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PubMed2004

Towards electronic paper displays made from microbial cellulose.

Cellulose (in the form of printed paper) has always been the prime medium for displaying information in our society and is far better than the various existing display technologies. This is because of its high reflectivity, contrast, low cost and flexibility. There is a major initiative to push for a dynamic display technology that emulates paper (popularly known as "electronic paper"). We have successfully demonstrated the proof of the concept of developing a dynamic display on cellulose. To the best of our knowledge, this is the first significant effort to achieve an electronic display using bacterial cellulose. First, bacterial cellulose is synthesized in a culture of Acetobacter xylinum in standard glucose-rich medium. The bacterial cellulose membrane thus formed (not pulp) is dimensionally stable, has a paper-like appearance and has a unique microfibrillar nanostructure. The technique then involves first making the cellulose an electrically conducting (or semi-conducting) sheet by depositing ions around the microfibrils to provide conducting pathways and then immobilizing electrochromic dyes within the microstructure. The whole system is then cased between transparent electrodes, and upon application of switching potentials (2-5 V) a reversible color change can be demonstrated down to a standard pixel-sized area (ca. 100 microm2). Using a standard back-plane or in-plane drive circuit, a high-resolution dynamic display device using cellulose as substrate can be constructed. The major advantages of such a device are its high paper-like reflectivity, flexibility, contrast and biodegradability. The device has the potential to be extended to various applications, such as e-book tablets, e-newspapers, dynamic wall papers, rewritable maps and learning tools.

Acetobacter↗
PubMed2004

Aminooxyacetic acid inhibits antheridiogenesis and development of Anemia phyllitidis gametophytes.

Cytomorphological studies of the development of young fern gametophytes (Anemia phyllitidis) have been used to investigate combined effects of gibberellic acid and ethylene on male sex expression. ACC (the key by-product in ethylene biosynthesis pathway) was found to exert a synergetic effect on the gibberellic acid-induced antheridia formation, and this phenomenon could be related with the specific stimulation of cell growth and activity of their differentiation. To complete and verify those observations male sex expression in the fern gametophytes treated with ACC-biosynthesis inhibitor was reinvestigated. Aminooxyacetic acid (AOA) restrained antheridia formation via inhibition of cell divisions. AOA influenced the arrangement and flexibility of cellulose microfibrils in the antheridial zone cells, thus affecting cell expansion. On the other hand, the level of DNA synthesis was not reduced. Transient increase in the number of S-phase cells, followed by the accumulation of G2-phase cells led to the enhancement of cell polyploidization. All these findings correspond with the previous observations and support participation of ethylene in gibberellic acid-induced male sex expression in ferns.

Amino Acids, Cyclic↗
PubMed2002

[Relevance of the pseudoexfoliation syndrome for the glaucomas].

Secondary chronic open-angle glaucoma associated with pseudoexfoliation (PEX) syndrome accounts for approximately 25% of all glaucomas and represents the most common identifiable cause of glaucoma overall. The underlying disorder, PEX syndrome, is a generalized process of the extracellular matrix characterized by production and progressive accumulation of an abnormal extracellular material in many intra- and extraocular tissues. Recent data support the pathogenetic concept of PEX syndrome as a type of elastosis affecting particularly elastic microfibrils. Active involvement of the trabecular meshwork in this characteristic matrix process may lead to glaucoma development in 40-60% of the patients. In addition, PEX syndrome also represents an important risk factor for a broad spectrum of spontaneous or intra- and postoperative ocular complications as well as for systemic cardiovascular diseases. PEX-associated open-angle glaucoma represents a relatively severe and progressive type of glaucoma with a generally poor prognosis due to high intraocular pressure levels and fluctuations in the diurnal pressure curve. The primary cause of chronic pressure elevation appears to be local production of PEX material by trabecular meshwork cells and Schlemm's canal cells with subsequent degenerative changes of Schlemm's canal and juxtacanalicular tissues. Additional pathogenetic factors contributing to pressure increase include pronounced melanin dispersion, increased protein concentrations of the aqueous humor, vascular factors, and connective tissue alterations of the lamina cribrosa. Other types of glaucoma, such as acute open-angle glaucoma, provoked by melanin showers during diagnostic mydriasis, or secondary angle closure glaucoma due to pupillary or ciliary block, are also common in PEX patients. The pathogenetic factors TGF-beta1 and TIMP-1/2 appear to be causally involved in this fibrotic process and thus may represent potential targets for specific, rational therapeutic approaches.

