A three-arm single blind randomised control trial of naïve medical students performing a shoulder joint clinical examination

BACKGROUND

Technological advances have previously been hailed as a new dawn in Higher Education, with the advent of 'massive open online courses' (MOOCs) and online learning. Virtual platforms have potential advantages such as accessibility and availability but simply transferring educational material to the online environment may not ensure high quality learning. Clinical examination is a fundamental principle of medical assessment, and this study aimed to assess the role of technology in teaching these skills.

AIMS/OBJECTIVES

To determine whether three teaching modalities were of equal efficacy in teaching examination of the shoulder joint to naïve medical students.

METHODS

Sixty-seven pre-clinical medical students naïve to large joint examination were recruited. Participants completed a learning style questionnaire and were then block randomised to three study: textbook study, face-to-face seminar, or video tutorial via online platform. The same examination technique was taught in all groups, with the intervention being the method of delivery All second year students were eligible for inclusion. The single exclusion criteria was previous exposure to clinical examination teaching. Students were assessed using a standardised scoring system at baseline (pre-intervention), and days 5 and 19 post-intervention (maximum score 30). Assessors were blinded to group allocation. The primary outcome was assessment score at day 5 post intervention.

RESULTS

There was no difference between the three groups at baseline assessment (mean scores 2.4 for textbook, 2.8 for face-to-face, and 3.1 for video; p = 0.267). Mean post-intervention scores were 16.5 textbook, 25.5 face-to-face, and 22.4 video (p < 0.001, η2 = .449). There was no change between day 5 and day 19 post-intervention assessment scores in any group (p = 0.373), Preferred learning style did not affect scores (p = 0.543).

CONCLUSION

Face-to-face teaching was the most effective method for teaching clinical examination of the shoulder. Technology can potentially increase accessibility and remove geographic barriers, but is not as effective if teaching techniques are simply mirrored in an online format. Online platforms allow in depth data analysis of how learners interact with educational material and this may have value in improving the design of online educational materials, and is a potential area for further research.

Estimated cumulative X-ray exposure and additional cancer risk during the evaluation and treatment of scoliosis in children and young people requiring surgery

INTRODUCTION

Clinicians and patients must weigh the benefits of radiological imaging against the risks of radiation exposure in the diagnosis and treatment of scoliosis. This report aims to estimate the cumulative absorbed and equivalent dose of radiation in patients undergoing surgical treatment for scoliosis, and to present this as an estimated risk of cancer compared to background radiation levels.

METHODS

Retrospective review of estimated absorbed dose on the Computerised Radiology Information System (CRIS^®). Patients undergoing surgical correction of scoliosis (age ≤ 25) from August 2010 to August 2015 investigated. Estimated absorbed dose [milligrays (mGy)] recorded. Pedicle screws inserted using image intensification. Equivalent dose [millisieverts (mSv)] and additional cancer risk calculated from the National Research Council document 'Health risks from exposure to low levels of ionising radiation' (2006).

RESULTS

271 patients identified. Mean age 15 (range 2-25). Mean total absorbed dose 2136 mGy [standard deviation (SD) 1700 mGy]. Mean number of plain spine radiographs was 8 (SD 3) with total 1884 mGy exposure (SD 1609 mGy). Additional dose provided by CT (mean 0.17 episodes), plain chest and abdominal radiographs and image intensification. Mean number of image intensification episodes was 1.1 with mean estimated exposure 180 mGy (SD 238 mGy). Image intensification accounted for 8% of the estimated absorbed dose during treatment. Estimated mean effective dose delivered was 20.952 mSv equating to an additional cancer risk of 0.27-0.45%.

CONCLUSION

Additional cancer risk from cumulative imaging is small and equivalent to approximately 8 years of natural background radiation. Use of image intensification for pedicle screw insertion is a minor contribution (8%) to the total patient dose.

Diagnosis and treatment of confirmed and suspected primary hyperparathyroidism in equids: 17 cases (1999-2016)

BACKGROUND

Primary hyperparathyroidism is uncommon in equids.

OBJECTIVES

To describe the diagnostic findings and efficacy of treatment in equids with primary hyperparathyroidism.

