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Biomedical subjects

J Streicher

Publications and source records attributed to J Streicher.

At least 19 recordsLinked to original sources
PubMed2001

Role of motility in embryonic development I: Embryo movements and amnion contractions in the chick and the influence of illumination.

This study provides a quantitative analysis of the active movements of the chick embryo and of the contractions of the amnion over the entire developmental period of 21 days. Four types of embryo movements are distinguished. The motor activity of the embryo shows two characteristic peaks, with maximum contraction frequencies on the 12th and on the 16th day. In contrast, the amnion activity is higher at earlier stages and decreases as the body activity increases. The amnion activity is largely independent of the body activity. Illumination has a strong influence on embryo movements. It is shown that increases of light intensity affect the patterns of activity of both the embryo and the amnion. While the effect of light on the embryo can be interpreted as being transmitted via the optic system, the mechanism of the amniotic response is unclear. The results suggest that the amnion itself may be sensitive to light. J. Exp. Zool. (Mol. Dev. Evol.) 291:186-194, 2001.

Amnion↗
PubMed2001

3D modelling of gene expression patterns.

The current genome-sequencing projects provide "word indices" of the book of life. A central post-genomic question will be how these words are three-dimensionally deployed in the generation of organism form. Gene expression studies of developing organisms contribute an increasing wealth of snapshot data on the activation of individual genes at selected locations and single moments in the developmental process. However, a comprehensive understanding of the dynamic activation of multiple genes and their functional role in controlling the 3D processes of collective cell behaviour, pattern formation and morphogenesis, requires special tools for a systematic description of spatio-temporal patterns of gene activation and the ensuing phenotypic effects. This article concentrates on new, computer-based tools for the 3D analysis of gene expression patterns in embryonic development and their use for the systematic establishment of comprehensive gene expression maps.

Animals↗
PubMed2000

Computer-based three-dimensional visualization of developmental gene expression.

A broad understanding of the relationship between gene activation, pattern formation and morphogenesis will require adequate tools for three-dimensional and, perhaps four-dimensional, representation and analysis of molecular developmental processes. We present a novel, computer-based method for the 3D visualization of embryonic gene expression and morphological structures from serial sections. The information from these automatically aligned 3D reconstructions exceeds that from single-section and whole-mount visualizations of in situ hybridizations. In addition, these 3D models of gene-expression patterns can become a central component of a future developmental database designed for the collection and presentation of digitized, morphological and gene-expression data. This work is accompanied by a web site (http://www.univie.ac.at/GeneEMAC).

Anatomy, Cross-Sectional↗
PubMed1999

Differential expression of tumor necrosis factor receptor subtypes on leukocytes in systemic inflammatory response syndrome.

OBJECTIVE: To determine the expression of tumor necrosis factor (TNF) receptor in patients with systemic inflammatory response syndrome (SIRS). DESIGN: Prospective study. SETTING: Intensive care unit and central laboratory. PATIENTS: Blood specimens from 18 healthy volunteers (controls) and 16 patients with SIRS. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Using monoclonal antibodies, fluorescence labeling, and high sensitivity flow cytometry, we measured the expression of membrane TNF receptor subtypes TNF-R55 and TNF-R75 on peripheral blood leukocytes. Receptor expression is expressed as mean fluorescence intensity +/- SD (units: detection channel number). In controls, TNF-R55 was only weakly expressed (monocytes: 2.5+/-1.8; neutrophils: 0.7+/-0.8), whereas expression of TNF-R75 was higher (monocytes: 28.6+/-9.0; neutrophils: 4.8+/-1.0) and was also found on lymphocytes (on CD8+ lymphocytes: 5.7+/-1.8; CD16+: 5.5+/-1.2; CD4+: 9.7+/-3.7). In SIRS, we observed increased expression of TNF-R55 on monocytes (6.9+/-3.4, p<.001) and neutrophils (2.2+/-1.9, p<.01), as well as decreased expression of TNF-R75 on monocytes (17.3+/-13.2; p<.001). The extent of TNF-R55 up-regulation did not correlate with that of TNF-R75 down-regulation. TNF-R55 on monocytes and neutrophils strongly correlated with body temperature but not with survival, whereas monocyte TNF-R75 was considerably lower in nonsurvivors, albeit not significantly (12.3+/-7.1 vs. 23.9+/-16.7; p = .07). CONCLUSIONS: These data indicate that leukocyte TNF-R55 and TNF-R75 react differentially and probably serve different functions in SIRS, which prompts the investigation of receptor subtype-specific therapeutic approaches.

