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At least 865 records · Page 48Linked to original sources
PubMed1978

The respiratory epithelium. VI. Histogenesis of lung tumors induced by benzo[a]pyrene-ferric oxide in the hamster.

Lung tumors were induced in female Syrian golden hamsters by intratracheal instillation of benzo[a]pyrene-Fe2O3. The tumors were characterized with the use of coordinated morphologic and histochemical techniques including electron microscopy. The lung carcinomas were classified according to their presumed cell of origin. Most were derived from mucous cells and/or basal cells, and they were classified as either epidermoid carcinomas or as combined epidermoid and adenocarcinomas. The tumors in the second group (57% of the total number of carcinomas) presented a wide spectrum of epidermoid and adeno components. The epidermoid component was characterized in well-differentiated tumors by the presence of intercellular bridges and/or keratinization. Well-developed desmosomes and numerous bundles of tonofilaments were observed ultrastructurally. In diagnosing adenocarcinoma, one no longer needs to depend on the presence of tubules or gross glandular structures as criteria for diagnosis. The presence of intracellular and/or extracellular alveoli, well-developed Golgi complex, and endoplasmic reticulum and/or evidence of mucous secretion provide more definitive criteria. A tumor composed of neurosecretory cells that morphologically resembled a bronchial carcinoid of man was observed. Nests of uniform, small, polygonal cells with round-to-oval nuclei were seen at the light microscopic level. Dense-core secretory granules 1,100-2,200 A were present in the cytoplasm of the tumor cells. Several fibrosarcomas were observed. The tumors showed a very cellular structure, composed of either densely packed ovoid or spindle-shaped cells. Ultrastructurally, the cells resembled fibroblasts. The results obtained in this study give strong support for a histogenetic classification, i.e., a classification based on the cell of origin.

Adenocarcinoma↗
PubMed1986

[Ultrastructural study of 36 lymph node sites of Hodgkin's disease].

The authors report their ultrastructural findings of 36 involved lymph-nodes in Hodgkin's disease (HD), before any treatment. More than 400 tumour cells were studied. An analytical study was carried out on the different aspects presented by the nuclei (uni or multi-lobated); the nucleoli (compact, reticulate or dispersed); and the cytoplasm (immunoblastic, complex, intermediate). No cellular structure evoking phagocytic activity with digestion, and consequently an eventual histiomonocytic origin, could be detected even on serial sections. The presence of lipid inclusions, sometimes of glycogen, as well as certain peculiar structures are described and discussed. The ultrastructural aspects could be easily correlated with the different types of tumour cell described in HD using light microscopy. The various kinds of cells which could could be detected in the same lymph node, may correspond to a real tumour cell lineage, consisting, firstly, of a cell of immunoblastic type with a mono- or bilobated nucleus, then an intermediate type with a bilobated or multisegmented nucleus, and finally a complex cell type with a multisegmented nucleus. The lacunar cells are characterised by a fragile hyaloplasm, without cellular organelles at their periphery, these being concentrated around the nucleus. This special organisation explains the aspects observed in light microscopy. However, no explanation could be offered to understand this particular aspect of the cytoplasm. The ultrastructural characteristics of the Reed-Sternberg cells and their variants did not allow a precise cellular origin to be proposed. The absence of phagolysosomes pleads against a histiocytic origin. However their similarity of the interdigitated reticular cells did not seem sufficient to propose this origin. The likeliness of the cytoplasm of cells with mono- or bilobated nuclei with that of immunoblasts, constitutes the most interesting morphological feature. This fact, associated with the appearance of immunoblasts similar to Reed-Sternberg cells of infectious mononucleosis, suggests a lymphoid origin. The study of the reactive cells around the tumor cells did not allow any consequences to be drawn. One could simply note that the Reed-Sternberg cells and their variants were surrounded by lymphocytes, forming a kind of crown. No etiological agent could be detected. These data are compared to those of other publications, and discussed. This ultrastructural study, therefore, does not offer the solution to most of the questions which still remain to be answered as to the origin of the Reed-Sternberg cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Biopsy↗
PubMed1989

Ultrastructural distribution of ribonucleoprotein complexes during mitosis. snRNP antigens are contained in mitotic granule clusters.