STUDY DESIGN

Retrospective case series describing 16 horses and one mule.

METHODS

Cases were identified by retrospective review of records at Cornell University and via an ACVIM listserv query. Inclusion criteria were an equid with hypercalcemia, normal renal function and high parathyroid hormone (PTH) or histopathological diagnosis of a parathyroid adenoma. Equids with normal PTH and PTH-related protein (PTHrP) in the face of hypercalcemia were included as suspect cases.

RESULTS

The most common presenting complaints were weight loss (12/17) and hypercalcemia (10/17). PTH was above reference range in 12/17 cases. Suspected parathyroid tumours were localised in 12/14 equids imaged using ultrasonography alone (2/3), technetium 99m Tc sestamibi scintigraphy alone (1/1) or both modalities (9/10). Three horses did not have imaging performed. Surgical exploration successfully excised tumours in six of 10 cases. Five were located at the thoracic inlet, and surgery resulted in complete cure. One tumour was excised from the thyroid lobe, and the horse remained hypercalcemic. Four other cases explored surgically, four treated medically and three that were not treated also remained hypercalcemic.

MAIN LIMITATIONS

The small study size prohibited statistical analysis.

CONCLUSIONS

Parathyroid adenomas in equids can be successfully localised with ultrasonography and scintigraphy. Surgical excision appears more likely to be successful for single gland disease at the thoracic inlet.

Evaluation of digital cryotherapy using a commercially available sleeve style ice boot in healthy horses and horses receiving i.v. endotoxin

BACKGROUND

Continuous digital cryotherapy experimentally prevents development and reduces severity of sepsis-associated laminitis. A sleeve style ice boot where ice is in direct contact with the skin, and water drains from the boot is being used clinically for distal limb cryotherapy. The degree of cooling achieved by this boot is unknown.

OBJECTIVES

Evaluate skin and lamellar cooling after application of the ice sleeve in healthy horses, and the same horses during an endotoxaemia model.

STUDY DESIGN

Prospective study, crossover design.

METHODS

In eight healthy horses thermocouples were inserted into dorsal lamellae of both front feet, and under skin on both metacarpi. One forelimb received cryotherapy using sleeve style ice boot, with contralateral limb as control. Temperature was recorded on data logging devices at 5 min intervals during each cryotherapy session. Day 1: temperature data was collected for healthy horses. Day 2: data was collected for the same horses during i.v. administration of endotoxin.

RESULTS

In healthy and endotoxaemic horses, the sleeve style ice boot significantly decreased mean skin (7.2°C and 5.8°C respectively) and lamellar (10.8°C and 9.6°C respectively) temperatures compared with control limbs (P<0.001). Skin and lamellar temperatures in endotoxaemic horses undergoing cryotherapy were significantly colder than in healthy horses (P = 0.01).

MAIN LIMITATIONS

Order of treatment not randomised.

CONCLUSIONS

The boot caused significant decreases in lamellar temperatures compared with untreated control limbs in all horses. Endotoxaemic horses had significantly colder lamellae and skin than healthy horses. This study is the first to show that a sleeve style boot, where ice does not cover the hoof, can cause significant decreases in lamellar temperatures through cooling of blood as it travels to the foot.

Operating list composition and surgical performance

BACKGROUND

Recent reviews suggest that the way in which surgeons prepare for a procedure (warm up) can affect performance. Operating lists present a natural experiment to explore this phenomenon. The aim was to use a routinely collected large data set on surgical procedures to understand the relationship between case list order and operative performance.

METHOD

Theatre lists involving the 35 procedures performed most frequently by senior surgeons across 38 private hospitals in the UK over 26 months were examined. A linear mixed-effects model and matched analysis were used to estimate the impact of list order and the cost of switching between procedures on a list while controlling for key prognosticators. The influence of procedure method (open versus minimally invasive) and complexity was also explored.

RESULTS

The linear mixed-effects model included 255 757 procedures, and the matched analysis 48 632 pairs of procedures. Repeating the same procedure in a list resulted in an overall time saving of 0·98 per cent for each increase in list position. Switching between procedures increased the duration by an average of 6·48 per cent. The overall reduction in operating time from completing the second procedure straight after the first was 6·18 per cent. This pattern of results was consistent across procedure method and complexity.

