Anterior Corner Research Articles

Glorund interactions in the regulation of gurken and oskar mRNAs

Precise temporal and spatial regulation of gene expression during Drosophila oogenesis is essential for patterning the anterior–posterior and dorsal–ventral body axes. Establishment of the anterior–posterior axis requires posterior localization and translational control of both oskar and nanos mRNAs. Establishment of the dorsal–ventral axis depends on the precise restriction of gurken mRNA and protein to the dorsal–anterior corner of the oocyte. We have previously shown that Glorund, the Drosophila hnRNP F/H homolog, contributes to anterior–posterior axis patterning by regulating translation of nanos mRNA, through a direct interaction with its 3′ untranslated region. To investigate the pleiotropy of the glorund mutant phenotype, which includes dorsal–ventral and nuclear morphology defects, we searched for proteins that interact with Glorund. Here we show that Glorund is part of a complex containing the hnRNP protein Hrp48 and the splicing factor Half-pint and plays a role both in mRNA localization and nurse cell chromosome organization, probably by regulating alternative splicing of ovarian tumor. We propose that Glorund is a component of multiple protein complexes and functions both as a translational repressor and splicing regulator for anterior–posterior and dorsal–ventral patterning.

The Oldest Known Stalk-eyed Trilobite, Parablackwelderia Kobayashi, 1942 (Damesellinae, Cambrian), and Its Occurrence in Shandong, China

Parablackwelderia is the oldest known stalk-eyed trilobite and thrived during the middle–late Cambrian (Guzhangian Age) in eastern Gondwanaland. The elongated palpebral lobe extends outward and forward from the anterior corner of the cranidium and shows positive allometry, becoming markedly longer and relatively thinner in large specimens. The animal occurred in muddy environments and may have been a predator that burrowed for concealment. Stalked-eyes were independently derived in several trilobite clades, but whenever they appeared were restricted to small numbers of taxa and thus do not appear to have served as a key innovation that promoted extensive diversification of species bearing the structure. The stalk-eyed condition in trilobites has a striking modern analog in the hypercephaly of diopsinid flies, where it is commonly associated with mate recognition and mate selection. We document the first occurrence of Parablackwelderia in Shandong, North China and describe a new species, Parablackwelderia luensis sp. nov.

The dynamics of fluorescently labeled endogenous gurken mRNA in Drosophila.

During Drosophila oogenesis, the targeted localization of gurken (grk) mRNA leads to the establishment of the axis polarity of the egg. In early stages of oogenesis, grk mRNA is found at the posterior of the oocyte, whereas in the later stages grk mRNA is positioned at the dorsal anterior corner of the oocyte. In order to visualize the real-time localization and anchorage of endogenous grk mRNA in living oocytes, we have utilized the MS2-MCP system. We show that MCP-GFP-tagged endogenous grk mRNA localizes properly within wild-type oocytes and behaves aberrantly in mutant backgrounds. Fluorescence recovery after photobleaching (FRAP) experiments of localized grk mRNA in egg chambers reveal a difference in the dynamics of grk mRNA between young and older egg chambers. grk mRNA particles, as a population, are highly dynamic molecules that steadily lose their dynamic nature as oogenesis progresses. This difference in dynamics is attenuated in K10 and sqd(1) mutants such that mislocalized grk mRNA in older stages is much more dynamic compared with that in wild-type controls. By contrast, in flies with compromised dynein activity, properly localized grk mRNA is much more static. Taken together, we have observed the nature of localized grk mRNA in live oocytes and propose that its maintenance changes from a dynamic to a static process as oogenesis progresses.

New stylophorans (Echinodermata) from the upper Cambrian of Guangxi, South China

This paper describes for the first time the cornute stylophorans (Echinodermata) in China. The new material came from the Guole Formation of the Furongian (Late Cambrian) in the Guole area of Jingxi, Guangxi Province, South China. These new cornute specimens are preserved in situ and found along with well-preserved trilobites and brachiopods. One new species, Phyllocystis jingxiensis sp. nov., is proposed to accommodate these unusual materials. The new species is defined by the small, heart-shaped theca with the frame composed of ten narrow, smooth and thick marginal plates, three adoral plates and distinctive zygal and aulacophore. Both supracentrals and infracentrals are polygonal-outlined. The marginal plate M1′ on the inferior face extends posteriorly to form zygal that possesses a broadened proximal end and the proximal portion joining with the conjunction between M4 and M5 on the inferior face. Aulacophore comprises ten segments at its proximal part and is conical at the middle part (named stylocone). Its distal portion is rather long and bears conspicuous ambulacrum grooves. Tectals are horizontally arranged on superior face and obliquely arranged on inferior face. Both cothurnopore and anal pyramid are vaguely seen on the right anterior corner and the extremity of theca’s superior face.