The great majority of snRNP and hnRNP ribonucleoproteins have been shown to be confined to the nucleus except during periods of cell division. We have now determined the fine structure distribution of polypeptides associated with these RNP complexes during interphase and mitosis in mammalian tissue culture cells using immunoelectron microscopy. Many hnRNP antigens are found at the periphery of heterochromatin masses, known to be the sites of non-rRNP proteins initially surround areas of condensing chromatin and later become generally dispersed throughout the mitotic cell. The Sm protein antigens of snRNP complexes are found diffusely distributed in interphase nuclei as well as concentrated in fields of interchromatin granules (ICG). Proteins of snRNP complexes, unlike those of hnRNP, are associated with discernible cellular structures during mitosis. By prometaphase/metaphase, dense granular clusters are observed to contain a high concentration of snRNPs. These mitotic granule clusters (MGCs) are often in close proximity to chromosomal masses by late anaphase/telophase. The MGC structures are morphologically similar to interchromatin granule fields found in interphase nuclei. Furthermore, like interchromatin granules, they are sites of a high concentration of snRNP antigens and do not contain detectable hnRNP proteins or DNA.

Antigens↗
PubMed1997

Regulation of mammalian acetyl-coenzyme A carboxylase.

Long-chain fatty acids are involved in all aspects of cellular structure and function. For controlling amounts of fatty acids, cells are endowed with two acetyl-coenzyme A carboxylase (ACC) systems. ACC-alpha is the rate-limiting enzyme in the biogenesis of long-chain fatty acids, and ACC-beta is believed to control mitochondrial fatty acid oxidation. These two isoforms of ACC control the amount of fatty acids in the cells. Phosphorylation and dephosphorylation of ACC-alpha cause enzyme inactivation and activation, respectively, and serve as the enzyme's short-term regulatory mechanism. Covalently modified enzymes become more sensitive toward cellular metabolites. In addition, many hormones and nutrients affect gene expression. The gene products formed are heterogeneous and tissue specific. The ACC-beta gene is located on human chromosome 12; the cDNA for this gene has just been cloned. The gene for the alpha-isoform is located on human chromosome 17. The catalytic core of the beta-isoform is homologous to that of the alpha-isoform, except for an additional peptide of about 150 amino acids at the N terminus. This extra peptide sequence makes the beta-form about 10,000 daltons larger, and it is thought to be involved in the unique role that has been assigned to this enzyme. The detailed control mechanisms for the beta-isoform are not known.

Acetyl-CoA Carboxylase↗
PubMed1991

Phosphocreatine pathway for energy transport: ADP diffusion and cardiomyopathy.

Chemically skinned (by treatment with saponin, 40 micrograms/ml) isolated cardiomyocytes were used to study the intracellular diffusion of ADP and creatine (Cr). Stimulation of respiration was studied in these cardiomyocytes without intact sarcolemma and in isolated heart mitochondrial by addition of ADP and Cr in the presence of 0.2 mM ATP (via mitochondrial creatine kinase reaction: Cr + MgATP = MgADP + PCr). The Michaelis constant (Km) for Cr was similar in both cases, 5.67 +/- 0.11 (SD) mM in skinned myocytes and 6.9 +/- 0.2 mM in mitochondria, showing that there is no significant restriction to the diffusion of this substrate. However, the apparent Km for external ADP increased from 17.6 +/- 1.0 microM for mitochondria to 250 +/- 38 microM for skinned cardiomyocytes, showing decreased diffusivity of ADP as a result of binding to cellular structures. In the presence of 25 mM Cr, the Km for ADP for myocytes decreased to 35.6 +/- 5.6 microM due to the coupling of the creatine kinase and oxidative phosphorylation reactions. Provision of substrate for the creatine kinase reaction amplified the weak ADP signal in the regulation of respiration. The activity of the mitochondrial creatine kinase was decreased by a factor of two in cardiomyopathic hamsters and human hearts and was associated with a twofold decrease in creatine-stimulated respiration. These data show a potentially key role of mitochondrial creatine kinase in the regulation of cellular respiration and the possible importance of changes in its activity for the functional disturbances of the cardiomyopathic heart.

