Search PubMed⌕ Search

Biomedical subjects

A Fischer

Publications and source records attributed to A Fischer.

At least 487 records · Page 27Linked to original sources
PubMed1994

Treatment of juvenile chronic myelomonocytic leukemia by allogeneic bone marrow transplantation.

Twelve of 15 patients with juvenile chronic myelomonocytic leukemia (JCMML) referred to our unit underwent allogeneic bone marrow transplantation (BMT) between 1982 and 1992. BMT was not performed in the remaining three cases because of poor overall condition in two and disease progression in one. Six patients received marrow from HLA-identical siblings after a chemotherapy conditioning regimen in five cases. BMT failed in one case. Long-term remission was achieved in three patients and two others are in remission 6 and 11 months after BMT. Remission was associated with autologous recovery in one patient and minimal mixed chimerism in another. In one patient, a first BMT procedure resulted in autologous recovery and relapse. A second transplant, with chemotherapy conditioning including TBI, was successful. BMT with marrow from a matched unrelated donor was also successful. IN contrast, BMT with marrow from mismatched related donors (five patients) failed because of graft failure and/or relapse. This single-center series indicates that HLA-identical BMT is an appropriate treatment for JCMML. However, on the basis of these results it cannot be ascertained whether chemotherapy or splenectomy are necessary prior to BMT. The best chemotherapy conditioning regimen remains to be defined, as regimens consisting exclusively of chemotherapy resulted either in long-term remission or in autologous recovery with relapse.

Antineoplastic Agents↗
PubMed1994

Defective transmembrane calcium influx demonstrated in a primary immunodeficiency by video-imaging.

A rise of intracellular calcium concentration triggered by the engagement of various membrane receptors is a key event in the control of cell growth. This increase involves both a release of calcium from intracellular stores and the opening of a transmembrane calcium conductive pathway. Using video imaging to measure intracellular calcium concentration in individual fura-2-loaded cells, we detected a defect in calcium influx in lymphocytes and fibroblasts collected from patients affected by a rare and new form of primary immunodeficiency. In these cells, pharmacological agents such as thapsigargin or ionomycin, and the physiological activator bradykinin, only induced transient increases in cytoplasmic calcium level, due to the emptying of internal stores, while in control cells, this initial step is followed by an additional and sustained transmembrane calcium influx. The fact that calcium influx is absent in patient's fibroblasts indicates that the related deficiency, which is clinically associated with a lack of proliferation of T lymphocytes, also affects cells of the non-hematopoietic lineages. This study emphasizes the adequacy of single cell imaging for determining whether some forms of pathologies are associated with a disregulation of ionic fluxes, and for identifying them accurately.

B-Lymphocytes↗
PubMed1994

Treatment of steroid-resistant acute graft-versus-host disease with an anti-IL-2-receptor monoclonal antibody (BT 563) in children who received T cell-depleted, partially matched, related bone marrow transplants.

Fifteen children with steroid-resistant acute graft-versus-host disease (GVHD, grade II-IV) were treated with a murine monoclonal antibody (BT 563) specific for the alpha subunit of the interleukin-2 receptor (IL-2R). All had inherited diseases of the bone marrow and had received T cell-depleted marrow from a partially matched related donor. BT 563 antibody was given at a daily dose of 0.2 mg/kg. Treatment was continued until GVHD was controlled and the methylprednisolone administration was tapered to < or = 2 mg/kg/day. No side-effects were noted. Eleven of the 15 patients reached complete remission and a partial remission occurred in two. This good response rate was associated with early treatment (mean time after GVHD onset 7.7 +/- 5.3 days) and prolonged treatment (mean 25.9 +/- 10.6 days) compared with previously published data on BT 563 antibody usage. Relapses occurred in six of the 13 responders but a further remission was induced by the same treatment. Chronic GVHD developed in six cases and one of them died of GVHD-associated infection. Ten of the 15 patients are long-term survivors and are free of chronic GVHD. The results of this pilot study indicate that early and lengthy treatment with anti-IL-2R monoclonal antibody is both safe and effective against steroid-resistant GVHD in young children and indicate that further trials of anti-IL-2R antibody as first-line therapy of acute GVHD are warranted.

Acute Disease↗
PubMed1994

Autosomal recessive osteopetrosis: variability of findings at diagnosis and during the natural course.