Vertebral Rounding Deformity in Pediatric Spondylolisthesis Occurs Due to Deficient of Endochondral Ossification of the Growth Plate

A study using rat spondylolisthesis models. To clarify pathomechanism of vertebral rounding deformity in pediatric spondylolisthesis. For high-grade slippage, rounding of sacrum surface associated with L5 spondylolisthesis is reported to be the most responsible risk factor. However, the exact pathomechanism of the rounding deformity is yet to be clarified. Spondylolisthesis rat model (4-week-old) was used. Radiographs were taken weekly for 5 weeks after the surgery. The lumbar spines were harvested for histology. Hematoxylin and eosin, alcian blue staining, and tartrate-resistant acid phosphatase staining were used. Immunohistochemically, the growth plate cartilage was studied for type II and X collagen. A modified bone histomorphometric analysis was also performed. Radiographs showed slippage 1 week after surgery. Rounding deformity was obvious 2 weeks after surgery. The rounding deformity progressed with time. Three weeks after surgery, the specific columns of growth plate were unclear at the anterior corner, which corresponded to the rounding surface observed on radiographs. Instead, a huge mass of cartilage was observed at that site. Tartrate-resistant acid phosphatase-positive cells were observed in the vicinity of the growth plate except in relation with the anterior corner. The growth plate and cartilage mass at the anterior corner stained positive for type II collagen. Chondrocytes in the hypertrophied layer stained positively for type X collagen; however, staining was faint at the anterior corner. The results suggested that the chondrocytes at the anterior did not form, morphologically and functionally, the normal growth plate. From histomorphometrical analysis, the normal posterior growth plate made endochondral bone growth in 510 +/- 20 microm for a week, whereas the anterior corner in 200 +/- 15 microm. Deficient endochondral ossification of the growth plate in the anterior upper corner of the vertebra could be the pathomechanism of the rounding deformity of the sacrum.

Roundabout the Dendritic Tree?

The secreted protein Slit and its receptor Robo stimulate growth cone collapse and repel axons from the midline during development. Noting that Slit signaling can promote neurite branching in vitro, and that expression of Slit and Robo persists beyond the developmental stage at which axonal repulsion occurs, Furrer et al . investigated their role in vivo in dendritic development of a Drosophila neuron, the anterior corner cell (aCC) motoneuron. Visualization of individual neurons filled with a fluorescent dye revealed that, in Drosophila embryos lacking Robo, aCCs had stunted collateral dendrites. Similar results were seen when RNAi constructs directed against Robo were specifically expressed in aCCs, whereas expression of wild-type Robo in aCCs of flies lacking Robo substantially rescued dendrogenesis. Immunocytochemical analysis of extracellular Slit during embryonic development of the Drosophila central nervous system (CNS) revealed that Slit had begun to accumulate in the region at which aCC dendrites develop (as well as was found at the midline) just as their dendrogenesis began. In developing flies lacking Robo (which would be expected to capture Slit at the cell surface), this secondary site of Slit accumulation was shifted medially, as were the small aCC dendrites. In flies lacking functional Slit, dendrites failed to develop. Ectopic expression of Slit in muscles contacted by motoneurons, however, did not stimulate collateral dendrogenesis; therefore, the effect of Slit may be limited to the CNS environment. Thus, the authors conclude that, in contrast to its effects on axons, in the developing Drosophila CNS Slit signaling through Robo regulates dendrogenesis. M.-P. Furrer, I. Vasenkova, D. Kamiyama, Y. Rosado, A. Chiba, Slit and Robo control the development of dendrites in Drosophila CNS. Development 134 , 3795-3804 (2007). [Abstract] [Full Text]

