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T Hecht

Publications and source records attributed to T Hecht.

At least 19 recordsLinked to original sources
PubMed2004

Competition for attachment of aquaculture candidate probiotic and pathogenic bacteria on fish intestinal mucus.

Probiotics for aquaculture are generally only selected by their ability to produce antimicrobial metabolites; however, attachment to intestinal mucus is important in order to remain within the gut of its host. Five candidate probiotics (AP1-AP5), isolated from the clownfish, Amphiprion percula (Lacepéde), were examined for their ability to attach to fish intestinal mucus and compete with two pathogens, Aeromonas hydrophila and Vibrio alginolyticus. Two different radioactive isotopes were used to quantify competition between pathogens and probionts. Attachment of the pathogens was enhanced by the presence of the candidate probiotics. However, the addition of the candidate probiotics after the pathogens resulted in reduced pathogen attachment. Only AP5 caused lower attachment success of V. alginolyticus when added before the pathogen. When AP5 was added first, the average attachment change was 41% compared with 72% when added after V. alginolyticus, suggesting that the probiotic is displaced but that enhanced attachment of the pathogen does not occur. Conversely, when V. alginolyticus was added first, followed by AP5, attachment change was 37% while AP5 had 92% attachment change when added second. This implies that the pathogen was displaced by the candidate probiotic and therefore it appeared that, based on the ability of probiont AP5 to attach to mucus, the growth of the pathogen in the digestive tract might be suppressed by the candidate probiont's presence.

Aeromonas hydrophila↗
PubMed2000

Role of the 2D surface state continuum and projected band gap in charge transfer in front of a Cu(111) surface

Electron capture by Li+ and H projectiles in grazing scattering from Cu(111) and Cu(110) surfaces is studied experimentally and theoretically. Whereas data for Cu(110) can be described by established theoretical methods treating resonant charge transfer with a free-electron metal, data for Cu(111) show pronounced deviations from this approach. We interpret our observations by the effect of the projected L-band gap of the Cu(111) surface. In particular, the quantum states of reduced dimension (2D surface state continuum) play a dominant role in electron transfer.

Journal Article↗
PubMed2000

Effect of the projected band gap on the formation of negative ions in grazing collisions from Cu surfaces.

The formation of negative ions (H-, O-, S-, F-, Cl-) is studied for grazing scattering of fast ions from Cu(110) and Cu(111) surfaces. In a detailed experimental and theoretical investigation we reveal that the projected L-band gap of the Cu metal affects charge transfer in a specific manner. From the analysis of the negative ion fractions as functions of projectile velocity we conclude that, for the Cu(111) surface the electronic 2D surface state continuum plays an essential role in the projectile-surface electron transfer.

Journal Article↗
PubMed1998

High levels of thrombopoietin in sera of patients with essential thrombocythemia: cause or consequence of abnormal platelet production?

Thrombopoietin (TPO) is the most important regulator of megakaryocyte development and platelet production. Platelet production is thought to be regulated by a negative regulatory feed back loop. In an attempt to evaluate the role of TPO in the pathobiology of essential thrombocythemia (ET), we have examined levels of TPO and other cytokines with thrombopoietic activity (interleukin-6 and interleukin-11) in sera obtained from 25 patients with ET (ten treated, 15 untreated) and 117 healthy control subjects. TPO serum levels were assessed using a sandwich-antibody ELISA that utilizes a polyclonal rabbit antiserum for both capture and signal. The mean serum TPO level in 25 ET patients was significantly elevated (545+/-853 pg/ml) as compared with that in healthy controls (95.3+/-54.0 pg/ml,p<0.001). The difference in TPO serum levels between ten treated (781+/-1229 pg/ ml) and 15 untreated ET patients (388+/-458 pg/ml) did not reach statistical significance (p = 0.09). We conclude that either consumption or production of TPO is altered in ET. Failure of appropriate feedback regulation and continued megakaryocyte stimulation by an elevated TPO may play an important role in the pathobiology of ET.

