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F Zepp

Publications and source records attributed to F Zepp.

18 recordsLinked to original sources
PubMed1992

Flow cytometric immunophenotyping: principles and pitfalls.

Within the last decade flow cytometry (FCM) has become an integral part of basic immunological research. Elaboration of this technology has been intensively stimulated by a rapidly growing sophistication in monoclonal antibody technology and vice versa. At present numerous applications are established that allow an increasingly detailed insight into the immune system, however, automation still must be considered the "cinderella of the arts". Thus, transition of this powerful approach from a basic to a routine clinical procedure is much more difficult than expected. Sufficient usage of flow cytometers still requires some knowledge of physics and its technical applications. Moreover, several problems arise from the complexity of the biological systems investigated. Here we give a brief introduction to immunofluorescence and FCM followed by a discussion of six exemplary pitfalls that we hope will emphasise the general importance of methodological considerations.

Antibodies, Monoclonal↗
PubMed1992

Battered child syndrome: cerebral ultrasound and CT findings after vigorous shaking.

Child abuse by whiplash-shaking can lead to severe cerebral damage, neurological defects and mental retardation. Cerebral damage has been found with and without external evidence of head injury. We report the sonographic findings in two children after traumatization due to repetitive vigorous whiplash shaking. Cerebral sonography revealed cerebral edema at admission or within 48 hours thereafter. Follow-up studies demonstrated development of marked brain atrophy in both cases. The sonographic findings were confirmed by cranial computerized tomography. Doppler sonography was used to monitor cerebral perfusion by measuring intracranial blood flow. The clinical history of the patients demonstrates that cerebral sonography in combination with Doppler sonography not only serves as a diagnostic tool but also allows adjustment of therapy to the actual clinical status of the patient.

Battered Child Syndrome↗
PubMed1992

Determination of cardiac output by an angle and diameter independent dual beam Doppler technique in critically ill infants.

OBJECTIVE: To compare cardiac output measurements in critically ill infants by the dual beam Doppler and thermodilution techniques. DESIGN: Prospective direct comparison of the two techniques. For statistical evaluation one randomly assigned paired measurement of every patient was used. SETTING: Paediatric intensive care unit in a university hospital. PATIENTS: 18 infants after open heart surgery aged 4-25 months (weight 4-10 kg). INTERVENTIONS: Cardiac output measurements by dual beam Doppler and thermodilution techniques were performed within 10 minutes of each other and without knowledge of the results of the other methods. Multiple measurements were performed on some patients with a pharmacological or electrophysiological intervention or with a minimum of six hours between each pair of measurements. MEASUREMENTS AND MAIN RESULTS: Three patients were excluded because of an inadequate Doppler signal or a significant residual shunt. Cardiac output measurements ranged from 0.4 to 2.2 l/min for the thermodilution technique and from 0.5 to 2.1 l/min for the dual beam Doppler technique. Agreement between both methods was acceptable. The mean difference between the two methods was 0.026 l/min with two standard deviations ranging from -0.20 to 0.26 l/min. CONCLUSION: The dual beam Doppler technique was shown to have promise for the non-invasive determination of cardiac output in critically ill infants.

Cardiac Output↗
PubMed1992

[Monoclonal hybrid antibodies. New perspectives for basic research and tumor therapy].

Monoclonal hybrid antibodies are bi-specific constructs of two monoclonal antibodies with defined specificity. Hybrid antibodies can be used to force interactions between cell populations that under normal circumstances would not react with one another. Applications include the field of basic research as well as employment in therapy of malignancies and infectious diseases. The first part of this review describes the characteristic properties of hybrid antibodies and gives a short introduction into basic techniques for the production of these molecules. In the second part we present our observations on T-lymphocyte development studied with hybrid antibodies in fetal thymic organ cultures. Finally, we show that hybrid antibodies encompassing a binding site to the T-cell receptor and a binding site to a surface marker on tumor cells can be used to recruit cytotoxic T-cells to eliminate efficiently the malignant cells. Our data demonstrate that monoclonal hybrid antibodies are useful in the future development of new therapeutical principles, through facilitation of the immune response.

Antibodies, Monoclonal↗
PubMed1992

Effects of tolazoline and prostacyclin on pulmonary hypertension in infants after cardiac surgery.