Adult↗
PubMed1999

Auditory ossicle abnormalities and hearing loss in the toothless (osteopetrotic) mutation in the rat and their improvement after treatment with colony-stimulating factor-1.

Osteopetrosis describes a group of skeletal metabolic diseases of heterogeneous etiology and varied severity that produces a generalized accumulation of skeletal mass, the result of reduced bone resorption. Inherited in a variety of species including humans, the most severe forms are lethal. Among common features are progressive blindness and deafness of controversial etiologies for which there are no universally effective treatments. We have studied the auditory responsiveness and auditory ossicle quantitative histomorphology and temporal bone vasculature in the toothless (tl) rat, a lethal osteopetrotic mutation with few osteoclasts, very low bone turnover, and limited angiogenesis in the axial skeleton. Compared with normal littermates, 3-week-old mutants showed significantly reduced auditory responsiveness, a hearing loss due to abnormalities in both form and tissue composition of the stapes, and little capillary sprouting in the vascular bed of the temporal bone. Treatment of mutants with colony-stimulating factor 1 (CSF-1), known to greatly reduce sclerosis in the axial skeleton, significantly improved hearing, stapedial form and tissue composition, and angiogenesis in the temporal bone. In normal rats, the stapes consisted of 89.3% bone, 9.1% mineralized cartilage, and 0.8% porosity. In osteopetrotic rats, the stapes consisted of 48.3% bone, 35.9% mineralized cartilage, and 15.9% porosity, while after CSF-1 treatment, the bone content increased to 55.2%, cartilage was decreased to 21.7%, and porosity increased to 23.0%, respectively. This is the first demonstration of an auditory abnormality in an osteopetrotic animal mutation and shows that the hearing loss in tl rats can be significantly improved following treatment with CSF-1.

Animals↗
PubMed1999

Up-regulation of LDL-receptor expression by LDL-immunoapheresis in patients with familial hypercholesterolemia.

BACKGROUND: Familial hypercholesterolemia (FH) is characterized by an autosomal dominantly inherited deficiency of LDL-receptor expression on the cell surface, leading to excess plasma LDL-cholesterol and severe premature atherosclerosis. In patients with heterozygous FH, a major therapeutic objective of conventional drug therapy is to stimulate maximally the residual cellular capacity to produce LDL-receptors via inhibition of endogenous cholesterol synthesis. In contrast, LDL-immunoapheresis aims at reducing the plasma LDL-cholesterol level by extracorporeal elimination of LDL particles. The present study investigates whether LDL-immunoapheresis applied in addition to conventional drug therapy is able to further stimulate residual LDL-receptor expression capacity in patients with heterozygous FH via the withdrawal of external cholesterol supply, thereby exerting a second accessory lipid lowering effect. METHODS: LDL-receptor expression--calculated by transforming mean fluorescence intensities into numbers of antibody binding sites per cell (S/C)--was determined flow-cytometrically on peripheral blood monocytes before and after LDL-apheresis. For a comparison with the maximum obtainable receptor expression capacity, in vitro stimulation experiments under completely LDL deficient conditions were performed. RESULTS: Prior to LDL-apheresis, LDL-receptor density was comparable in patients (N = 7; 2014 +/- 359 S/C) and controls (N = 10; 1782 +/- 252 S/C). Under in vitro conditions LDL-receptor expression of controls exceeded that of patients with FH by 1.6 times. Immediately after apheresis, LDL-receptor expression significantly increased to almost the same level as obtained by in vitro stimulation (3640 +/- 423 S/C and 3632 +/- 572 S/C). The LDL-receptor expression in FH subsequent to LDL-apheresis exhibited two patterns of kinetics [Type 1: maximal receptor stimulation (288 +/- 70%; P < 0.07) already during apheresis; Type 2: highest receptor density 24 hours after treatment (149 +/- 11%; P < 0.01)]. CONCLUSIONS: These results demonstrate that despite drug therapy, LDL-apheresis significantly stimulates the residual LDL-receptor expression in FH via the reduction of available extracellular cholesterol resulting in delayed reappearance of hypercholesterolemia in between treatments.