Blood Platelets↗
PubMed1998

Thrombopoietin serum levels in patients with aplastic anaemia: correlation with platelet count and persistent elevation in remission.

In an attempt to evaluate the role of thrombopoietin (TPO) in the pathobiology of aplastic anaemia (AA), we have examined TPO levels in sera from 54 AA patients and 119 healthy controls. A total of 92 samples were collected from AA patients: 43 samples were harvested at diagnosis, 23 samples in the cytopenic period after treatment, and 26 samples when patients were in partial (n=10) or complete remission (n=16) following immunosuppressive treatment. TPO serum levels were assessed by a sandwich-antibody ELISA that utilized a polyclonal rabbit antiserum for both capture and signal. Serum samples from normal donors revealed a mean TPO level of 95.3 +/- 54.0 pg/ml (standard deviation). Mean TPO levels in AA sera collected at diagnosis and before onset of treatment were 2728 +/- 1074 pg/ml (P<0.001 compared to normal controls: mean platelet count at that time: 27x10(9)/l). TPO serum levels of AA patients in partial or complete remission after immunosuppressive treatment were significantly lower than TPO levels at diagnosis (P<0.001). However, despite normal platelet counts (mean 167x10(9)/l), TPO levels remained significantly elevated in complete remission (mean TPO 1009 +/- 590 pg/ml, P<0.001 compared to normal controls). There was a significant inverse correlation between serum TPO levels and platelet counts in AA patients who were not transfused for at least 2 weeks prior to sample collection (coefficient of correlation (r) = -0.70, P<0.0001). In summary, TPO levels were highly elevated in sera of patients with AA. Thus there is no evidence to suggest an impaired TPO response contributing to thrombocytopenia in AA. Thrombopoietin did not return to normal levels in remission, indicating a persisting haemopoietic defect in remission of AA. We hypothesize that elevated levels of TPO may be required to maintain normal or near normal platelet counts in remission of AA.

Adolescent↗
PubMed1996

Influence of gelatin matrices cross-linked with transglutaminase on the properties of an enclosed bioactive material using beta-galactosidase as model system.

Transglutaminase (protein-glutamine: amine gamma-glutamyltransferase, EC 2.3.2.13) from Streptoverticillium mobaraense has been used to stabilize immobilisates produced with beta-galactosidase (beta-D-galactoside galactohydrolase, EC 3.2.1.23) from Aspergillus oryzae and acid-processed gelatins of different qualities as support. The isopeptide level of N epsilon-(gamma-L-glutamyl)-L-lysine bonds formed by transglutaminase was determined to estimate their influence on the kinetic properties of the enclosed beta-galactosidase. An HPLC procedure using precolumn derivatization of the gelatin hydrolysates with FMOC-chloride was chosen which permits the analysis of cross-linked lysine with satisfactory precision. Depending on the gelatin quality, the degree of cross-links necessary for the transformation of gelatin into an insoluble protein was in the range 0.3-32.3% of the available lysine residues. beta-Galactosidase was entrapped in the gelatin matrices with a yield of 8-46% of the initial activity. Long reaction times for cross-linking were due to low yields rather than to the number of isopeptide bonds. Repeated use of the immobilisates did not lead to an appreciable loss of activity. The Vmax of beta-galactosidase were diminished by immobilization caused by a tighter package of the protein chains rather than by the extent of cross-links, while the obtained Km values of the free enzyme and the immobilisates were quite similar. Also, the pH and temperature of optima of the free enzyme and the gelatin immobilisates differ only slightly. The data suggest that the immobilization procedure only moderately affects the activity of enzymes catalysing the reaction of a small compound if gelatin with high jelly strength is cross-linked in a 10% solution with transglutaminase.

Aspergillus oryzae↗
PubMed1995

Results of a randomised, controlled, multicentre study of recombinant human granulocyte colony-stimulating factor (filgrastim) in patients with Hodgkin's disease and non-Hodgkin's lymphoma undergoing autologous bone marrow transplantation.

