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PubMed2000

Developmental morphological and histological studies on structures of the human fetal elbow joint.

In the present work, morphological changes in the developing human elbow joint were studied at different prenatal ages (8, 12, 16, 20, 29 and 40 weeks) and were compared with the same structures in the adult joint. The elbow joint had gone through its most important developmental changes during the 20th week of prenatal life, probably due to the direct dynamic effect of the newly developed fetal movement. During later prenatal development, the articular surfaces of the lower end of humerus and the upper ends of radius and ulna developed their characteristic congruencies, so that the highly curved convexities always articulate with the highly curved concavities. That process progressed postnatally and even till adult age. In full-term infants it was found that the lower end of humerus had acquired its adult shape, while the shape of the upper ends of radius and ulna were still not fully developed. They continued development in postnatal life even till adult age. In the present work, histological prenatal studies were done on longitudinal sections from the back of the capsule and synovial tissue, early (8 weeks) and late in full term, and the results were also compared with the same structures in adults. It was found that at all ages, the capsules were formed of cellular and fibrous elements, but at early prenatal age (8 weeks), this cellular condensation was more massive and prominent while in full-term infants, it became generally more fibrous, but was still different compared to adults. Basic cellular structures of the synovial tissue changed very little during the late prenatal developmental stage, as it did not become more fibrous than cellular during these periods, but differences in vascularity became more obvious. The cartilaginous content of the articular surface at 8 weeks was highly cellular with very little intercellular matrix. In contrast to that of full term, this cartilage became fully chondrogenous with a notable decrease in cellular density and massive increase in matrix content.

Adult↗

PubMed1989

A temporal bone preparation for the study of cochlear micromechanics at the cellular level.

An in vitro preparation of the guinea pig temporal bone was developed for studying the micromechanical behaviour of the cochlea. The preparation consists of the cochlea opened at the apex, allowing observation of cellular structures within the cochlear partition with an optical sectioning microscope and measurements of cellular vibration with laser interferometry. The middle ear ossicles and the tympanic membrane are left intact as well as the bony part of the external auditory canal, which is used for delivering a sound stimulus to the cochlea.

Acoustic Stimulation↗

PubMed1999

Morphological and biochemical analyses of the salivary glands of the malaria vector, Anopheles darlingi.

Adult Anopheles darlingi salivary glands are paired organs located on either side of the esophagus. The male glands consist of a single small lobe. The female gland is composed of two lateral lobes, with distinct proximal and distal portions, and a medial lobe. The lobes are acinar structures, organized as a unicellular epithelium that surrounds a salivary canal. The general cellular architecture is similar among the lobes, with secretory material appearing as large masses that push the cellular structures to the periphery of the organ. Cells of the proximal-lateral lobes show asynchronous cycles of secretory activity and contain secretory masses with finely filamentous aspect. In the distal-lateral lobes, cells display synchronous cycles of activity, and have a dense secretory product with mottled pattern. Cells of the medial lobe have secretory masses uniformly stained and highly electrondense. Biochemical analysis of the adult female salivary glands revealed apyrase, alpha-glucosidase and lysozyme activities. Alpha-glucosidase and lysozyme activities are detected mostly in the proximal lobes while apyrase is mainly accumulated in the distal lobes. This differential distribution of the analyzed enzymes reflects a specialization of different regions for sugar and blood feeding. Thus, the morphological differences observed in the lobes correlate with functional ones.

Animals↗

PubMed2005

Magnetic resonance in surgical oncology: I - on the origin of the spectrum.

The discovery of the phenomenon of nuclear magnetic resonance occurred just 60 years ago. The profusion of subsequent discoveries in this domain has led to the development of magnetic resonance spectroscopy - refined as an analytical tool to discern molecular structure - and magnetic resonance imaging, a cornerstone of modern radiology. Observable alterations in cellular structure and metabolism can be discerned using the non-destructive chemical analysis of magnetic resonance spectroscopy in vitro or in vivo. Differences may thus be discerned between malignant and normal tissues.

Humans↗

PubMed1981

Simultaneous demonstration of glycogen and protein in glycosomes of cardiac tissue.

