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Biomedical subjects

J Kellner

Publications and source records attributed to J Kellner.

At least 19 recordsLinked to original sources
PubMed2006

Bronchial hyperreactivity is correlated with increased baseline airway tone.

Physiologically, airways are not completely relaxed but maintain a baseline airway tone (BAT). Although not fulfilling the criteria for obstructive airway disease, increased BAT may nevertheless be important because the same amount of airway narrowing can be well tolerated or can cause severe airway obstruction depending on the starting point of the narrowing. In this study, we aimed at studying if BAT is correlated with bronchial hyperreactivity (BHR). For in vitro studies, airways in murine lung slices were digitally recorded and the change in cross-sectional area with time was quantified. BAT was measured by the amount of relaxation induced by permeabilization of the cell membrane with beta-escin in zero external calcium. BHR was induced by incubation of lung slices with interleukin-13 (IL-13). T-bet knock-out mice served as an additional model for BHR. T-bet knock-out mice show a shift towards TH2-lymphocytes and display histological as well as functional characteristics of asthma. In vivo, the specific airway resistance of healthy non-smoking volunteers was assessed before and after inhalation of formoterol and bronchial challenge was performed using methacholin. In murine lung slices that had been cultivated without serum, only a minimal BAT could be observed. But, after cultivation with 10 % new born calve serum, airways showed a BAT of approximately 13 % that could be reduced by incubation with an IL-13 receptor antagonist. Atropine, isoproterenol and indomethacin failed to relax airways regardless of cultivation with serum. Incubation of lung slices without serum but with IL-13 increased BAT as well as airway responsiveness to acetylcholine and both effects were more pronounced in small compared to large airways. In lung slices from T-bet knock-out mice, airways were hyperreactive compared to airways in slices from wild type mice and BAT was found to be increased. Again, both effects were more pronounced in small compared to large airways. In human non-smokers without airway obstruction, increased BAT was correlated with bronchial hyperreactivity. We therefore conclude that although not fulfilling the criteria for obstructive airway disease, increased airway tone may yet be relevant in asthma.

Acetylcholine↗
PubMed2006

[Ca2+-signaling in smooth muscles cells of the airways in T-bet knock-out mice].

BACKGROUND: Airway smooth muscle cells (ASMC) play a key role in bronchial hyperresponsiveness (BHR). A major component of the signalling cascade leading to ASMC contraction is calcium. T-bet knock-out (KO) mice show the key features of allergic asthma such as a shift towards T (H2)-lymphocytes and display a broad spectrum of asthma-like histological and functional characteristics. In this study, we aimed at investigating whether Ca (2+)-homeostasis of ASMC is altered in T-bet KO-mice as an experimental model of asthma. METHODS: Lung slices of 100 to 200 microm thickness were obtained from T-bet KO- and wild-type mice. Airway contractions in response to acetylcholine (ACH) were measured by video-microscopy and Ca (2+)-signaling in single ASMC of lung slices was assessed using two-photon microscopy. RESULTS: Airways from T-bet KO-mice showed increased baseline airway tone (BAT) and BHR compared to those of wild-type mice. The increased BAT was correlated with an increased incidence of spontaneous changes in intracellular Ca (2+)-concentrations, whereas BHR correlated with higher ACH-induced Ca (2+)-transients and an increased proportion of ASMC showing Ca (2+)-oscillations. Emptying intracellular Ca (2+)-stores using caffeine or cyclopiazonic acid induced higher Ca (2+)-elevations in ASMC from T-bet KO compared to wild-type mice. CONCLUSIONS: Altered Ca (2+)-homeostasis of ASMC contributes to increased BAT and BHR in lung slices from T-bet KO mice as a murine asthma model. We propose that a higher Ca (2+)-content of the intracellular Ca (2+)-stores is involved in the pathophysiology of these changes.

Animals↗
PubMed2006

Ex vivo expansion of mafosfamide-purged PBPC products.