Bartonaspis new genus, a trilobite species complex from the base of the Upper Cambrian Sunwaptan Stage in North America

Despite being reported widely from basal Sunwaptan strata, Dellea? punctata Palmer, 1965, is known from only four figured cranidia. New material from Nevada, Utah and Oklahoma, including librigenae and pygidia, indicate that specimens assigned previously to D.? punctata are best interpreted as a complex of related species that are assigned to a new genus, Bartonaspis. This genus is diagnosed by punctate sculpture, a pair of fossulae at the anterior corners of the glabella, and by a subelliptical pygidium with a short convex axis composed of three segments. Three new species, B. fredericksoni, B. palmeri, and B. wilsoni, are described and B. punctata (Palmer) is restricted to its holotype. Bartonaspis is known only from the Irvingella major Zone, and its first appearance defines the base of the Sunwaptan Stage. Dellea Wilson, 1949, is related to Bartonaspis and is differentiated from it primarily by pygidial morphology. In contrast to Bartonaspis, the pygidium of Dellea has an axis composed of four, rather than three, segments and a narrow concave border.

Can Transesophageal Pulse‐Wave Tissue Doppler Imaging Be Used to Evaluate Left Ventricular Function?

This study aimed to evaluate the efficiency of transesophageal tissue Doppler echocardiography (TDE) in evaluation of the left ventricular functions. To this end, the data obtained by transoesophageal tissue Doppler echocardiography and by transthoracic tissue Doppler echocardiography were compared simultaneously. Nineteen consecutive patients (7 female and 12 male) underwent a clinically indicated study. In transthoracic (TTE) and transoesophageal (TEE) echocardiographic study, a Vingmed System Five Doppler echocardiographic unit (GE Vingmed) was used. For the assessment of the left ventricular function using transthoracic and transoesophageal TDE, the mitral annular peak systolic (S), early diastolic (E), late diastolic velocities (A), late to early velocity ratio (E/A), deceleration times (DT), left ventricular isovolumetric relaxation times (IVRT) were measured at the lateral, medial, anterior, and posterior corners at the mitral annulus by activating TDE mode in the transthoracic and transoesophageal apical four- and two-chamber view. Bland-Altman plots were used to compare the two measurement techniques. The differences between the groups were assessed by Mann-Whitney U test. All the data were expressed as mean +/- SD. A P-value of <0.05 was considered significant. There were no significant differences between two techniques in terms of blood pressure and heart rate. Two techniques were compared for the transthoracic and transoesophageal TDE parameters. Bland-Altman analysis showed comparable values for E, A, E/A, S, and mE/E, although the measurements of DT and IVRT were different. PW tissue Doppler echocardiographic approach during TEE may be suitable for assessment of the left ventricular function.

Two new species of Tanaidacea of the genus Kalliapseudes Stebbing, 1910 (Crustacea: Apseudomorpha: Kalliapseudidae) from Australia

Two new species of kalliapseudid tanaidacea from Australia, Kalliapseudes longisetosus and Kalliapseudes messingi, are described from marine waters off Sydney, New South Wales and the Northwest continental shelf, respectively. Kalliapseudes longisetosus is distinguished from the other congeners by the presence of a single, very long simple seta on the anterior corners of the pereonites (about as long as the first pereonite) and several very long simple setae on the basis of the second and third pereopods (about as long as the basis). This new species is the second member of the genus to be reported from New South Wales. Kalliapseudes messingi is distinguished by having two small setae medially on the dactylus of pereopods 4 and 5, by the female having a tuft of sensory setae subterminally on the dactylus of pereopod 6, and by having three plumose setae on both the cheliped and pereopod 1 exopodite and is the first member of the genus to be reported from the Northwest continental shelf of Australia. Both species have a needle-like tip on the dactylus of the second and third pereopods. A table giving the distribution data for the species of Kalliapseudes and a key to the genera and species of Kalliapseudidae now known from Australia are presented.