Exfoliation Syndrome↗
PubMed2000

Ultrastructural architecture and mechanical properties of attachment pads in Tettigonia viridissima (Orthoptera Tettigoniidae).

Natural releasable attachment systems of insect legs, where attachment-detachment performances are often very fast, seem to be optimized to get a maximum of real contact to the substratum. Tarsi of Tettigonia viridissima bear flexible attachment pads with unusual ultrastructural architecture of the cuticle. The indentation of the attachment pads was measured under different loads using a force-tester. Since the mechanical properties are influenced by material structure, the freeze-substitution experiments were undertaken to investigate the influence of loads on material structure. Both profile changes of the surface and the orientation of cuticle microfibrils were visualized by means of scanning electron microscopy followed by fracturing of the frozen material. The results show that the flexible pad material deforms replicating the substrate profile down to the micrometer roughness. The pad material showed both elastic and viscous behavior under loads. Elastic deformation of the pad occurred under normal force applied for 4-6 s (elastic modulus 27.2 +/- 11.6 kPa). Two viscous relaxation processes were found, of time constants tau1 = 1.88+/-0.616 s and tau2 =41.2 +/- 9.95 s. Low stiffness of material studied here aids in surface replication and increase of area of real contact between the pad and the underlying substrate.

Animals↗
PubMed1998

[Marfan syndrome: prevalence and natural course of cardiovascular manifestations].

The Marfan syndrome is an autosomal dominant disorder of the connective tissue with mutations on the fibrillin-1 gene encoding for fibrillin, a major component of the extracellular microfibrils. The prevalence of the syndrome is 7-17/100,000. The mean life expectancy for untreated patients with Marfan syndrome is 32 years with aortic dissection, aortic rupture or cardiac failure due to mitral and aortic valve regurgitation as the predominant cause of death in > 90% of the cases. In severely affected cases with neonatal Marfan syndrome, patients are likely to survive only a few months. According to the literature database the prevalence of aortic dilatation is 76%, 26% for aortic regurgitation, 62% for mitral valve prolapse, and 29% for mitral valve regurgitation in adult patients with classic Marfan syndrome. Pathogenesis and the natural cause of each cardiovascular manifestation is thoroughly discussed with the problems resulting from associated cardiac arrhythmias, sudden cardiac death, endocarditis, and less frequent cardiovascular manifestations of the Marfan syndrome. Special focus is placed on the analysis of cardiovascular complications during pregnancy.

Adolescent↗
PubMed2002

Elastic fibres in the human placenta.

Recent studies described the presence of elastic fibres within stem villi of human term placenta. This particular study focuses on changes of the elastic fibre system in placental villous tree from placentas of different gestational ages. The presence of elastic fibres was researched by light and electron microscopy in first-, second-trimester and term human placentas. Light microscopic analysis revealed elastic fibres in the stroma of main stem villi and in large vessels present in the chorionic plate of term placentas. Transmission electron microscopy revealed a wide variation in microfibrillar component deposition in placentas from all the gestational ages studied. Although minimal amount of the microfibrillar component was observed only in some main stem villi of second-trimester placentas, abundant microfibrillar material was present in all types of placental villi in placental sections from term pregnancies. The amorphous component was only occasionally identified in sections from the chorionic plate of second trimester placentas. In ultra-thin sections from placental tissues from the 37th to the 42nd weeks of gestation, we can observe the amorphous component of the elastic fibres. Bundles of microfibrils with scanty participation of the amorphous component of the elastic fibres can be observed in stem villi. In mature intermediate villi, cells and their processes with distinct plasma membranes were seen close to some bundles of microfibrillar component, at times with small spots of the amorphous component. This study shows that elastic fibres of the villous stroma, are mainly composed of the microfibrillar component, while the amorphous component appears more frequently in advanced stages of villous differentiation of term placentas.

