Cup-shaped Depressions Research Articles

Compositional and micromorphological features of hypoplastic enamel in children’s permanent teeth

Enamel hypoplasia is the most common disease of hard tooth tissues of non-carious origin emerging before their eruption. It develops as a result of a delayed and perverse function of ameloblasts leading to the violation of the processes of formation and mineralization of tooth protein structures. The clinical manifestations of enamel hypoplasia are spots, defects in the form of pits, cup-shaped depressions, grooves on various surfaces of child’s teeth. The work is devoted to a comparative investigation of microstructural and compositional features of intact and hypoplastic enamel in children’s permanent teeth using analytical scanning electron microscopy with energy-dispersive X-ray spectroscopy. The hypoplastic enamel is enriched in organic substance and has an irregular structure without keyhole-shaped prismatic structure. Mineral deposition is indicated for hypoplastic enamel including hydroxyapatite with globular structure and calcite and halite, which might have been caused by the violation of extracellular local environment probably due to the enamel hypoplasia development.

Origin and sedimentary evolution of sinkholes (buracas) in the Abrolhos continental shelf, Brazil

Cup-shaped depressions (termed buracas by local fishermen) are common geomorphic features on the northeastern Abrolhos continental shelf (Brazil). Samples collected by technical diving from the walls of two depressions (Buraca Funda, B1, top at 59m, and Buraca Rasa, B2, top at 26m) and seismic profiles provide evidence of the processes leading to their formation. The top of the sedimentary succession consists of two units bounded by erosion unconformities. Unit 1 overlies an erosion surface (MR1) and is older than the radiocarbon dating limit. It is made up of packstone to rudstone accumulated on mid- to outer-shelf paleoenvironments. Voids in the limestone are filled by a meteoric cement 29,000calyrs BP in B2. It is assumed that Unit 1 formed in the late Pleistocene, mainly during MIS 5e. An erosion surface (MR2) carved sinkholes in Unit 1, with karstification taking place while the ACS was emergent during the last glacial period. The timing and span of subaerial exposure changes with depth within the shelf. Unit 2 accumulated on this karst surface in the Holocene, after postglacial sea level rise. At the B1 margin, Unit 2 consists of early-lithified packstone to rudstone with attached corals. In B2, the Holocene unit comprises a boundstone of encrusting invertebrates and calcareous algae similar to the living ones attached to the wall today. High productivity in the sinkholes probably promoted the growth of encrusting suspension feeders but also led to intense, multistory bioperforation of carbonates on the wall. The cup-shaped depressions are, therefore, the result of sinkhole formation during the last-glacial low sea levels and later carbonate accretion at sinkhole margins during the Holocene.

Buracas: Novel and unusual sinkhole-like features in the Abrolhos Bank

Novel and unusual sinkhole-like features are described for the Abrolhos Bank continental shelf, eastern Brazil, based on geophysical and geological assessments. These unusual structures are large cup-shaped depressions similar to sink/blueholes (10–75m in diameter, 8–39m in height), occurring in a consolidated carbonate substrate in the mid and outer shelf. A total of 36 such features, locally named buracas, were found between 41 and 161km off the coast and between 24 and 65m depth (the bottom of these features may be as deep as 93m). The buracas’ walls are mainly composed of encrusting coralline algae. Radiocarbon dating has provided ages of 5400±90yr Cal BP, 8630±90yr Cal BP and 39,200±400yr BP. Besides providing a comprehensive description of these novel structures within the mesophotic zone, the potential mechanisms by which these sinkhole-like structures originated are discussed here, as well as the possible active mechanisms impeding their filling with sediments and biogenic material. We hypothesize that their origin could be related to either typical sinkhole formation during subaerial exposure or to a partially Holocene growth pattern influenced by antecedent morphology and gas/fluid escaping due to organic matter decomposition. The buracas are relevant not only because they comprise outstanding novel features, but also because they are relevant targets for marine conservation, as they enhance productivity and aggregate biomass in a region under growing fishing pressure.