Adult↗
PubMed1998

Anticytokeratins are a potential source of false-positive indirect immunofluorescence assays for C-ANCA.

Antibodies to neutrophil cytoplasmic antigens (ANCA) targeted toward granule enzymes have been recognized as a valuable diagnostic tool in the detection of Wegener's granulomatosis and systemic vasculitides. However, the most commonly used method of detection, the indirect immunofluorescence assay, is prone to false-positive results due to antibodies of different pathological significance either targeted to, or cross-reacting with, similarly distributed epitopes. Using double immunofluorescence, the present study demonstrates that anticytokeratin antibodies are able to produce false-positive C-ANCA immunofluorescence assays. In addition, a case of natural appearance of cytokeratin-reactive antibodies causing a false-positive "pseudo-ANCA" staining pattern in a patient presenting with sepsis is reported. Since the expression of cytokeratins is almost exclusively confined to epithelial cells, the most plausible explanation for both phenomena is a crossreaction of anticytokeratin antibodies with granule associated epitopes. Due to the natural appearance of anticytokeratin antibodies in association with a variety of other pathologic entities, it is of crucial importance for the diagnostic significance of the C-ANCA immunofluorescence assay to exclude anticytokeratin caused false-positive results. It is shown that supplementary indirect immunofluorescence tests performed on cultured human epithelial cells readily distinguish anticytokeratin caused "pseudo-ANCA" from true C-ANCA.

Antibodies, Antineutrophil Cytoplasmic↗
PubMed1998

A new episcopic method for rapid 3-D reconstruction: applications in anatomy and embryology.

The topographic relations of complex structures and the morphogenesis of organ systems can only be fully understood in their three-dimensional context. Three-dimensional (3-D) reconstruction of physically sectioned specimens has become an indispensable tool in modern anatomical and embryological research. Teaching also makes increasingly use of 3-D representations, in particular in the case of embryonic systems that undergo complicated transformations of form and shape. At present no cheap and simple technique is available that generates accurate 3-D models of sectioned objects. In this study we describe a novel technique that rapidly provides faithful 3-D models of sectioned specimens. The images are captured directly from the cutting surface of the embedding block after each sectioning and "on block" staining step. Automatic image processing generates a stack of binary images of the specimen contour. Binary images of internal structures are obtained both by automatic segmentation and manual tracing. Since these image series are inherently aligned, they can be reconstructed three-dimensionally without time-consuming alignment procedures. The quality and the flexibility of the method are demonstrated by reconstructing three kinds of specimens of different histological composition and staining contrast: a 4 mm mouse embryo together with several of its inner organs, a cavernous sinus region of a human infant, and a segment of a human carotid artery. Very short processing times and the faithful representation of complex structural arrangements recommend this technique for routine use in morphological research and for creating embryologic teaching models or 3-D embryonic staging series.

Anatomy, Cross-Sectional↗
PubMed1998

Therapeutic efficiency of lipoprotein(a) reduction by low-density lipoprotein immunoapheresis.

