bluuebunny/crossref_metadata_2025_split huggingface dataset:
Integrating laccase–mediator treatment into an industrial‐type sequence for totally chlorine‐free bleaching of eucalypt kraft pulp
Authors: Ibarra David , Camarero Susana , Romero Javier , Martínez María Jesús , Martínez Angel T 
Published: May 2006

AbstractEnzymatic delignification using the high‐redox potential thermostable laccase from the fungus Pycnoporus cinnabarinus and a chemical mediator (1‐hydroxybenzotriazole) was investigated to improve totally chlorine‐free (TCF) bleaching of Eucalyptus globulus kraft pulps. Different points of incorporation of the enzyme treatment into an industrial‐type bleaching sequence (consisting of double oxygen, chelation and peroxide stages) were investigated in pressurized laboratory reactors. The best final pulp properties were obtained using an OOLQPoP sequence, where a laccase–mediator stage (L) was incorporated between double oxygen and chelation. The worse results, when the enzymatic and chelation treatments were combined in a unique stage, seemed related to partial inhibition of laccase‐mediator activity by the chelator. The new TCF sequence including the laccase stage permitted to improve eucalypt pulp delignification to values around kappa 5 (hexenuronic acid contribution over 50%) compared to kappa 7 using only TCF chemical reagents. In a similar way, the final brightness obtained, over 91% ISO, was 3–4 points higher than that obtained in the chemical sequences. Although technical and economic issues are to be solved, the results obtained show the feasibility of integrating a laccase–mediator treatment into a TCF sequence for bleaching eucalypt kraft pulp. Copyright © 2006 Society of Chemical Industry
Strategies for enhanced malolactic fermentation in wine and cider maturation
Authors: Zhang Daosheng , Lovitt Robert W 
Published: May 2006

AbstractMalolactic fermentation (the conversion of malate to lactate) has been recognised as a desired process in wine and cider making and is being progressively developed. It not only concerns the conversion of malate but also involves flavour‐related biotransformations catalysed by malolactic fermentation bacteria. This review considers strategies to improve the reliability and performance of malolactic fermentation and documents the development of cell propagation systems and maturation processes, especially in relation to the physiology and biochemistry of malolactic fermentation bacteria. This includes the use of starter cultures and high cell concentrations for propagation and biotransformation, the types of bioreactors and their operational modes, especially those associated with the process of malolactic fermentation. Oenococcus oeni, the predominant organism associated with malolactic fermentation, is an acidophilic bacterium and is able to grow in wine at pH 3.5 or lower in the presence of ethanol and sulphite. As malolactic fermentation takes place in a highly alcoholic (up to 13% v/v) and highly acidic (pH 3.5 or lower) environment, slow growth and poor yields are frequently encountered when starter cultures are used. As a result, it requires several weeks or even months in such conditions to achieve full maturation. The malolactic fermentation process is also affected by temperature, malate concentration, nutrient composition and cell concentration. With an improved understanding of malolactic fermentation and the use of high cell concentrations, appropriate bioreactor designs and various operational modes, process innovation involving the separation of cell propagation from the maturation process now looks feasible. The review assesses the performance of malolactic fermentation systems and the relative benefits of high‐cell‐concentration biotransformation systems (free cells, immobilised cells or membrane bioreactor) to achieve malolactic fermentation with high productivity. Copyright © 2006 Society of Chemical Industry
Mouse oocyte differentiation during antral follicle development
Authors: Cecconi Sandra , Rossi Gianna , Palmerini Maria Grazia 
Published: May 2006