Cardiac conduction fibers fixed either in glutaraldehyde and OsO4 or treated additionally en bloc with uranyl acetate were studied in order to demonstrate the structure of glycosomes (protein-glycogen complex). Sections were stained histochemically by periodic acid-thiosemicarbazide-silver proteinate (PA--TSC--SP) for glycogen followed by uranyl acetate and lead citrate (U-Pb) for protein. In control sections periodic acid was replaced by hydrogen peroxide (H2O2). Glycogen appeared in all sections stained by PA-TSC-SP. Protein was poorly contrasted in periodic acid treated histochemical sections taken from fixed in glutaraldehyde and OsO4. Simultaneous staining of glycogen and protein was achieved in sections of tissue treated en bloc with uranyl acetate. This treatment revealed two classes of glycosomes: 1) glycosomes deposited freely in the cytoplasm whose structure was disintegrated after treatment with uranyl acetate: 2) glycosomes associated with other cellular structures that remained intact. Staining of glycogen and protein in the same section demonstrated for the first time the structure of intact glycosomes.

Animals↗

PubMed2002

A heritable structural alteration of the yeast mitochondrion.

Prions have revived interest in hereditary change that is due to change in cellular structure. How pervasive is structural inheritance and what are its mechanisms? Described here is the initial characterization of [Leu(P)], a heritable structural change of the mitochondrion of Saccharomyces cerevisiae that often but not always accompanies the loss of all or part of the mitochondrial genome. Three phenotypes are reported in [Leu(P)] vs. [Leu(+)] strains: twofold slower growth, threefold slower growth in the absence of leucine, and a marked delocalization of nuclear-encoded protein destined for the mitochondrion. Introduction of mitochondria from a [Leu(+)] strain by cytoduction can convert a [Leu(P)] strain to [Leu(+)] and vice versa. Evidence against the Mendelian inheritance of the trait is presented. The incomplete dominance of [Leu(P)] and [Leu(+)] and the failure of HSP104 deletion to have any effect suggest that the trait is not specified by a prion but instead represents a new class of heritable structural change.

Heat-Shock Proteins↗

PubMed1989

[Transmission electron microscopic studies of fine structure by fast freeze method on Actinomyces israelii ATCC 12102].

Recently, one of the major objectives was to observe cellular structures in biological-materials including microorganisms as raw as possible. For this purpose, Actinomyces israelii ATCC 12102, an experimented strain, was fixed by a fast freeze method using liquid nitrogen as a cryogen, followed by transmission electron microscopic observations on fine structures. Then, the following results were obtained. 1) Cell wall was an electron dense and thick monolayer. In certain cells, numerous granules were found on cell walls, showing lamellar structures. The cell wall surface to be a wave like structure of which limit was unclear. 2) Cytoplasmic membrane consisted of two electron less dense layers holding an electron dense layer in then. However, fine layers with different electron density crossed over one another, representing a formation of stripe structure in other cells. 3) In cytoplasm, we observed that fine fibers with high electron density crossed over fine fibers with low electron density. 4) We also observed that the specialized ring structure in cytoplasm.

Actinomycetales↗

PubMed1990

Replication of chromosomal and episomal DNA in X-ray-damaged human cells: a cis- or trans-acting mechanism?

Episomal plasmids and viruses in mammalian cells present small targets for X-ray-induced DNA damage. At doses up to 100 Gy, DNA strand breaks or endonuclease III-sensitive sites were not discernible in 10.3-kb Epstein-Barr virus-based plasmid DNA or in 4.9-kb defective simian virus 40 DNA. DNA replication in these small molecules, however, was inhibited strongly by X-ray doses of greater than or equal to 20 Gy, decreasing to only 20 to 40% of control values. Inhibition was relieved slightly by growth in caffeine but was increased by growth in 3-aminobenzamide. Inhibition of DNA replication in episomal DNA molecules that are too small to sustain significant damage directly to their DNA may be due to either (a) a trans-acting diffusible factor that transfers the consequences of DNA breakage to episomes and to other replicating molecules, (b) a cis-acting mechanism in which episomes are structurally linked to genomic chromatin, and replication of both episomal and chromosomal replicons is under common control, or (c) radiation damage on other cellular structures unrelated to DNA. The resolution of these cellular mechanisms may shed light on the X-ray-resistant replication in ataxia-telangiectasia and may suggest strategies for molecular characterization of potential trans- or cis-acting factors.

Benzamides↗

PubMed1987

Cytoplasmic bar-like structures of alveolar type II cells: an ultrastructural study in freshly isolated cells from rat lungs.