CONCLUSION

There is a robust relationship between operating list composition and surgical performance (indexed by duration of operation). An evidence-based approach to structuring a theatre list could reduce the total operating time.

Survival Time of Cross-Match Incompatible Red Blood Cells in Adult Horses

Background

There is a markedly reduced half‐life of transfused RBCs when donor and recipient cats or humans are cross‐match incompatible. Only 10–20% of horses have naturally occurring alloantibodies. Therefore, cross‐match testing before blood transfusion is not always performed.

Hypothesis

Cross‐match incompatibility predicts shortened RBC survival time as compared to that of compatible or autologous blood.

Animals

Twenty healthy adult horses.

Methods

Prospective trial. Blood type, anti‐RBC antibody screen (before and 1 month after transfusion) and major and minor cross‐match determined 10 donor‐recipient pairs. Two pairs were cross‐match compatible, the remainder incompatible. Donor blood (4 L) was collected into citrate phosphate dextrose adenine‐1, labeled with NHS‐biotin, and transfused into recipients. Samples were collected at 1 hour and 1, 2, 3, 5, 7, 14, 21, 28, and 35 days after transfusion, and biotinylated RBCs were detected by flow cytometry. Horses were monitored for transfusion reaction during transfusion and daily for 5 days.

Results

Cross‐match incompatibility was significantly associated with decreased RBC survival time (P < .001). The half‐life of transfused incompatible (cross‐match >1+) allogenic equine RBCs was 4.7 (95% CI, 3.2–6.2) days versus 33.5 (24–43) days for compatible pairings. Cross‐match incompatibility was associated with acute febrile transfusion reaction (P = .0083). At day 30, only 1 horse had developed novel anti‐RBC antibodies.

Conclusions and Clinical Importance

Cross‐match incompatibility was predictive of febrile transfusion reaction and shortened transfused RBC survival, but did not result in production of anti‐RBC antibodies at 30 days. Cross‐match testing before transfusion is recommended.

The Association of Fibrinous Pleural Effusion with Survival and Complications in Horses with Pleuropneumonia (2002-2012): 74 Cases

BACKGROUND

Fibrinous parapneumonic pleural effusions are associated with decreased efficacy of pleural fluid drainage and increased risk of medical treatment failure in people, but similar associations have not been established in horses.

HYPOTHESIS/OBJECTIVES

We hypothesized that fibrin deposition in the pleural cavity of horses with parapneumonic effusions increases the risk of poor outcome.

ANIMALS

Seventy four horses with bacterial pleuropneumonia diagnosed by culture and cytology of tracheal aspirates, pleural fluid, or both, and pleural effusion diagnosed by ultrasonographic examination.

METHODS

Retrospective study of cases was from 2002 to 2012. Information obtained from the medical records included signalment, history, sonographic findings, treatments, and outcome. The primary outcome investigated was survival and secondary outcomes were development of complications and surgical intervention. Fisher's exact test and logistic regression were applied for categorical variables. A t-test was used to find differences in continuous variables between groups.

RESULTS

Seventy four horses met study criteria and 50 (68%) survived. Fibrinous pleural effusion was associated with higher respiratory rate and pleural fluid height at admission, necrotizing pneumonia, increased number of indwelling thoracic drains required for treatment, and decreased survival.

CONCLUSIONS AND CLINICAL IMPORTANCE

Fibrin accumulation in parapneumonic effusions is associated with increased mortality. Direct fibrinolytic treatment might be indicated in affected horses.

The Use of Recombinant Tissue Plasminogen Activator (rTPA) in The Treatment of Fibrinous Pleuropneumonia in Horses: 25 Cases (2007-2012)

Background

Information about treatment protocols, adverse effects and outcomes with intrapleural recombinant tissue plasminogen activator (rTPA) use in horses with fibrinous pleuropneumonia is limited.

Hypothesis/Objectives

Describe factors that contribute to clinical response and survival of horses treated with rTPA intrapleurally.

