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PubMed1976

[New fluorescent microscopical technique in diagnostic microbiology (author's transl)].

The practicability of 4',6-diamidino-2-phenylindole (DAPI) in the fluorescent microscopical demonstration of bacterial and other cellular structures for medical diagnostic purposes was investigated. Polar bodies in diphtheria bacilli and spores of spore-forming bacteria showed up well. The demonstration of phagocytosed bacteria in urinary sediment and the morphology of human spermatozoa are particularly impressive. Noteworthy advantages of DAPI are its stability (no bleaching of stained preparations), its use in minute quantities, rapid staining (within minutes), and simplicity of use.

Bacteriological Techniques↗
PubMed1992

The new immunology.

Among the biomedical sciences, immunology stands out as a discipline in which knowledge emanating from fundamental research has rapidly been transferred to the clinical paradigm, with consequent improvement in human health. Virtually all medical subspecialties have benefitted from diagnostic reagents and technologies provided by basic immunology. In terms of numbers of lives saved, immunologic-based therapeutic strategies, most notably vaccination, rank among the most effective measures ever achieved by medical intervention. Yet, despite immunology's profound impact on medicine and the longstanding recognition of many of the general principles and cellular components involved in immunity, until relatively recently, the operational workings of the immune system eluded precise definition. The abstract nature of the immune system rendered the field intangible or, at the very least, confusing, to the nonimmunologic medical community. However, in recent years, this situation has changed radically, as cell cloning, hybridoma, and recombinant DNA technologies have provided the means to delineate the precise immunologic cellular structures and interactions. The purpose of this review is to highlight a few of the most significant advances in immunology during the past decade, and to show how they have made possible the translation of abstract concepts of classical immunology into tangible, structural information. Striking gains in the understanding of antigen recognition, one of the most fundamental aspects of immunity, are described as an illustrative case.

Antibodies, Monoclonal↗
PubMed1992

[Experiences up to now with the ultrasound dissection instrument in gynecologic oncology].

The energy of high frequency ultrasound is used to disrupt cellular structures. Since the water content of each individual cell is of utmost importance for the physical destruction of the cell, there may be a tissue-selective effect in respect of tissues such as epithelium (high water content) and mesenchyma (low water content). The various therapeutic modalities are described in the following four cases. Ultrasonic tumor destruction was highly effective with regard to maximum reduction of tumor masses, especially for tumor sites which could not be removed by conventional tumor surgery. Blood vessels and nerves surrounded by tumor could be carefully and completely dissected--even in advanced stages. Peritoneal metastases from an ovarian carcinoma could be removed entirely, as well as the metastases within a tumor bulk (e.g. ureter within tumor mass); also the layers of tissue which were lost could be visualized again. So far, no increase in complications during and after surgery has been observed.

Adult↗
PubMed1993

Blood cell activation: new perspectives from ultrastructural morphometry.

The new computerized approaches for image analysis available for a few years permit, in an excellent and detailed way, monitoring cellular structural modifications during activation processes. Here, we presented morphometric data obtained on blood cells (platelets, monocytes, and PMN cells) after in vitro activation and under in vivo conditions related to atherosclerosis studied by means of electron microscopy. Area and perimeter form factors, nucleus to cytoplasma area ratio, and the surface density of platelet plasma membrane openings of SCCS presented significant differences compared with the respective significant differences compared with the respective controls. Ultrastructural markers of blood cell activation were revealed by the computerized morphometry applied on ultrastructural images.

Animals↗
PubMed1988

Cerebro-ocular dysplasia and muscular dystrophy: report of two cases.

The authors report two cases with severe cerebro-ocular malformations and muscular dystrophy who died at 14 and 8 months of age. In both, muscular dystrophy was confirmed by EMG and high muscle enzyme values. In one case, autopsy showed severe cerebral malformation consisting of lissencephaly, hydrocephalus, agenesis of corpus callosum, chiasma and olfactory bulb and lobe, absence of pyramides and cerebellar vermis. In sections of cerebral cortex a clear absence of structural cellular organization and spongiosis of the white matter were evident. Similar disorganization was found in the cerebellum where numerous calcifications were present. The muscle showed signs of primitive muscular dystrophy. The clinical autonomy of the cerebro-ocular-dysplasia-muscular-dystrophy syndrome is discussed. The clinical and pathological data are compared with the two other similar syndromes (i.e. Fukuyama's and Warburg's diseases).

Abnormalities, Multiple↗
PubMed1981

[Herpes oesophagitis: cytological diagnosis of a rare viral disease (author's transl)].