Adenosine Diphosphate↗
PubMed1984

Effects of non-toxic doses of ouabain on sodium, potassium, calcium distribution in guinea pig papillary muscle. Electronprobe microanalysis.

The mechanisms and the cellular structures which are definitely involved in the accumulation and release of calcium in heart muscle treated with cardiac glycosides are not yet known. The distribution of sodium, potassium and calcium in small papillary muscles of the guinea pig right ventricle was examined with the aid of energy dispersive x-ray microanalysis and cryotechniques. The primary aim of the present study was twofold: firstly, to determine whether an increase in intracellular sodium concentration is detectable in muscles showing positive inotropy resulting from treatment with non-toxic doses of ouabain; and secondly, whether at the end of diastole cellular stores are detectable accumulating Ca which could be responsible for the pronounced contraction which normally would follow. Analyses on interstitium, cell membrane, sarcomeres, Z-lines and mitochondria of 7 muscles strips treated with non-toxic doses of ouabain and frozen at the end of diastole showed the following: sodium concentration in the sarcoplasm was significantly higher than over the mitochondria; it was also higher than over the sarcoplasm of non-treated muscles frozen at the end of diastole. High calcium concentrations were also measured over the cell membrane. These calcium concentrations were higher than that detected in sarcomeres, Z-lines and mitochondria. Over the sarcomeres, the calcium concentration was higher than in experiments on non-treated muscles which were also frozen at the end of diastole. Mitochondria did not accumulate any detectable concentration of calcium.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2005

Unravelling the functional interaction structure of a cellular network from temporal slope information of experimental data.

Due to the unavoidable nonbiological variations accompanying many experiments, it is imperative to consider a way of unravelling the functional interaction structure of a cellular network (e.g. signalling cascades or gene networks) by using the qualitative information of time-series experimental data instead of computation through the measured absolute values. In this spirit, we propose a very simple but effective method of identifying the functional interaction structure of a cellular network based on temporal ascending or descending slope information from given time-series measurements. From this method, we can gain insight into the acceptable measurement error ranges in order to estimate the correct functional interaction structure and we can also find guidance for a new experimental design to complement the insufficient information of a given experimental dataset. We developed experimental sign equations, making use of the temporal slope sign information from time-series experimental data, without a specific assumption on parameter perturbations for each network node. Based on these equations, we further describe the available specific information from each part of experimental data in detail and show the functional interaction structure obtained by integrating such information. In this procedure, we use only simple algebra on sign changes without complicated computations on the measured absolute values of the experimental data. The result is, however, verified through rigorous mathematical definitions and proofs. The present method provides us with information about the acceptable measurement error ranges for correct estimation of the functional interaction structure and it further leads to a new experimental design to complement the given experimental data by informing us about additional specific sampling points to be chosen for further required information.

Cell Physiological Phenomena↗
PubMed2004

Naiadocystis phykoterion n. gen., n. sp. (Apicomplexa: Eugregarinida: Hirmocystidae), from the Mexican pygmy grasshopper, Paratettix mexicanus (Orthoptera: Tetrigidae), in the Texas big thicket with recognition of three previously described species of Naiadocystis.

Naiadocystis phykoterion n. gen., n. sp. (Apicomplexa: Eugregarinida: Hirmocystidae), is described from the Mexican pygmy grasshopper, Paratettix mexicanus (Orthoptera: Tetrigidae), collected from sandbars along Harmon Creek, Walker County, Texas, in the western edge of the Texas Big Thicket. Naiadocystis n. gen. is distinguished by the form of the epimerite complex, a simple cordoid or toroid epimerite with an interior obconoid structure resembling a funnel that tapers to a distinct axial canal bisecting the protomerite, which is conspicuous in all stages of development, and a satellite protomerite reduced to a linearly crateriform cup or sucker that receives and enfolds posterior end of primite deutomerite. Association is precocious, caudofrontal, and biassociative. Gametocysts are spherical. Sporoducts are present but vestigial and irregular in number. Oocysts are broadly elliptoid with 4 small spherical polar knobs, 1 each at 30 degrees, 150 degrees, 210 degrees, and 330 degrees, and dehisce en masse. The species described herein are differentiated by their overall size and relative proportion of cellular structures. Naiadocystis acantholobae (Hoshide, 1952) n. comb., Naiadocystis acrydiinarum (Semans, 1939) n. comb., and Naiadocystis tetrigis (Corbel, 1968) n. comb. are recognized as members of Naiadocystis previously placed within Gregarina (Apicomplexa: Eugregarinida: Gregarinidae).