OBJECTIVE: To evaluate the hemodynamic effects of tolazoline and prostacyclin in infants with pulmonary vasospasm after cardiac surgery. DESIGN: Prospective cohort study. SETTING: Pediatric ICU. PATIENTS: The cohort consisted of 42 infants and children with congenital heart disease and pulmonary hypertension who underwent corrective surgery and were monitored postoperatively using pulmonary artery catheters. Fourteen infants (2 to 12 months old) in this group required postoperative treatment with tolazoline or prostacyclin. INTERVENTIONS: Tolazoline was administered as a bolus of 0.5 mg/kg for treatment of persistent pulmonary hypertension or acute pulmonary hypertensive crisis. If its effectiveness was proved after 30 mins by hemodynamic measurements, a continuous iv infusion of 0.5 mg/kg/hr was established. Higher doses of tolazoline were avoided. If tolazoline treatment did not fulfill the criteria for pulmonary vasodilation, prostacyclin was given by continuous iv infusion at a starting rate of 5 ng/kg/min, followed by 10 ng/kg/min. In three patients, the infusion rate was increased to 15 ng/kg/min. RESULTS: Bolus administration of tolazoline resulted in a distinct pulmonary vasodilation in seven infants: mean pulmonary artery pressure and pulmonary vascular resistance decreased by an average of 35% and 45%, respectively. In these patients, tolazoline was infused over the following 12 to 72 hrs. One infant who received tolazoline for 72 hrs developed a clinically important gastrointestinal hemorrhage. In seven nonresponders to tolazoline, prostacyclin (PGI2) at an infusion rate of 5 ng/kg/min led to pulmonary vasodilation in five patients, at an iv infusion rate of 10 ng/kg/min in all seven infants studied. The latter dose of PGI2 reduced the mean pulmonary artery pressure by an average of 37%, and pulmonary vascular resistance by 43%. Transient withdrawal of prostacyclin in five infants demonstrated its short half-life and clinical effectiveness. Apart from a facial flush, no side-effects were encountered using PGI2 as an infusion over durations ranging from 12 to 504 hrs. CONCLUSIONS: These data suggest that, if tolazoline in a relatively low dose proves to be inefficient, prostacyclin can still be used as a safe and effective drug for treatment of pulmonary vasospasm. Prostacyclin offers more than a pharmacologic alternative to increased tolazoline dosages.

Drug Evaluation↗
PubMed1991

Schimke immuno-osseous dysplasia: a newly recognized multisystem disease.

On the basis of five cases personally observed and one previously reported, we describe a disorder characterized by skeletal dysplasia, rapidly progressive nephropathy, episodes of lymphopenia, and pigmentary skin changes. Defects of T-cell function were compatible with an autoimmune process. The disorder is probably of genetic origin and inherited as an autosomal recessive trait.

Antigens, CD↗
PubMed1991

Reduced CD4 and CD8 expression in human thymuses treated with soluble CD4.

Recent data suggest that accessory molecules like CD4 and CD8 act as co-receptors in intrathymic T-cell development. Soluble CD4 (sCD4) molecules offer a novel experimental approach to investigate the relevance of CD4 interaction with its putative intrathymic receptor for T-cell maturation. We attempted to inhibit binding of surface CD4 on thymocytes to its intrathymic receptor competitively by introduction of human sCD4 into human thymus tissue cultures. Our results demonstrate that sCD4, while not affecting peripheral T-cell responses as shown in control experiments, significantly affects intrathymic development of T lymphocytes. Immature CD4CD8 double positive (DP) thymocytes responded with reduced expression of both CD4 and CD8 molecules. This phenomenon could be followed up to the stage of single positive (SP) thymocytes: density of CD4 molecules on CD4 SP thymocytes and, even more interestingly, CD8 expression on CD8 SP cells, were reduced, indicating that the effect observed in immature DP thymocytes persists during their further development. Beyond that, analysis of T-cell receptor (TCR) expression in the low density CD4CD8 DP population revealed a slight decrease of alpha beta-TCR surface expression, suggesting a possible role of CD4 engagement in the generation of TCR in man. Since sCD4 is considered a therapeutical agent in HIV infections, these findings are not only of basic but also of clinical interest.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1991

[Catheterization of the jugular venous bulb in comatose children].

Ischemia and hypoxia are frequent potential sources of secondary brain damage after a variety of brain injuries. Cerebral oxygen extraction may be altered by coma as well as therapeutic interventions. In consequence, monitoring of cerebral O2 availability and utilization has become an important challenge for clinicians. However, measurement of cerebral oxygen extraction in children currently is not included into routine clinical care. This paper describes the measurement of O2-saturation in the jugular bulb in four comatose infants and children (in one continuously) following cardiac arrest or head injury. Our data demonstrate that this procedure served as a valuable tool in the management of those patients. Arterio-jugular oxygen content and lactate differences were used for the establishment and adjustment of therapeutic procedures and moreover, provided relevant information for the interpretation of other cerebral surveillance parameters.

Adolescent↗
PubMed1990

[HELLP syndrome].

Explore the source record for details and available documents.

Alanine Transaminase↗
PubMed1989

Recruitment of alloreactive cytotoxic T lymphocytes by an antigenic peptide.

