Sleep and memory consolidation in aging: A neuroimaging perspective

Recently acquired information is strengthened and consolidated during sleep. For hippocampus-dependent memory, this process is assumed to occur mainly during slow wave sleep. Changes in sleep patterns in older adults can contribute to the disruption of the consolidation process during sleep and thus lead to cognitive impairment. Current findings suggest that reduced gray matter volume, particularly in frontal areas, Aβ and tau accumulation in combination with age-related changes of specific oscillations during sleep may contribute to memory deficits. This non-exhaustive review aims at providing a comprehensive picture of the associations between sleep changes and memory consolidation in aging, mainly based on neuroimaging studies. Overall, data confirm the utmost importance of sleep for healthy aging and the need to develop interventions aiming at improving sleep to reduce cognitive decline observed with advancing age.

Correlation between magnetic resonance, X-ray imaging alterations and histological changes in an ovine model of age-related disc degeneration

Sheep are one of the many animal models used to investigate the pathophysiology of disc degeneration and the regenerative strategies for intervertebral disc (IVD) disease. To date, few studies have thoroughly explored ageing of ovine lumbar IVDs. Hence, the objective of the present study was to concomitantly assess the development of spontaneous age-related lumbar IVD degeneration in sheep using X-ray, magnetic resonance imaging (MRI) as well as histological analyses. 8 young ewes (< 48 months old) and 4 skeletally mature ewes (> 48 months old) were included. Disc height, Pfirrmann and modified Pfirrmann grades as well as T2-wsi and T2 times were assessed by X-ray and MRI. The modified Boos score was also determined using histology sections. Pfirrmann (2 to 3) and modified Pfirrmann (2 to 4) grades as well as Boos scores (7 to 13) gradually increased with ageing, while T2-weighted signal intensity (1.18 to 0.75), T2 relaxation time (114.36 to 70.65 ms) and disc height (4.1 to 3.2 mm) decreased significantly. All the imaging modalities strongly correlated with the histology (p < 0.0001). The present study described the suitability of sheep as a model of age-related IVD degeneration by correlation of histological tissue alterations with the changes observed using X-ray and MRI. Given the structural similarities with humans, the study demonstrated that sheep warrant being considered as a pertinent animal model to investigate IVD regenerative strategies without induction of degeneration.

Thoracolumbar spinal fracture in children: Conservative or surgical treatment?

PURPOSE

Spinal thoracolumbar fractures represent 10-14% of pediatric fractures. Most children concerned by such fractures are above 10 years of age. No guidelines presently exist. Analysis of spine pathophysiology and of the various common therapeutic attitudes led us to conduct a review of the different therapeutic approaches in pediatric thoracolumbar fracture.

METHODS

A review of the literature was carried out using the Medline and Embase databases with the search-term "pediatric thoracic lumbar spine fractures".

RESULTS

The systematic review identified 44 studies, 24 of which were selected, and 19 were included for analysis. Physiological age was categorized on Risser's classification. In Risser 1 with Magerl A1 fracture, surgical treatment was not necessary and functional (rest and analgesics) or conservative treatment (bracing for 6 weeks) was sufficient. In Risser 1 with Magerl A2, A3 or B fracture, conservative treatment (bracing for 3 months) was the first-line option. In Risser 2-4, conservative treatment with bracing for 3 months was possible in the absence of instability, with kyphosis>20° and canal compression>33%; otherwise, treatment should be surgical. Subsequently, in case of onset of secondary instability, surgical treatment can be proposed. We highlight the importance of MRI assessment for diagnosis of thoracolumbar fracture and associated lesions of the intervertebral discs and posterior ligament complex. Children classified as Risser 5 can undergo the same treatment as adults.

CONCLUSION

Two main parameters should be assessed in treatment decision-making for thoracolumbar fracture: the Risser scale and the Magerl classification.

[Median nerve compression in the carpal tunnel in children - a delayed diagnosis. About 20 clinical cases]

OBJECTIVES

The carpal tunnel syndrome is rare in children. We performed a retrospective study of 10 children. The aim is to show that the diagnosis of carpal tunnel syndrome is difficult in children.

PATIENTS AND METHODS

We identified all children with median nerve compression in the carpal tunnel between 2010 at 2020, managed in our service.