Mapping the micro-abrasion resistance of a Ni-based coating deposited by PTA on gray cast iron

Micro-scale abrasion was used to characterize abrasion resistance of a nickel-based hardfacing alloy deposited by Plasma Transferred Arc on gray cast iron using silica as abrasive agent. In order to investigate the occurrence of different abrasion mechanisms, several test conditions were used, namely: different silica abrasive contents and a range of normal loads and test durations. A scanning electron microscope (SEM) was used to study the morphologies of the spherical cup-shaped depressions induced by different test conditions. The results are discussed in terms of the effect of the dominant wear mechanisms on the abrasion resistance and the influence of the test conditions on the mechanism transition. The wear results lead to the conclusion that the specific wear rate essentially depends on the wear mechanisms (rolling or grooving) involved and not on the tests conditions employed, since these do not produce changes in the wear mechanism.

Genetic characterization of a novel calicivirus from a chicken

We describe the identification and genetic characterization of a novel enteric calicivirus, detected by transmission electron microscopy and RT-PCR in two clinically normal chickens and in a chicken with runting and stunting syndrome from different flocks in southern Germany. Positive findings were confirmed by sequencing. The complete nucleotide sequence and genome organization of one strain (Bavaria/04V0021) was determined. The genome of the Bavaria virus is 7,908 nt long and contains two coding open reading frames. Phylogenetic analysis of the deduced partial 2C helicase/NTPase, 3C cysteine protease, RNA-dependent RNA polymerase and complete VP1 capsid protein amino acid sequences showed that the virus is genetically related to but distinct from sapoviruses and lagoviruses. Morphologically, the Bavaria virus particles are 37-42 nm in diameter and exhibit characteristic cup-shaped surface depressions.

117. Phylogenetic analysis of vesiviruses

The family Caliciviridae comprises four genera: Vesivirus, Lagovirus, Norovirus, and Sapovirus. Vesiviruses include vesicular exanthema of swine virus and feline calicivirus, lagoviruses include rabbit hemorrhagic disease virus and European brown hare syndrome virus, while Norwalk and Sapporo viruses are the prototype members of the other two genera. Vesicular exanthema is a foot and mouth disease like disease of pigs last diagnosed in the United States in 1952. Feline calicivirus is a very common, worldwide cause of acute upper respiratory tract disease in cats. Rabbit hemorrhagic disease is a highly transmissible, highly fatal, generalized hemorrhagic disease of rabbits. Noroviruses and sapoviruses are important, common causes of human gastroenteritis. The family name derives from the cup-shaped (calix = cup) surface depressions that give the virion its unique appearance. By cryoelectron microscopy virions are 40.5 nm in diameter with 32 cup-shaped surface structures comprising 90 arch-like capsomers. The individual capsomers are dimers of the ∼60 kDa capsid protein. The RNA genomes consist of a linear, positive-sense, single-stranded RNA molecule of 7.3–8.6 kb. Viruses of each genus have a characteristic open reading frame arrangement but different arrangements are found between the genera. Only vesiviruses have been cultured in conventional cell cultures.

Detection and molecular characterization of cultivable caliciviruses from clinically normal mink and enteric caliciviruses associated with diarrhea in mink.

Summary. Enteric caliciviruses are emerging pathogens responsible for diarrhea or gastroenteritis in their respective hosts. In this report, mink enteric caliciviruses (MEC) were detected in feces from diarrheic mink by both immune electron microscopy (IEM) and RT-PCR using a broadly reactive primer pair (p289/290) targeting the highly conserved RNA polymerase regions of the enteric caliciviruses, Norwalk-like viruses (NLVs) and Sapporo-like viruses (SLVs). The MEC possess classical caliciviral morphology with typical cup-shaped depressions on the viral surface. Sequence analyses based on nucleotide and predicted amino acid (aa) sequences of the RT-PCR products indicated that MEC is most closely related genetically to SLVs of humans and animals. The MEC shared the highest aa identities (64–71%) in the RNA polymerase region with both human SLVs and the porcine enteric calicivirus (PEC) Cowden strain SLV, indicating that MEC may belong to an individual genogroup or subgroup in the SLV genus. The MEC shared only limited aa identities in the RNA polymerase region with vesiviruses (40–51%) and NLVs (29–33%). The RNA polymerase regions of the cultivable, non-enteric mink caliciviruses (MCV) were also amplified by RT-PCR using the primer pair Pol1/Pol3 based on sequences of vesiviruses, and the primer pair p289/290. Sequence analysis indicated that these MCV shared higher aa identities in the RNA polymerase region with vesiviruses (58–81%) than with SLVs (43–51%) including the MEC, lagoviruses (35–37%) and NLVs (27–35%), suggesting that they are most closely related genetically to vesiviruses. The MEC associated with diarrhea in mink are morphologically similar to but are genetically distinct from the cultivable MCV and likely represent a new member of the SLV genus.