Bar-like structures are tubular cytoplasmic inclusions found in situ in pulmonary epithelial type II cells of several animal species. The physiological significance and mode of formation of these inclusions are not fully established. In this paper, we describe bar-like structures as found in freshly isolated type II cells from rat lungs. Pulmonary cells were dissociated from the tissue with elastase and separated on a discontinuous density gradient of Percoll. The complete isolation procedure yielded 17 X 10(6) type II cells per animal (purity = 80%). Either from the crude cell suspensions or the purified preparations, only a small fraction of the type II cell population harbored the inclusions (less than 5%). It is shown that the bounding membranes of the bar-like structures can derive from the endoplasmic reticulum, the nuclear membrane, or the Golgi apparatus. Occasional connections with lamellar bodies were observed, and different levels of complexity in the bar-like structures were also found. The apparent rigid conformation and the orientation of the bar-like structures were taken as evidence for a role of the cytoskeleton in their formation. Because the inclusions do not appear to be new organelles or cellular structures performing a specific function, we propose that their formation may be a transient and limited cellular event in normal cells. However, the stabilization and the generation of the osmiophilic structures, as well as their overproduction, may reflect alterations of the normal physiology of the type II cells.

Animals↗

PubMed2004

Changes in the structure and function of the kidney of rats chronically exposed to cadmium. II. Histoenzymatic studies.

Early effects of cadmium (Cd) on the structure and function of the kidney were studied in an experimental model using rats intoxicated with Cd at the levels of 5 and 50 mg Cd/l drinking water. The effect of Cd was evaluated histopathologically and biochemically. Damage to the cellular structures was assessed on the basis of histoenzymatic analyses of the activity and localization of indicator enzymes (succinate dehydrogenase, lactate dehydrogenase, glucose-6-phosphatase, Mg(2+)-dependent adenosine triphosphatase and acid phosphatase). The histochemical observations indicate that Cd causes damage to the organization and function of the nephron. Several structures, i.e. endoplasmic reticulum, mitochondrion, lysosome, cellular and intracellular membrane, as well as their biological functions, i.e. aerobic and anaerobic respiration, transport functions and biochemical processes taking place in the endoplasmic reticulum, were affected. The cytotoxic action of Cd occurs mainly in the tubules and partially also in the glomeruli. The results clearly indicate that Cd damages kidney structurally and functionally even at a relatively low level (5 mg/l) corresponding to human environmental exposure, and they confirm our previous hypothesis that the threshold for the kidney effects of Cd is less than 4.08+/-0.33 microg/g kidney wet weight and higher than 2.40+/-0.15 microg/g. The target for Cd action in the kidney is the tubules (proximal convoluted tubules and straight tubules), and disturbance in their function is the main toxic effect of Cd. Renal glomeruli are also injured, but only partially, whereas in other parts of the nephron the damage is slight. The results, together with observations reported in the first paper of the study, incline us to conclude that humans environmentally exposed to Cd are at risk of tubular damage.

Acid Phosphatase↗

PubMed1978

Chromatin structure in the cellular slime mold Dictyostelium discoideum.

The structure of Dictyostelium discoideum chromatin has been studied by the following techniques: electron microscopy, staphylococcal nuclease digestion, acrylamide gel electrophoresis, sucrose gradient centrifugation, and melting. The basic unit of chromatin is the nucleosome, which is a particle 98.6 A in diameter. Approximately 50% of the chromatin is protected from nuclease digestion, but this decreases when protease activity is not inhibited. The nucleosome contains 187 base pairs of DNA, including a 137-base-pair core and a 50-base-pair linker. The monomer nucleosome has an s20,w value of 11.5 S on isokinetic sucrose gradients. When the chromatin is melted, four transitions are observed, at 54.5 degrees, 66.7 degress, 74.9 degrees, and 79.7 degrees. The structure of Dictyostelium chromatin is very similar to that seen in higher eukaryotes.

Centrifugation, Density Gradient↗

PubMed2001

Identification of a caspase-9 substrate and detection of its cleavage in programmed cell death during mouse development.