RESULTS

Ten children with 20 hands included. There was different etiologies of carpal tunnel syndrome: 5 lysosomal storage diseases, 4 idiopathic carpal tunnel syndrome, 1 genodermatose, 1 Byler syndrome and 1 VACTERL syndrome. Common presenting symptoms were pain (five patients) and under use of fingers (five patients). Two children had opposition deficit of the thumb. We operated 19 hands. Median age at diagnosis was 4 years and 7 months. One children or 2 hands had a reanimation of opposition by tendinous transfer of flexor digitorum superficialis tendon of the ring finger. All children had a complete regression of the painful symptoms, a use improvement of fingers and recovery of the opposition of the thumb.

CONCLUSION

The diagnosis of carpal tunnel syndrome is difficult in children. It is common to be confronted with an advanced clinical symptoms. The atypical symptoms may cause diagnostic delay. Due to the quality of the clinical results obtained, we recommend open carpal tunnel release even when the diagnosis seems delayed.

LEVEL OF EVIDENCE

IV.

Management of loss of tissue substance in children's limbs. What are the salient peculiarities? A proposed algorithm

Loss of tissue substance in children's limbs has the same etiologies and in many cases, the same severity as in adults' limbs, and the means placed at the disposal of a surgeon are likewise comparable. It may nonetheless prove difficult to strategically position the different treatment methods in a decision-making tree. After all, a child presents numerous peculiarities: high quality of vascularization (both microcirculation and macrocirculation), better ability to achieve nerve regeneration and durable bone consolidation and, last but not least, a pronouncedly superior overall functional prognosis. Moreover, a child's future needs to be taken into account ; it is not only cicatrization per se, but also the quality of healing that should dictate therapeutic choices, which will consequently be determined in view of avoiding functional disorders during the growth process. On the basis of their experience and following a review of the literature, the authors have assessed the interest of each relevant technique and drawn up a decision-making tree.

Negative Pressure Wound Therapy in children: A 25 cases series

Negative Pressure Wound Therapy is a device applied to a wound that causes local depression. There are a few series showing the effectiveness of this treatment in Pediatric. The objective of this work is to try to clarify the indications in children. This is a retrospective series of 25 children between 2004 and 2019. The inclusion criteria were all children with a wound treated with Negative Pressure Wound Therapy. The characteristics retained were their age, the context of occurrence, the treatment time, the depression applied, the technique of skin covering wound and the average healing time. We included 25 patients. The average age was 8.8 years. The context of the wound occurrence was mainly a road (44%) or a domestic (36%) accident. Substance losses were mainly located in the lower limb (84%). The depression applied was -90mmHg. The healing time was 18.4 days. Thin skin grafting was the main method chosen (88%). No complications related to Negative Pressure Wound Therapy equipment have been identified. Despite the weakness of the literature and the lack of consensus regarding its use, Negative Pressure Wound Therapy is an essential therapy in pediatric. It is a simple and effective technique in children. It can reduce the need for flaps coverage, even in the event of exposure of noble elements. The flaps should not, however, be excluded from the decision-making algorithm, on pain of complications or sequelae.

Social stability influences the association between adrenal responsiveness and hair cortisol concentrations in rhesus macaques

Hair cortisol concentrations are increasingly being used in both humans and nonhuman animals as a biomarker of chronic stress. However, many details regarding how hair cortisol concentrations relate to the dynamic activity and regulation of the HPA axis are still unknown. The current study explores 1) how the regulation of the HPA axis in infancy relates to hair cortisol concentrations (HCC) in infancy 2) whether this relationship persists into adulthood under conditions of social stability, and 3) how social instability impacts these relationships. All subjects were rhesus monkeys housed in large social groups at the California National Primate Research Center, and all had participated in a 25-hr. long BioBehavioral Assessment (BBA) at 3-4 months of age when four plasma samples were taken to assess HPA regulation, in particular cortisol responses to 1) 2-hour social separation and relocation, 2) sustained challenge, 3) dexamethasone and 4) ACTH administration. In Study 1, hair samples were collected at the end of the BBA testing from 25 infant rhesus monkeys from 2 different stable social groups. In Study 2, hair samples were obtained at three timepoints from 108 adults from 3 different stable social groups (1 in the Spring/Summer and 2 in the Fall/Winter) to examine the temporal stability of the relationship between HCC and HPA axis regulation. In Study 3, subjects included 31 infants and 33 adults from a single social group experiencing social instability following the same procedures as in Studies 1 and 2. Generalized linear models were used to determine if infants' HPA axis activity and regulation predicted HCC in infancy (Study 1), in adulthood with animals living in stable social conditions (Study 2) or in animals living in an unstable social group (Study 3). Results indicated that for both infants and adults living in stable social groups, HCC are associated with the adrenal response to ACTH in infancy. Samples collected in the winter also had higher HCC than those collected in summer. In the unstable social group, adult hair cortisol levels were higher than in the stable social groups. Additionally, there were no consistent relationships between HCC and infant HPA axis regulation among adults or infants living in a group experiencing social instability. These results suggest that the aspects of the HPA axis that drive HCC may differ depending on context. Under stable, non-stressed conditions there seems to be a trait-like association between adrenal responsivity and HCC in infancy and adulthood. However, this association may be reduced or eliminated under conditions of social stress.