Animals↗
PubMed1987

Morphometric characterization of the human neuroendocrine Merkel cells.

In this study, the neuroendocrine Merkel cells (NEMCs) from adult human epidermis are defined morphometrically, using the MOP 20 image analyzer to measure 21 parameters of either the cell as a whole, or particular cellular structures. Maximum diameter (8.09 microns), perimeter (26.51 microns), area (36.87 microns2) and form factor (0.626) for the cell as a whole, and maximum diameter (5.08 microns), perimeter (18.74 microns), area (12.54 microns2) and form factor (0.452) for the nucleus were determined. Also measured were nuclear-cytoplasmic ratio (0.5595), filament thickness (10 nm), and granular numerical density (7.02 granules/micron2). Maximum diameter, area, and form factor of neurosecretory granules were 94.23 nm, 5020.05 nm2, and 0.93, respectively. Length of desmosomes linking NEMCs to keratinocytes was determined (286.9 nm) and compared with that of interkeratinocytic desmosomes (385 nm). In addition, length and diameter of cellular processes (spine-like processes (1.58 micron X 0.26 micron), interstitial processes (1.39 micron X 0.25 micron), and microvilli (0.35 micron X 0.25 micron) were measured after separation and classification according to the particular morphologic characteristics of each.

Adult↗
PubMed2000

Epithelial structural proteins of the skin and oral cavity: function in health and disease.

Epithelial tissues function to protect the organism from physical, chemical, and microbial damage and are essential for survival. To perform this role, epithelial keratinocytes undergo a well-defined differentiation program that results in the expression of structural proteins which maintain the integrity of epithelial tissues and function as a protective barrier. This review focuses on structural proteins of the epidermis and oral mucosa. Keratin proteins comprise the predominant cytoskeletal component of these epithelia. Keratin filaments are attached to the plasma membrane via desmosomes, and together these structural components form a three-dimensional array within the cytoplasm of epithelial cells and tissues. Desmosomes contain two types of transmembrane proteins, the desmogleins and desmocollins, that are members of the cadherin family. The desmosomal cadherins are linked to the keratin cytoskeleton via several cytoplasmic plaque proteins, including desmoplakin and plakoglobin (gamma-catenin). Epidermal and oral keratinocytes express additional differentiation markers, including filaggrin and trichohyalin, that associate with the keratin cytoskeleton during terminal differentiation, and proteins such as loricrin, small proline-rich proteins, and involucrin, that are cross-linked into the cornified envelope by transglutaminase enzymes. The importance of these cellular structures is highlighted by the large numbers of genetic and acquired (autoimmune) human disorders that involve mutations in, or autoantibodies to, keratins and desmosomal and cornified envelope proteins. While much progress has been made in the identification of the structural proteins and enzymes involved in epithelial differentiation, regulation of this process is less clear. Both calcium and retinoids influence epithelial differentiation by altering the transcription of target genes and by regulating activity of enzymes critical in epithelial differentiation, such as transglutaminases, proteinases, and protein kinases. These studies have furthered our understanding of how epithelial tissue and cell integrity is maintained and provide a basis for the future treatment of skin and oral disorders by gene therapy and other novel therapeutics.

Animals↗
PubMed2004

Mitosomes of Entamoeba histolytica are abundant mitochondrion-related remnant organelles that lack a detectable organellar genome.