In 54 patients with malignant lymphoma, haematopoietic recovery after high-dose chemotherapy and autologous bone marrow transplantation (BMT) was compared between patients randomised to receive 10 or 30 micrograms/kg/day of r-metHuG-CSF (filgrastim) or no growth factor. After standard high-dose chemotherapy with cyclophosphamide, etoposide and BCNU (CVB regimen for patients with Hodgkin's disease) or BCNU, etoposide, cytosine arabinoside and melphalan (BEAM regimen for patients suffering from non-Hodgkin's lymphoma) followed by autologous BMT, r-metHuG-CSF was administered by continuous intravenous infusion from the first day after autologous BMT until neutrophil recovery. When the r-metHuG-CSF groups were compared with the control group the major findings were: the median time to reach an absolute neutrophil count (ANC) > or = 0.5 x 10(9)/L was 20 days in the control group and 12 and 14 days, respectively, in the r-metHuG-CSF groups (P = 0.0004). The duration of neutropenia (ANC < 0.5 x 10(9)/L) was reduced from 27 days in the control group to 11 and 13 days in the r-metHuG-CSF groups (P = 0.0001). In addition, fewer days of febrile neutropenia were observed in the r-metHuG-CSF groups (5 and 6 days) than in the control group (10 days; P = 0.036). No significant effects of r-metHuG-CSF administration on the number of days with fever, the use of intravenous antibiotics and hospitalisation were detected. R-metHuG-CSF was well tolerated without any serious side-effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Peripheral blood progenitor cells mobilized by chemotherapy plus granulocyte-colony stimulating factor accelerate both neutrophil and platelet recovery after high-dose VP16, ifosfamide and cisplatin.

We report on the chemotherapy plus granulocyte colony-stimulating factor (G-CSF) induced mobilization of peripheral blood progenitor cells (PBPCs) and their impact on haematopoietic recovery following high-dose chemotherapy. Twenty-four patients with advanced solid tumours or lymphomas received standard-dose chemotherapy with VP16, ifosfamide and cisplatin (VIP) followed by filgrastim (G-CSF; 5 micrograms/kg s.c. daily for 14 d) for the prevention of chemotherapy induced neutropenia and for the simultaneous mobilization of PBPCs. Maximal numbers of progenitors of different lineages were reached at day 11 (range 9-14) after VIP chemotherapy. A median of 0.415 x 10(9)/l CD34+ cells (range 0.11-1.98), 9000 CFU-GM/ml (range 2800-17,700), 3500 BFU-E/ml (range 400-10,800) and 200 CFU-GEMM/ml (range 0-4400) were recruited. One single apheresis yielded a median of 1.6 x 10(8) mononuclear cells/kg (range 0.2-5.4) or 5.4 x 10(6) CD34+ cells/kg body weight (range 0.2-24.2). Fourteen patients who showed at least a partial remission after two cycles of the standard-dose chemotherapy regimen were subjected to high-dose VIP chemotherapy (cumulative doses of 1500 mg/m2 VP16, 12 g/m2 ifosfamide and 150 mg/m2 cisplatin) with or without PBPC support. The first six patients were treated with growth factors only (IL-3/GM-CSF) and did not receive PBPCs, whereas the following eight patients were supported with PBPCs in addition to IL-3 and GM-CSF. Neutrophil recovery as well as platelet recovery were significantly faster in patients receiving PBPCs with a median of 6.5 d below 0.1 x 10(9) neutrophils/l and 3 d below 20 x 10(9) platelets/l as compared to 10.5 d and 8 d in control patients receiving growth factors only. The accelerated platelet recovery in patients supported with PBPCs might be explained--in the absence of detectable colony-forming units megakaryocyte--by the presence of glycoprotein IIb/IIIa+, non-proliferating endomitotic megakaryocytic precursor cells within G-CSF mobilized PBPCs. Our data demonstrate that chemotherapy plus G-CSF mobilized PBPCs accelerate both neutrophil and platelet recovery after high-dose VIP chemotherapy in patients with solid tumours or lymphomas.