Postoperative infections after limb-sparing surgery for primary bone tumors of the pelvis: Incidence, characterization and functional impact

INTRODUCTION

Surgical site infections (SSI) represent the most common postoperative complication after limb sparing surgery for primary malignant bone tumors, with incidence ranging from 10 to 47%. There is no consensus concerning about the optimal surgical strategy, or the adequate antibiotic prophylaxis in pelvic resections. A greater knowledge of these infections and their surgical trajectories seem essential to obtain.

MATERIALS AND METHODS

We retrospectively studied 45 cases of pelvic resection, including at least the periacetabular zone 2 of Enneking, performed between 1989 and 2013 in the same center. Infection rate, risk factors and surgical trajectories were analyzed. The impact of a postoperative infection on the quality of life and functional recovery was evaluated by the Musculoskeletal Tumor Society scoring system (MSTS).

RESULTS

Sixteen patients presented a SSI in the first post-operative year (35.6%). We found as risk factors the pre-operative ASA score, the age at surgery and the number of packed red cells transfused during surgery. In case of failure of an initial washout, an iterative procedure is responsible for a high failure rate of 88.9%. Irrespective of the type of reconstruction, our functional results show that this surgery is often a source of handicap with a MSTS score of 13.77 in infected patients versus 17.70 in non-infected patients, at two-year follow-up.

DISCUSSION

In case of failure of an initial wash, prosthetic material must be removed and a hip transposition procedure should be preferred to a second-look surgery. Concerning prophylactic antibiotherapy, a dual therapy for at least 48 h after surgery should probably be preferred.

[Vascular relationships of the right great splanchnic nerve in the thorax]

AIM

The surgical assumption of responsibility of the pancreatic pain requires either a truncular coelioscopic or radicular neurectomy of greater splanchnic nerves (gsn). The goal of our work is to describe the way and relations of the right gsn which are variable and rarely described. This constitutes an undeniable peroperational hemorrhagic risk during splanchnicectomy.

MATERIAL AND METHODS

After a double side thoracotomy and a bilateral sterno-clavicular desarticulation on 15 adult cadaveric subjects preserved by method of Winckler we removed the sterno-costal drill plate as well as the ventral rib arch and proceeded to a mediastinal evisceration of the thorax. Then we respected only the thoracic aorta and the oesophagus, the azygos venous system, the thoracic duct and the thoracic sympathetic chain. In some of the subjects, the azygos vein was injected (after catheterization of its stick) using gelatine coloured with blue paint. We studied the way and vascular relations of the right gsn. We measured the transverse distances between the origin of the gsn on one hand and the longitudinal axes of the azygos vein and the thoracic duct on the other hand.

RESULTS

The relations of the right gsn trunk during its way related to the azygos vein in particular its constitutive origin and its affluents: ascending lumbar vein and twelfth intercostal vein. Sometimes the thoracic duct even a lymphatic node was near the gsn in the posterior infra-mediastinal space. A classification of the way and vascular relations of the right gsn in the thorax identified 3 anatomical types. The average distances separating the right gsn on one hand from the azygos vein and the thoracic duct on the other hand were respectively 5.7 mm and 11.2 mm.

CONCLUSION

The vascular relations of the right gsn are very variable from one subject to another but primarily venous, sometimes lymphatic. They concerned the great thoracic vessels whose respect is essential in particular at the time of mini-invasive access procedure for a cœlioscopic splanchnicectomy.

Evolution of slipped capital femoral epiphysis after in situ screw fixation at a mean 11 years' follow-up: a 222 case series

INTRODUCTION

Slipped capital femoral epiphysis (SCFE) can lead to hip impingement, more or less rapidly depending on initial slippage severity and on surgical technique. Various surgical options are applicable, including in situ fixation (ISF). The aim of the present study was to look for long-term signs of radiological impingement in hips treated for SCFE by IFS, in order to identify a slip threshold beyond which impingement more regularly appears.