This study was performed to investigate the effect of low-density lipoprotein (LDL) immunoapheresis on lipoprotein(a) [Lp(a)] reduction in patients with heterozygous and homozygous familial hyperlipidemia (N=16) and insufficient response to lipid-lowering agents. By desorption of approximately 5,700+/-500 mL of plasma, a mean reduction in total cholesterol of 62% (P < .001) and in LDL-cholesterol of 70% (P < .001) was achieved. Lp(a), which was elevated at study entry in seven of these patients (82.1+/-34.3 mg/dL; range, 48 to 148 mg/dL), was reduced during the initial LDL-apheresis procedure by 74.8%+/-14.1% (P < .001). Long-term apheresis treatment performed at weekly intervals resulted in an mean reduction in Lp(a) pretreatment values to 39.1+/-28.5 mg/dL (-54%; P < .001). Desorbed Lp(a) was measured at the waste of the columns for 31 apheresis treatments. Lp(a) concentration of the column waste was higher in patients with elevated serum Lp(a) pretreatment values as compared with those with Lp(a) serum values within the normal range (elevated Lp(a), 1,420+/-380 mg; without elevated Lp(a), 235+/-190 mg; P < .001). The rate of return of Lp(a) following apheresis treatment scheduled at weekly intervals was comparable to that of LDL-cholesterol.

Adolescent↗
PubMed1997

Toward a new reference method for the leukocyte five-part differential.

A flow cytometric method performing a five-part leukocyte differential based on three-color staining with anti-CD45-fluorescein isothiocyanate (FITC), anti-CD-14-phycoerythrin (PE)/Cy5, and a cocktail of PE-labeled anti-CD2, anti-CD16, and anti-HLA-DR antibodies was evaluated. Results obtained by using three different sample preparation procedures and two different flow cytometers were compared with those of a 1,000-cell manual differential for evaluation of accuracy. We observed excellent correlations with the manual differential for all leukocyte subclasses and even higher correlations between the different flow cytometric methods. Flow cytometric basophil results were identical to the manual counts, regardless of which sample preparation technique or flow cytometer was used. Therefore, we propose our flow cytometric method as the first acceptable automated reference method for basophil counting. The flow cytometric results for the other leukocyte subclasses were apparently influenced by the sample preparation, which could not be explained by cell loss during washing steps. Moreover, a small influence of the flow cytometer was also observed. Assessing the influence of sample storage, we found only minimal changes within 24 h. In establishing reference values, high precision of flow cytometric results facilitated detection of a significantly higher monocyte count for males (relative count: 7.08 +/- 1.73% vs. 6.44 +/- 1.33%, P < 0.05; absolute count: 0.536 +/- 0.181 x 10(9)/liter vs. 0.456 +/- 139 x 10(9)/liter, P < 0.01). Our data indicate that monoclonal antibody-based flow cytometry is a highly suitable reference method for the five-part differential: It also shows, however, that studies will have to put more emphasis on methodological issues to define a method that shows a high interlaboratory reproducibility.

Antibodies, Monoclonal↗
PubMed1997

External marker-based automatic congruencing: a new method of 3D reconstruction from serial sections.

BACKGROUND: Computer-based three-dimensional (3D) visualizations reconstructed from sectional images represent a valuable tool in biomedical research and medical diagnosis. Particularly with those imaging techniques that provide virtual sections, such as CT, MRI, and CLSM, 3D reconstructions have become routine. Reconstructions from physical sections, such as those used in histological preparations, have not experienced an equivalent breakthrough, due to inherent shortcomings in sectional preparation that impede automated image-processing and reconstruction. The increased use of molecular techniques in morphological research, however, generates an overwhelming amount of 3D molecular information, stored within series of physical sections. This valuable information can be fully appreciated and interpreted only through an adequate method of 3D visualization. METHODS AND RESULTS: In this paper we present a new method for a reliable and largely automated 3D reconstruction from physically sectioned material. The 'EMAC' concept (External Marker-based Automatic Congruencing) successfully approaches the three major obstacles to automated 3D reconstruction from serial physical sections: misalignment, distortion, and staining variation. It utilizes the objectivity of external markers for realignment of the sectional images and for geometric correction of distortion. A self-adapting dynamic thresholding technique compensates for artifactual staining variation and automatically selects the desired object contours. CONCLUSIONS: Implemented on a low-cost hardware platform, EMAC provides a fast and efficient tool that largely facilitates the use of computer-based 3D visualization for the analysis of complex structural, molecular, and genetic information in morphological research. Due to its conceptual versatility, EMAC can be easily adapted for a broad range of tasks, including all modern molecular-staining techniques, such as immunohistochemistry and in situ hybridization.