BACKGROUND: Multiple studies have demonstrated that 'purging' of autografts with 4-hydroperoxycyclophosphamide (4HC) or the related compound mafosfamide (Mf), to eradicate residual leukemia, produces the best results associated with autologous blood and marrow transplantation for AML. However, 4HC purging results in prolonged aplasia. Therefore, we evaluated the potential of ex vivo expansion of Mf-treated CD34+ cells from mobilized PBPC. METHODS: CD34+ cells were isolated from PBPC products and treated with 30 microg/mL Mf. The Mf-treated CD34+ cells were washed and cultured for 14 days in StemLine II-defined media containing recombinant human (rh) SCF, G-CSF and thrombopoietin (Tpo). RESULTS: Treatment with Mf resulted in 90% killing of progenitor cells (GM-CFC) but maintenance of SCID-repopulating cells (SRC). Ex vivo culture of the Mf-treated CD34+ cells resulted in decreased cell numbers (10-20% of the starting cell dose) during the first week. Nevertheless, in the second week of culture the total cell numbers expanded to approximately 20-fold above starting cell numbers and progenitor cells returned to approximately pre-treatment levels. DISCUSSION: These studies demonstrate the potential of ex vivo culture to expand both total cell numbers and progenitor cells following treatment of PBPC CD34+ cells with Mf. Clinical studies are currently being initiated to evaluate the engraftment potential of these purged and expanded products.

Adjuvants, Immunologic↗
PubMed2005

Outgrowth of a transformed cell population derived from normal human BM mesenchymal stem cell culture.

BACKGROUND: Human mesenchymal stem cells (hMSC) have been isolated and characterized extensively for a variety of clinical applications. Yet it is unclear how the phenomenon of hMSC plasticity can be safely and reasonably exploited for therapeutic use. METHODS: We have generated mesenchymal stem cells (MSC) from normal human BM and identified a novel cell population with a transformed phenotype. This cell population was characterized by morphologic, immunophenotypic, cytogenetic analyzes and telomerase expression. Its tumorigenicity in NOD/SCID mice was also studied. RESULTS: A subpopulation of cells in hMSC culture was noted to appear morphologically distinct from typical MSC. The cells were spherical, cuboidal to short spindle in shape, adherent and exhibited contact independent growth. Phenotypically the cells were CD133(+), CD34(-), CD45(-), CD90(low), CD105(-), VEGFR2(+). Cytogenetic analysis showed chromosome aneuploidy and translocations. These cells also showed a high level of telemerase activity compared with typical MSC. Upon transplantation into NOD/SCID mice, multiple macroscopic solid tumors formed in multiple organs or tissues. Histologically, these tumors were very poorly differentiated and showed aggressive growth with large areas of necrosis. DISCUSSION: The possible explanations for the origin of this cell population are: (1) the cells represent a transformed population of MSC that developed in culture; (2) abnormal cells existed in the donor BM at rare frequency and subsequently expanded in culture. In either case, the MSC culture may provide a suitable environment for transformed cells to expand or propagate in vitro. In summary, our data demonstrate the potential of transformed cells in hMSC culture and highlight the need for karyotyping as a release criteria for clinical use of MSC.

AC133 Antigen↗
PubMed2004

Ex vivo expansion of cord blood mononuclear cells on mesenchymal stem cells.

BACKGROUND: Cord blood (CB) cells are being used increasingly as a source of hematopoietic cells to support high dose chemotherapy. However, CB units contain low numbers of cells, including CD34+ cells, and thus their use is associated with significant delays in engraftment of neutrophils and platelets. Exvivo expansion of CB has been proposed to increase the numbers of cells available. We and others have reported the requirement of CD34 selection for optimal expansion of CB products'; however, the selection of frozen CB products in clinical trials results in significant loss of CD34+ cells, with a median recovery of 50, but less than 40% recovery in more than one-third of products. In the present studies we evaluated the potential of mesenchymal stem cells (MSC) to support ex vivo expansion of unselected CB products. METHODS: Mononuclear cells (MNC) from CB products were isolated and cultured on preformed MSC layers in T150 flasks containing 50 mL Stemline II media plus hematopoietic growth factors. Various culture conditions were compared for optimal expansion of the CB MNC. RESULTS: Ex vivo expansion of CB MNC on MSC resulted in 10- to 20-fold expansion of total nucleated cells, seven- to 18-fold expansion of committed progenitor cells, two- to five-fold expansion of primitive progenitor cells and 16- to 37-fold expansion of CD34+ cells. DISCUSSION: These studies demonstrated significant expansion of CB products without CD34 cell selection using culture conditions that are clinically applicable. Our current focus is to initiate clinical trials to evaluate the in vivo potential of CB cells expanded with these conditions.