The existence of mitochondrion-related relict organelles (mitosomes) in the amitochondrial human pathogen Entamoeba histolytica and the detection of extranuclear DNA-containing cytoplasmic structures (EhKOs) has led to the suggestion that a remnant genome from the original mitochondrial endosymbiont might have been retained in this organism. This study reports on the mutually exclusive distribution of Cpn60 and extranuclear DNA in E. histolytica and on the distribution of Cpn60-containing mitosomes in this parasite. In situ nick-translation coupled to immunofluorescence microscopy failed to detect the presence of DNA in mitosomes, either in fixed parasite trophozoites or in partially purified organellar fractions. These results indicate that a remnant organellar genome has not been retained in E. histolytica mitosomes and demonstrate unequivocally that EhKOs and mitosomes are distinct and unrelated cellular structures.

Animals↗
PubMed1992

Extracellular reduction of alloxan results in oxygen radical-mediated attack on plasma and lysosomal membranes.

Alloxan participation in extracellular redox processes results in the formation of the reactive oxygen species (ROS) superoxide anions (O2-), hydroxyl radical (OH.) and hydrogen peroxide (H2O2), causing cell damage through a number of complex interactions probably involving several different cellular structures. These involve the plasma membrane, and we have recently presented evidence for lysosomal interference. The present study elucidates the early (within 15 min) events in a model system of macrophage-like cells (J-774) in culture. Addition of 2 mM alloxan and 1 mM cysteine to the medium surrounding the cells (phosphate-buffered saline, PBS, 37 degrees C, pH 7.4) resulted in rapid lysosomal membrane damage with disappearance of the proton gradient as visualized by acridine orange relocalization, as well as plasma membrane alterations leading to increased leakage of fluorescein after fluorescein diacetate staining. These events were later (greater than 30 min) followed by cellular degeneration in the form of blebbing. Mitochondrial damage (rhodamine 123 relocalization) was a late event. Cells pretreated with desferrioxamine (Des) and superoxide dismutase (SOD) or Des, SOD and catalase (CAT) to induce partial (H2O2 formation only) or almost full protection (no ROS formation) showed about the same reactions as when cells were exposed to alloxan and cysteine without scavengers (O2-, H2O2 and OH. formation) or with PBS only, respectively. The results are interpreted as indicating that the cytotoxicity is a consequence mainly of H2O2 involvement and probably of lysosomal influx of H2O2 with ensuing OH.formation within secondary lysosomes containing trace amounts of reactive iron. It is suggested that the resultant lysosomal membrane damage is followed by leakage of lysosomal hydrolases and ensuing cellular degeneration.

Acridine Orange↗
PubMed2002

Analysis of altered gene expression during sustained atrial fibrillation in the goat.

OBJECTIVE: Atrial fibrillation (AF) is characterised by electrical, gap junctional and structural remodelling. However, the underlying molecular mechanisms of these phenomena are largely unknown. To get more insight into atrial remodelling at the molecular level we have analysed changes in gene expression during sustained AF in the goat. METHODS: The differential display technique (DD) was used to identify genes differentially expressed during sustained AF (13.9 +/- 5.2 weeks) as compared to sinus rhythm (SR). Dot-blot analysis was performed to confirm the altered gene expression and to establish the changes in expression after 1, 2, 4, 8 and 16 weeks of AF. Immunohistochemistry and western blotting were used to validate the DD approach and to further characterise the changed expression of the beta-myosin heavy chain gene at the protein level. RESULTS: Of the approximately 125 fragments that showed changed expression levels during AF, 34 were cloned and sequenced. Twenty-one of these represented known genes involved in cardiomyocyte structure, metabolism, expression regulation, or differentiation status. The changed expression of 70% of the isolated clones could be confirmed by dot-blot analysis. In addition, time course analysis revealed different profiles of expression as well as transient re-expression of genes, e.g. the gene for hypoxia-inducible factor 1 alpha during the first week of AF. During sustained AF the frequency of cardiomyocytes expressing beta myosin heavy chain (beta MHC) increased from 21.8 +/- 2.1 to 47.9 +/- 2.5% (S.E.M.). The overall expression of MHC (alpha+beta) appeared to be down-regulated during AF. CONCLUSIONS: AF is accompanied by changes in expression of proteins involved in cellular structure, metabolism, gene expression regulation and (de-)differentiation. Most alterations in expression confirm or support the hypothesis of cardiomyocyte de-differentiation. Furthermore, the results suggest a role for ischemic stress in the early response of cardiomyocytes to AF, possibly via activation of hypoxia-inducible factor 1 alpha.

