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Biomedical subjects

H Lenz

Publications and source records attributed to H Lenz.

At least 19 recordsLinked to original sources
PubMed1992

Combinatorial functions of two chimeric antibodies directed to human CD4 and one directed to the alpha-chain of the human interleukin-2 receptor.

The general feasibility of chimerization of monoclonal antibodies (mAbs) has already been shown for a large number of them. In order to evaluate in vitro parameters relevant to immunosuppressive therapy, we have chimerized and synthesized two anti-CD4 mAbs recognizing two different epitopes on the human T-lymphocyte antigen, CD4. The chimerized mAbs are produced at levels corresponding to those of the original hybridoma cell lines. With respect to activation of human complement, the individual Abs are negative; however, when used in combination, complement activation was performed. When applied in combination, they were found to modulate the CD4 antigen, whereas the individual mAb do not display this property. Individually they mediate an up to 60% inhibition of the mixed lymphocyte reaction (MLR). However, by combination of an anti-CD4 mAb with one directed against the alpha-chain of the human IL2 receptor, nearly 100% inhibition of the MLR was achieved, even with reduced dosage of the mAbs. Our data suggest that the combination of an anti-CD4 mAb and an anti-IL2R alpha chain mAb is more effective with respect to immunosuppression than each mAb by itself, indicating that this mAb cocktail could be a new strategy for immunosuppressive therapy.

Amino Acid Sequence↗
PubMed1991

Synthesis and functional characterization of a recombinant monoclonal antibody directed against the alpha-chain of the human interleukin-2 receptor.

We have determined the sequence of the light and heavy chains of mAb 3G-10 (IgG1), a monoclonal antibody competing with interleukin 2 (IL2) for binding to the human IL2 receptor Tac protein. The antibody-encoding genes were chimerized by introducing splice donor and part of the intron sequences into the cDNA and subsequently linking it to the constant parts of the human IgG1 gene. The chimeric mAb was produced in mouse myeloma cells and purified. Murine and chimeric mAbs showed similar properties with respect to inhibition of T-cell proliferation. In contrast to its murine counterpart, the chimeric mAb exhibited Ab-dependent cellular cytotoxicity and, when combined with an Ab recognizing a different epitope on the IL2 receptor Tac protein, was able to activate human complement. The chimerized mAb might therefore have improved therapeutic efficacy.

Amino Acid Sequence↗
PubMed1991

Genes encoding a mouse monoclonal antibody are expressed in transgenic mice, rabbits and pigs.

To study the expression pattern of immunoglobulin-encoding genes in transgenic animals, we have introduced the genes for the light and heavy chain of a mouse monoclonal antibody (mAb) into the germ-line of mice (control), rabbits and pigs. The transgenes were detected in the mouse lines, two rabbit lines and pigs. Titers of 100-200 micrograms mAb/ml (rabbits) and up to 1000 micrograms mAb/ml (pig) were measured in the sera of the transgenic animals. Isoelectric focusing experiments with serum followed by immunofixation revealed that in the transgenic pig only a minority of the bands were identical to those of the purified mouse mAb. In transgenic rabbits we found no coincidence of bands at all. The results can be explained by assuming tissue- and cell-type-specific glycosylation, modification and possible heterologous chain associations. Expression of Ab in the serum of animals could help to protect against diseases (e.g., influenza in pigs).

Animals↗
PubMed1990

Expression of heterobispecific antibodies by genes transfected into producer hybridoma cells.

We report the expression of heterobispecific antibodies (Ab) by transferred genes. The kappa and gamma 1 genes of a mouse anti-idiotypic Ab (IgG1) were transfected into a mouse hybridoma cell line secreting Ab (IgG1), directed against an isoenzyme of human creatine kinase. Stable cell lines secreting the parental Ab derived from the introduced genes and a mixture of hybrid Ab were established. The transfected Ab specificity was expressed at similar levels as in a nonproducer background (50 ng-1 microgram/ml), heterobispecific Ab was expressed in microgram quantities (1-4 micrograms/ml) in all cell lines examined. As shown by isoelectric focusing analysis, hybrid Ab (heterobifunctional and other species) are expressed to a similar extent in the transfected cell lines as the Ab in the parental Ab-producing cells.

Animals↗
PubMed1990

Lymphokine release, suppressor cell generation, cell surface markers, and cytotoxic activity in cancer patients receiving natural interleukin-2.