AbstractDuring antral follicle development mouse oocytes undergo rearrangement of granulosa cell interactions and the oocytes released from follicles at the beginning or at the end of antral development are either devoid of denuded oocytes (DO) or strictly associated with cumulus‐intact (CI) cumulus cells. In this study, these two oocyte classes were analyzed before germinal vesicle (GV) and after in vitro maturation (IVM) to evaluate (a) the ultrastructural aspect of oolemma microvilli by scanning electron microscopy analysis and (b) specific morphological markers of differentiation (chromatin organization, mitochondria, cortical granules, microfilaments, and spindle of metaphase II– MII–). At GV‐stage, CI oocytes exhibited remarkable differences (a) in the oolemma microvillar ultrastructure and distribution with respect to DO and (b) in the chromatin organization that was typical of meiotically competent germ cells. By contrast, homogeneous patterns of distribution of mitochondria, cortical granules, and microfilaments characterized both the oocyte classes. At the end of culture, CI oocytes, even when matured without cumulus cells, reached more efficiently the MII stage and acquired an ultrastructural microvillous configuration different from DO. In addition, MII‐arrested DO had a higher percentage of meiotic spindles with abnormal morphology in comparison with preovulatory oocytes, while cortical granule and microfilament patterns revealed no appreciable differences between the groups. With regard to mitochondria, a polarized distribution of these organelles was found in 82% of DO and in 97% of CI oocytes. These observations suggested that the achievement of the full antral follicle development is a condition for the acquisition of specific qualitative properties that are essential for the production of fertilizable oocytes, both in in vivo and in vitro models as well. Microsc. Res. Tech., 2006. © 2006 Wiley‐Liss, Inc.
Morphodynamics of ovarian follicles during oogenesis in mice
Authors: Sato Eimei , Kimura Naoko , Yokoo Masaki , Miyake Yuko , Ikeda Joh‐E 
Published: May 2006

AbstractIn the mouse, oogonia enter the prophase of the first meiotic division and differentiate into oocyte while developing in the fetal ovary. Shortly after birth, all oocytes are arrested in the dictyate stage of late prophase in the developing follicles; a small number of follicles reach the ovulatory stage; the rest are lost by apoptosis. The resumption of meiotic division and nuclear progression to metaphase II (oocyte maturation) occur in the ovulatory follicles. In this article we review recent morphological data that have clarified how cytokines and glycosaminoglycans (GAGs) are involved in mouse follicular development, atresia, and maturation during oogenesis, as exogenous/endogenous factors. (1) Microvascular networks and angiogenic factors (epidermal growth factor; GAGs) are deeply involved in selective mouse oocyte growth beyond ∼20–30 μm in diameter. (2) Gonadotropin‐inducible neuronal apoptosis inhibitory protein may indirectly affect oocyte survival as a result of the inhibition of apoptotic granulosa‐cell death during folliculogenesis. (3) The pattern of oocyte degeneration depends on follicle and oocyte developmental stages, and follicle stimulating hormone accelerates the process of degeneration of oocytes. (4) The process of degeneration of mouse oocytes/eggs is modulated by tumor necrosis factor‐α that is accumulated in the expanded cumulus during oocyte maturation. (5) A colloidal iron‐positive substance was detected in the intercellular spaces of follicular tissue, especially in the cumulus mass. Cells located where the cumulus mass and granulosa cell layer interwound became enlarged during the resumption of oocyte meiosis. Colloidal iron‐positive substances accumulated extensively within the intercellular spaces of the enlarged cells. Microsc. Res. Tech., 2006. © 2006 Wiley‐Liss, Inc.
Oocyte–follicle cell interactions during ovarian follicle development, as seen by high resolution scanning and transmission electron microscopy in humans
Authors: Makabe Sayoko , Naguro Tomonori , Stallone Tiziana 
Published: May 2006