Adult↗
PubMed1990

Hematopoietic growth factors in bone marrow transplantation.

Preliminary clinical results demonstrate the activity of recombinant human granulocyte (rHuG) and granulocyte/macrophage (rHuGM) colony stimulating factors (CSFs) in enhancing bone marrow engraftment after autologous and allogeneic bone marrow transplantation (BMT). In several analyses of prospective, controlled clinical trials of rHuG- and rHuGM-CSF, reduced morbidity and cost, as well as improved survival have been observed. There is reason to hope that more profound understanding of the in vivo biology of these and other cytokines will lead to further reduction in morbidity and mortality associated with both autologous as well as allogeneic BMT. These advances could significantly broaden the spectrum of diseases amenable to treatment by BMT.

Bone Marrow↗
PubMed1988

LGL-1: a non-polymorphic antigen expressed on a major population of mouse natural killer cells.

Rat mAb have been raised to mouse liver-derived large granular lymphocytes (LGL). One of these mAb (4D11) binds specifically to mouse LGL and appears to recognize a non-allelic determinant on NK-active cell populations. The Ag recognized by 4D11 is expressed on LGL of all mouse strains tested, including C57BL/6 (B6), BALB/c, C3H/HeJ, and SJL/J; thus, we have provisionally called this Ag LGL-1. Analysis of various lymphoid and hemopoietic tissues has indicated that only normal tissues known to contain NK activity have 4D11+ cells. With B6 and B6 congenic strains, a positive correlation exists between the number of LGL in a sample and the percentage of 4D11 immunofluorescence-positive cells detected by flow cytometric analysis. Dual color immunofluorescence analyses indicate that some LGL-1+ cells are also stained for Ly-1 and Thy-1. A very small subset exists that is weakly positive for CD3 and LGL-1. However, virtually no cells are seen which co-express LGL-1 and Ly-2. LU activity against YAC-1 targets was increased 7- to 700-fold in LGL-1+ spleen cells obtained by cell sorting from several different strains of mice (B6, BALB/c, C3H/HeJ, SJL/J, and athymic/nude). Sorted, LGL-1- spleen cells contained little or no NK activity. Cells positively selected for LGL-1 also contained between 50 and 60% LGL by morphology. By using facilitated in vitro antibody plus C' treatments, the majority of NK activity can be depleted from both B6 spleen and liver-derived leukocyte populations enriched for NK cells. mAb 4D11 was also shown to precipitate a protein of approximately 87 kDa from the surface of enriched murine NK cells. This mAb should prove valuable for understanding the role of NK cells in the immune response.

Animals↗
PubMed1988

Acute lymphoblastic leukemia in adult identical twins.

The development of acute lymphoblastic leukemia (c-ALL) in identical twins is reported. The first born had ALL in 1982 and bone marrow transplantation was performed in first complete remission (CR) from his healthy twin-brother the same year. The bone marrow donor developed ALL in 1985; he received an autologous bone marrow transplantation in first CR in 1986. Unfortunately, both patients relapsed in 1986. Cytogenetic studies of the first born revealed multiple chromosomal abnormalities and a marker chromosome whereas the second patient had a Philadelphia chromosome. Genetic reasons or exposure to leukemogenic agents may be responsible for the onset of these leukemias.

Adult↗
PubMed1987

Characterization of the Epstein-Barr virus-induced early polypeptide complex p50/58 EA-D using rabbit antisera, a monoclonal antibody, and human antibodies.