MATERIAL AND METHODS

A multicenter retrospective study assessed the clinical and radiological evolution of patients operated on by ISF for SCFE, with a minimum 10 year's follow-up. Coxometric analysis of postoperative and last follow-up radiographs was performed. Functional outcome was assessed on Oxford hip score and radiographic osteoarthritis on the Tönnis classification. Alpha angle was measured on lateral views to highlight hip impingement.

RESULTS

Two hundred and twenty-two hips were included, with a mean 11.2 years' follow-up. Mean age at diagnosis was 12.8 years. Mean preoperative Southwick angle was 38.8°, with 43% of hips at stage I, 42% at stage II and 15% at stage III. At latest follow-up, mean Oxford score was 14.86, with 88% of hips rated Tönnis 0 or I. Only 15 cases of impingement were diagnosed. There seemed to be a non-significant trend for hip impingement in SCFE exceeding 35°.

CONCLUSION

ISF led to hip impingement in moderate to severe initial epiphyseal displacement. However, in smaller displacement, the consequences were milder, with perfectly satisfactory function scores and no clinical or radiological evidence of impingement. The threshold seemed to be around 35° slippage, beyond which other surgical options than ISF should be considered. Thus, it seems reasonable to propose isolated ISF in SCFE<35° and to treat symptomatic impingement by surgery in stage II slips.

[New recommendations for the management of children after minor head trauma]

Minor head trauma is a common cause for pediatric emergency department visits. In 2009, the Pediatric Emergency Care Applied Research Network (PECARN) published a clinical prediction rule for identifying children at very low risk of clinically important traumatic brain injuries (ciTBI) and for reducing CT use because of malignancy induced by ionizing radiation. The prediction rule for ciTBI was derived and validated on 42,412 children in a prospective cohort study. The Société Française de Médecine d'Urgence (French Emergency Medicine Society) and the Groupe Francophone de Réanimation et Urgences Pédiatriques (French-Language Pediatric Emergency Care Group) recommend this algorithm for the management of children after minor head trauma. Based on clinical variables (history, symptoms, and physical examination findings), the algorithm assists in medical decision-making: CT scan, hospitalization for observation or discharge, according to three levels of ciTBI risk (high, intermediate, or low risk). The prediction rule sensitivity for children younger than 2 years is 100 % [86.3-100] and for those aged 2 years and older it is 96.8 % [89-99.6]. Our aim is to present these new recommendations for the management of children after minor head trauma.

Scapulo-humeral arthrodesis using a pedicled scapular pillar graft following resection of the proximal humerus

BACKGROUND

Scapulo-humeral arthrodesis (SHA) is a proven reconstruction method in patients with proximal humerus malignancies requiring resection of the shoulder abduction apparatus (rotator cuff and deltoid muscles) or its nerve supply. Standard practice consists in using a pedicled fibular flap. We use instead a pedicled autologous bone graft harvested from the ipsilateral scapular pillar.

HYPOTHESIS

The objective of this study was to assess functional outcomes and radiological healing after SHA using a pedicled scapular pillar graft.

MATERIALS AND METHODS

We retrospectively reviewed the charts of the 12 patients managed at a single center by a single surgeon between 1994 and 2011. SHA was performed using a vascularised ipsilateral scapular pillar graft after proximal humerus resection to treat a bone malignancy. The graft was harvested from the ipsilateral scapular pillar, pedicled on the circumflex scapular artery, fitted into the remaining proximal humerus, and secured to the glenoid using screws. A humerus-scapular spine plate was added to stabilize the arthrodesis. Radiographic results were assessed on standard radiographs obtained at last follow-up. Functional outcomes were evaluated using the MusculoSkeletalTumour Society (MSTS) score and Toronto Extremity Salvage Score (TESS).

RESULTS

After a mean follow-up of 4.9 years, 87.5% of SHA junctions were healed, mean MSTS score was 71%, and mean TESS score was 70%.

DISCUSSION

The outcomes in our patients were similar to those reported after SHA using a pedicled fibular flap. However, our technique does not require microsurgery. It is simple, reproducible, and effective. Its indications of choice are intra- or extra-articular resection of the proximal humerus including the attachments of the rotator cuff and deltoid muscle tendons or the nerves supplying these muscles.

LEVEL OF EVIDENCE

Level IV (retrospective study).

Arterial supply to the tibial tuberosity: involvement in patellar ligament transfer in children

PURPOSE

The aims were to study arterial blood supply of the tibial tuberosity, and to evaluate its remaining blood supply after patellar ligament transposition in children.