OBJECTIVE: To determine the variability and the natural course of children suffering from autosomal recessive osteopetrosis to allow optimal counseling and decision making with respect to therapeutic intervention. DESIGN: Retrospective and longitudinal evaluation of clinical symptoms and natural course with emphasis on survival and sensoneurologic and hematologic findings. SETTING: Two large referral-based pediatric bone marrow transplantation units in Europe. PATIENTS: Thirty-three patients with autosomal recessive osteopetrosis admitted to units in Paris and Leiden between 1972 and 1988 were analyzed until last follow-up or the time at which bone marrow transplantation was performed. The great number of patients and unprecedented amount of data make this report one of the single largest clinical studies on autosomal recessive osteopetrosis. MAIN RESULTS: Ocular involvement occurring at a median age of 2 months was the symptom at initial examination in half of the patients. A striking variability between patients was found. Retinal degeneration was present in three patients and associated generalized neurodegeneration was present in two. The probability of survival until the age of 6 years was about 30% for the group as a whole. The cumulative risk of developing visual or hematologic impairment in the first year of life was about 75% and leveled off afterward. Patients with early hematologic impairment, ie, before 3 months of age, especially when combined with early visual impairment, had a very poor prognosis regarding life expectancy. CONCLUSIONS: Autosomal recessive osteopetrosis seems to be a variable disorder with a poor prognosis, especially in children with early visual and hematologic impairment. Allogenic bone marrow transplantation remains the only curative approach.

Bone Marrow Transplantation↗
PubMed1994

Clinical consequences and treatment of primary immunodeficiency syndromes characterized by functional T and B lymphocyte anomalies (combined immune deficiency).

OBJECTIVE: To review the clinical presentation and outcome of patients with an unusual primary T + B lymphocyte immunodeficiency syndrome, characterized by the presence of T lymphocytes with no detectable gross phenotypic anomaly, but which are not activated in vitro or in vivo in response to antigens, although they do respond to mitogens. METHODS: A retrospective analysis of clinical and immunological data recorded in 25 cases. Acquired immunodeficiencies and known primary T cell immunodeficiency syndromes (severe combined immunodeficiency syndrome, Di-George syndrome, Wiskott-Aldrich syndrome, cartilage hair hypoplasia, Omenn's syndrome, ataxia telangiectasia, defective expression of major histocompatibility complex class II molecules, and defective expression of the CD3/T cell receptor complex) were excluded. RESULTS: The patients had severe and particularly protracted infections, mainly of the respiratory tract and gut. Severe viral infections, generally due to herpes viruses, occurred in nearly two-thirds of the patients, with a median follow-up of 54 months. Autoimmune manifestations are frequent (60%), targetting mainly marrow-derived cells, and were characterized by a tendency to relapse and by a dependence on immunosuppressive therapy. Allergic manifestations were also frequent (48% of cases). Eight of the 19 patients who had not undergone bone marrow transplantation died. All but one of the 11 survivors had moderate to severe sequelae. Bone marrow transplantation seemed to be the treatment of choice, because four of six recipients of HLA-identical (n = 2) or nonidentical (n = 4) marrow are alive and the immune deficiency has been corrected. CONCLUSION: Early recognition of these life-threatening syndromes may improve the chances of cure. Despite common clinical manifestations and prognosis, these functional immunodeficiencies appear heterogeneous regarding inheritance pattern and at least existence of a B cell immunodeficiency.

Adolescent↗
PubMed1993

Treatment of familial hemophagocytic lymphohistiocytosis with antithymocyte globulins, steroids, and cyclosporin A.

Familial hemophagocytic lymphohistiocytosis (FHL) is a potentially fatal disease characterized by diffuse infiltration by histiocytes and T lymphocytes. Treatment with myelotoxic drugs, such as etoposide, brings about remission in most patients, but problems of toxicity remain, and the development of disease resistance can cause secondary relapses. We have used an alternative approach, based on the suggested primary role of T-cell activation in FHL, comprising combined treatment with steroids (2 to 5 mg/kg/d methylprednisolone intravenously, followed by progressive tapering) and rabbit antithymocyte globulins (10 mg/kg/d for 5 days), followed by maintenance therapy with cyclosporine A (CSA). In a pilot study of six patients (four with a family history of FHL), all showed systemic remission within 7 days, which was complete in five cases; despite treatment with intrathecal methotrexate, one patient died of severe brain involvement. Two patients received T-cell--depleted HLA--non-identical bone marrow transplants, which was successful in one case. The other three patients, who have been on CSA maintenance therapy for periods of 6 to 24 months, are in complete remission. We have observed no side-effects (there has been no persisting T-cell immunodeficiency). These results suggest that nonmyelotoxic treatments for FHL may be safe, effective, and worthy of further investigation; they also support the key role of T lymphocytes in the disease.

Antilymphocyte Serum↗
PubMed1993

Busulfan disposition below the age of three: alteration in children with lysosomal storage disease.