We monitored patients treated for 5 days with continuous infusion of increasing doses (3 to 6 x 10(6) U/d) of natural interleukin-2 (IL-2). CD16+, CD25+, and CD56+ cells increased after treatment. Plasma tumor necrosis factor-alpha (TNF-alpha) levels, but not interferon-gamma (IFN-gamma) levels, increased during IL-2 treatment, but spontaneous and IL-2-stimulated TNF-alpha secretion in vitro remained abnormally low. However, mitogen-stimulated TNF-alpha release was normal. Mitogen-stimulated, but not IL-2-stimulated, IFN-gamma release was strongly depressed. Low spontaneous and IL-2-stimulated cytotoxicity on K562 or Daudi increased after treatment. Low suppressor cell generation also normalized after treatment. This appears to be the first reported study of immunologic monitoring of cancer patients treated with natural rather than recombinant IL-2.

Antigens, Differentiation↗
PubMed1990

[Basic considerations on the use of the Excimer laser in dentistry].

SEM studies showed that irradiation in the energy density range of 4-6 J/cm2 resulted in the removal of hard tooth structure without causing thermal alterations of the tissues. In this process (photoablation) the natural structures of the tissues are "exposed". The surface structure thus produced in dentin depends on whether the dentin tubules are hit transversally or longitudinally and varies accordingly. The surface structure of enamel, as well, is determined by the alignment of the prisms. When the laser beam was optimally adjusted (energy densities of 4-6 J/cm2 and peripheral fading), no structural changes could be demonstrated in the depth of the tissue.

Dental Cavity Preparation↗
PubMed1989

[Removal of hard tooth substance with Excimer lasers].

The usefulness of an Excimer laser (wavelength 308 nm) to remove enamel and dentin was assessed by examining the necessary energy flow density, micromorphological changes, and irradiated surfaces. Our results demonstrated that it is possible to remove dentin and enamel with the Excimer laser in controlled fashion. The temperature in the pulp cavity rose as a function of the distance to the site of irradiation (corresp. to distance between temperature measuring probe and irradiated tooth surface) and the duration of exposure and amounted to 3.5 degrees C-18.3 degrees C. Differences in the micromorphology of the surface structures were observed as a function of the material (enamel or dentin) and the duration of irradiation.

Dental Cavity Preparation↗
PubMed1989

[Root canal preparation using Excimer laser beams].

An in vitro investigation of root canal preparation on extracted human teeth by 308 nm Excimer Laser radiation was performed. It could be demonstrated that a secure and effective root canal preparation is possible by Excimer Laser radiation. SEM investigations on axially splitted roots showed root canal walls free of smear layer or any other soiling. The dentin-tubuli where open and free of clogging. There was no case of via falsa or overinstrumentation.

Evaluation Studies as Topic↗
PubMed1989

[Fluorescence diagnosis of porphyrin-marked urothelial tumors. Status of experimental development].

On the basis of selective storage of fluorescing hematoporphyrin derivative (HpD) in tumors, a method has been developed that enables the endoscopic detection of early-stage cancer by monitoring fluorescent images. The contrast-reducing portion of the superposed tissue autofluorescence is suppressed by the use of two-wavelength excitation and subsequent image processing in realtime. The amount of photosensitizing HpD necessary for diagnostic purposes is considerably reduced by means of sensitive detection devices. A clear distinction between benign and malignant bladder tissue seems possible according to the results of animal studies.

Animals↗
PubMed1989

[Usefulness of Excimer lasers in dentistry].

In vitro investigation on the influence of 308 nm excimerlaserradiation on extracted human teeth. Depending on the distance of the area of radiation to the pulp the temperaturerise ranged from 3.5 degrees C (6 mm) to 18.2 degrees C (less than 0.5 mm). REM investigations of radiated surfaces indicate a good retention of filling materials. TEM investigations of radiated dental hard tissues demonstrated that there is no structural change of the ultrastructure below the radiated surface.

Dental Restoration, Permanent↗
PubMed1988

[A laser surgery procedure in the treatment of tattooing with the argon ion laser].

A laser surgery procedure for treating tattoos using argon ion laser is described. The epithelial changes during continuous radiation are land marks for laser surgery procedure: 1. The coagulation zone, 2. its bubble-like rise, 3. its breaking, 4. the beginning of the carbonisation zone and 5. setting of a decreasing coagulation zone for smoothing the edges. From the very onset of the carbonisation zone radiation is discontinued and continued only in the periphery producing a decreasing coagulation zone. Punctiform and line-pattern laser application is employed; the untreated areas in between are treated in the following session. The average time between the sessions is 7 weeks and the average number of sessions for a tattoo is 3.1. The observation time is on an average 2 years and 1 month. 134 tattoos of 43 patients are treated by this technique. In 18.6% of the tattoos very good results are achieved, in 51.5% a good result, in 28.4% a satisfactory result and in 1.5% an unsatisfactory result. Hypopigmentations are seen in 19.4%, atrophic scars in 12.7%, hypertrophic scars in 14.9% and a rest of tattoos in 8.9%. Keloids are not seen. Using this argon laser technique for treating tattoos you will obtain better results with fewer side effects than in those studies which are accomplished treating tattoos with argon lasers and described in literature up to now.

