for several years before the diagnosis of hepatocellular carcinoma. RESULTS: Liver alterations distant from the tumor site were compatible with ongoing exposure to VC in both cases. Several areas containing dysplastic hepatocytes were present in nontumoral liver in one patient. Both patients are alive after partial liver resection, and 1 has had 5 years of follow-up without recurrence. CONCLUSIONS: Exclusion of classic risk factors for noncirrhotic hepatocellular carcinoma of the liver in both patients suggests a relationship between VC exposure and observed tumors. Systematic long term follow-up with biology and ultrasonography for workers exposed to VC may result in relatively early diagnoses of liver tumors and long term survival in some cases.

Carcinoma, Hepatocellular↗
PubMed1997

Modulation of pacemaker activity in sheep cardiac Purkinje fibers by stimulation of beta-adrenoceptor subtypes.

The electrophysiological effects mediated by beta 1- and beta 2-adrenoceptors in spontaneously active sheep cardiac Purkinje fibers were investigated using the non-selective agonist (-)-isoproterenol (IPN) and the selective agonists (-)-noradrenaline (beta 1) and procaterol (beta 2) in the absence and presence of the selective antagonists bisoprolol (beta 1) and ICI 118,551 (beta 2). IPN (0.01 mumol/l) increased the spontaneous rate by 54% and the slope of diastolic depolarization by 68% of the respective control values. Further, IPN increased the action potential duration at -20 mV (APD -20 mV) from 96 to 154 ms, reduced the APD-70 mV by 17% and the duration of the diastole by 39% and slightly hyperpolarized the maximum diastolic potential. These effects were partially inhibited by ICI 118,551 (0.03 mumol/l), diminished by bisoprolol (0.1 mumol/l) and almost completely blocked by the combination of both antagonists. Concentration response curves of IPN were influenced by the selective antagonists as follows: ICI 118,551 (0.03 mumol/l) shifted the curves to the right by 0.2-0.4 log units and increased the slope factor. Bisoprolol (0.1 mumol/l) induced a greater shift to the right by 1.1-1.5 log units. Combination of bisoprolol with ICI 118,551 shifted the curves to the right by 1.5-1.7 log units. Noradrenaline (0.3 mumol/l) elicited similar actions as IPN. Bisoprolol (0.1 mumol/l) shifted the concentration response curves of noradrenaline to the right by 1.1-1.9 log units. Actions of procaterol (0.1 mumol/l) were weak, attained only 15-35% of the maximal effects of IPN and could be blocked by ICI 118,551 (0.03 mumol/l). These results show that the increase of pacemaker activity induced by catecholamines in sheep cardiac Purkinje fibers is predominantly mediated by stimulation of beta 1-receptors. However, contribution of beta 2-receptor mediated effects could be demonstrated.

Adrenergic alpha-Agonists↗
PubMed1997

[Electrophysiologic effects of K+ and Mg2+ in the hypoxia model].