An assessment of alternate keyboards using finger motion, wrist motion and tendon travel

Objective. To assess the biomechanical impact of commercially available alternate keyboard designs. Design. A repeated measures study was conducted in a laboratory setting, with planned comparisons of Pitch, Roll and Yaw angles of the keyboards. Ten keyboard conditions were tested. Dependent measures included tendon travel, wrist deviations, and wrist and finger kinematics. Background. Various alternate keyboard designs have recently been introduced, which vary Pitch, Roll and Yaw angles, separation distance between keyboard halves, and include other novel features such as cup-shaped depressions for the keys. Yet little objective research has been conducted regarding the biomechanical implications of these various design features. This study attempts to quantify the keyboard designs in terms of several recognized risk factors associated with cumulative trauma disorders that arise with repetitive typing. Methods. Wrist and finger goniometers were used to measure joint motions during a standardized typing task. 15 experienced typists (8 women, 7 men) served as subjects. Regression equations were used to generate estimates of tendon travel. Results. Tendon travel was affected primarily by Pitch but not Roll or Yaw angles while wrist deviations responded to changes in all three angles. Males had significantly greater amount of tendon travel than female subjects; this difference was only partially accounted for by anthropometry. Differences in joint motion may have a greater impact on the amount of tendon travel. Conclusions. Alternate keyboard designs can affect tendon travel by as much as 11%. Relevance As various alternate keyboard designs are marketed, quantifiable biomechanical data such as that provided by this study, will help to assess their impact on the risk factors for cumulative trauma disorders.

Electron- and immunoelectron-microscopic investigation on the rabbit haemorrhagic disease virus

Electron- and immunoelectron-microscopic methods were used for detection and investigation of rabbit haemorrhagic disease virus (RHDV). The observed virus particles were uncoated, with an icosahedral symmetry, with a 35–40 nm dia and capsids built up by 32 capsomers with a central hollow part and a 3.5–5 nm dia. Particles with empty capsids could also be seen among them. Single virions visible in 5-fold symmetry, exhibited 10 projections on the surface. Virions with a 33–34 nm dia and cup-shaped surface depressions were a rare finding. Some of these particles were indistinguishable from the caliciviruses, but in most of them the cup-shaped depressions were single or no more then 2–3 in number, localized predominantly unilaterally or asymmetrically. Particles 25–29 nm large with full or empty capsids without capsomers could also be seen. Most probably they were some immature forms in the process of development of the RHDV.

Haemorrhagic disease of lagomorphs: evidence for a calicivirus

Studies on the aetiological agents of rabbit haemorrhagic disease (RHD) and European brown hare syndrome show that the viruses responsible for these infections can be placed in the family Caliciviridae. Established members of this group are vesicular exanthema virus (prototype), San Miguel sea lion virus and feline calicivirus. The human hepatitis E virus and the Norwalk agent may soon be included. The RHD virus genome consists of a positive stranded RNA molecule composed of 7437 nucleotides. A major subgenomic RNA of 2.2 kb, colinear with the 3′ end of the genomic RNA, can also be recovered from infected liver tissue, and both RNAs are enclosed within viral capsids formed by a single major protein of approximately 60 kDa. Electron microscopic examination of organ suspensions from diseased animals shows two types of particle; 35–40 nm complete virions have the regularly arranged cup-shaped depressions typical of calicivirus morphology, and 23–25 nm smooth particles resulting from degradation of the outer surface structures of the complete virions.

Purification and characterization of a calicivirus as the causative agent of a lethal hemorrhagic disease in rabbits

The causative viral agent of a lethal rabbit hemorrhagic disease has been purified and characterized. In negative-stained preparations, the virions were icosahedral, measured 27 to 35 nm in diameter, were without an envelope, and showed 10 peripheral cup-shaped depressions. The major structural protein was 60 kilodaltons, which constitutes a unique characteristic of the Caliciviridae.