Animals

Horses with bacterial pneumonia and fibrinous pleural effusion diagnosed by ultrasonography, that were treated with rTPA intrapleurally.

Methods

Retrospective multicenter case series from 2007–2012. Signalment, history, clinical and laboratory evaluation, treatment, and outcome obtained from medical records. Regression analysis used to identify associations between treatments and outcomes.

Results

Thirty three hemithoraces were treated in 25 horses, with 55 separate treatments. Recombinant tissue plasminogen activator (375–20,000 μg/hemithorax) was administered 1–4 times. Sonographically visible reduction in fibrin mat thickness, loculations, fluid depth, or some combination of these was seen in 32/49 (65%) treatments. Response to at least 1 treatment was seen in 17/20 (85%) horses with sonographic follow‐up evaluation after every treatment. Earlier onset of rTPA treatment associated with increased survival odds. No association was found between cumulative rTPA dose or number of rTPA doses and survival, development of complications, duration of hospitalization or total charges. Clinical evidence of hypocoagulability or bleeding was not observed. Eighteen horses (72%) survived to discharge.

Conclusions and clinical importance

Treatment with rTPA appeared safe and resulted in variable changes in fibrin quantity and organization within the pleural space. Recombinant tissue plasminogen activator could be a useful adjunct to standard treatment of fibrinous pleuropneumonia, but optimal case selection and dosing regimen remain to be elucidated.

Treatment of idiopathic headshaking in horses with pulsed high-dose dexamethasone

BACKGROUND

Treatment of idiopathic headshaking in horses is complicated by an incomplete understanding of underlying pathophysiology and partially effective treatments. If an inflammatory etiology exists, corticosteroids could be beneficial.

HYPOTHESIS

An anti-inflammatory dose of dexamethasone reduces the signs of idiopathic headshaking in a field setting.

ANIMALS

Convenience sample of 20 adult horses with idiopathic headshaking syndrome. Cases were recruited from the general population and diagnosed by attending veterinarians.

METHODS

Prospective, blinded clinical trial. Pulsed dosing was with oral dexamethasone (60 mg PO Q24h × 4 days, q3 weeks for 4 months) or placebo (inert paste). Owners were blinded and asked to score the headshaking from 0 to 4 (4 = most severe) 3 days per week. The change in headshaking scores (HS) over each treatment pulse was compared between groups by ordinal logistic regression.

RESULTS

Twelve horses completed the trial. There was no significant difference between treated or placebo horses (P = .987). Sun (P ≤ .001), wind (P = .028), and exercise (P ≤ .045) significantly increased HS.

CONCLUSIONS AND CLINICAL IMPORTANCE

No benefit of dexamethasone treatment was detected for idiopathic headshaking. The results confirmed previous reports of common triggers for headshaking behavior

Effects of cyclooxygenase inhibitors flunixin and deracoxib on permeability of ischaemic-injured equine jejunum

REASONS FOR PERFORMING STUDY

Recent studies have shown that flunixin prevented recovery of equine jejunum post ischaemia. However, the use of a purported cyclooxygenase (COX)-2 preferential inhibitor, etodolac, also prevented recovery. These findings may have implications for the use of nonsteroidal anti-inflammatory drugs in colic patients.

OBJECTIVE

To compare the effects of deracoxib, a highly selective canine COX-2 inhibitor, with flunixin on in vitro recovery of ischaemic-injured equine jejunum.

METHODS

Six horses underwent 2 h jejunal ischaemia, after which mucosa was mounted in Ussing chambers and recovered for 240 mins. Transepithelial electrical resistance (TER) and mucosal-to-serosal fluxes of 3H-mannitol were monitored as indices of barrier function in the presence of flunixin or deracoxib.

RESULTS

The TER of ischaemic-injured tissue recovered significantly over 240 mins in the presence of no treatment, but not in the presence of flunixin or deracoxib. In addition, flunixin-treated ischaemic jejunum was significantly more permeable to mannitol when compared with untreated tissue by the end of the recovery period, whereas deracoxib treatment did not increase permeability. Addition of the PGE1 analogue misoprostol to flunixin-treated tissue restored recovery of TER.

