Distal Fissure Research Articles

Three new species of Delicatophycus M.J. Wynne (Bacillariophyta) from China, all possessing apical pore fields

Delicatophycus wulingensis sp. nov., D. qinghainensis sp. nov., and D. menyuanensis sp. nov., are described, illustrated, and compared to similar taxa. Two types of apical pore fields (APFs) in the genus Cymbella are defined. The three new Delicatophycus all possess the type II APF found in some species of Cymbella, i.e. the APF is divided by the distal raphe fissure into two areas, one larger than the other. They also share a further three distinct features: variable central dorsal portion of valve, stigmata, and a notch on the dorsal side of the distal raphe fissure. Since there are many species of Delicatophycus without APFs, such as D. sinensis M.J. Wynne, D. williamsii M.J. Wynne and D. chongqingensis M.J. Wynne; D. williamsii and D. liuweii Li both possess stigmata, thus proposed diagnostic characters for Delicatophycus are the tilde-shaped areolae and the dorsally curved distal fissures.

Inhibitory effect of exogenous IL-4 on orthodontic relapse in rats.

Interleukin-4 is proven to regulate bone metabolism. This study aimed to assess the effect of exogenous interleukin-4 on orthodontic relapse. Bilateral maxillary first molars of 25 male Sprague Dawley rats were moved mesially for 3weeks using orthodontic appliances an activating force of 50g. After tooth movement, exogenous interleukin-4 was injected into the buccal and palatine sides of the right maxillary first molars (experimental group), and phosphate-buffered saline was injected at the same sites on the left side (negative control group). At the end of the study, the relapse distance between the mesial fissure of the first molar and the distal fissure of the second molar was measured. Three different histological stains were used to visualize the changes in the periodontium. After interleukin-4 injection, the relapse distance significantly reduced. Time-dependent effects played a more important role than the dose-dependent effects, and there was no correlation between these factors. Tissue staining showed that interleukin-4 reduced osteoclastogenesis and promoted osteoblastogenesis. Exogenous interleukin-4 reduced the relapse of orthodontically treated teeth by promoting osteoblastogenesis and inhibiting osteoclastogenesis. Our findings can potentially benefit specialists in the future by improving their patients' treatment outcomes.

Historical Volcanism and the State of Stress in the East African Rift System

Crustal extension at the East African Rift System (EARS) should, as a tectonic ideal, involve a stress field in which the direction of minimum horizontal stress is perpendicular to the rift. A volcano in such a setting should produce dykes and fissures parallel to the rift. How closely do the volcanoes of the EARS follow this? We answer this question by studying the 21 volcanoes that have erupted historically (since about 1800) and find that 7 match the (approximate) geometrical ideal. At the other 14 volcanoes the orientation of the eruptive fissures/dykes and/or the axes of the host rift segments are oblique to the ideal values. To explain the eruptions at these volcanoes we invoke local (non-plate tectonic) variations of the stress field caused by: crustal heterogeneities and anisotropies (dominated by NW structures in the Protoerozoic basement), transfer zone tectonics at the ends of offset rift segments, gravitational loading by the volcanic edifice (typically those with 1-2 km relief) and magmatic pressure in central reservoirs. We find that the more oblique volcanoes tend to have large edifices, large eruptive volumes and evolved and mixed magmas capable of explosive behaviour. Nine of the volcanoes have calderas of varying ellipticity, 6 of which are large, reservoir-collapse types mainly elongated across rift (e.g. Kone) and 3 are smaller, elongated parallel to the rift and contain active lava lakes (e.g. Erta Ale), suggesting different mechanisms of formation and stress fields. Nyamuragira is the only EARS volcano with enough sufficiently well-documented eruptions to infer its long-term dynamic behaviour. Eruptions within 7 km of the volcano are of relatively short duration (<100 days), but eruptions with more distal fissures tend to have greater obliquity and longer durations, indicating a changing stress field away from the volcano. There were major changes in long-term magma extrusion rates in 1977 (and perhaps in 2002) due to major along-rift dyking events that effectively changed the Nyamuragira stress field and the intrusion/extrusion ratios of eruptions.