The effect of graft placement on the clinical outcome of the anterior cruciate ligament reconstruction: a prospective study

The effect of the graft placement on the clinical outcome of patients after anterior cruciate ligament (ACL) reconstruction has been studied sparsely. We conducted a prospective follow-up of 140 patients who underwent an arthroscopic ACL reconstruction with a hamstring graft. One hundred and four of them (74%) could be examined at the 2-year follow-up. Clinical examination included Lysholm, Tegner, and International Knee Documentation Committee rating scores, arthrometric anterior-posterior knee laxity assessment, and muscle strength assessments. The graft placement was measured from lateral radiographs using a system recommended for measuring the attachment positions of the cruciate ligaments as well as a method called 'the sumscore of the graft placement', which takes into account both the femoral and the tibial graft placements simultaneously. The sumscore was smaller in knees with normal anterior-posterior knee laxity in the Lachman test (P = 0.002) and normal rotational knee laxity in the pivot shift test (P = 0.01) than in those with abnormal laxity. The tibial graft placement was more anterior when the Lachman test was normal (P = 0.04). The Lysholm score was better when the femoral graft placement was more posterior (r = -0.20, P = 0.04). The optimal femoral graft placement was between 25 and 29% of length of the femoral condyle along the Blumensaat's line from posterior to anterior. The optimal tibial graft placement was between 32 and 37% of the length of the tibial plateau from the anterior corner, and the optimal sumscore was between 61 and 66. The sumscore and its components (the femoral and tibial graft placements) showed a clear association with the clinical outcome of the patients. The best outcome was achieved when the sumscore was small; that is the graft placement showed posterior enough in the femur, and anterior enough in the tibia.

Loricifera from the deep sea at the Galápagos Spreading Center, with a description of Spinoloricus turbatio gen. et sp. nov. (Nanaloricidae)

Specimens of a new species of Loricifera, Spinoloricus turbatio gen. et sp. nov., have been collected at the Galapagos Spreading Center (GSC) during the cruise SO 158, which is a part of the MEGAPRINT project. The new genus is positioned in the family Nanaloricidae together with the three already described genera Nanaloricus, Armorloricus and Phoeniciloricus. The postlarvae and adults of Spinoloricus turbatio gen. et sp. nov. are characterized by a mouth cone with eight oral ridges and basally with a cuticular reinforcement named mouth cone pleat; eighth row with 30 whip-like spinoscalids and 30 “alternating” plates; thorax with eight single and seven double trichoscalids, where the single trichoscalids are twice the length of the double ones, and the secondary appendage on the double trichoscalid is smooth whereas the others are serrated; lorica with eight cuticular plates with additional spikes in the anterior corners and intercalary plicae between the plates. Some of these genus-specific characters such as the mouth cone pleat, the “alternating” plates and the intercalary plicae have not been observed in Nanaloricidae before. The Higgins-larvae of Spinoloricus turbatio gen. et sp. nov. are characterized by six rectangular plates in the seventh row with two teeth, an indistinct honeycomb sculpture and long toes with little mucrones. The SO 158 cruise has yielded a minimum of ten new species of Loricifera out of only 42 specimens. These new species belong to two different orders, where one being new to science, and three different families. This result indicates a high diversity of loriciferans at the GSC. Nearly all the collected loriciferans are in a moulting stage, hence there is a new stage inside the present stage. This prolongation of life stages and the occurrence of multiple life stages inside each other are typical of deep-sea loriciferans. Here exemplified by the two postlarvae with adults inside, which is observed for the first time in Nanaloricidae.

Tissue Doppler Velocity Is Not Totally Preload-Independent: A Study in a Uremic Population after Hemodialysis