The caspase family of proteases represents the main machinery by which apoptosis occurs. In vitro studies have revealed that upstream caspases are activated in response to apoptotic stimuli, and the active caspases in turn process downstream effector caspases that are involved in the destruction of cellular structure. Caspase-9 is an upstream caspase that can become active in response to cellular damage, including deprivation of growth factors and exposure to oxidative stress in vitro. Little is known, however, about how activation of caspase-9 is temporally and spatially regulated in vivo, e.g. during development. We have identified vimentin as the first example of a caspase-9 substrate that is not a downstream procaspase. Immunohistochemical analysis, using a specific antibody against the vimentin fragments generated by caspase-9, showed that caspase-9 cleaves vimentin in apoptotic cells in the embryonic nervous system and the interdigital regions. This result is consistent with observations that gene knockouts of caspase-9 and its activator, Apaf-1, result in developmental defects in these tissues. Our results show that the specific antibody is useful for in situ detection of caspase-9 activation in programmed cell death.

Animals↗

PubMed1997

Inactivation of the cyclin-dependent kinase Cdc28 abrogates cell cycle arrest induced by DNA damage and disassembly of mitotic spindles in Saccharomyces cerevisiae.

Eukaryotic cells may halt cell cycle progression following exposure to certain exogenous agents that damage cellular structures such as DNA or microtubules. This phenomenon has been attributed to functions of cellular control mechanisms termed checkpoints. Studies with the fission yeast Schizosaccharomyces pombe and mammalian cells have led to the conclusion that cell cycle arrest in response to inhibition of DNA replication or DNA damage is a result of down-regulation of the cyclin-dependent kinases (CDKs). Based on these studies, it has been proposed that inhibition of the CDK activity may constitute a general mechanism for checkpoint controls. Observations made with the budding yeast Saccharomyces cerevisiae, however, appear to disagree with this model. It has been shown that high levels of mitotic CDK activity are present in the budding yeast cells arrested in G2/mitosis as the result of DNA damage or replication inhibition. In this report, we show that a novel mutant allele of the CDC28 gene, encoding the budding yeast CDK, allowed cell cycle passage through mitosis and nuclear division in the presence of DNA damage and the microtubule toxin nocodazole at a restrictive temperature. Unlike the checkpoint-defective mutations in CDKs of fission yeast and mammalian cells, the cdc28 mutation that we identified was recessive and resulted in a loss of the CDK activity, including the Clb2-, Clb5-, and Clb6-associated, but not the Clb3-associated, CDK activities. Examination of several known alleles of cdc28 revealed that they were also, albeit partially, defective in cell cycle arrest in response to UV-generated DNA damage. These findings suggest that Cdc28 kinase in budding yeast may be required for cell cycle arrest resulting from DNA damage and disassembly of mitotic spindles.

Antineoplastic Agents↗

PubMed2003

Ischemic preconditioning of renal tissue: identification of early up-regulated genes.

Given the important effects of ischemic preconditioning (IPC) in minimizing tissue damage induced by sustained ischemia in several tissues, this study evaluated the effect of IPC in preserving renal function and identified up-regulated genes after 30 min of preconditioning. IPC induced by 2, 3 and 4 min of ischemia, intercalated by 5 min of reperfusion, induced a measurable protection of renal function and morphology. The improved functional and histological parameters occurred in parallel with up-regulation of 39 genes, as evaluated by subtractive hybridization; for 13 of them we could show, by RNAse protection assay, a significant increase in mRNA levels. These genes code for chaperones/chaperonins and cytoskeleton proteins that could be involved in preservation of protein folding and cellular structures after sustained ischemia; proteins related to oxidative metabolism that might be relevant for cellular use of alternate sources of energy or for faster recovery of ATP levels in this condition, and proteins that are putative scavengers of oxidant products. Summarizing, ischemic preconditioning induced up-regulation of genes that code proteins whose functional roles suggest their involvement in the tolerance of the preconditioned tissue to sustained ischemia.

Animals↗

PubMed2003

Near-infrared spectroscopic monitoring of the diffusion process of deuterium-labeled molecules in wood. Part II: hardwood.