Elastic Tissue↗
PubMed2005

The symbiotic fauna of the African termite Hodotermes mossambicus identification of four flagellate species of the genera Spironympha, Trichomonoides and Retortamonas.

Two Spironympha species were described by light immunofluorescence and electron microscopy. Spironympha fibrosa n. sp. has a narrow columella, several axostylar fibres and original striated myoneme-like fibres attached to the last basal body of each flagellar line. Spironympha simplex n. sp. is small and has non-striated microfibrils attached to the basal body section and an axostyle composed of two fibres. Trichomonas termitidis, as reported by Dogiel (Researches on parasitic protozoa from the intestine of termites. II. Lophomonadidae. Sci Res Zool Exped Brit E Africa made by Prof. V. Dogiel and I. Sokolow in 1914 10:20-35, 1917), has the features of Trichomonoides trypanoides, as reported by Brugerolle and Bordereau (Eur J Protistol 40:163-174, 2004). Retortamonas hodotermitis n. sp. shares the characteristics of insect retortamonads, as reported by Brugerolle (Protistologica 8:233-240, 1976), but does not correspond to any species described to date. The species identification differs from that of described in Dogiel (Russkii Arkhiv Protistologii 1:172-234, 1922).

Animals↗
PubMed2005

A homozygous COL6A2 intron mutation causes in-frame triple-helical deletion and nonsense-mediated mRNA decay in a patient with Ullrich congenital muscular dystrophy.

Ullrich congenital muscular dystrophy (UCMD) is a severe disorder caused, in most cases, by a deficiency in collagen VI microfibrils. Recessive mutations in two of the three collagen VI genes, COL6A2 and COL6A3, have been identified in eight of the nine UCMD patients reported thus far. A heterozygous COL6A1 gene deletion, resulting in a mutant protein that exerts a dominant negative effect, has recently been described in a severely affected UCMD patient. Here we describe a patient in whom reverse transcription-PCR analysis of fibroblast RNA suggested a heterozygous in-frame deletion of exon 13 in the triple-helical domain of COL6A2, which is predicted to be dominantly acting. However, a homozygous A --> G mutation at -10 of intron 12 was found in the genomic DNA. The intron mutation activated numerous cryptic splice acceptor sites, generating normal and exon 13-deleted COL6A2 mRNA, and multiple aberrant transcripts containing frameshifts that were degraded through a nonsense-mediated decay mechanism. Northern analysis indicated diminished COL6A2 mRNA expression as the primary pathogenic mechanism in this UCMD patient. Our results underscore the importance of multifaceted analyses in the accurate molecular diagnosis and interpretation of genotype-phenotype correlations of UCMD.

Base Sequence↗
PubMed1999

Molecular analysis of eight mutations in FBN1.

Mutations in the gene encoding extracellular glycoprotein fibrillin-1 (FBN1) cause Marfan syndrome (MFS) and other related connective tissue disorders. In this study, eight mutations have been detected in MFS patients by heteroduplex analysis. These comprise two missense mutations, C1835Y and C2258Y in calcium-binding epidermal growth factor-like domains, two nonsense mutations, R1541X and R2394X in transforming growth factor beta1-binding protein-like domains, one splice site mutation, which has been detected previously, and three small insertions or deletions resulting in a frameshift. Fibroblast cells have been established from seven of the MFS patients and the biochemical effects of the mutations on fibrillin-1 synthesis and secretion assessed by pulse-chase analysis. Each cysteine mutation resulted in the delayed secretion of fibrillin-1 and both nonsense and frameshift mutations caused reduced levels of synthesis and/or deposition of fibrillin-1. Indirect immunofluorescence and rotary shadowing electron microscopy analysis of fibrillin microfibrils revealed no major differences between normal and patient samples. We discuss the relative merits of the biochemical techniques used in this study.