Antigens, CD34↗
PubMed1995

Cyfra 21-1. A new potential tumor marker for squamous cell carcinoma of head and neck.

OBJECTIVE: Evaluation of Cyfra 21-1 (cytokeratin fraction 21-1) in squamous cell carcinoma of the head and neck. DESIGN: Prospective study. PATIENTS: Serum Cyfra 21-1 concentration was measured in 250 samples from patients with squamous cell carcinoma of head and neck, patients with benign tumors of head and neck, healthy control subjects, and patients in remission from squamous cell carcinoma of head and neck. RESULTS: Cyfra 21-1 concentration was elevated in 60% of the new patients with squamous cell carcinoma but only in 8% of patients with benign tumors and 3.5% of the healthy controls. At a cutoff of 1.3 ng/mL, the sensitivity of the test was 60%, the specificity was 94%, positive predictive value was 75%, and negative predictive value was 89%. The marker levels tended to follow the clinical course of the disease and were useful for therapy monitoring. Cyfra 21-1 levels were in good correlation with the tumor stage expressed by the local (T) and the lymphatic spread (N) and were inversely correlated with histologic grade, eg, higher in poorly differentiated carcinoma than in well-differentiated squamous cell carcinoma. CONCLUSION: Cyfra 21-1 evaluation in head and neck squamous cell carcinoma is worthwhile for performance of an ample study that will prove and establish its routine use.

Adult↗
PubMed1995

The specificity and affinity of polyclonal antibodies raised in rabbits against a hapten conjugated to rabbit serum albumin.

In this study, rabbit antisera to hapten-rabbit serum albumin conjugates were investigated regarding antibody titer, affinity, specificity, and affinity distribution. Methyl phosphonic acid p-amino-phenyl 1,2,2-trimethylpropyldiester (MATP) served as model hapten. Four MATP-rabbit serum albumin conjugates with various hapten densities (with and without spacer) were synthesized and used for immunization of rabbits. Antisera were collected over a 130 day-period and characterized with different ELISA methods. We found that immunogens with rabbit serum albumin gave antisera with lower titers, but similar affinity as compared to polyclonal or monoclonal antibodies obtained with non-rabbit protein as carrier protein. Immunogens with a low hapten density led to higher final titers without affecting antibody affinity or specificity. Immunogens containing a bridging group resulted in higher antibody affinity with a changed specificity. The pattern of antibody affinity distribution differed considerably among individual rabbits and showed a non-Gaussian subpopulation distribution.

Animals↗
PubMed1995

Breakdown of the round window membrane permeability barrier evoked by streptolysin O: possible etiologic role in development of sensorineural hearing loss in acute otitis media.

Sensorineural hearing loss is a common sequela of acute and chronic otitis media, and the round window membrane (RWM) is currently being considered as a major route for noxious agents to pass from the middle ear cavity to the cochlea. Streptococcus pneumoniae, a major causative agent of otitis media, and Streptococcus pyogenes A produce molecularly related toxins, pneumolysin and streptolysin O (SLO), that form large pores in target membranes. In this study, we analyzed the effects of SLO on the permeability of the RWM. Resected RWMs from a total of 104 guinea pigs were embedded between two chambers of an in vitro system. One chamber was designated as the tympanal (cis) compartment, and the other was designated as the inner ear (trans) compartment. The permeability of normal and SLO-damaged RWMs towards Na+, [14C]mannitol, and proteins was investigated. SLO evoked permeability defects dose dependently in the RWM with fluxes of both Na+ and [14C]mannitol being demonstrable over a time span of up to 8 h. Serum proteins and radioiodinated SLO were also shown to pass through the damage RWM. Scanning electron microscopy revealed the morphological correlates to these results. We propose that damage to the RWM by potent pore-forming cytolysins leads to leakage of ions from the perilymph. Ionic disequilibrium and passage of noxious macromolecules to the cochlea could contribute to disturbances of the inner ear function.