Adolescent↗
PubMed1987

Cloning and nucleotide sequence of heavy- and light-chain cDNAs from a creatine-kinase-specific monoclonal antibody.

Determination of creatine kinase isoenzymes by inhibition assay is a useful tool for the diagnosis and monitoring of myocardial infarction. We have established several mouse hybridoma lines secreting monoclonal antibodies with creatine kinase M-subunit inhibitory capacity. One of the monoclonal antibodies (MAK33) inhibits creatine kinase-MM by 80% without influencing the activity of creatine kinase-MB. A combination of two monoclonal antibodies increased the inhibition of creatine kinase MM up to 99.4%. Poly(A) + RNA of hybridoma cells secreting MAK33 was isolated and used for cloning cDNA of both heavy and light chains of this antibody. Full-length cDNA clones were obtained by hybridization with gamma 1 and kappa constant region cDNA probes. The complete nucleotide sequences from the variable regions including signal peptide and part of the 5'-untranslated regions have been determined.

Amino Acid Sequence↗
PubMed1987

Reconstitution of functionally active antibody directed against creatine kinase from separately expressed heavy and light chains in non-lymphoid cells.

We report here for the first time reconstitution and secretion of functionally active antibody in non-lymphoid cells. Expression vectors for the light and the heavy chain of a monoclonal antibody directed against creatine kinase (EC 2.7.3.2) were introduced into COS and CHO Chinese hamster ovary dhfr- cells. Introduction of the expression vectors separately gave rise to immuno-reactive material in the culture supernatants, but only cotransfection of the expression plasmids resulted in secretion of protein with immuno-reactivity against antibodies directed against mouse heavy and light chains as well as specific antigen-binding affinity, as determined by enzyme-linked immunosorbent assay. Secreted kappa and gamma chains from reconstituted antibody were characterized by immunoadsorption and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In COS cells, reconstituted antibody was transiently secreted; cotransfection of kappa and gamma chain expression plasmids with a dihydrofolate reductase (DHFR)-expression plasmid into CHO dhfr- cells gave rise to stable transformants secreting functionally active antibody.

Animals↗
PubMed1987

Denial of lineage: clinical investigation of 50 cases.

Fifty randomly selected Chinese schizophrenic patients with denial of lineage were investigated. This delusion concerns the generation of parents, sisters, but not the offspring. Twenty-four of them manifested delusion of high-ranking lineage or of distinguished leadership lineage. Denial of lineage, involving the delusion of high-ranking lineage and the delusion of leadership lineage, may occur at the onset or during the course of schizophrenia. The clinical characteristics of this delusion are described and its concept, diagnosis, differential diagnosis, course and also possible mechanism are discussed. One possible mechanism is of psychodynamical origin. Emotional conflicts resulting from dissatisfaction of the primary need of being loved from birth may contribute to the onset of the denial of lineage. The second possible mechanism is a sociocultural fact. Far Eastern culture is based on the clan whereas occidental culture is based on the self. Thus can observe the denial of lineage in the Far East, but in the occident we can experience instead the idea of surmounting our self so as to be god or now to experience the omnipotence in form of technical ideas, e.g. the rays.

Adult↗
PubMed1987

A monoclonal antibody that specifically inhibits human salivary alpha-amylase.

Our monoclonal antibody 88E8 specifically binds to and inhibits human salivary alpha-amylase (EC 3.2.1.1) and cross reacts negligibly with the pancreatic isoenzyme, inhibiting it by less than 1%, as compared with about 90% for the salivary isoenzyme. The antibody binds the S1 and S2 types of salivary alpha-amylase, but no pancreatic alpha-amylase isoenzyme forms. A pancreatic alpha-amylase assay involving 88E8 is under development, with alpha-glucosidase as auxiliary enzyme and p-nitrophenyl-maltoheptaoside as substrate; we give preliminary data on this assay. The assay has to be done by substrate start, because the antibody interacts very slowly with the enzyme in the presence of substrate. Assay results for pancreatic alpha-amylase correlate well with those for isoamylase assayed with use of an inhibitor from wheat-germ.

Antibodies, Monoclonal↗