To investigate the requirements for induction of cytotoxic T lymphocytes (CTL) by peptides we chose the 16-residue nucleoprotein peptide (NPP; 365-380) from the influenza virus A/NT/60/68 as model substrate that is recognized in conjunction with major histocompatibility complex H-2d. Here we present that CTL can be raised from naive animals by repeated in vitro stimulation with high concentrations of peptide. The frequency of this response can be boosted by immunization of the animals with NPP-conjugated to ovalbumin as a carrier. However, in contrast to NPP-specific CTL lines raised from virus-primed animals none of the peptide-induced CTL lines were able to lyse virus-infected targets. Although they did not show an apparent difference in fine specificity of the peptide recognized, their affinity to the target cells was 100-fold lower than that of CTL from virus-primed animals as estimated from the peptide concentration needed to achieve significant lysis. In addition, the activity of peptide-induced CTL was very sensitive to blocking by anti-CD8 antibodies as compared to virus-specific CTL. Furthermore, all peptide-induced CTL showed a high second reactivity for allogeneic H-2k targets. Therefore, it is argued that high epitope density achieved by high peptide concentrations can in vitro recruit lymphocytes of another specificity. For the tested peptide the reactive T lymphocytes showed high alloreactivity.

Amino Acid Sequence↗
PubMed1989

Engraftment of T-depleted major histocompatibility complex-mismatched bone marrow in T-deficient versus natural killer-deficient recipients.

When bone marrow transplantation recipients undergo standard pre-transplant immunosuppressive therapy, engraftment failures are significantly more frequent with the use of T-depleted allogeneic donor bone marrow cells than with T cell-containing allogeneic donor bone marrow cells. The relative importance of T versus natural killer (NK) cells in the rejection process of T-depleted donor bone marrow cells remains debatable. Here, NK- and T-deficient mouse mutants were transplanted across the same major histocompatibility complex (MHC) differences with homozygous or heterozygous T-depleted bone marrow cells. Results show that under the experimental conditions described, residual host NK cells are almost exclusively responsible for the increased rejection rate.

Animals↗
PubMed1989

[Simultaneous double fluorescence flow cytometry of lysed whole blood for prenatal diagnosis of combined immunodeficiency].

Simultaneous two-color flow cytometry of lysed whole blood allows the collection of maximal information from minimal blood volumes. This method was used for prenatal diagnosis of severe combined immunodeficiency by analysis of fetal blood. The data demonstrate that flow cytometry of lysed whole blood provides a reliable tool for prenatal diagnosis of certain immunodeficiencies. Moreover, the method described seems highly suitable for immunological monitoring of preterm infants and newborns. To enable the diagnosis of more subtle immunodeficiency states in these patients, however, valid normal values for all investigated parameters need to be defined first for the respective age/weight groups.

Female↗
PubMed1988

Thymic selection process induced by hybrid antibodies.

Thymus-derived (T) lymphocytes using the alpha beta T-cell antigen receptor (TCR) recognize fragmented antigen in conjunction with surface molecules encoded by genes of the major histocompatibility complex (MHC). Peripheral T lymphocytes preferentially see antigen presented by self rather than by foreign MHC molecules, and autoreactive T lymphocytes are deleted. Thus, the peripheral T-lymphocyte repertoire is skewed towards recognition of antigen in the context of self-MHC and towards tolerance to self-antigens. During T-lymphocyte development in the thymus, this repertoire is formed by the interaction of TCR with MHC molecules resulting in positive and negative selection phenomena. Hybrid antibodies (HAbs) that carry binding sites to the TCR and to a surface marker on another cell can engage all T lymphocytes regardless of their specificity. It should be possible to mimic selection processes in normal animals with HAb that specifically link members of a TCR family to MHC molecules on the thymic stroma. We have probed T-lymphocyte development with HAbs linking V beta 8-positive TCR to either class I or class II MHC products in thymic organ culture. Thymocytes exposed to either HAb in an early stage of maturation respond with a significant increase in the frequency of V beta 8-carrying cells. At a later stage of development V beta 8-positive thymocytes are depleted. These results illustrate the succession of positive and negative selection in the developing thymus of normal mice.

Animals↗
PubMed1988

Antibacterial capacity of buccal epithelial cells from healthy donors and children with recurrent urinary tract infections.