Animals↗
PubMed1997

Anatomical compartments of the parasellar region: adipose tissue bodies represent intracranial continuations of extracranial spaces.

The cavernous sinus is traditionally described as a single anatomical compartment that contains cranial nerves, blood vessels, and connective tissue. A detailed analysis of 45 infant and 4 fetal parasellar regions shows that this view must be modified. The spatial arrangement, the topographic relations, and the expansion of the adipose and connective tissue spaces were analysed and reconstructed 3-dimensionally on a computer. It is shown that 3 different anatomical compartments, which are strictly demarcated by connective tissue, compose the parasellar region of infants. Two represent intracranial continuations of extracranial tissue spaces. The 3rd compartment corresponds to the so-called 'cavernous sinus' of the adult. Each of the 3 compartments contains characteristic adipose tissue bodies. Because the cavernous sinus represents only one compartment of the area, we propose to use the term 'parasellar region' to designate the entire anatomical region on either side of the sella turcica.

Adipose Tissue↗
PubMed1996

Evaluation of automated basophil counting by using fluorescence-labelled monoclonal antibodies.

The shortcomings of current methods of basophil enumeration detract from the clinical value of the basophil count. Moreover, sophisticated and costly techniques of automated basophil counting hardly can be validated for lack of a suitable reference method. We investigated whether a flow cytometric technique using double staining with fluorescence-labelled monoclonal antibodies (mAb) CD45-FITC and CD14-PE on a Coulter Epics Profile II could be used to evaluate basophil counting performance of hematology analyzers. The technique was compared with the 800-cell manual differential, the Coulter STKS, and the Cobas Argos 5 Diff. Precision: STKS, Argos and Profile II showed a precision analogous to a 2,173, 2,250-, and 14,705-cell differential, respectively, illustrating the superiority of automated methods. Accuracy (150 normal and abnormal samples): Using the Profile II as reference the STKS showed a notably weaker correlation than the Argos (r = 0.581 and 0.718, respectively), although this difference was nearly concealed when the imprecise manual differential served as reference (r = 0.517 and 0.562, respectively). The Profile II correlated relatively well with the manual differential (r = 0.730). Analyzing 137 healthy adult subjects, we obtained a reference range of 0.33 to 1.35% (0.020 to 0.102 x 10(9) basophils/L) for the mAb-based method. These data would recommend mAb-based basophil counting as a valuable tool for instrument evaluation. However, an observed bias of 0.09% against the manual differential suggests that modifications are necessary before this technique can be considered as new reference method.

Adult↗
PubMed1996

[3-dimensional reconstruction of histological serial sections using a computer].

This paper reports the development of an objective and time-saving method for the three-dimensional reconstruction of sectioned morphological specimens on the computer. The development of a fiducial marker technique, the design of program extensions for the automatic thresholding and realignment of images, and a technique for the transfer of marker-derived reference points into images of higher magnification are described. The method is based on the use of resin as embedding material and drill holes as fiducials. Images are digitized by a video camera, and NIH-Image is used for image processing. Special macros were written for the automation of a number of operations, such as object and marker segmentation, image reorientation, image scaling, dirt removal, and marker transfer. The so-treated image series were transferred to a workstation and were reconstructed using "Image Volumes". The reconstructs obtained from this largely automated technique exhibit a perfect alignment of the sections. The 3-D representations of the sectioned objects have a much higher degree of objectivity than those obtained by manual image orientation or by semiautomated techniques that do not use fiducials.

Computer Systems↗
PubMed1990

Effect of circulatory assist devices on stunned myocardium.