METHODS

The anatomic study was carried out on 15 lower limbs after latex injection, and on two fetuses after diaphanization.

RESULTS

Tibial tuberosity was vascularized by an arterial network mainly supplied by anterior tibial recurrent artery. Other arteries from the popliteal artery or its branches were also involved in the tibial tuberosity blood supply.

CONCLUSIONS

Our findings confirm the safety of transposition of patellar ligament in children due to dense arterial network supplying tibial tuberosity.

[The common celiacomesenteric trunk: about one case]

The discovery of a coeliacomesenteric trunk is often fortuitous in a context of morphological or vascular exploration. About one case of this rare arterial remind us of its characteristic and different type. We emphasize the interest of not being unaware of this variation in radiological practice and vascular pathology. In our observation, the coeliacomesenteric trunk's ostium is oval with a tall axis of 14 mm; its route of 8mm is median and its arterial ending divide into hepatosplenogastric trunk and superior mesenteric trunk. It is a type I coeliacomesenteric trunk which is the most frequent type of this arterial variation in Higashi's classification.

[Use of muscle free flaps in lower limbs reconstruction in children]

A series of 12 muscle free flaps was performed from 2000 to 2005 in 11 children 3 to 15 years of age (mean: 10.6): seven serratus anterior, four latissimus dorsi and one rectus abdominis. The defects (acute or as a result of sequelae) were always located in lower limbs: seven in feet, three in the lower third of the leg and one in the knee. None of the children was re-operated within 72 hours. Total necrosis due to venous thrombosis occurred at Day 5 in one case. After mean follow-up of 2.5 years (minimum: 1 year), the flaps show good integration. Functional or esthetic sequelae are considered acceptable by the health-care team as well as the children's parents. No repercussions on growth have been observed. Our series confirms the results of previous studies, indicating that free flaps should be part of the therapeutic arsenal in pediatric surgery.

Internal hernias: anatomical basis and clinical relevance

The aim of this study was to present and discuss the anatomical basis of internal hernias thanks to our clinical experience of 14 cases. Internal hernias are uncommon cases of acute intestinal obstruction when a viscera protrudes through an intraperitoneal orifice, remaining inside the peritoneal cavity. It excludes iatrogenic post surgical hernias. From an anatomical point of view, three kinds of orifices may be interested. The orifice may be normal: epiploic or omental (Winslow's) foramen, or abnormal through a pathologic transomental hole realizing an internal prolapsus or procidentia, without sac. Or this orifice may be a paranormal peritoneal fossa (para duodenal or retrocaecal) acting as a trap for the bowel: these hernias possess a sac and are considered as true hernias. The clinical diagnosis is always difficult. CT scan can be useful confirming the obstruction and leads to an urgent operation. This retrospective study evaluates diagnosis, management and follow-up according to the type of anatomical orifice and delay of surgery.

A comparison of bone strain measurements at anatomically relevant sites using surface gauges versus strain gauged bone staples

Instrumented bone staples were first introduced as an alternative to surface-mounted strain gauges for use in human in vivo bone strain measurements because their fixation to bone is secure and requires not only minimally invasive surgery. Bench-top bone bending models have shown that the output from strain gauged bone staples compares favorably to that of traditional mounted gauges. However their within- and across-subject performance at sites typically instrumented in vivo has never been examined. This study used seven human cadaver lower extremities with an age range of 23-81 years old and a dynamic gait simulator to examine and compare axial strains in the mid tibial diaphysis and on the dorsal surface of the second metatarsal as measured simultaneously with strain gauged bone staples and with traditional surface-mounted gauges. Rosette configurations were used at the tibial site for deriving principal compression and tension, and shear strains. Axial outputs from the two gauge types demonstrated strong linear relationships for the tibia (r(2)=0.78-0.94) and the second metatarsal (r(2)=0.96-0.99), but coefficients (slopes) for the relationship were variable (range 7-20), across subjects and across sites. The apparent low reliability of strain gauged staples may be explained by the fact that both strain gauged staples and surface strain gauges are inexact to some degree, do not measure strains from exactly the same areas and strain gauged staples reflect surface strains as well as deformations within the cortex. There were no relationships for the principal tibia compression, tension or shear strain measurements derived from the two rosette gauge types, reflecting the very different anatomical areas measured by each of the constructs in this study. Strain gauged bone staples may be most useful in comparing relative axial intra-subject differences between activities, but inter-subject variability may require larger sample sizes to detect differences between populations.