AbstractThe aim of this article is to summarize and update, through an integrated analysis by transmission electron microscopy (TEM) and high resolution scanning electron microscopy (SEM) after osmium‐dimethyl sulfoxide‐osmium (ODO) maceration, the studies of our research group on the morphodynamics of oocyte–follicle cell associations during follicle development in humans. In resting oocytes, follicular cells project few and short cytoplasmic processes in the perioocytic space. They often form bulbous terminals very close to the oolemma where zonulae adherentes, maculae adherentes, and gap junctions are present. The oolemma mostly appears smooth with short and scanty microvilli. In early growing follicles, follicular cell projections appear as (a) long and tortuous microvilli or (b) large and short extensions. The oolemma shows numerous short microvilli. By TEM, long and thin follicular “intraooplasmic processes” have been seen to penetrate deeply into some oolemma invaginations. In macerated samples, they are observed by SEM to come very close to the nucleus and contact different oocyte organelles. These processes are more likely involved in early oocyte growth. In late growing follicles, oocyte–somatic cell interactions—now established through the interposition of the zona pellucida (ZP)—preserve the general features of early growth stage, with the exceptions of “intraooplasmic processes,” which are no more present. In mature follicles subjected to a long ODO maceration, corona cells appear to contact the oocyte through an apical plume of numerous very long “curly hair‐like microvilli.” Corona cell microvilli, quite likely provide a sort of cytoplasmic skeleton for the ZP and they are possibly involved in (a) release of nutrients or removal catabolites to/from oocyte and vice versa and (b) transfer of substances to build up ZP. In conclusion, among oocyte and somatic cells a structural and functional association is revealed. This association, certainly highly dynamic in vivo, plays a key role in regulating the healthy folliculogenesis to assure a correct and timed oocyte maturation and ovulation. Microsc. Res. Tech., 2006. © 2006 Wiley‐Liss, Inc.
Role of granulosa and theca cell interactions in ovarian follicular maturation
Authors: Tajima Kimihisa , Orisaka Makoto , Yata Hirotsugu , Goto Kenji , Hosokawa Kumiko , Kotsuji Fumikazu 
Published: May 2006

AbstractWe developed a culture system in which two types of ovarian follicular cells were allowed to attach to opposite sides of a collagen membrane. Using this in vitro cell culture system, we studied the effects of granulosa‐ and theca‐cell interaction on the morphology, structure, and function of bovine ovarian follicular cells. In the first part of the study, we explored how the interaction between theca and granulosa cells affects the morphology and structure of the cells. This study was done using follicular cells collected from bovine ovarian follicles at the early developmental stage. Granulosa cells cultured alone were flattened, and formed a monolayer sheet. By contrast, granulosa cells cultured with theca cells were convex, and formed multilayer sheets. Theca cells cultured alone were thin, flat, and spindle‐shaped. Theca cells cultured with granulosa cells were also spindle‐shaped; however, they appeared convex and more densely packed when compared with theca cells cultured alone. In the second part of the study, the possible role of the cellular interaction in the control of differentiation and growth of granulosa and theca cells was investigated. When follicular cells were isolated from the early stage of follicular development, theca cells reduced progesterone and inhibin production by granulosa cells and augmented the growth of granulosa cells. When the cells were isolated from the late stage of follicular development, by contrast, theca cells augmented hormonal production by granulosa cells, and did not affect the growth of granulosa cells. The growth and androstenedione production by theca cells were increased by the presence of granulosa cells, irrespective of the origin of follicular cells. These results demonstrated that communication between two types of follicular cells results in reciprocal modulation of their morphology, structure, growth, and function. Cellular interactions seem to be one of the major factors controlling the differentiation and growth of the follicular cells during the follicular maturation process. In contrast to granulosa and theca cells cultured alone, cells in the coculture seemed to possess morphological and functional characteristics more similar to those of cells in the growing follicular wall in vivo. Thus, we speculate that the interaction between these two types of follicular cells is essential for the maintenance of original structure and function of the bovine follicular wall. Microsc. Res. Tech., 2006. © 2006 Wiley‐Liss, Inc.
Morphological patterns of angiogenesis in ovarian follicle capillary networks. A scanning electron microscopy study of corrosion cast
Authors: Macchiarelli Guido , Jiang Jin‐yi , Nottola Stefania A. , Sato Eimei 
Published: May 2006