During gastroscopy on a 75-year-old man because of bleeding from the upper gastro-intestinal tract, a white wallpaper-like covering was noted along the whole length of the oesophagus. Cytology of smears demonstrated typical cellular structure of Herpes, characterized by multinuclear cells with pale, flattened opaque glass-like nuclei. Subsequently the patient died of other organic complications.

Aged↗
PubMed2004

Nonlinear interactions in the density fingering of an acidity front.

Density fingering of the chlorite-tetrathionate reaction has been studied experimentally in a Hele-Shaw cell. The initially emerging cellular structure transforms into a single cell with constant--asymmetric and symmetric--shape in narrow reaction vessels. The interactions of fingers in wider Hele-Shaw cells lead to the coarsening of the patterns, however, splitting of fingers is observed as well. The long time evolution has been quantitatively described by the change in the mixing length, i.e., the amplitude of the patterns, and by the power-averaged cell number of the structures.

Journal Article↗
PubMed2000

Is human myometrial sampling at the time of cesarean delivery safe?

OBJECTIVE: The mechanism for the initiation of human labor remains unknown and is under extensive investigation. Myometrium from patients in labor and not in labor is the ideal tissue to study structural, cellular, and molecular changes that occur during parturition. This study was designed to determine whether myometrial sampling at the time of cesarean delivery increases maternal morbidity. STUDY DESIGN: This is a prospective cohort study including 118 study and 236 control patients. A full-thickness myometrial sample was obtained from the superior edge of a transverse uterine incision at the time of cesarean delivery. Demographics and standard surgical morbidity data were collected. Statistical methods used included univariate and multivariate analysis. RESULTS: The study and control groups did not differ significantly with respect to age, gravidity, parity, birth weight, and Apgar scores. The estimated intraoperative blood loss was greater in the control group (P <.02); however, the change in hematocrit level (preoperative vs postoperative values) was not different. There were no significant differences in the rates of endometritis, wound infection, and venous thrombosis up to 6 weeks post partum. When study and control patients were stratified into term in labor, term not in labor, preterm in labor, and preterm not in labor categories and compared for maternal morbidity, there were still no significant differences for any of the outcome measures evaluated. CONCLUSION: On the basis of our data, human myometrial sampling at cesarean delivery does not increase overall maternal morbidity, irrespective of gestational age and the presence or absence of labor.

Adult↗
PubMed2003

DNA damage and repair system in spinal cord ischemia.

BACKGROUND AND PURPOSE: Spinal cord ischemia-reperfusion injury may be initiated by a number of mediators, including reactive oxygen species. Recent studies have shown that human MutY homologue (hMYH), human 8-oxo-7,8-dihydrodeoxyguanine (8-oxoG) glycosylase (hOGG1), and human MutS homologue 2 (hMSH2) are important DNA mismatch repair genes. We hypothesized that ischemia-reperfusion injury in spinal cord causes DNA damage manifested by 8-oxoG production and activates the DNA repair system involving hMYH, hOGG1, and hMSH2. METHODS: Spinal cords of rabbits were removed at 1, 3, 6, 24, and 48 hours after 30 minutes of infrarenal aortic occlusion. DNA damage was determined with 8-oxoG staining. The expression and localization of DNA repair enzymes, such as hMYH, hOGG1, and hMSH2, were studied with Western blot analysis and immunohistochemical staining. The level of apoptosis was determined with TUNEL study. Activation of caspase-3, an enzyme induced by cellular injury that leads to apoptosis by degrading cellular structural proteins, was also studied. RESULTS: DNA damage monitored with 8-oxoG level was significantly present from 1 hour to 6 hours after reperfusion in gray matter neurons of ischemic spinal cord. The levels of hMYH, hOGG1, and hMSH2 were markedly increased in gray matter neurons at 6 hours after reperfusion. Caspase-3 was also induced at 6 hours to 24 hours after reperfusion in ischemic spinal cord. However, the peak level of TUNEL reactivity was found at 48 hours after reperfusion in spinal cord neurons. CONCLUSION: This study has shown, for the first time, the rapid expression of DNA damage-repair processes associated with spinal cord ischemia and subsequent reperfusion.

Animals↗
PubMed2002

Allometric scaling of metabolic rate from molecules and mitochondria to cells and mammals.