Albumins↗
PubMed1994

Identification of antigenic differences of recombinant and pituitary bovine growth hormone using monoclonal antibodies.

For characterization and determination of recombinant bovine GH (rbGH) eight monoclonal antibodies (MAb) were produced against rbGH from Monsanto. The various MAb showed different affinities to rbGH, pituitary bovine GH (pbGH), and pituitary ovine GH (poGH). With epitope analysis several MAb were shown to recognize different epitopes of rbGH. The MAb MUC-rbGH-3A11 and MUC-rbGH-1E5 were used to develop a Sandwich ELISA. By checking the specificity of the assay no cross reactivity was found with pituitary porcine GH, pituitary human GH, bovine or ovine prolactin and little cross reactivity with poGH could be found. The Sandwich ELISA detected various rbGH (Monsanto, Elanco, Cyanamid) with different N-terminal amino acids and discriminated between rbGH and pituitary bovine GH by an affinity factor of 2.0. The detection level was 2 ng rbGH per ml PBS buffer. The recovery was about 86% in bovine serum. It might therefore be possible to detect rbGH-treated cows using a Sandwich ELISA, but this would need a field study.

Animals↗
PubMed1993

[New possibilities in oral immunoprophylaxis of newborn diarrhea in calves--a field study using specific egg antibodies].

To investigate the effect of oral immunoprophylaxis in diarrhea of newborn calves egg powder with antibodies specific to E. coli K99 (ETEC) and rotavirus were used in a field trial in south west Germany. Fourteen farms with a total of 105 calves were selected. Egg powder (21 g per day) was fed as a supplement to the regular diet for the first 14 days after birth. Animals of the control group received egg powder derived from hens not immunized with the antigens. Frequency, duration and severity of diarrhea, fecal dry matter and weight gain were examined in order to evaluate the influence of the specific egg powder. Using a Lactovac test kit pathogens were detected in the feces of 76.2% of the calves, with 24.7% infected with E. coli K99, 39.1% with rotavirus, 19.0% with coronavirus and 32.4% with cryptosporidia. An overall reduction in diarrhea frequency from 68.5% to 52.9% was observed in calves fed with specific antibodies. Animals with an E. coli K99 infection showed a reduction from 92.3% to 30.7% and those infected exclusively with E. coli K99 from 83.3% to 0%. The duration of diarrhea was significantly reduced (42 h) in animals fed with specific antibodies in comparison to the control animals (60 h). With the exception of animals infected with coronavirus a marked reduction in the severity of diarrhea was observed in antibody treated calves. During the first 14 days after birth antibody treated calves showed a weight gain of 5.6 kg on average in comparison with 3.5 kg in the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Development of a direct and indirect chemiluminescence immunoassay for the detection of an organophosphorus compound.

The following study describes the development of two immunoassays for the semiquantitative determination of the organophosphorus compound methyl phosphonic acid, p-aminophenyl 1,2,2-trimethyl-propyl diester (MATP). These assays are a direct competitive, labelled-hapten, enzyme immunoassay and a competitive enzyme immunoassay with indirectly labelled antibody, both with luminescence determination of peroxidase. A camera luminometer was used to determine final signal strength. A constant light reaction was reached using luminol (5-amino-2,3-dihydro-1,4-phalazinedione), and by adding coumaric acid as an enhancer. A five minute interval was selected as exposure time. This phototechnical system makes a semiquantitative detection of MATP possible. The detection limits for both assays were at 10(-6)mol/l MATP. With the help of a microtiter luminometer (reader) the detection limit was reduced to 5 x 10(-8) mol/l MATP, by measuring the real intensity of the chemiluminescence signal.