Busulfan disposition is age-dependent with a higher clearance and a larger volume of distribution in children than in adults. The optimal dosage of busulfan needed to achieve bone marrow (BM) displacement in young children with malignant or nonmalignant disease remains to be defined. Using a gas chromatography-mass spectrometry assay, we evaluated plasma pharmacokinetics of busulfan in 33 children (median age, 9 months; range, 2 months to 2.75 years) with immune deficiencies, lysosomal storage diseases, acute leukemias, and malignant lymphohistiocytosis after an oral dose ranging from 0.9 to 2.6 mg/kg. The busulfan clearance (assuming a bioavailability of 1) ranged from 2.1 to 13.4 mL/min/kg with a mean of 6.8 mL/min/kg, which is higher than that reported in older children (4.5 mL/min/kg) and adults (2.9 mL/min/kg). Six children with lysosomal storage disease (5 with Hurler's disease, 1 with San Filippo's disease) had a prolonged elimination half-life (4.9 v 2.4 hours), a larger volume of distribution (3.4 v 1.2 L/kg) and a faster clearance (8.7 v 6.3 mL/min/kg) than the other 27 children. This suggests that a higher dose of busulfan will be required to achieve BM displacement in children with lysosomal storage disease. Over the dose range of 0.9 to 2.6 mg/kg, busulfan pharmacokinetics were linear. However, only 46% of the interpatient variation in systemic exposure could be ascribed to the dose. Given the wide interpatient variability in busulfan disposition, dose adjustment and drug monitoring will be needed to achieve the optimal dosage of busulfan in young children. The plasma busulfan levels required to achieve BM displacement need to be defined, especially in lysosomal storage diseases.

Age Factors↗
PubMed1993

B-50 (GAP-43) in Onuf's nucleus of the adult cat.

The nucleus of Onuf in the sacral spinal cord contains motoneurons that innervate the pelvic floor muscles and possess somatic and autonomic characteristics. We show in this study that in the intact adult cat, the immunocytochemical labelling of the nervous tissue-specific growth-associated protein, B-50 (GAP-43), which persists in Onuf's nucleus, differs markedly from that in the remaining 'purely somatic' motor nuclei of the sacral spinal cord. At the light microscopic level, an intense B-50 (GAP-43) immunoreactivity (B-50-IR) in the neuropil of Onuf's nucleus contrasts with a faint staining in the other spinal motor nuclei. Ultrastructurally, B-50-IR is found in Onuf's nucleus within some unmyelinated small diameter nerve fibres and numerous axon terminals on dendritic and somatic surfaces. Conversely, in all other motor nuclei only a few of these structures are stained. No other cellular profiles show B-50-IR in the tissue examined. According to the proposed functions of B-50 (GAP-43), its persistence in mature spinal axon terminals may indicate a latent capability of functional and structural remodeling, as well as an involvement in long-term enhancement in synaptic transmission. If so, these properties would be considerably more pronounced in Onuf's nucleus as compared to purely somatic motor nuclei.

Animals↗
PubMed1993

CD40 ligand mutations in x-linked immunodeficiency with hyper-IgM.

Signalling for the B-cell immunoglobulin isotype switch requires T-cell-derived cytokines and T-B cell interaction, which operates primarily through the CD40 molecule on B cells with its ligand (CD40L) on activated T cells (reviewed in ref. 1). The CD40L is a type II membrane protein with homology to tumour necrosis factor-alpha and -beta, and has important functions in B-cell activation and differentiation. Human CD40L maps on Xq26.3-27.1 (ref. 3), the region where a primary immunodeficiency characterized by an immunoglobulin isotype switch defect (the hyper-IgM immunodeficiency syndrome, HIGM1) has been localized. The hypothesis that HIGM1 involves an abnormality of the CD40L has been tested. We report here the lack of CD40L expression in four unrelated male children with the hyper-IgM syndrome. CD40L transcripts in these patients showed either deletions or point mutations clustered within a limited region of the CD40L extracellular domain. These genetic alterations with abnormal CD40L expression provide a molecular basis for immunoglobulin isotype switch defects observed in this immunodeficiency.

Base Sequence↗
PubMed1993

Nitric oxide synthase in guinea pig lower airway innervation.

The inhibitory non-adrenergic non-cholinergic (i-NANC) innervation of the guinea pig airways was suggested to be mediated, at least partially, by nitric oxide (NO). The enzyme catalyzing the generation of NO and citrulline from L-arginine, nitric oxide synthase (NOS), was found to be identical with neuronal nicotinamide-adenine dinucleotide hydrogen phosphate (NADPH)-diaphorase. In the present study, we report the distribution of NOS in guinea pig lower airways and in vagal sensory and sympathetic ganglia as revealed by NOS immunohistochemistry and NADPH-diaphorase histochemistry. The distribution of NOS was identical using either technique and displayed a similar distribution pattern in all parts of the lower airways. Yet, the number of NOS-containing fibres was increasing from cervical trachea towards principal bronchi and decreasing to complete absence in bronchioli. Innervation with NOS-containing nerve fibres was densest in the smooth muscle layer and in the lamina propria of the mucosa. Single fibres were found in the respiratory epithelium. Labelling was absent from nerve fibres innervating the submucosal glands. Perivascular fibre networks enmeshed tracheal arteries, pulmonary arteries and veins. A substantial number of NOS-immunoreactive and NADPH-diaphorase-positive neurons was observed in vagal sensory ganglia, whereas such neurons were rather sparse in sympathetic ganglia. Tracheal and peribronchial ganglia of the airways were devoid of labelling. These findings suggest that extrinsic rather than intrinsic (tracheal and peribronchial) neurons are the source of NO release from guinea pig airway nerve fibres after electrical field stimulation. These extrinsic nerve fibres may originate from both sympathetic and vagal sensory ganglia.