The effect of buccal epithelial cells (BEC) on bacterial growth was investigated in healthy subjects as well as in patients with recurrent urinary tract infections (UTI) and compared to the antibacterial capacity of uroepithelial cells (UEC) of the same individuals. Epithelial cells were obtained from the following groups: healthy female controls; females without further UTI after reflux operation; females with asymptomatic bacteriuria (ABU); females with further UTI despite successful reflux operation; and patients with meningomyelocele (MMC) and recurrent UTI due to significant residual urinary volume. Cocultivation of Escherichia coli with BEC as well as UEC from healthy females or patients with MMC resulted in significant suppression of bacterial growth. However, neither type of epithelial cell showed an antibacterial effect when they were obtained from patients with recurrent UTI in the absence of urological abnormalities (ABU patients; reflux-corrected patients with further UTI). From these results it is concluded that a generalised epithelial defence defect is one important pathogeneic factor for recurrent idiopathic UTI.

Adolescent↗
PubMed1987

Intrathymic tolerance induction: determination of tolerance to class II major histocompatibility complex antigens in maturing T lymphocytes by a bone marrow-derived non-lymphoid thymus cell.

Two new experimental approaches were established to analyse the influence of the thymus on tolerance induction to major histocompatibility complex (MHC) antigens: The aim of the first experiment was to perform successful transplantation of adult allogeneic thymus tissue into nude mice, an attempt that has been unsuccessful in the past. Tolerance for the MHC genotype of a prospective thymus graft recipient (A) was induced in mice of strain B by injection of (A X B) splenocytes during the neonatal period. Adult thymic tissue obtained from these allogeneic donors (B) were grafted into the nude mice of strain A. The allogeneic thymus was accepted by the nude mice and immunoreconstitution was achieved. Subsequently the recipients developed tolerance to the MHC antigens of the allogeneic thymus donor as proved by mixed lymphocyte cultures and the acceptance of skin grafts. The second experiment was designed to determine which Ia-positive thymic compartment participates in conferring tolerance to MHC antigens in maturing T lymphocytes. Chimaeric thymus grafts were created by transplantation of neonatal thymus (A) into allogeneic nude mice (B) for a period of 8 weeks. The graft was populated with host bone marrow-derived Ia antigen-positive cells. The chimaeric thymuses consisting of type A epithelium but populated with both type A and B lymphocytes and non-lymphoid cells (i.e. Ia-positive macrophages and dendritic cells), were newly transplanted into nude mice of strain A. The engraftment lead to immunological reconstitution and the nude mice acquired tolerance to the MHC antigens expressed by the allogeneic Ia-positive cells populating the chimaeric graft. Irradiation of the chimaeric thymus prior to transplantation allowed transplantation of chimaeric thymus devoid of living thymocytes but still populated with functionally intact Ia-positive non-lymphoid cells. Transplantation of irradiated chimaeric thymuses resulted in immunoreconstitution and induced exactly the same allotolerance pattern as described above. The results demonstrate that not thymus epithelial cells but a bone-marrow-derived non-lymphoid thymus cell, most likely the Ia-antigen-positive thymic macrophage of dendritic cell, is responsible for the induction of tolerance to MHC antigens in developing T lymphocytes.

Age Factors↗
PubMed1986

Biochemical, morphological and immunological findings in a patient with a cutis laxa-associated inborn disorder (De Barsy syndrome).

Clinical symptoms of a male infant are described and compared with cases now classified as the De Barsy syndrome, a distinct disorder related to cutis laxa. Morphologically, elastic fibres in skin were frayed and reduced in number and density. The collagen fibril network was normal. Biochemical studies on collagen metabolism in a skin specimen and in cultured skin fibroblasts showed a normal amino acid content and a normal electrophoretic pattern of collagen constituents. The chemotactic migration of cultured fibroblasts was diminished when compared with fibroblasts from donors of different age groups. Immunological investigations revealed an imparied granulocyte function.

Chemotaxis↗
PubMed1985

Comparison of the antibacterial effect of uroepithelial cells from healthy donors and children with asymptomatic bacteriuria.

Bacterial attachment to uroepithelial cells (UEC) and the effect of UEC on bacterial growth was investigated in 15 healthy persons and 12 patients suffering from asymptomatic bacteriuria (ABU) with recurrent urinary tract infections (UTI). Desquamated UEC and mannose-resistant Escherichia coli were co-cultivated for up to 90 min. While no difference in bacterial adherence was observed between healthy controls and patients, 33.4% of the bacteria attached to normal UEC were found to be dead under microscopic evaluation (acridine orange staining), whereas no killing effect could be observed in patients' UEC 5 min after the onset of incubation. This phenomenon was confirmed by investigating the E. coli growth rate in the presence of UEC, measured by counting bacterial colony forming units (CFU) on agar plates. While E. coli showed exponential growth in RPMI medium, the addition of normal UEC suppressed bacterial growth (P less than 0.01). UEC from patients with ABU, however, did not show this effect. It has been concluded that bacterial adhesion may initiate an epithelial defence function, present in healthy controls and lacking in ABU patients.

Adolescent↗