AbstractTo describe the morphological characteristics of the ovarian follicle (F) capillary neoformation and regression, the angiogenic figures were studied by means of scanning electron microscopy of corrosion casts in developing and mature F of rabbit, pig, and cow. Developing F showed gradual neoformation of thecal capillaries characterized by budding and then sprouting, likely from preexisting interstitial vessels. Postcapillary venules frequently showed vasoconstriction rings (sphincters). Vasodilation followed capillary elongation. Mature F, in addition to vessel elongation and dilation, also presented infolding of dilated capillary walls, followed by capillary duplication and sinusoidalization. Periovulatory F mainly showed functional changes, such as capillary dilation, signs of iperpermeabilization, and ischemia, the latter being limited to the apical follicular area. Vessel regression was characterized by thinning of capillaries and presence of avascular areas within the atretic F wall at any stage. This study showed two main types of angiogenic patterns. (a) longitudinal elongation (in series, sprouting angiogenesis) characterizing the initial phase of F development and (b) parallel duplication (in parallel, infolding or intussusceptive angiogenesis), ending in capillary lateral replication or splitting, secondary to functional microvascular changes. Indirect evidence of the establishment of postcapillary resistances contributing to capillary remodeling, was also shown. It is concluded that the sequence of capillary neoformation in mammalian ovarian F occurs in six steps: (1) budding, (2) sprouting (and elongation), (3) dilation, (4) infolding (intussusception), (5) duplication (splitting and elongation), and (6) sinusoidalization. Capillary regression hits F at any stage and characterizes F atresia. Microsc. Res. Tech., 2006. © 2006 Wiley‐Liss, Inc.
Structural changes and cell properties of human ovarian surface epithelium in ovarian pathophysiology
Authors: Okamura Hitoshi , Katabuchi Hidetaka , Nitta Makoto , Ohtake Hideyuki 
Published: May 2006

AbstractThe surface epithelial cells of the ovary, which are modified peritoneal cells, form a single, focally pseudostratified layer. The Müllerian ducts differentiate after invagination of the coelomic mesothelium over the gonadal ridges during the 6th week of embryonic life. On the basis of the embryologically putative Müllerian potential of this epithelium, endometriosis can be explained by coelomic metaplasia from the peritoneum, including ovarian surface epithelium. Some pelvic endometriosis specimens have shown that epithelial cells on the ovary or pelvis are serially changed to endometriotic gland cells. Immunohistochemistry as well as scanning electron microscopy also reinforce the light‐microscopical findings. A three‐dimensional culture system demonstrated that human ovarian surface epithelial cells exhibited a glandular–stromal structure when they were cocultured with endometrial stromal cells in an estrogen‐rich environment. Ovarian carcinomas in the epithelial–stromal category are thought to arise from the surface epithelium and its inclusions. The ovarian surface epithelium is physiologically involved in follicular rupture, oocyte release, and the subsequent repair of follicle wall during reproductive age. Simultaneously, ovulation may cause a loss of integrity of the surface epithelium, followed by accumulation of multiple mutations. The cortical invagination, surface stromal proliferation, and Müllerian differentiation of these cells are likely not to be an early step in the cancer development. However, the inclusion cysts are closely related with carcinogenesis because they are significantly more common in ovaries contralateral to those containing epithelial cancers than in control ovaries. As an in vitro study, ovarian carcinoma cell lines were established from simian virus 40 large T antigen‐transformed human surface epithelial cells of the ovary. Further investigations of these cell lines may lead to insights into the preneoplastic and early stages of carcinomas. To clarify the pathogenesis of endometriosis and epithelial ovarian cancer, specifically designed studies of ovarian surface epithelium are required. Microsc. Res. Tech., 2006. © 2006 Wiley‐Liss, Inc.
Ultrastructural characteristics of human granulosa cells in a coculture system for in vitro fertilization
Authors: Nottola Stefania A. , Heyn Rosemarie , Camboni Alessandra , Correr Silvia , Macchiarelli Guido 
Published: May 2006