Adult↗
PubMed1997

Light-microscopical investigation of the distribution of extracellular matrix molecules and calcifications in human dental pulps of various ages.

The distribution of extracellular matrix molecules, especially collagen types I, III, V, and VI, in the extracellular matrix of the connective tissue of human dental pulp of various ages was studied by polarization and indirect immunofluorescence microscopy by using a conventional fluorescence microscope and a confocal laser scanning microscope. Polarization and immunofluorescence microscopy of paraffin sections showed thick fibers of collagen type I, which represented the main component of the connective tissue matrix of the dental pulp. By indirect immunofluorescence, thin fibers and small bundles of collagen type III were determined to be one of the main fibrillar elements present in the dental pulp matrix. Collagen type IV was detected by a clear intense staining of the basement membrane of blood vessels at all ages examined. Collagens type V and VI formed a dense meshwork of thin microfibrils throughout the stroma of the connective tissue of the dental pulp. These fibers were localized around blood vessels and appeared to be enriched in the subodontoblastic layer. Investigations by means of confocal laser scanning microscopy revealed fibers of collagen type VI spiralling between fully differentiated odontoblasts toward the predentin layer. With advancing age, the connective tissue matrix appeared to be condensed and aggregates of thick fiber bundles could be observed. Furthermore, the participation of various collagen types in the composition of pulp stones was shown. These calcifications and diffuse calcifications increased in frequency with advancing age in a statistically significant manner.

Adolescent↗
PubMed2003

The rhizoplast of chrysomonads, a basal body-nucleus connector that polarises the dividing spindle.

An ultrastructure study of the rhizoplast in Synura petersenii, Mallomonas fastigiata, and M. insignis shows that it consists of 15-20 striated rootlets that form a claw or an incomplete cone over the nucleus. These rootlets course along one face of the nucleus between the nuclear membrane and the cis-face of the Golgi stack of cisternae. They converge and merge above the nucleus, forming a stub attached to the proximal section of the two basal bodies. These cross-striated rootlets are composed of closely packed longitudinal microfibrils. By immunofluorescence, the basal bodies and the rootlets forming the claw were decorated by the anti-centrin monoclonal antibody ICL19 raised against the Paramecium tetraurelia acidic centrin protein and by two antibodies raised against the striated parabasal and costal striated fibres of trichomonads. Only the anti-centrin monoclonal antibody 20H5 raised against Chlamydomonas reinhardtii centrin strongly labelled the 20-22 kDa protein bands from the extracted cytoskeleton of S. petersenii by immunoblotting. Electron micrographs of mitosis in S. petersenii cells revealed that the segregated pairs of basal bodies are linked by the striated rootlets of the rhizoplast to the poles of the mitotic spindle. The spindle microtubules arise perpendicularly from the striated rootlets of the basal body-nucleus connector forming the centrosome. In conclusion, in these cells there is a basal body-nucleus connector similar to that of C. reinhardtii and other chlorophytes. It contains centrin proteins, it is involved in the linkage of the basal bodies to the nucleus and is a component of the spindle pole body or centrosome in the dividing cell.

Animals↗
PubMed2003

Ultrastructure of basement membranes in monkey and shark teeth at an early stage of development.