A polypeptide complex (p52) belonging to the D-subspecificity of the EBV-induced early antigens (EA-D) was purified from chemically induced P3HR-1 cells. Rabbit antisera raised against the isolated polypeptides reacted with components of EA-D as could be shown by indirect immunofluorescence and immunoperoxidase staining of IdU-induced EA positive Raji cells, ELISA, and immunoblotting. In one-dimensional immunoblots the rabbit antisera detected a predominant polypeptide complex of 52 kDa. Two-dimensional immunoblots prepared with proteins from IdU-induced Raji cells showed that the rabbit sera detect three series of polypeptides of 52 kDa (pl 8.5-6.2), 55-58 kDa (pl 6.2-4.5), and 48-50 kDa (pl 6.0-4.5). These three groups of polypeptides could also be identified by 50 high titered anti-EA-D positive human sera and a specific monoclonal antibody (R3) as being the main components of EA-D in Raji and B95-8 cells. All polypeptides of the p50/58 complex showed DNA binding properties either by themselves or by an interaction with other proteins. When TPA or IdU-induced Raji cells were labeled with 2Pi, two phosphorylated polypeptides pp50 and pp58 could be immunoprecipitated with the rabbit sera and a high anti-EA titered human serum. The time course of the synthesis of polypeptides associated with the EA-D complex was studied by 2-D immunoblots: EA polypeptides of 52 kDa appeared as early as 6 hr after the addition of IdU to Raji cells in culture, polypeptides of 55-58 and 48-50 kDa after 18 and 25 hr, respectively. The coordinated appearance of these groups of polypeptides and their similar size and reactivity with human sera and rabbit antisera produced against the isolated p52 as well as with a monoclonal antibody (R3) suggested that most of these polypeptides are derived from post-translational modifications of one or a few initially synthesized polypeptides, possibly p52. Phosphorylation seems to be at least one possibility of post-translational modification.

Animals↗
PubMed1987

Disseminated testicular cancer with bulky disease: results of a phase-II study with cisplatin ultra high dose/VP-16/bleomycin.

This is a preliminary analysis of the AIO-Testicular Tumour Study Group trial in patients with disseminated bulky testicular cancer. Treatment plan: cisplatin 35 mg/m2 days 1-5, VP-16 120 mg/m2 days 1-5 (two daily divided doses), bleomycin 15 mg/m2 days 1, 8, 15. Of 98 patients at present evaluable 63% had complete remission or have no evidence of disease (CR/NED), 30% had partial remission (PR) and 7% had no change or progressive disease (NC/P). Relapse-free survival is 93% for the CR/NED group after a median follow up of 2.2 years: the overall survival for the entire patient population is 70%. Toxicity included predominantly granulocytopenic fever and infection with septicaemia, thrombocytopenia, nausea, vomiting, neurotoxicity and lung toxicity, with 7% fatal toxicity. A prospective randomized trial is warranted to evaluate the apparent superior activity of ultra high dose cisplatin in combination with VP-16 and bleomycin.

Adolescent↗
PubMed1986

Increased incidence of IgA antibodies to the Epstein-Barr virus-associated viral capsid antigen and early antigens in patients with chronic lymphocytic leukemia.

Antibody titers to Epstein-Barr virus (EBV)-associated early antigens (EA) and the viral capsid antigen (VCA) were determined by ELISA on 263 sera obtained from healthy donors, patients with Hodgkin's disease (HD), non-Hodgkin lymphomas (NHL), infectious mononucleosis (IM), Burkitt's lymphoma (BL), and nasopharyngeal carcinoma (NPC). As expected, most lymphoma patients showed markedly elevated anti-VCA IgG and anti-EA IgG antibody titers. Only one patient in the NHL group (n = 56) consisting of patients with lymphomas other than chronic lymphocytic leukemia (CLL) and hairy-cell leukemia (HCL), and 3 patients with HCL (n = 19) had high antibody titers of the IgA class to VCA and EA. Seventeen out of 48 patients (36%) with CLL had high IgA anti-VCA titers and 10 of these sera (21%) also contained IgA anti-EA. The geometric mean titer (GMT) of IgA anti-VCA was 2,510, the GMT of IgA anti-EA was 780. These antibody titers were about 10 times lower than the corresponding GMT of the NPC patients investigated in this study. The elevated IgG and IgA antibody titers to VCA and EA in CLL and HCL patients seem to reflect an immunodeficiency secondary to the malignant disease leading to reactivation of latent EBV infection. The possibility that at least some of these B-cell lymphomas are associated with EBV cannot be excluded.

Adult↗