Metatarsal strains are sufficient to cause fatigue fracture during cyclic overloading

Human in vivo tibial strains during vigorous walking have not been found to exceed 1200 microstrains. These values are below those found in ex vivo studies (>3000 microstrains) to cause cortical bone fatigue failure, suggesting that an intermediate bone remodeling response may be associated with tibial stress fractures. Metatarsal stress fractures, however, often develop before there is time for such a response to occur. Simultaneous in vivo axial strains were measured at the mid diaphysis of the second metatarsal and the tibia in two subjects. Peak axial metatarsal compression strains and strain rates were significantly higher than those of the tibia during treadmill walking and jogging both barefoot and with running shoes and during simple calisthenics. During barefoot treadmill walking metatarsal compression strains were greater than 2500 microstrains. During one- and two-leg vertical jumps and broad jumping, both metatarsal compression and tension strains were >3000 microstrains. Compression and tension strains in the metatarsus unlike those of the tibia may be sufficiently high even during moderate exertional activities to cause fatigue failure of bone secondary to the number of loading cycles without an intermediate bone remodeling response.

Double common bile duct with ectopic drainage into the stomach. Case report and review of the literature

A rare abnormal biliary tract consisting in a double common bile duct with an ectopic biliary tree draining into the stomach is described. This congenital anomaly, associated with lithiasis in the ectopic duct, was detected for the first time on MR-cholangiopancreatography. Only 23 cases of abnormal biliary drainage into the stomach have been reported in the literature. Embryogenesis and potential risks, such as lithiasis in the ectopic duct and the development of gastric carcinoma, are discussed.

Towards multiporphyrinic alpha-helices with a polypeptidic backbone as system endowed with light harvesting capabilities

Starting from a porphyrin functionalized derivative of the L-lysine, three peptides, bearing, respectively, two, four, and eight chromophores, were synthesized using an iterative synthetic strategy based on the choice of mild conditions for the deprotection steps.

Interruption of the inferior vena cava with azygos termination associated with congenital absence of portal vein

The authors report an exceptional and well-documented case of interruption of the retrohepatic segment of the inferior vena cava with an "azygos continuation", combined with absence of the portal vein. The only known combination of congenital anomalies of the inferior vena cava and the portal vein was that of an "azygos continuation" and a preduodenal portal vein. The double interruption, portal and inferior caval, may be associated with a disturbance of preferential flows induced by the left umbilical thrust. According to hemodynamic theory, the left umbilical flow is the determining factor in organogenesis of the portal vein and the retrohepatic segment of the inferior vena cava.

A comparison of diagnostic methods for the detection of bovine respiratory syncytial virus in experimental clinical specimens

Virus shedding was monitored in nasal secretions of 12 calves experimentally infected with bovine respiratory syncytial virus (BRSV) using an antigen capture enzyme-linked immunosorbent assay (ELISA) detecting the nucleoprotein (NP) antigen of BRSV, by a polymerase chain reaction (PCR) amplifying the fusion protein of BRSV, and by a microisolation assay combined with immunoperoxidase staining for the F protein of BRSV. Under the conditions of this study, similar limits of detection and quantitative results were obtained from all three assays. BRSV was detected in nasal secretions of all calves for a minimum of 4 d. Virus shedding began on Day 2 after infection, peaked on Days 3-5, and was cleared in most calves by Day 8. The PCR, and to a lesser extent the ELISA, may detect virus shedding for a longer period after infection than virus isolation, possibly due to neutralization of the virus by rising mucosal antibody. Simulated environmental conditions likely to be experienced during transport of clinical field specimens markedly reduced the sensitivity of virus isolation but had a minimal effect on the results of the NP ELISA. Actual field transport conditions (overnight on ice) had minimal apparent effect on the results of the PCR assay. The less stringent specimen handling requirements, combined with low limits of detection, of both the nucleoprotein ELISA and PCR, indicate either of these assays are more suitable for diagnostic applications than virus isolation.

Biomechanics of the hip joint and the effects of fracture of the acetabulum

The biomechanical analysis of the normal and arthritic hip joint have been the subject of numerous publications in orthopaedics. Biomechanical investigations focusing on the effect of fractures of the acetabulum on the alteration of hip joint mechanics have been a recent development. This paper outlines currently available methodologies for simulating load across the hip, and as measuring articular contact and contact stresses. Results of investigations of posterior wall fractures and transverse fractures of the acetabulum are presented. Directions for future research in the area of mechanical investigations of acetabular fractures are discussed.

Detection and characterization of porcine circovirus associated with postweaning multisystemic wasting syndrome in pigs

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