Objectives: The aim of this study was to investigate the changes of regional tissue Doppler velocity after volume removal following regular hemodialysis (HD) in uremic patients. Is tissue Doppler velocity really preload-independent? Background: Diastolic dysfunction was divided into four stages: normal pattern, abnormal relaxation pattern, pseudonormalization pattern, and restrictive pattern. Pulse wave Doppler and color Doppler echocardiography were important diagnostic tools for these forms of diastolic dysfunction. However, they were preload-dependent and sometimes there was confusion between the normal pattern and the pseudonormalization pattern. Tissue Doppler echocardiography was promising for problems in diastolic dysfunction and appeared to be preload-independent. However, there are still some disputes over this point. Methods: Ninety-three uremic patients receiving regular HD were included in the study. There were 45 males and 48 females aged 59 ± 14 years. The mean volume removed after HD was 2.3 ± 0.9 kg. The mean heart rates before and after HD were 77 ± 11 and 76 ± 12 beats per minute, respectively (p = 0.73). All patients received complete transthoracic echocardiography examinations before and after HD. The studies included cardiac chamber size, left ventricular systolic performance, pulse wave Doppler echocardiographic data of mitral inflow and the right upper pulmonary vein including peak velocity of early diastolic E wave, E wave time velocity integral (TVI-E), peak velocity of late diastolic A wave, A wave TVI, systolic phase of pulmonary vein (S wave TVI), early diastolic phase of pulmonary vein (D wave TVI) and atrial contraction phase of pulmonary vein (Ar wave TVI). Pulsed tissue Doppler echocardiography (TDE) was performed and a 4-mm sample volume was placed at the 6 corners of the mitral annulus including septal, lateral, anterior, inferior, anteroseptal and posterior corners. Five to ten cardiac cycles were recorded and the data were averaged. Measurements performed included peak velocity of systolic phase (Sa), early diastolic phase (Ea), late diastolic phase (Aa), Ea/Aa ratio and time from the beginning of electrocardiogram Q wave to the beginning of Sa (Q-Sa time). The same measurements were repeated after HD. Results: After HD, left atrium diameter and left ventricular internal dimensions at end diastole became smaller. There were significant reductions for mitral peak E wave velocity, TVI-E, peak A wave velocity and E/A ratio. As for the pulmonary vein, systolic phase of pulmonary vein and early diastolic phase of pulmonary vein decreased significantly. Peak Ar wave did not change significantly. For TDE, Sa and Aa did not change but Ea did decrease. Conclusion: After HD, there is a significant reduction of intravascular effective volume. No significant change is found for myocardial peak systolic velocity and peak late diastolic velocity. However, there is a significant reduction of myocardial early diastolic phase peak velocity. This suggests that TDE is not completely preload-independent; at least, it is phase-dependent within each cardiac cycle.

SAPHO Syndrome: MR Appearance of Vertebral Involvement

To retrospectively evaluate the magnetic resonance (MR) imaging findings of vertebral involvement in patients with synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome. Ethics committee approval and informed patient consent were not required for this retrospective study. MR images obtained in 12 patients (seven female, five male; mean age, 42 years; range, 16-65 years) with SAPHO syndrome involving the spine were reviewed. One vertebral lesion separated by one or more normal vertebrae was analyzed as a distinct lesion. For each lesion, the number of associated vertebrae with abnormal signal intensity (SI) (ie, single vertebra, two adjacent vertebrae, or more than two adjacent vertebrae) was noted. The following MR imaging findings were evaluated: cortical bone erosion, abnormal vertebral body SI compared with normal vertebral body SI, increased anteroposterior diameter of the vertebral body, soft-tissue involvement, vertebral body height loss of more than 30%, and abnormal SI of the adjacent intervertebral disk compared with the SI of the other disks. Of 24 vertebral lesions found, 17 involved a single vertebra, four involved two adjacent vertebrae, and three involved three or four adjacent vertebrae. Vertebral corner cortical erosion was present in all lesions, and 23 (96%) lesions had anterior vertebral corner involvement. The erosion was confined to a vertebral corner in five (21%) lesions and included the adjacent endplate and/or the anterior cortex of the vertebral body in the remaining 19 (79%) lesions. In four (17%) lesions, involvement of two adjacent vertebral corners on either side of an intervertebral disk mimicked to some extent early disk space infection. An adjacent disk space was narrowed in six (25%) lesions and exhibited abnormal SI in two (8%). Prevertebral tissue thickening was observed in eight (33%) lesions. Erosion of a vertebral body corner is consistently seen on MR images of SAPHO vertebral lesions and may support the diagnosis of SAPHO syndrome in the appropriate clinical context.