The influence of Mg2+ and K+ on reoxygenation arrhythmias following 18 min of hypoxia (pO2 about 1 mm Hg, no glucose, 10 mmol/l2-desoxyglucose) has been investigated in isolated guinea-pig left atria (stimulation rate 1 Hz). Duration of reoxygenation arrhythmias was slightly reduced by increase in Mg2+ (0.6 to 4.8 mmol/l) and enhanced by decrease in Mg2+ (0.1 mmol/l), however, this effect was not significantly different from control (0.6 mmol/l). In contrast, low K+ (< 4 mmol/l) led to a significant (p < or = 0.05) prolongation and high K+ (> 5 mmol/l) to a significant abbreviation of reoxygenation arrhythmias. Increase in Mg2+ significantly attenuated the proarrhythmic effects of low K+ and enhanced the antiarrhythmic effects of high K+. Furthermore, the influence of Mg2+ and K+ on action potential parameters has been investigated in hypoxic guinea-pig papillary muscles (pO2 65 to 75 mm Hg). Action potential duration at 30% (APD30) and 90% repolarization (APD90) were increased by both electrolytes whereas resting potential, amplitude of the action potential and maximum upstroke velocity were not changed with the exception of a depolarization induced by elevated K+. 1 mmol/l Mg2+ increased APD30 to 145 +/- 16% (n = 6, p < 0.05) and APD90 to 117 +/- 9% (n = 6, p > 0.05) of control (0.6 mmol/l Mg2+). Increase of K+ from 2 mmol/l (control) to 4.7 mmol/l increased APD30 to 188 +/- 13% (n = 6, p < 0.05) and APD90 to 136 +/- 13% (n = 6, p < 0.05). The delay in repolarization observed already in therapeutic concentrations showed no inverse use dependence as it was not attenuated if stimulation rate was increased from 0.17 to 1 Hz which is in contrast to the effects of class 3 antiarrhythmic drugs (for example sotalol). Increase in concentration of both electrolytes led to an additive increase in action potential duration. Mg2+ (0.6 to 4.8 mmol/l) suppressed late afterdepolarizations and -contractions in K(+)-depolarized guinea-pig papillary muscles (27 mmol/l K+, 0.5 mmol/l Ba2+) induced by 2 x 10(-8) mol/l isoprenaline. The change in the triphasic contraction cycle by elevation of Mg2+ indicates that Mg2+ additionally increases stimulus-induced release of Ca2+ from the sarcoplasmic reticulum and reduces slow Ca2+ inward current. The described electrophysiological actions of the electrolytes represent mechanisms, which may explain their antiarrhythmic actions observed in clinical studies.

Animals↗
PubMed1997

Effects of 17beta-estradiol on action potentials and ionic currents in male rat ventricular myocytes.

This study describes electrophysiological effects of estrogens in isolated male rat ventricular myocytes. According to the literature these cells do not express the nuclear estrogen receptor. Action potentials or membrane currents were recorded in the whole-cell configuration with standard techniques. Action potential durations (APD) measured at a level of 0 mV (APD 0) and -70 mV (APD -70) were prolonged by 17beta-estradiol (0.5 Hz stimulation frequency, 24-26 degrees C). Threshold concentration was 1 micromol/l. At the highest concentration used (30 micromol/l) no saturation of the response was reached and APD 0 was 162% and APD -70 was 230% of the respective control. The resting potential remained unaffected in most cells. The prolongation induced by 17beta-estradiol developed fast and reached a steady state 10 min after start of hormone superfusion. Effects of estrogen were completely reversible during 10-15 min wash-out with hormone-free solution. The extent of prolongation (10 micromol/l 17beta-estradiol) was frequency dependent. Expressed as percentage of the respective control APD 0 (or APD -70) was 115% (188%) at 0.05 Hz, 118% (163%) at 0.5 Hz and 99% (129%) at 5 Hz stimulation frequency. The response was stereoselective, because 30 micromol/l 17alpha-estradiol did not prolong action potentials (APD 0: 101%, APD -70: 104% of the respective control, 0.5 Hz stimulation frequency). The endogenous estrogens estrone and estriol were less effective than 17beta-estradiol. With 30 micromol/l estrone (0.5 Hz stimulation frequency) APD 0 was 103% and ADP-70 148% of control and with 30 micromol/l estriol APD 0 was 135% and APD -70 137% of control. The prolongation of action potentials can be explained by inhibition of transient outward current which, in rat ventricle, is composed of fast (i[to,f]) and slowly (i[to,s]) inactivating components. At 30 micromol/l 17beta-estradiol i(to,f) was reduced to 50% and i(to,s) to 43% of their maximal amplitudes. The voltage sensor of i(to,f) or i(to,s) was hardly affected. Additionally, 17beta-estradiol decreased the calcium current (i[Ca,L]) to 76% (10 micromol/l) and 38% at 30 micromol/l. The inwardly rectifying potassium current (i[K1]) was reduced partly with 30 micromol/l 17beta-estradiol and its amplitude was 72% of control at -90 mV (inward current flow) and 65% at -40 mV (outward current flow). These results show that 17beta-estradiol is active in cardiac cells which do not express the nuclear estrogen receptor. The hormone exerts class III activity and reduces calcium inward current. These effects, however, occur in vitro with concentrations above the physiological level and therefore may be without significance in vivo.