Animals↗
PubMed1999

Structural requirements for cellular uptake of alpha-helical amphipathic peptides.

The structure of the cell-permeable alpha-helical amphipathic model peptide FLUOS-KLALKLALKALKAALKLA-NH2 (I) was modified stepwise with respect to its helix parameters hydrophobicity, hydrophobic moment and hydrophilic face as well as molecular size and charge. Cellular uptake and membrane destabilizing activity of the resulting peptides were studied using aortic endothelial cells and HPLC combined with CLSM. With the exceptions that a reduction of molecule size below 16 amino acid residues and the introduction of a negative net charge abolished uptake, none of the investigated structural parameters proved to be essential for the passage of these peptides across the plasma membrane. Membrane toxicity also showed no correlation to any of the parameters investigated and could be detected only at concentrations higher than 2 microM. These results implicate helical amphipathicity as the only essential structural requirement for the entry of such peptides into the cell interior, in accord with earlier studies. The pivotal role of helical amphipathicity was confirmed by uptake results obtained with two further pairs of amphipathic/non-amphipathic 18-mer peptides with different primary structure, net charge and helix parameters from I. The amphipathic counterparts were internalized into the cells to a comparable extent as I, whereas no cellular uptake could be detected for the non-amphipathic analogues. The mode of uptake remains unclear and involves both temperature-sensitive and -insensitive processes, indicating non-endocytic contributions.

Animals↗
PubMed1990

Microinjection of p34cdc2 kinase induces marked changes in cell shape, cytoskeletal organization, and chromatin structure in mammalian fibroblasts.

We have examined the effects of elevating the intracellular levels of p34cdc2 kinase by microinjection into living mammalian cells. These studies reveal rapid and dramatic changes in cell shape with cells becoming round and losing the bulk of their cell-substratum contact. Such effects were induced at all times in the cell cycle except at S phase and were fully reversible at S phase or mitosis. Similar results were obtained with the homogeneous catalytic subunit of p34cdc2 kinase or p34cdc2 kinase associated with cyclin B. These alterations were accompanied by a marked reduction in interphase microtubules without the spindle formation, actin microfilament redistribution, and premature chromatin condensation. Although these changes closely mimic the events occurring during early phases of mitosis, p34cdc2 kinase-injected cells were not induced to pass further into division. These data provide detailed evidence that p34cdc2 kinase plays a major prerequisite role in the rearrangement of cellular structures associated with mammalian cell mitosis.

Actin Cytoskeleton↗
PubMed1993

A light-microscopic study on pineal organ structure and innervation in the catfish, Heteropneustes fossilis.

In Heteropneustes fossilis, the pineal organ consists of a long hollow stalk (PS) and an elongate spindle-shaped end vesicle (EV) which lies beneath a highly specialized window. The EV is formed of a dorsal thin and ventral thick parenchymal layer, separated by a lumen and contains photoreceptor, supportive and ganglion cells. The numerous photoreceptor cells are characterized by apical processes which are AF- and PAS-positive. In Holmes' silver preparation, the apical processes showed parallel silver-positive lamellae embedded in luxol fast blue coagulum. The supportive cells are ependymal or glial-like. The ganglion cells or neurons are bipolar or multipolar with prominent dendrites and long, beaded and occasionally branched axonal processes. The neurons are strongly acetylcholinesterase (AChE)-positive. The EV also showed strong toluidine blue-positive mast cells and AF-positive granules and fibres. The PS is composed of the same cellular structures. The neurons are small and AChE-positive. Pineal tract fibres were arranged into dorsal and ventral bundles in the middle and proximal regions of the PS. Silver-positive neurons were found among or close to the pineal tracts. The pineal tract fibres innervate the habenular commissure, habenular nucleus, subcommissural organ, posterior commissure and pretectum, and are AChE-positive. At the origin of the stalk, the pineal tract fibres were seen to project into the ventricle and innervate the subcommissural organ both supraependymally and transependymally.