AbstractThe use of somatic cells for cocultures during in vitro fertilization (IVF) is currently finalized to obtain a higher number of healthy and viable embryos with a high potential of implantation. Among the different cell lines that can be used as feeder cells for cocultures, granulosa cells (GCs) are autologous cells, safe and easy to recover. The aim of the present study was to analyze the fine structure of human GCs used in a coculture system to evaluate, from a morphodynamic point of view, their role in supporting embryo development. GCs were collected during oocyte pick‐up, 36 h after human chorionic gonadotropin administration, from patients undergoing IVF procedures, who had given their informed consent to be included in this protocol. After coculture, GCs were fixed and processed for light microscopy (LM) and transmission electron microscopy (TEM). By LM, GCs appeared as clusters of loosely packed cells, irregularly rounded or polyhedral in shape, varying in diameter from 18 to 25 μm. Mitotic cells, as well as regressing elements (with pyknotic nuclei or dense cytoplasm) and cell fragments were occasionally observed. By TEM, the plasma membrane was irregular due to the presence of cytoplasmic evaginations. Linear and annular gap junctions between neighboring GCs were found. GC nuclei, rounded and eccentrically located, contained finely dispersed chromatin, one (often two) prominent nucleoli and, infrequently, peripheral patches of heterochromatin. Numerous organelles populated the GC cytoplasm, among them, mitochondria were rod‐shaped or elongated, usually provided with tubular–vesicular cristae but occasionally showing atypical, longitudinally oriented cristae. Membranes of smooth endoplasmic reticulum, Golgi stacks and vesicles, secretory‐like granules, cisternae of rough endoplasmic reticulum (RER), free ribosomes and polysomes, lysosomal‐like bodies, microfilaments, and lipid droplets were also seen in the GC cytoplasm. In most cells, RER was scarcely represented and numerous lipid droplets filled the perinuclear space. On the contrary, some GCs contained an abundant RER and rare lipid droplets scattered in the cytoplasm. In conclusion, our data demonstrated the presence, in a coculture system, of GCs provided with ultrastructural characteristics typical of healthy, metabolically active, mostly steroidogenic cells. Protein‐synthetic cells have also been detected. These data, evaluated at the light of biochemical and clinical studies, sustain the capability of human GCs cocultures to positively affect early embryo development in vitro by the secretion of steroids and proteins, putative “embryotrophic” factors. Microsc. Res. Tech., 2006. © 2006 Wiley‐Liss, Inc.
Histological changes in rat nasal epithelia after unilateral neonatal naris occlusion
Authors: Cámara José A. , Garrosa Manuel , Gayoso Manuel J. 
Published: May 2006

AbstractThe authors studied the extent of the different epithelia lining the nasal fossae of the albino rat after neonatal closure of one naris. Newborn pups were anesthetized by hypothermia and the external opening of their right naris cauterized, while littermates served as controls. Animals were sacrificed at 3 months, and the occluded (OCF) and nonoccluded (NOF) fossae of experimental animals as well as both fossae of control animals (CTF) were histologically studied. In both control and experimental animals, nasal fossae were lined by five different types of epithelia: squamous stratified, transitional, metaplastic, respiratory, and olfactory epithelia. It was found that closure of one naris provokes reorganization of the epithelial lining in both the occluded and nonoccluded side. In CTF airflow, physical conditions as well as pollutants and biological agents irritate the epithelial lining, causing squamous metaplasia as well as metaplastic epithelium showing inflammation in rostral levels. In CTF caudal levels, the metaplastic epithelium appears to a lesser degree and the respiratory epithelium prevails, except for the most caudal level where the olfactory epithelium is prevalent. In OCF, the protected environment created prevents the occurrence of metaplastic epithelium, the transitional, respiratory, and olfactory epithelia developing in the corresponding area instead. In NOF, where the airflow is double, the same pattern occurs as in CTF, although metaplastic epithelium values are approximately double, suggesting a clear linear effect. An outstanding feature observed was the increased extent of the olfactory epithelium in OCF regarding NOF, although changes in its morphological structure were not found. Airflow properties, including pressure, coldness, velocity, and turbulence, as well as biological and chemical hazards present in inflow, cause histological reorganization of the nasal epithelium lining during postnatal development. Results prove the need to consider airflow changes in nasal fossae surgery and point to the protective value of naris closure in ENT clinics, supporting it as a treatment of atrophic rhinitis. Microsc. Res. Tech., 2006. © 2006 Wiley‐Liss, Inc.