The fact that metabolic rate scales as the three-quarter power of body mass (M) in unicellular, as well as multicellular, organisms suggests that the same principles of biological design operate at multiple levels of organization. We use the framework of a general model of fractal-like distribution networks together with data on energy transformation in mammals to analyze and predict allometric scaling of aerobic metabolism over a remarkable 27 orders of magnitude in mass encompassing four levels of organization: individual organisms, single cells, intact mitochondria, and enzyme molecules. We show that, whereas rates of cellular metabolism in vivo scale as M(-1/4), rates for cells in culture converge to a single predicted value for all mammals regardless of size. Furthermore, a single three-quarter power allometric scaling law characterizes the basal metabolic rates of isolated mammalian cells, mitochondria, and molecules of the respiratory complex; this overlaps with and is indistinguishable from the scaling relationship for unicellular organisms. This observation suggests that aerobic energy transformation at all levels of biological organization is limited by the transport of materials through hierarchical fractal-like networks with the properties specified by the model. We show how the mass of the smallest mammal can be calculated (approximately 1 g), and the observed numbers and densities of mitochondria and respiratory complexes in mammalian cells can be understood. Extending theoretical and empirical analyses of scaling to suborganismal levels potentially has important implications for cellular structure and function as well as for the metabolic basis of aging.

Animals↗
PubMed2004

Coupling morphogenesis to mitotic entry.

In eukaryotes, cyclin B-bound cyclin-dependent protein kinase 1 promotes mitotic entry but is held in check, in part, by Wee1 protein kinase. Timely mitotic entry in budding yeast requires inactivation of Swe1 (Wee1 ortholog). Perturbations of the septin collar at the bud neck lead to Swe1 stabilization, delaying the G(2)/M transition. Swe1 is recruited to the neck and hyperphosphorylated before ubiquitin-mediated degradation. Hsl1 kinase (Nim1 ortholog), a negative regulator of Wee1, is required for efficient Swe1 localization at the neck but seems not to phosphorylate Swe1. Here, we show that two other kinases targeted sequentially to the neck, Cla4/PAK and Cdc5/Polo, are responsible for stepwise phosphorylation and down-regulation of Swe1. This mechanism links assembly of a cellular structure to passage into mitosis.

Cell Cycle Proteins↗
PubMed2005

Nanoscale visualization and characterization of Myxococcus xanthus cells with atomic force microscopy.

Multicellular microbial communities are the predominant form of existence for microorganisms in nature. As one of the most primitive social organisms, Myxococcus xanthus has been an ideal model bacterium for studying intercellular interaction and multicellular organization. Through previous genetic and EM studies, various extracellular appendages and matrix components have been found to be involved in the social behavior of M. xanthus, but none of them was directly visualized and analyzed under native conditions. Here, we used atomic force microscopy (AFM) imaging and in vivo force spectroscopy to characterize these cellular structures under native conditions. AFM imaging revealed morphological details on the extracellular ultrastructures at an unprecedented resolution, and in vivo force spectroscopy of live cells in fluid allowed us to nanomechanically characterize extracellular polymeric substances. The findings provide the basis for AFM as a useful tool for investigating microbial-surface ultrastructures and nanomechanical properties under native conditions.

Bacterial Adhesion↗
PubMed2005

Spatial regulation of the cAMP-dependent protein kinase during chemotactic cell migration.

Historically, the cAMP-dependent protein kinase (PKA) has a paradoxical role in cell motility, having been shown to both facilitate and inhibit actin cytoskeletal dynamics and cell migration. In an effort to understand this dichotomy, we show here that PKA is regulated in subcellular space during cell migration. Immunofluorescence microscopy and biochemical enrichment of pseudopodia showed that type II regulatory subunits of PKA and PKA activity are enriched in protrusive cellular structures formed during chemotaxis. This enrichment correlates with increased phosphorylation of key cytoskeletal substrates for PKA, including the vasodilator-stimulated phosphoprotein (VASP) and the protein tyrosine phosphatase containing a PEST motif. Importantly, inhibition of PKA activity or its ability to interact with A kinase anchoring proteins inhibited the activity of the Rac GTPase within pseudopodia. This effect correlated with both decreased guanine nucleotide exchange factor activity and increased GTPase activating protein activity. Finally, inhibition of PKA anchoring, like inhibition of total PKA activity, inhibited pseudopod formation and chemotactic cell migration. These data demonstrate that spatial regulation of PKA via anchoring is an important facet of normal chemotactic cell movement.

Animals↗
PubMed2003

An approach to electrical modeling of single and multiple cells.