AGA technical review on the diagnosis and care of patients with anal fissure

Anal fissure is a disruption of the skin at the distal anal canal. Most anal fissures are located in the posterior midline, with 10% to 15% occurring anteriorly. “Off the midline” fissures must be viewed with suspicion for underlying pathology such as Crohn's disease, HIV/AIDS, tuberculosis, syphilis, or anal carcinoma. Early fissures have the appearance of a simple tear in the anoderm. With the passage of time, chronic fissures develop thickened skin margins, and fibers of the internal anal sphincter (IAS) become visible at the fissure's base. Many patients with chronic fissures develop a sentinel skin tag at the distal fissure margin and a hypertrophied anal papilla just proximal to the fissure within the anal canal.GASTROENTEROLOGY 2003;124:235-245

The posterior intrahepatic approach to liver resection

Background Hepatic resectional surgery has rapidly evolved since the realisation of the segmental anatomy of the liver and the intrahepatic distribution of the portal trinity (the hepatic artery, hepatic duct and portal vein). This portal trinity is enveloped by a sheath, derived from Glisson's capsule. In the classical intrafascial or extrahepatic approach, the appropriate branch of the portal vein, hepatic artery and the hepatic duct is isolated outside the liver substance, whereas in the extrafascial approach the whole sheath of the pedicle is dissected, after division of a substantial amount of hepatic tissue. In the transfissural or intrahepatic approach, these sheaths can be approached either anteriorly (after division of the main, right or umbilical fissure) or posteriorly, from behind the porta hepatis, through the distal fissure. Methods We describe the technique of the intrahepatic posterior approach to the glissonian sheath, with its contained hepatic pedicle structures and branches. Results This technique allows early delineation of a liver segment, without the need for ancillary manoeuvres. Discussion The indications for the use of this technique in an oncological setting are also discussed.

The Byssus and Byssus Glands in Chlamys islandica and Other Scallops (Lamellibranchia)

The foot has at its proximal end, a pouch opening by a duct onto the sole of the foot containing 25–40 thin lamellae. The primary byssus gland secretes into the spaces between these lamellae. A secondary byssus gland secretes into a groove which runs forwards from the duct opening for about two‐thirds of the length of the foot. Polyphenoloxidase is produced by cells surrounding the distal end of this groove. The tip attachment gland secretes into the distal fissure at the tip of the foot. The sole of the foot and the neck of the duct are lined with mucus cells. Ribbons of byssus are produced by the primary byssus gland. These are spun out in the groove and attached directly to the substratum at the distal end of the groove in an area presmeared by the tip attachment gland. The ribbon is enveloped in the groove by a sheath produced by the secondary byssus gland. Subsequent ribbons are bound to the existing byssus by a new sheath. Both the tip attachment gland and the ribbons contain some phenolic protein which is probably tanned in the presence of polyphenoloxidase to form a bond with the substratum. The homologies between this system and that in Mytilidae is discussed.

A study of the variability of dental plaque microorganisms in littermate wistar rats retaining a natural oral flora

Similar types of bacteria, selected on the basis of their distinctive colony morphology on mitis-salivarius agar and trypticase soy agar plates, were recoverable from the plaque of weanling littermate rats. The proportional distribution of these bacteria was highly variable within a litter, irrespective of whether a pellet diet or a powdered non-cariogenic diet was fed before weaning, or whether plaque was sampled from the central and distal fissures and the approximal surfaces of lower first and second molars or from only the central fissures of these teeth. Corresponding observations were made in rats fed a cariogenic diet after weaning. In this case, the caries experience of littermates appeared to be less variable than the proportional distribution of bacteria from plaque in the central fissure of their lower first and second molars. The results preclude the extrapolation from one rat to its littermates of quantitative bacteriological data relating to plaque.