Fourier transform near-infrared (FT-NIR) transmission spectroscopy was applied to monitor the diffusion process of deuterium-labeled molecules in hardwood (Beech). The results are compared with previous data obtained on softwood (Sitka spruce) in order to consistently understand the state of order in cellulose of wood. The saturation accessibility and diffusion rate varied characteristically with the OH groups in different states of order in the wood substance, the diffusants, and the wood species, respectively. The variation of saturation accessibility should be associated with the fundamental difference of the fine structure such as the microfibrils in the wood substance. The effect of the anatomical cellular structure on the accessibility was reflected in the variation of the diffusion rate with the wood species. The size effect of the diffusants also played an important role for the diffusion process in wood. Since the volumetric percentage of wood fibers and wood rays is relatively similar, the dichroic effects due to the anisotropy of the cellulose chains were apparently diminished. Finally, we proposed a new interpretation of the fine structure of the microfibrils in the cell wall by comparing a series of results from hardwood and softwood. Each elementary fibril in the hardwood has a more homogeneous arrangement in the microfibrils compared to that in the softwood.

1-Butanol↗

PubMed1985

Review of melanoma antigens recognized by monoclonal antibodies (MAbs). Their functional significance and applications in diagnosis and treatment of melanoma.

The introduction of monoclonal antibody techniques has led to a rapid advance in information concerning antigenic structures in melanoma cell membranes. These have been classified according to the extent of their expression on cells of other tissues, but it is evident that a more precise classification based on their biochemical nature is possible. Several monoclonal antibodies appear to define antigens restricted to melanoma cells and fetal tissues. Many antibodies recognize antigens shared with gliomas and nevi, whereas other groups can be defined which recognize antigens on melanocytes or other carcinomas. One of the commonly detected antigens was shown to be a high molecular weight (MW) proteoglycan which may be involved in reactions with other cells and the intercellular matrix. A second antigen was shown to be a ganglioside which may have receptor functions in cells. A third was shown to be a glycoprotein with iron transport functions. The latter antigen and the large MW proteoglycan have been a focus of attention for in vivo targeting studies in treatment and diagnosis. The ganglioside, large MW proteoglycan and a melanocarcinoma antigen may be detected in the circulation of patients and are being evaluated for monitoring of disease activity in patients with melanoma. Several monoclonals may be of value in histological evaluation of melanoma, e.g. diagnosis of preneoplastic lesions, metastatic lesions of unknown origin and identification of cell structures related to metastatic behaviour in the host. Further studies should help to define cellular structures recognized by the immune system in humans.

Antibodies, Monoclonal↗

PubMed1996

A program for analyzing the morphological organization of tessellated cellular mosaics.

We have constructed a computer program that allows sequential sets of data from tessellated cellular mosaics to be evaluated such that the presence and position of abnormal cells in the mosaic can be easily, quickly, and quantitatively identified. Conventional parametric analysis of the global morphological organization of large tessellated cellular mosaics does not provide the necessary granularity of analysis to allow for rapid identification of such atypical cellular structures. Our program, written in C using structured programming techniques, provides the needed analytical granularity for detailed studies of subsections of large cellular mosaics, while also providing conventional statistical evaluation of the data set. The architecture of the program is modular and designed as a set of procedures and subprocessess that can either analyze the entire mosaic or discrete sets of cells within the larger sample. The types of morphological heterogeneity (or dishomogeneity) that the program can investigate occur in a variety of biological mosaics where there is a continuum of the structural features, including fairly regular linear stacked arrays of cells or tissue partitions, to less regular mosaics of epithelial or endothelial cell layers, to heterogeneous patterns found on tissue surfaces, such as fluorescein dye-highlighted features on the human conjunctiva. The program has been used to successfully evaluate several different types of mosaics.

Body Patterning↗

PubMed2003

Distinct roles of Bazooka and Stardust in the specification of Drosophila photoreceptor membrane architecture.

Photoreceptors form during Drosophila pupal development and acquire elaborate membrane structures, including the rhabdomeres and stalk membranes. Here, we show that the development of these cellular structures involves two distinct processes: the establishment of apical-basal polarity that requires Bazooka (Baz), and the regionalization of apical membrane into stalk membranes and rhabdomeres that requires Stardust (Sdt). In the absence of Baz, the apical-basal polarity is compromised in early pupal photoreceptors, and no identifiable apical membrane domain is formed. Sdt, in contrast, plays a more limited role in apical-basal polarity but is essential for the proper localization of transmembrane protein Crumbs (Crb), known to be required in the biogenesis of stalk membrane. Loss of Sdt causes strong defects in stalk membrane and rhabdomere resembling crb mutant phenotype. Thus, proteins required for establishing the early embryonic epithelial polarity are used later for the morphogenesis of photoreceptors, with Baz and Sdt functioning in different aspects of the formation of the apical-basal cellular architecture.

Animals↗