Acetylcholinesterase↗
PubMed2001

Expression of fungal desaturase genes in cultured mammalian cells.

Long-chain polyunsaturated fatty acids (LC-PUFA) are important components of cellular structure and function. Most of LC-PUFA are derived from linoleic acid and alpha-linolenic acid. In plants and fungi, these two acids can be synthesized from oleic acid via the action of two enzymes, delta12 and delta15-desaturases. Due to lack of these enzymatic activities and the ability to synthesize these two essential fatty acids, animals must obtain them from the diet. In this report, we demonstrated the expression of a fungal delta12-desaturase gene in mouse L cells incubated in serum-free medium. The results showed a significant increase in the amount of linoleic acid with a concomitant decrease of oleic acid in cellular lipids. Most of the newly formed linoleic acid was incorporated into cellular phospholipids, particularly phosphatidylcholine. The increase of linoleic acid provided the substrate for the endogenous synthesis of (n-6) LC-PUFA, such as eicosadienoic acid (EDA), dihomo-gamma-linoleic acid (DGLA) and arachidonic acid (AA). Prolonged incubation further increased the levels of linoleic acid derived from oleic acid by the action of delta12-desaturase, and the levels of 20:2n-6 produced from linoleic acid by the action of the endogenous elongase. However, prolonged incubation suppressed significantly the formation of DGLA and AA. In a separate study, a fungal delta6-desaturase gene has also been expressed in the mouse L cells incubated in serum-containing medium. The result shows a significant increase in levels of 20:3n-6 and 20:4n-6. These findings demonstrate that through genetic modification, it is possible to (1) generate cell lines which no longer require dietary 'essential' fatty acids and (2) alter the endogenous fatty acid metabolism to enhance the production of LC-PUFA and their derivatives.

Animals↗
PubMed1976

Retrosplenial cortex in the rhesus monkey: a cytoarchitectonic and Golgi study.

The laminar and cellular structure of retrosplenial cortex in the rhesus monkey was studied with Nissl stained and rapid Golgi impregnated tissue and the results were used to evaluate morphological features of a cortical transition zone. The granular layer of retrosplenial granular cortex is composed primarily of small, density packed, star pyramidal cells. These cells branch within the granular layer itself, while the apical dendrite enters layer I where it branches infrequently or not at all. This cell type is similar to the star pyramid first described by Lorente de No except in its areal and laminar distribution. Cytoarchitectonic observations of retrosplenial agranular cortex show, that, although this area is relatively "agranular" in comparison to other cortical areas, it does possess an incipient layer II and layer IV. These layers are composed mainly of small and medium sized pyramidal cells, but many non-pyramidal cell types were found in these and other layers in this area in rapid Golgi preparations. Stellate cells with beaded or smooth, lightly spinous dendrites were found throughout layer I-IV, while fusiform cells with smooth or very lightly spinous dendrites appear in layers III-VI. Areas surrounding retrosplenial cortex in the posterior cingulate region were also evaluated in Nissl and Golgi preparations including the indusium griseum, subiculum (dorsal to the corpus callosum) and area 23. The laminar and cellular constitutents of retrosplenial cortex were then evaluated in the context of cortical architectonic transition. The transition from one cellular layer in the indusium griseum to five cellular layers in area 23 is made by the addition of layers II, III, IV and VI in retrosplenial cortex to the one ganglionic layer of the indusium griseum and subiculum. Besides the addition and subdivision of layers in retrosplenial cortex, two aspects of cell morphology were found to change in this region. First, the structure of pyramidal cells progressively changes from those in the indusium griseum which have predominently round or oval somata and a preponderance of apical and few basal dendrites to those in layer V of retrosplenial cortex and area 23 which have pyramidal shaped somata and a great number of basal dendrites which branch frequently and spread horizontally for hundreds of microns. Second, there is a change in the number and distribution of non-pyramidal cell types. Evidence was not found that the indusium griseum, dorsal subiculum or layer V of retrosplenial granular cortex contain a significant number of stellate or fusiform cells. At the retrosplenial granular/agranular border, though, these cells gradually begin to constitute a greater proportion of the cell population and in area 23 form a major component of layer IV...

Animals↗