We studied the effects of mechanical circulatory assist devices on left ventricular oxygen consumption, the integrals of systolic left ventricular wall stress (SSI), and end-systolic elastance (Ees) in 8 sheep after 25 minutes of global ischemia. Extracorporeal membrane oxygenation at 35 mL/kg/min, intraaortic balloon counterpulsation, and an intraaortic double-balloon pump were studied alone or in combination. Left ventricular oxygen consumption, SSI, and Ees were measured before and during mechanical circulatory assistance. Left ventricular oxygen consumption was calculated from transit-time measurements of left main coronary artery blood flow and fiberoptic measurements of coronary sinus blood oxygen saturation. Three pairs of sonomicrometry crystals placed across three orthogonal ventricular axes were used to calculate instantaneous ventricular volumes and pressure-volume loops from which the SSI data were derived. The Ees was measured using a new single-beat aortic occlusive method. Extracorporeal membrane oxygenation alone increased SSI and did not change Ees in postischemic poorly contracting hearts. Intraaortic balloon counterpulsation alone significantly reduced SSI and increased Ees. The combination of extracorporeal membrane oxygenation and either the intraaortic balloon pump or the intraaortic double-balloon pump reduced SSI, increased Ees, and reduced left ventricular oxygen consumption. In postischemic dilated, poorly contracting hearts, the combination of extracorporeal membrane oxygenation and intraaortic balloon counterpulsation has important advantages over extracorporeal membrane oxygenation alone.

Animals↗
PubMed1990

Myocardial oxygen utilization after reversible global ischemia.

We tested in 20 sheep the hypothesis that oxygen consumption increases after reversible, global myocardial ischemia. Left ventricular oxygen consumption before and after 25 minutes of warm (37 degrees C) global ischemia was linearly related to a function (integral) of left ventricular circumferential systolic wall stress, altered by changing afterload. The relation is expressed in the two regression equations: LVO2 (preischemic) = 1.06.SSI + 16.8 (n = 129; r = 0.79); LVO2 (postischemic) = 4.35.SSI + 5.6 (n = 89; r = 0.65). The fourfold increase in slope (4.35 versus 1.06) indicates (p = 0.0001) a massive increase of oxygen consumption in postischemic, globally "stunned" myocardium. The inferences are that globally stunned myocardium causes severe impairment of oxygen utilization efficiency, and increased vulnerability to further ischemia if coronary vessels are diseased.

Animals↗
PubMed1989

Ontogeny of the syndesmosis tibiofibularis and the evolution of the bird hindlimb: a caenogenetic feature triggers phenotypic novelty.

The underlying theme of this study is the contribution of developmental mechanisms to the generation of morphological novelty in evolution. The syndesmosis tibiofibularis, an important structural and functional link between the two zeugopod bones of the bird hindlimb, is used as a model for evolutionary novelty. We analyze the structural, developmental and adaptive aspects of its origin in a combined descriptive, experimental, and comparative approach. The ontogeny of the syndesmosis in the chick embryo involves several developmental steps, including the formation of a separate cartilage rudiment that in turn stimulates the formation of an osseous crest on the tibia, which will eventually replace the cartilage element itself. Some of the epigenetic requirements for the formation of the cartilage element and the osseous crest are demonstrated by experimentally increasing the distance between the two zeugopod bones, an operation that results in the absence of both cartilage and crest. Although a syndesmosis tibiofibularis associated with an osseous crest on the tibiotarsus is unique to birds in extant vertebrates, the presence of a distinct crest at the corresponding location in theropod dinosaurs indicates that a syndesmosis also existed in this group of archosaurs. The results of the study suggest that in the case of the syndesmosis tibiofibularis phenotypic evolutionary novelty is based on a caenogenetic feature, i.e. a feature that initially arose in response to changing developmental conditions. In conclusion we propose a model for the stepwise evolutionary modification of the sauropsid hindlimb, integrating adaptive trends and developmental mechanisms that interactively determine the transformations of skeletal limb morphology. The syndesmosis tibiofibularis and the mechanisms of its formation are not only shown to have played a key-role in this process, but its presence in theropod dinosaurs also points towards the origin of birds.

Animals↗