Stress analysis of the anterior tibial post in posterior stabilized knee prostheses

Recent retrieval studies have indicated a high incidence of polyethylene wear on the anterior tibial post caused by impingement. This study investigated the influences of post-cam design features and component alignment on the stress distribution in the anterior tibial post when subjected to the impingement loading. Two three-dimensional finite element models of posterior stabilized knee prostheses were constructed, one with flat on flat (FF) and another with curve on curve (CC) contact surfaces between anterior tibial post and femoral cam. The polyethylene insert was modeled with elastoplastic properties. Nine cases, three hyperextension angles (0 degrees , 5 degrees , and 10 degrees ) combined with three axial tibial rotations (0 degrees , 2.5 degrees , and 5 degrees ) simulating different component alignments were analyzed. A vertical compressive load of 2,000 N and an extension moment of 45 Nm were applied simultaneously. The FF model had larger stress increases than the CC model in both hyperextension and tibial rotation compared with the neutral position. The maximum increase for the FF model was 68% in peak contact stress, 125% in von Mises stress, and 58% in tensile stress in the extreme case of 10 degrees of hyperextension combined with 5 degrees of axial rotation. Stress concentration was found at the anterior corner of the post in the FF model; this was not found in the CC model. The curve on curve design can reduce edge loading on the tibial post, especially during axial tibiofemoral rotation.

A new species of the deep-sea isopod genus Katianira Hansen, 1916 (Crustacea: Asellota: Katianiridae) from the Kumano Basin, Japan

ABSTRACT Katianira platyura, new species, is described from the mid-bathyal zone of the Kumano Basin, southern Japan, the first record for the family from the North Pacific. Katianira platyura differs from its congeners by having the head with a pair of broad, deeply divided, bilobed lappets; pereonite 1 laterally rounded; anterior and posterior corners of pereonites blunt; mandibular molar process rudimentary; pereopod 3 flattened and broad; distal part of pleopod 1 with 32 setae; protopod of pleopod 2 trapezoidal; tip of endopod of pleopod 2 reaching to approximately 0.9 of protopod; and broad, leaf-shaped uropods.

Principal Bid vs. Agency Trading

<h3>Background</h3> Bone formation and bone loss are both present in ankylosing spondylitis (AS). New bone formation can lead to the formation of syndesmophytes, ankylosis of the spine and sacroiliac joints, and bone formations on enthesal sites. <h3>Objectives</h3> To investigate the relation between the presence of syndesmophytes and bone turnover markers (BTM) in AS patients with active disease. <h3>Methods</h3> 55 consecutive outpatients with AS based on the modified New York criteria (n=54) or the ASAS criteria for axial spondyloarthritis (n=1) and active disease defined by Bath AS Disease Activity Index (BASDAI) ≥4 (range 0-10) or based on expert opinion were included. Patients with recent fractures, use of bisphosphonates, and/or inflammatory bowel disease were excluded. The lateral view of radiographs of the cervical and lumbar spine were blinded and scored for the presence of syndesmophytes at the anterior corners of the vertebrae by two independent observers. In case of discrepancy between the two observers, there was a consensus meeting afterwards. Markers of bone formation procollagen type 1 N-terminal peptide (PINP) and bone-specific alkaline phosphatase (BALP), and marker of bone resorption serum collagen-telopeptide (sCTX) were measured. Z-scores of BTM were calculated using matched 10-years-cohorts of a Dutch reference group (200 men or 350 women) to correct for the normal influence that age and gender have on bone turnover. <h3>Results</h3> Mean age of the 55 AS patients was 40.4 years (SD ± 11.2), median duration of symptoms was 15 years (range 3-46), median time since diagnosis was 5 years (range 0-27), mean BASDAI was 6.1 (SD ± 1.8), and 58% were male. Syndesmophytes were present in 33 of the 55 (60%) patients. Patients with syndesmophytes had significantly higher levels of PINP (median Z-score: 0.41 vs. -0.17, p=0.005) and sCTX (median Z-score: -0.02 vs. -0.58, p=0.025) than patients without syndesmophytes. No significant differences were found in BALP (median Z-score: 1.56 vs. 0.67, p=0.213) and BASDAI (mean: 6.2 vs. 5.9, p=0.581) between patients with and without syndesmophytes. <h3>Conclusions</h3> This cross-sectional analysis in AS patients with active disease shows that markers of both bone formation (PINP) and bone resorption (sCTX) are significantly higher in patients with syndesmophytes compared to patients without syndesmophytes. Further longitudinal studies are needed to investigate whether BTM can serve as potential biomarkers for radiographic damage in AS. <h3>Disclosure of Interest</h3> None Declared

Progressive non-infectious anterior vertebral fusion (Copenhagen Syndrome) in three children: features on radiographs and MR imaging