Antibodies, Monoclonal↗
PubMed1992

The influence of various adjuvants on antibody synthesis following immunization with an hapten.

For the production of specific antibodies to the hapten MATP (4-Amino-1,2,2-trimethyl-phenylphosphonate) in Balb/c mice various non-toxic adjuvants were compared to Freund's complete adjuvant (FCA). For immunization the hapten MATP was coupled to the carrier human serum albumin (HSA). The immunostimulating effect of the synthetic lipopeptides Pam3Cys-OH, Pam3Cys-Ser-Ser-Asn-Ala and different concentrations of the lipohexapeptide Pam3Cys-Ser-(Lys)4 (Pam3Cys = S-[2,3-bis(palmitoyloxy)-(2RS)-propyl]-N- palmitoyl-(R)-cysteine as well as of aluminium hydroxide were tested. IgG antibody titers in serum were determined in ELISA. In dose-response studies 50 micrograms Pam3Cys-Ser-(Lys)4 per mouse was the most effective dose with a long period of high antibody levels after the second booster. Pam3Cys-Ser-Ser-Asn-Ala provoked only low antibody titers. Immunostimulation with Pam3Cys--OH did not result in an increased production of specific antibodies. Compared to the control group an enhanced antibody synthesis could be provoked with aluminium hydroxide. However, the increase was much smaller than by using FCA. The lipopeptide Pam3Cys-Ser-(Lys)4 turned out to be a very potent adjuvant. One week after booster injection into mice 50 micrograms of this substance helped to elicit a higher antibody titer than FCA. Hence, as far as the degree of antibody production is concerned, Pam3Cys-Ser--(Lys)4 represents an alternative adjuvant to FCA.

Adjuvants, Immunologic↗
PubMed1991

[Staging of rectal carcinoma by endorectal ultrasonography].

Staging of rectal carcinoma is essential for its management. 23 patients with rectal lesions were examined by endorectal ultrasonography. Of these 19 had rectal carcinoma and in 4 there was an abscess of the rectal wall, previously diagnosed by sigmoidoscopic biopsy. 10 of those with carcinoma were examined by computerized tomography as well, and 10 were operated on. In most cases the staging of rectal carcinoma by endorectal ultrasonography was accurate and compared well with the operative histological results. We conclude that endorectal ultrasonography is the method of choice for staging of rectal carcinoma prior to treatment.

Carcinoma↗
PubMed1991

Influence of various adjuvants on the synthesis of specific antibodies of chicken, sheep and rabbit following immunization with an hapten.

In order to obtain high amounts of specific antibodies against the hapten methylphosphoric acid, para-aminophenyl-1,2,2-trimethyl-propyldiester (MATP) different animals were immunized with MATP coupled to the carrier protein human serum albumin (MATP12-HSA) using several adjuvants. The best specific immune response in sheep, rabbit and chicken was reached with Freund's complete adjuvant with animal specific differences being tested by an ELISA. The adjuvants aluminium hydroxide (5% and 10%) and diphosphoryl lipid A showed no significant difference compared to the control group (NaCl with MATP12-HSA). In rabbits and chickens MATP12-HSA can be used to reach an immune response without the help of an adjuvant.

Adjuvants, Immunologic↗
PubMed1987

[Pressure measurements of the round window membrane in the guinea pig cochlea].

Some clinical observations suggest that sudden hearing loss or dizziness can be due to rupture of the round window membrane. Experiments on 16 guinea pigs showed that after injection of fluid the pressure in the scala tympani of the basal turn increases. This leads to rupture of the round window membrane. The pressure was recorded via a piezoresistant transducer. Morphological changes were visualised by scanning electron microscopy.

Animals↗
PubMed1985

Ectopic prostatic tissue in urethra.

Ectopic prostatic tissue in the urethra is an uncommon lesion. It appears more often in young males. The common presenting symptoms are hematuria or hemospermia. It is a benign lesion, and transurethral fulguration is believed to be adequate treatment.

Choristoma↗