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Biomedical subjects

E Bender

Publications and source records attributed to E Bender.

At least 37 records · Page 2Linked to original sources
PubMed1994

Human monoclonal Fab fragments from a combinatorial library prepared from an individual with a low serum titer to a virus.

An IgG1k lambda Fab library was generated on the surface of phage beginning with bone marrow RNA from a healthy 22-year-old human donor. The donor had been immunized to measles in his early childhood but had only a low serum titer to a measles antigen preparation. The resulting library of approximately 10(7) clones was panned against the measles antigen preparation and three positive Fab-producing clones identified by ELISA. One of the Fabs was found to be specific to measles and to bind with high apparent affinity (10(8) M-1). The other two bind with lower affinity and show marked cross-reactivity with a number of other antigens. They possess heavy chains derived, with extensive somatic modification, from the single member gene family VH6. The study indicates that both high-affinity specific antibodies and lower affinity polyreactive antibodies can be derived from the library approach under appropriate conditions.

Adult↗
PubMed1994

[Limits of osseous reconstruction of the mandible with autologous spongiosa, hydroxyapatite granules and titanium mesh, especially after radiotherapy].

Over the past twenty years the titanium mesh combined with autologous iliac crest spongiosa and hydroxylapatite has performed well in the restoration of mandibular discontinuity defects in 79 patients. In 14 irradiated patients with a transplant bed of inferior quality, however, complications and failures occurred more often than in the 65 not irradiated patients. The results of our investigation clearly show, that the success of mandibular reconstruction mainly depends on a well vascularized transplant bed.

Adult↗
PubMed1993

Linkage analysis in German breast cancer families with early onset of the disease, using highly polymorphic markers from the chromosome 17q11-q24 region.

Linkage analysis in German breast cancer families with early onset of the disease by using six markers on chromosome 17q11-q24 has been carried out. In the region between markers D17S250 and GH, three markers showed positive LOD scores at an estimated distance of zero. Evidence for linkage is greatest for D17S250, with a LOD score of 2.42.

Adult↗
PubMed1993

Recombinant human antibodies: linkage of an Fab fragment from a combinatorial library to an Fc fragment for expression in mammalian cell culture.

The combinatorial phage library approach to immunoglobulin repertoire cloning recently made it possible to isolate gene fragments encoding human immunoglobulin G1 Fabs binding with high affinity to specific antigens. Here we describe the construction of genes encoding whole human anti-tetanus toxoid antibodies based on one of these gene fragments and the efficient expression of these constructs by co-transfection of separate heavy and light chain vectors into a Chinese hamster ovary cell line constitutively expressing a viral transactivator protein. This system will be generally useful for the rapid analysis of recombinant antibodies derived from combinatorial libraries.

Amino Acid Sequence↗
PubMed1990

Secretory synthesis of human interleukin-2 by Streptomyces lividans.

To study the ability of Streptomyces lividans to produce heterologous proteins by secretion, we directly fused DNA encoding the leader peptide of the alpha-amylase inhibitor, tendamistat, produced by Streptomyces tendae, with DNA encoding the mature part of interleukin-2 (IL-2). Such cloned fusion constructs are translated in S. lividans, in spite of the quite different codon usage. The active Il-2 is secreted into the culture broth, though the amounts are much less than that of the alpha-amylase inhibitor. The presence of IL-2 in the supernatants could be demonstrated both by an activity assay and by immunoblotting. In addition to the secreted form, three different species of Il-2 antibody immunoreactive proteins, with different Mrs, are either present in the cells or attached to the cells. This indicates that inefficient processing and translocation of the precursor is a major reason for the low activities found in the supernatant.

Base Sequence↗
PubMed1990

Synthesis and secretion of hirudin by Streptomyces lividans.

To examine the secretory production of heterologous proteins by Streptomyces lividans, we fused the DNA encoding the signal peptide of the alpha-amylase inhibitor tendamistat, derived from S. tendae with a synthetic gene encoding the thrombin inhibitor hirudin. The analysis of secretion by immunoblots revealed an efficient translocation of hirudin through the membrane, with no detectable immunoreaction among the cellular proteins. The secreted hirudin was stable in the shaking culture for about 6 days. A comparison of the hirudin secreted by S. lividans and recombinant reference hirudin from yeast by immunoblots and thrombin inhibition assays shows that hirudin from Streptomyces has a lower specific activity, which may be due to a different aminoterminal sequence or to inexact processing of the precursor.