Ultrastructural study of Helicobacter pylori‐associated gastritis

Endoscopic biopsies of antral mucosa from 26 patients with Helicobacter pylori-associated gastritis were studied by electron microscopy (EM). Scanning electron microscopy (SEM) showed clustering of H. pylori in the intercellular areas, being entrapped by the microvilli which were decreased at the sites where the bacilli were seen. The observations of SEM were confirmed by transmission electron microscopy (TEM), which showed adherence of the bacilli to the cell surface, producing cup-shaped depressions in the epithelial cells, and occasionally intracellular infiltration by H. pylori. There were also depletion of mucus granules, degenerative changes, and disruption of intercellular junction complexes of the epithelial cells. Post-treatment biopsies showed complete disappearance of the bacilli, and ultrastructural changes associated with H. pylori infection were resolved.

Serial propagation of porcine enteric calicivirus-like virus in primary porcine kidney cell cultures.

A porcine enteric calicivirus-like virus was adapted to serial propagation in primary porcine kidney cell cultures. Attempts to propagate this virus in primary porcine kidney cells in the presence of trypsin or pancreatin or without medium supplementation were unsuccessful. A low-pH medium (pH 6.8) was also ineffective in virus propagation. Successful serial propagation of the virus required the presence of an intestinal-content preparation, derived from uninfected gnotobiotic pigs, in the cell culture medium. The best results were obtained with six-well plate cultures which were centrifuged after virus inoculation. Infected cells were detected by immunofluorescent staining of cell monolayers or detached cells which were harvested by centrifugation. Infected cells were first detected at passage 4 (1% infected cells), and infectivity increased with successive passages, with as many as 80% of the cells infected by passage 16. Extensive cytopathic effects were observed in inoculated cell cultures, but not in uninoculated control cell cultures, at each passage level after passage 13. The infected cells became separated, rounded, and detached, forming holes in the cell monolayer. Only virus particles exhibiting the six-pointed star appearance or stain-filled, cup-shaped depressions characteristic of caliciviruses were detected in inoculated cell culture supernatants by immune electron microscopy. Attempts to determine the titer of the virus by a cell culture immunofluorescence assay or plaque assay were unsuccessful.

Dysentery caused by Escherichia coli (S102-9) in calves: natural and experimental disease.

A dysentery syndrome was recognized among the Institute's calves at 18 to 21 days of age. It was reproduced experimentally in gnotobiotic calves with an atypical Escherichia coli (S102-9) isolated from the affected calves. In both natural and experimental disease the calves passed copious bright red blood in the feces and developed diarrhea. Walls of the colon and rectum were thickened, and the mucosa was reddened and covered by an exudate that contained mucus and blood clots. Bacteria were seen closely adherent to the luminal surfaces of enterocytes, often in cup-shaped depressions or on cytoplasmic pedestals. Microvilli were distorted, disorientated or absent. There was exfoliation of infected enterocytes and a mild acute inflammation of the underlying lamina. In two of five calves with natural disease, the adherent bacteria did not stain by the immunoperoxidase method with antisera raised against E. coli (S102-9). This indicated that there was possibly more than one bacterial cause of the syndrome. Lesions in experimentally infected calves were indistinguishable from those produced by some E. coli which are enteropathogenic for man, rabbits, and pigs.

Caliciviridae.

The caliciviruses, as a proposed family Caliciviridae, have a distinct virion morphology with cup-shaped depressions on a spherical capsid surface. The viruses have single-stranded RNA, which has a molecular weight about 2.6 x 10(6) and is infectious. The RNA is covalently linked to a small protein. A single major polypeptide is found in the capsid. A subgenomic RNA, molecular weight about 1 x 10(6), coding for the capsid polypeptide is found in infected cells. Caliciviruses infecting swine, pinnipeds and cats have been characterized. Viruses which are morphologically identical to the known caliciviruses have been identified in human feces; these viruses have been shown to be associated with gastroenteritis, but they have not yet been propagated in the laboratory.