Previous theoretical approaches to understanding effects of electric fields on cells have used partial differential equations such as Laplace's equation and cell models with simple shapes. Here we describe a transport lattice method illustrated by a didactic multicellular system model with irregular shapes. Each elementary membrane region includes local models for passive membrane resistance and capacitance, nonlinear active sources of the resting potential, and a hysteretic model of electroporation. Field amplification through current or voltage concentration changes with frequency, exhibiting significant spatial heterogeneity until the microwave range is reached, where cellular structure becomes almost "electrically invisible." In the time domain, membrane electroporation exhibits significant heterogeneity but occurs mostly at invaginations and cell layers with tight junctions. Such results involve emergent behavior and emphasize the importance of using multicellular models for understanding tissue-level electric field effects in higher organisms.

Cells↗
PubMed2001

A chemical inhibitor of N-WASP reveals a new mechanism for targeting protein interactions.

Cell morphology and motility are governed largely by complex signaling networks that ultimately engage the actin cytoskeleton. Understanding how individual circuits contribute to the process of forming cellular structures would be aided greatly by the availability of specific chemical inhibitors. We have used a novel chemical screen in Xenopus cell-free extracts to identify compounds that inhibit signaling pathways regulating actin polymerization. Here we report the results of a high-throughput screen for compounds that inhibit phosphatidylinositol 4,5-bisphosphate (PIP(2))-induced actin assembly and the identification of the first compound, a cyclic peptide, known to block actin assembly by inhibiting an upstream signaling component. We identify the target of this compound as N-WASP, a protein that has been investigated for its role as a node interconnecting various actin signaling networks. We show that this compound prevents activation of the Arp2/3 complex by N-WASP by allosterically stabilizing the autoinhibited conformation of N-WASP.

Actin-Related Protein 2↗
PubMed2001

A protein trap strategy to detect GFP-tagged proteins expressed from their endogenous loci in Drosophila.

In Drosophila, enhancer trap strategies allow rapid access to expression patterns, molecular data, and mutations in trapped genes. However, they do not give any information at the protein level, e.g., about the protein subcellular localization. Using the green fluorescent protein (GFP) as a mobile artificial exon carried by a transposable P-element, we have developed a protein trap system. We screened for individual flies, in which GFP tags full-length endogenous proteins expressed from their endogenous locus, allowing us to observe their cellular and subcellular distribution. GFP fusions are targeted to virtually any compartment of the cell. In the case of insertions in previously known genes, we observe that the subcellular localization of the fusion protein corresponds to the described distribution of the endogenous protein. The artificial GFP exon does not disturb upstream and downstream splicing events. Many insertions correspond to genes not predicted by the Drosophila Genome Project. Our results show the feasibility of a protein trap in Drosophila. GFP reveals in real time the dynamics of protein's distribution in the whole, live organism and provides useful markers for a number of cellular structures and compartments.

Animals↗
PubMed1969

The condensation of the adenylates of the amino acids common to protein.

Simultaneous formation of the adenylates of the 18 amino acids common to protein, followed by cocondensation, has yielded polymers containing all of those amino acids. The condensation occurred rapidly at room temperature above pH 7. The activated amino acids were reacted with thermally synthesized polyanhydro-alpha-amino acids to yield polymers of substantially increased size. The modified polyamino acids form micron-sized particles which demonstrate internal synthesis by growth and budding. These particles are stable over a wide range of pH. From thermal polyamino acids alone, answers have earlier been obtained, in principle, to questions of the primordial origin of enzymes, cellular structure, membranes, systematic anhydroamino acid sequences, and propagation of microsystems. Such a model is largely heterotrophic; the mixed adenylate condensation provides, in principle, a partial answer to the origin of syntheses of peptide bonds within protocellular structures.

Adenine Nucleotides↗
PubMed1974

Morphology, motility, and surface behavior of lymphocytes bound to nylon fibers.

Mouse B lymphocytes that were specifically bound to dinitrophenylated bovine serum albumin on nylon fibers exhibited continuous morphological changes, whereas bound T lymphocytes remained more or less spherical. Cinematomicrographic studies showed that the shape changes were associated with local and global movements, although the attached cells did not translocate along the fiber. Cap formation induced by anti-immunoglobulin was always found to be opposite to the point of attachment. The movements and the shape changes were prevented by cytochalasin B and colchicine. Treatment with these agents did not prevent cap formation but led to randomization of the position of the caps with respect to the fiber. Exposure to concanavalin A or attachment of cells to concanavalin A fibers prevented both movement and patch and cap formation, suggesting that cellular structures regulating the mobility of various receptors are altered by binding to concanavalin A fibers. These observations also indicate that interactions of local areas of the lymphocyte surface with certain ligands and substrates can strongly affect the movement and morphology of the entire cell.

Animals↗