The basement membrane, which separates the inner enamel epithelium from the dental papilla in the early stages of tooth development, is known to play a significant role in odontogenesis. In this review article, this basement membrane was described in detail based on our recent findings with the use of high-resolution electron microscopy. Tooth germs of a monkey (Macaca fuscata) and a shark (Cephaloscyllium umbratile) were processed for thin-section observations. During the early stage of development, the basement membrane of the inner enamel (dental) epithelium was composed of a lamina lucida, lamina densa, and much wider lamina fibroreticularis. At higher magnification, the lamina densa in both species was made up of a fine network of cords, which are generally the main constituents of the basement membranes. In the monkey tooth, the lamina fibroreticularis was rich in fibrils, which were now characterized as basotubules, 10-nm-wide microfibril-like structures. The space between the basotubules was filled with a cord network that extended from the lamina densa. Dental papilla cell processes were inserted into the lamina fibroreticularis, and their surface was closely associated with numerous parallel basotubules via 1.5- to 3-nm-wide filaments. In the shark tooth during its early stage of development, the basotubules were absent in the lamina fibroreticularis and only narrow extensions, 60-90 nm wide and 1-2 microm long, of the cord network of the lamina densa were present. The dental papilla cells were immobilized by means of the binding of their processes to the extensions. These results indicate that basement membranes in both monkey and shark teeth at early stage of development are specialized for functions as anchoring and firm binding, which are essential for the successful differentiation of the odontoblasts.

Animals↗
PubMed2006

An ultrastructural study on the ligamentum flavum of the cervical spine in patients with ossification of the posterior longitudinal ligament.

Some histological analyses of the ossification of the posterior longitudinal ligament (OPLL) have been reported, but no ultrastructural studies of the ligamentum flavum (LF) in patients with OPLL have been published to date. To understand the pathology of the ossification of the spinal ligament, we examined, by electron microscopy, ultrastructural changes in the LF in cases of OPLL and made a comparison with the LF in cervical spondylotic myelopathy (CSM). Subjects were three men and two women with cervical OPLL who underwent longitudinal spinous process-splitting laminoplasty. During surgery, a small piece of the LF was collected from C2-C3 to C7-T1 and was then analyzed by light and electron microscopy. We observed atrophic elastic bundles with a two-layer structure and disarrangement, a partially torn area, the disappearance of microfibrils, and an enlarged interstitium with an irregular alignment of collagen fibrils. We observed some properties of a cell preceding its death: the initial phase may be the disappearance of the plasma-membrane, followed by the scattering of many organellae around its degenerated nucleus. Finally, many extracellular plasma membrane-invested particles that resemble matrix vesicles remain there without phagocytosis. These results suggest that ultrastructural abnormalities exist in the spinal ligament in cases of ossification of the spinal ligament.

Aged↗
PubMed2006

Recent progress in genetics of Marfan syndrome and Marfan-associated disorders.

Marfan syndrome (MFS, OMIM #154700) is a hereditary connective tissue disorder, clinically presenting with cardinal features of skeletal, ocular, and cardiovascular systems. In classical MFS, changes in connective tissue integrity can be explained by defects in fibrillin-1, a major component of extracellular microfibrils. However, some of the clinical manifestations of MFS cannot be explained by mechanical properties alone. Recent studies manipulating mouse Fbn1 have provided new insights into the molecular pathogenesis of MFS. Dysregulation of transforming growth factor beta (TGFbeta) signaling in lung, mitral valve and aortic tissues has been implicated in mouse models of MFS. TGFBR2 and TGFBR1 mutations were identified in a subset of patients with MFS (MFS2, OMIM #154705) and other MFS-related disorders, including Loeys-Dietz syndrome (LDS, #OMIM 609192) and familial thoracic aortic aneurysms and dissections (TAAD2, #OMIM 608987). These data indicate that genetic heterogeneity exists in MFS and its related conditions and that regulation of TGFbeta signaling plays a significant role in these disorders.

Abnormalities, Multiple↗
PubMed1992

A Danish kindred with familial amyloid cardiomyopathy revisited: identification of a mutant transthyretin-methionine111 variant in serum from patients and carriers.