Amino Acid Sequence↗
PubMed1990

[The use of 60Co-gamma ray-sterilized calf serum in cell culture].

The use of 60Co-gamma-radiation-sterilised calf sera in cell culturing is reported in this paper. Evidence was produced to the effect that 60Co-gamma-irradiation, using a dosage of 3 kGy and a dose rate of 8 kGy/h, of fetal calf serum, neonatal calf serum, and calf serum did not substantially alter the growth-stimulating properties of those sera during 42-day tests. With almost all cell lines and sera used, for all practical purposes, they were identical with the properties of control sera. The following cell lines were used in the experimental programme: one human mammary tumor, MaTu, one human embryonic cell line--E VI, one bat lung cell line--Tb1-Lu, and one human rhabdomyosarcoma--A 204. Growth stimulation was twelve percent below the control value only with Tb1-Lu on Eagle-MEM culturing medium with 3-kGy-irradiation of neonatal calf serum. On the other hand, cell growth was stimulated by 28 percent in A 204 on RPMI 1640 culturing medium, again with 3-kGy-irradiation of neonatal calf serum. Loss of activity by up to 30 percent, depending on the serum used, must be expected from irradiation doses of 10 kGy and 20 kGy which are capable of causing drastic reduction or even complete elimination of serum-borne microorganisms (Bender et al., 1989). Sera irradiated that way would be only conditionally applicable, when it comes to highly vulnerable cell strains.

Animals↗
PubMed1990

Contrast echocardiography: a method to visualize changes in regional myocardial perfusion in the dog model for CABG surgery.

The ability of contrast echocardiography to assess regional myocardial perfusion during cardiopulmonary bypass in a dog model for coronary artery bypass surgery was evaluated. Sonicated Renograffin-76 microbubbles (meglumin diatrigoate and sodium diatrigoate) were injected into an aortic root proximal to an aortic occlusion clamp root while dogs were on cardiopulmonary bypass, with the heart arrested in diastole. Echocardiographic contrast-enhanced regions of myocardial perfusion were easily visualized. Differences in contrast-enhanced myocardial regions depended on coronary artery occlusion or patency. The contrast-enhanced images of myocardial perfusion showed that, for a given myocardial segment of the supplying vessel, the presence or absence of contrast effect reliably predicted vessel occlusion or patency (P less than .01). In the future contrast echocardiography may allow the direct assessment of regional myocardial perfusion in the operating room.

Animals↗
PubMed1989

Effects of warm and cold ischemia on mitochondrial functions in brain, liver and kidney.

The purpose of this work was to study the effects of warm (37 degrees C) and cold (4 degrees C) ischemia on different mitochondrial functions in rat brain, liver and kidney. After 10 to 60 minutes of ischemia at 37 degrees C the energy coupled respiration as well as the ADP-induced malate-aspartate shuttle activity in brain and liver mitochondria or the rate of mitochondrial ATP synthesis in kidney were significantly decreased. However, the respiratory rates and the shuttle activity in the absence of ADP remained unchanged. These data suggest that ischemia primarily affects electron transport in the respiratory chain rather than the hydrogen shuttle and the energy coupling system. When the temperature during the indicated ischemic periods was decreased to 4 degrees C, in brain and liver no significant alterations of these mitochondrial functions were found in comparison with the non-ischemic controls. When rat kidneys were stored for 36 hours at 4 degrees C according to Collins mimicking transplantation conditions, the mitochondrial respiration and ATP synthesis were only slightly decreased. It therefore appears that hypothermia can prevent effectively mitochondrial dysfunction due to ischemia.

Adenosine Triphosphate↗
PubMed1989

[The inactivation of mycoplasmas and bacteria in calf serum by 60Co gamma rays].