Progressive non-infectious anterior vertebral fusion is a rare childhood disease of unknown aetiology. It commonly presents with kyphosis associated with progressive fusion in the thoracolumbar spine. MR imaging features have not previously been described to our knowledge. Three cases presenting to our institution are described. All three children had other congenital or developmental problems. Plain radiographs showed typical features with narrowing and irregularity of the anterior endplates and developing anterior vertebral fusion. MR imaging was available in all (in one case sequentially at ages 1 and 12 years), and features demonstrated were anterior disc narrowing and anterior endplate irregularity progressing to fusion. Associated bone oedema or fatty replacement was seen in the endplates, and was most marked at the anterior corners.

FIRST ADULT AND EGG DESCRIPTIONS OF CAUDATELLA EDMUNDSI (EPHEMEROPTERA: EPHEMERELLIDAE) FROM MONTANA (U.S.A.), WITH HABITAT OBSERVATIONS

Series of reared material from Montana provide the bases for the first descriptions of the adults of Caudatella edmundsi. Male adults are differentiated from congeners based on their having abdominal sterna with dark anterior corners and penes with the gonopores subparallel and projected dorsally. The first description of Caudatella eggs shows them to have a chorion without reticulations. Larvae of C. edmundsi usually are associated with moss in moderate to slow current regions of cool, clear, shaded streams.

Biomechanical Analysis of Tibial Strength After Harvest of Unicortical Tibial Grafts from Two Different Sites

Use of tibial strut grafts has several potential advantages over other donor sites and would be ideal as a harvest site for bone grafts if there are minimal or no resulting risks to tibial stability. Ten matched-pair cadaver tibiae were randomized to have a 1.5 x 4.0 cm cortical graft harvested from the tibial crest or 1 cm posterior to the tibial crest. Both locations were 6 cm distal to the tibial plateau. The grafts were removed using a high-speed oscillating saw, and each end of the tibia was mounted for testing and loaded onto a servohydraulic test frame. The samples were axially loaded with 720 N (162 lbs) of force, and an external rotational torque was applied at 5 degrees per second to failure. Failure torque for each tibia was recorded. A paired Student's t-test was used to determine whether any observed differences in failure torques were significant. The torque to failure range for on-crest grafts was 11.65 to 81.76 Nm (average, 44.53 Nm; SD, 22.82 Nm). The torque to failure range for the tibiae with the graft 1 cm off-crest was 13.30 to 70.45 Nm (average, 41.64 Nm; SD, 17.83 Nm). All fractures were spiral, included the distalmost anterior corner of the donor site, and extended distally. There was no significant difference in torque to failure between the two donor sites (p = 0.22). The grafts varied consistently in quality. Considering that there was no statistically significant difference in torque to failure between the two groups of tibiae, the site for tibial bone graft can be selected based on the shape of the cortical graft necessary for each specific surgery.

Digestive System of the Sacoglossan Plakobranchus ocellatus (Gastropoda: Opisthobranchia): Light- and Electron-Microscopic Observations with Remarks on Chloroplast Retention

The sacoglossan Plakobranchus ocellatus feeds by sucking the cytoplasmic contents from algae and retains intact algal chloroplasts within the cells of the digestive gland. Morphology of the entire digestive system of this species was firstly described by means of a combination of histology and electron microscopy (both SEM and TEM). The short alimentary canal is confined to the head, and the anus opens at the anterior right corner of the pericardial swelling, as is the case in many non-shelled sacoglossans. The alimentary canal of the specimens examined rarely contained ingesta, suggesting that the retained chloroplasts provide sufficient nourishment to the sacoglossan hosts and that sea slugs with empty stomachs survive well in the field. The digestive gland, with the retained chloroplasts, branches from the stomach and is sparsely distributed throughout the body, including the head region, but is aggregated mainly in the dorsal lamellae. Chloroplasts were occasionally found in the epithelial cells in the transitional region from the stomach wall to the digestive gland, which may be a site at which chloroplasts are incorporated into the animal cells by endocytosis. Numerous microvilli filling the lumen of the digestive gland suggest that molecules are actively transferred within the gland. The sea slug thus apparently provides a favorable environment to support the long-term retention and function of chloroplasts.