PURPOSE: In familial amyloid cardiomyopathy of Danish origin, the amyloid microfibrils contain a mutant transthyretin (TTR) with a methionine-for-leucine substitution at the molecular position 111. We studied the possible occurrence of this variant TTR-Met111 in serum from afflicted as well as nonafflicted family members and their offspring, in order to define its possible role as predictor of the disease and to describe its mode of inheritance. PATIENTS AND METHODS: Stored, frozen serum samples obtained from 1959 through 1960 from 36 of 40 living members of the kindred were analyzed. The method employed to detect the abnormal TTR was based on the electrophoretic separation of fragments produced by cyanogen bromide cleavage at the two methionine sites. RESULTS: All sera from family members with amyloid cardiomyopathy contained the variant transthyretin TTR-Met111 as did sera from half of their offspring. In contrast, nonafflicted family members and their offspring were seronegative for TTR-Met111. Three cousins from the second generation died between 1980 and 1986 of amyloid cardiomyopathy. The presence of variant TTR-Met111 preceded their deaths by 20 to 26 years. CONCLUSIONS: The occurrence in serum of the mutant transthyretin TTR-Met111 is linked to the occurrence of amyloid cardiomyopathy in patients and their offspring, while unafflicted branches of the family are negative for the variant protein. That the occurrence in serum of TTR-Met111 precedes the onset of clinical amyloid cardiomyopathy by several decades makes the variant TTR a marker for the disease. The distribution of afflicted family members and seropositivity for the variant TTR shows an autosomal dominant mode of inheritance. CLINICAL SIGNIFICANCE: The results make possible early detection of potential patients and provide tools for genetic counseling. Cardiac transplantation may provide a new therapeutic option.

Adult↗
PubMed1979

Ultrastructural effects of estrogen replacement on postmenopausal endometrium.

Endometrial adenocarcinoma occurs almost exclusively in postmenopausal women, and excessive or unopposed estrogen stimulation is suspect as a causative factor in its pathogenesis. Furthermore, the incidence of endometrial adenocarcinoma has increased in women undergoing estrogen replacement therapy. In the present study, the cellular response of premenopausal and postmenopausal endometrium to estrogenic stimulation was compared with endometrial adenocarcinoma by the electron microscope. Tissues were obtained at hysterectomy, endometrial biopsy, or endometrial curettage and were processed routinely for light and electron microscopy. Ultrastructurally the endometrium from postmenopausal patients undergoing estrogen replacement therapy was similar to normal cyclic endometrium in the late proliferative phase. At least three features of the estrogen-treated postmenopausal tissue resembled those observed in adenocarcinoma of the endometrium: accumulation of lipid droplets, irregular nuclei, and perinuclear whorls of microfibrils.

Adenocarcinoma↗
PubMed1984

Ultrastructural evidence of nerve and oxytalan fibre associations in the endoneurium of human periodontal ligament.

Human periodontal ligament from premolars contained numerous fibres of the oxytalan meshwork system affiliated with unmyelinated endoneurium and myelinated nerves in the endoneurium. These fibres consisted of bundles of microfibrils and were present within 0.5 mu of Schwann cells and their unmyelinated axons. This ultrastructural association has not been previously demonstrated.

Adolescent↗
PubMed1986

The immunohistochemical distribution of collagens type IV, V, VI and of laminin in the human oral mucosa.

The distribution of collagens type V (form AB2) and VI was investigated on cryostat sections of normal human oral mucosa by indirect immunofluorescence. For comparison, antibodies to fragments of type IV collagen and laminin were also used to delineate basement membrane containing structures. All antibodies used were raised against human proteins. Type V collagen appeared as a microfibrillar structure throughout the interstitium, apparently touching but not being present within epithelial or vascular basement membranes. Microfibrils in blood vessel walls were limited to the intimal layer. Pericellular areas were not specifically stained. Type VI collagen appeared as an almost amorphous stromal structure becoming more prominent and more fibrillar in the upper connective tissue papillae. Intense staining was observed in the media of blood vessels and around smooth muscle cells. A possible role of type VI collagen in tissue stabilization may be expected from this ubiquitous and abundant distribution. The findings identify types V and VI collagen as important structures in the oral mucosa and serve as a basis for understanding morbid changes.

Antibody Specificity↗