Reported in this paper is the use of 60Co gamma radiation to inactivate mycoplasmas in calf serum, newborn calf serum, and fetal calf serum. A dose of 3 kGy, independent of dose rate, was found to be sufficient for inactivation in the above sera of several mycoplasmas, including Acholeplasma laidlawii, Mycoplasma (M.) orale, M. arginini, M. hyorhinis, and M. bovis. The critical dose proved to be at 2 kGy. No difference was found to exist between the above species in susceptibility to irradiation in diluted sera (50%) and 10% in Eagle MEM). Sensibility of wild mycoplasma strains was found to be identical with that of laboratory strains. Hence, 60Co gamma irradiation of sera appears to be a safe method by which to make sera mycoplasma-free. Bacillus subtilis in calf serum was inactivated by doses above 18 kGy, with the critical dose being 15 kGy.

Animals↗
PubMed1988

Effects of excess thymidylate on thymidylate low-requiring strains of Saccharomyces cerevisiae: high mutagenicity and absence of DNA strand breaks.

dTMP exposure concentrations of 0.1 mM or higher are genotoxic in exponentially growing cells of thymidylate low-requiring mutants of Saccharomyces cerevisiae. Mutagenicity of excess dTMP is highest in an exposure concentration 10-fold of that needed for external supplementation of endogenously blocked thymidylate synthesis. Still higher dTMP concentrations are primarily cytotoxic. The canavanine forward-mutation system shows excess dTMP to be as potent a mutagen as irradiation by ultraviolet light. Mutagenicity of excess dTMP, however, differs from that of direct DNA-attacking mutagens in that it is highest in the absence of significant toxicity. Alkaline sucrose gradient centrifugation shows that excess dTMP does not induce significant numbers of DNA single- or double-strand breaks, while conditions of thymidylate deprivation lead to DNA-strand breaks and thymineless death.

Canavanine↗
PubMed1985

Collagen fiber formation in repair tissue: development of strength and toughness.

Dermal repair tissue shows a progressive increase in collagen content which may be related to the wound tensile strength. Wound strength and extensibility are lower than those found in normal skin. In animals, wounds closed by metal clips are chosen as a model to study the proliferative and remodeling phases of healing from a mechanical and morphological point of view. During the proliferative phase the low wound strength is associated with formation of collagen fibers of small diameter, later, (days 28-45) an acute change appears corresponding to the remodeling phase, with increased collagen fiber diameters observed by scanning electron microscopy and light microscopy, and increased tensile strength and toughness. By 180 days, wound strength and collagen fiber morphology were close to that observed in the normal skin. These observations show a direct relationship between collagen fiber diameter and tensile strength. In addition, packing density of collagen fibrils (determined by the birefringence retardation per unit thickness under polarized light) was unchanged until day 90, although collagen fiber diameters increased during this time.

Animals↗
PubMed1984

Characterization of the immunosuppressive effect of burned tissue in an animal model.

The immunosuppressive effect of burned tissue was studied using a mouse burn model. To evaluate the immunologic status an in vivo measure of cell-mediated immunity (CMI) involving contact sensitization of mice by painting the skin with dinitrofluorobenzene was used; mice were challenged 5 days later by painting the ear with the same antigen. Ear swelling in response to antigenic challenge was used as a quantitative measure of CMI; diminution in ear swelling in treatment mice compared to sensitized, unburned control mice indicated the degree of immunosuppression. A full-thickness steam burn covering 20% body surface ares (BSA) was profoundly immunosuppressive as reflected by ear swelling of 45 to 60% of that found in normal mice; partial thickness burns and burns of 10% BSA extent were not significantly immunosuppressive. Transfer into unburned mice of burned skin equivalent in size to a 20% BSA burn eschar resulted in marked immunosuppression, but transfer of smaller amounts of burned skin, or of larger amounts of unburned skin and normal and burned liver tissue, did not produce immunosuppression. Mice receiving a very high-temperature (300 degrees C), dry burn were only slightly more suppressed than mice receiving a standard steam burn. Normal immunity was preserved in burned mice which received daily application of cerium nitrate to the wound for 7 days, but application of other topical agents commonly used in burn treatment did not preserve immunity. Postburn immunosuppression thus appears related quantitatively to toxic factors in burned skin, and these toxic factors can be abrogated in burned mice by the topical application of cerium nitrate.

Animals↗