Action Potentials↗
PubMed1997

Intensive therapy with peripheral stem cell transplantation in 16 patients with mantle cell lymphoma.

BACKGROUND: Despite improved detection of mantle cell lymphoma (MCL), results of its treatment with conventional therapies remain disappointing and the survival rate poor. The role of high-dose chemotherapy has recently been investigated but no potential benefit has been clearly established. We report here our experience with MCL patients treated with intensive chemotherapy and autologous stem cell transplantation (ASCT). PATIENTS AND METHODS: Of the 16 MCL patients who received high-dose chemotherapy and ASCT beginning in 1989, six were treated in first-line and 10 in sensitive relapse. Twelve of 16 patients received regimens which included total body irradiation. All patients received peripheral blood stem cells (PBSC) with the exception of one, who underwent bone marrow transplantation. RESULTS: Three patients died of toxic effects of treatment, Three months after transplant, seven achieved complete response, (CR) and two partial responses (PR), two were stable and two had progressed. With a median follow-up after transplant of 22 months, five of the six surviving patients were without progression, and three were in CR. The median times for event-free survival (EFS) and overall survival (OS) were, respectively, 249 and 317 days. The expected three-year EFS and OS were 24%. The median survival after diagnosis was only 29 months. None of the criteria appeared to be significantly associated with a better outcome, but first-line intensification and a short delay after initial diagnosis may be favorable. CONCLUSION: In this study we were not able to confirm the hypothetical benefit of high-dose chemotherapy and PBSC transplantation in mantle cell lymphoma, even though this approach may be promising in a subgroup of patient.

Antineoplastic Agents, Alkylating↗
PubMed1997

[The recording of parenchymal lung changes in smokers by high-resolution computed tomography].

PURPOSE: It has been the aim of the study to assess parenchymal changes in the lung with high-resolution CT in healthy heavy, moderate, and non-smokers. MATERIAL AND METHODS: We prospectively evaluated CT changes in 42 healthy heavy smokers (gr. (group) 2, > or = 30 pack-years), 40 moderate smokers (gr. 1, < 30 pack-years) and 38 non-smokers (gr. 0). For CT-analysis, we used a visual grading and computer-based analysis system (Mipron, Kontron GmbH, Munich, Germany). RESULTS: Productive cough, dyspnoea and chronic bronchitis were more common in smokers than in non-smokers (p < 0.05). Pathological CT-findings were found in 6/38 non-smokers and in 71/82 smokers (p < 0.01). In particular, in smokers (gr. 1 [%], gr. 2 [%]) the following pathological findings were found: dystelectases in dependent lung areas in 50% (62, 38), centrilobular emphysema in 44% (43, 20), pleural thickening in 38% (38, 38), panlobular emphysema in 36% (52, 20), ground-glass pattern in 33% (36, 30), paraseptal emphysema in 21% (31, 10), prominent or thickened interlobular septa in 18% (29, 8) and centrilobular micronodules in 13% (10, 18). Computer-based analysis demonstrated thicker bronchial walls in smokers as compared to non-smokers. CONCLUSION: Although feeling healthy, smokers demonstrate various parenchymal abnormalities in the lung. In smokers, subpleural dystelectases, centrilobular and panlobular emphysema are dependent on cigarette consumption, ground glass pattern, centrilobular micronodules, pleural thickening and bronchial wall thickening are independent on cigarette consumption.

Adult↗