Amino Acid Oxidoreductases↗
PubMed1993

Human immunodeficiency virus gp120 and derived peptides activate protein tyrosine kinase p56lck in human CD4 T lymphocytes.

Human immunodeficiency virus binds to CD4 T lymphocytes by interaction between its envelope glycoprotein gp120 and the CD4 molecule. The latter is non-covalently associated with a src-related tyrosine kinase, p56lck. CD4 cross-linking increases the activity of p56lck, leading to phosphorylation of several cellular substrates. We report here that gp160/120 increases both the autophosphorylation of p56lck and its enzymatic activity (reflected by phosphorylation of an exogenous substrate) in normal T cells and the HUT78 CD4+ T cell line. This effect was detectable 5 min after activation and persisted for 40 min in normal T cells. It did not require gp120 cross-linking and was associated with phosphorylation of tyrosine residue on several proteins, as shown by phosphotyrosine Western blot analysis. The pattern of proteins phosphorylated on tyrosine residues in response to gp120 activation was distinct from that induced by anti-CD4 antibodies. p56lck activation required its association with CD4, since p56lck activity was not modified in HUT78 T cell lines expressing a truncated or mutated form of CD4 unable to associate with p56lck. Peptides mimicking residues 418 to 434 and 449 to 464 of HIV-1 Bru gp120, regions known to participate in gp120 binding to CD4, also increased p56lck activity and triggered phosphorylation of similar substrates. Taken together, these results show that gp160/120 and derived peptides can transiently increase p56lck activity without the need for CD4 cross-linking. This activation led to a specific pattern of tyrosine phosphorylation on cellular proteins that may be of significance in the biological effects of the gp120/CD4 interaction, e.g. syncytium formation and inhibition of T cell activation.

Amino Acid Sequence↗
PubMed1993

Normal T cell receptor V beta usage in a primary immunodeficiency associated with HLA class II deficiency.

The human T cell receptor was studied using an anchored-polymerase chain reaction (A-PCR) and hybridization with V beta-specific oligonucleotide probes, together with the few anti-V beta monoclonal antibodies (mAb) available. After confirming the semiquantitative and reproducible nature of the A-PCR technique, we assessed the complete V beta repertoire in sorted CD4+ and CD8+ lymphocyte populations from three normal donors. These experiments confirmed the absence of V beta-restricted deletions in human peripheral cells, in contrast to several mouse strains. This feature makes it difficult to study negative selection in man, given the apparent absence of an endogenous superantigen corresponding to the Mls system in the mouse. To investigate human V beta repertoire shaping, we studied V beta usage in CD4+ and CD8+ T cells from children with an inherited immunodeficiency characterized by defective expression of human leukocyte antigen class II molecules. An initial study using anti-V beta monoclonal antibodies failed to show significant abnormalities in V beta usage. Four patients analyzed using the A-PCR method all had a polyclonal V beta repertoire, suggesting normal positive selection and raising questions as to the importance of V beta major histocompatibility complex (MHC) interactions and the role of thymic MHC density in shaping the V beta repertoire.

Base Sequence↗
PubMed1993

Lack of selective V beta deletion in peripheral CD4+ T cells of human immunodeficiency virus-infected infants.

To investigate the possibility of super-antigen-mediated deletions of T cells expressing particular T cell receptor V beta (TcR V beta) gene segments during human immunodeficiency virus (HIV) infection, TcR V beta usage in CD4+ and CD8+ subsets was analyzed in a cohort of infants maternally infected by HIV and in a group of healthy neonates. We used a semi-quantitative anchored polymerase chain reaction technique together with cytofluorographic analysis with anti-V beta monoclonal antibodies. The representation of the 24 V beta families in CD4+ and CD8+ T cells from normal neonates was very similar to that in adults. Preferential expression of V beta 2 in the CD4+ subset was observed in both the neonates and in healthy adults. The representation of the 24 V beta families in peripheral CD4+ T cells from the HIV-infected infants showed no selective V beta deletion, even when the CD4+ subset was globally depleted. Moreover, the main characteristics of the control group (predominance of certain V beta families and V beta 2 skewing towards the CD4+ subset) were also present in all the HIV-infected infants.

Adult↗