CONCLUSIONS AND POTENTIAL RELEVANCE

Treatment of horses with ischaemic jejunal disease with flunixin may result in a prolonged permeability defect in recovering mucosa. Addition of misoprostol or replacement of flunixin with deracoxib may ameliorate effects of COX inhibitors on recovering mucosa.

Temporary ectopic implantation of digits prior to reconstruction of a hand without metacarpals

Temporary ectopic implantation has been described for a variety of injuries, with several different implantation sites used. Although varied results have been achieved, many feel this technique has a role to play under special circumstances. We describe the ectopic implantation of digits to the contralateral forearm, with subsequent reconstruction of the injured hand when combined with microvascular toe transfer. The outcome was a functionally useful hand which could be incorporated into daily life, and a cosmetic appearance preferable to that of amputation. We feel ectopic implantation still has a valuable role to play in carefully selected cases.

Post operative neutrophilic inflammation in equine small intestine after manipulation and ischaemia

REASONS FOR PERFORMING STUDY

Post operative ileus (POI) remains an important cause of post operative morbidity and mortality in the horse. However, clinical progression of naturally occurring cases of POI in both horse and man does not entirely support the 'neurogenic' hypothesis as the sole mechanism of POI; and the hypothesis that inflammation plays a major role at 12-24 h after surgery requires validation.

HYPOTHESIS

An inflammatory infiltrate in the muscularis externa and myenteric plexus of equine jejunum is present 18 h following a period of ischaemia.

METHODS

Samples of normal jejunum, jejunum from the proximal resection margins of clinical cases and jejunum obtained 18 h after 1 or 2 h ischaemia or manipulation alone were evaluated for neutrophil infiltration. Samples obtained 18 h after surgery were additionally evaluated for leucocyte activation using calprotectin immunohistochemistry. Results were evaluated by ANOVA and P < 0.05 was considered significant.

RESULTS

Significant neutrophilic inflammation was identified in the samples from the proximal resection margins of clinical cases compared to uninjured jejunum. In experimental cases, neutrophilic inflammation appeared to be increased further by 18 h and was identified through all intestinal layers, particularly in the serosa, fascial planes around circular and longitudinal muscle fibres, and myenteric plexus. This elevated level of neutrophilic inflammation was mirrored by an increased number of calprotectin-positive cells in these intestinal layers, indicating leucocyte activation.

CONCLUSIONS

Significant neutrophilic inflammation occurs in equine jejunal myenteric layers 18 h after surgery.

POTENTIAL RELEVANCE

This neutrophilic inflammation coincides with the clinical time point at which POI is identified and may indicate that inflammatory pathways, rather than solely neurogenic pathways, are responsible for POI in the horse.

Ultrasonographic abnormalities detected in the sacroiliac area in twenty cases of upper hindlimb lameness

REASONS FOR PERFORMING STUDY

The pelvis is covered with extensive musculature and often presents a challenge in diagnostic imaging. Ultrasonography provides diagnostic information about soft tissue, articular cartilage and bone surfaces, although little information exists about the normal ultrasonographic appearance of the equine sacroiliac region.

OBJECTIVES

To determine the clinical applicability of ultrasonographic examination in horses with sacroiliac pain.

METHODS

Horses presented to the University of Minnesota Veterinary Teaching Hospital for hindlimb lameness were evaluated and lower limb lameness was ruled out with examination and local anaesthesia. Twenty cases were diagnosed with sacroiliac pain, characterised by response to palpation over the tuber sacrale. Seven of the 20 had visible asymmetry of the tuber sacrale. Ultrasonography was performed percutaneously and per rectum. Structures imaged were measured and compared to normal reference measurements. Other methods used to confirm diagnoses included thermography, scintigraphy and radiology.

RESULTS

All 20 cases with sacroiliac pain showed ultrasonographic abnormalities of the sacroiliac area. Abnormalities were detected in the dorsal sacroiliac ligaments. Ligament size was significantly different from the normal ranges (P < 0.01). Malalignment of the sacroiliac area and sacral fractures were also imaged.

CONCLUSIONS

Ultrasonography of the sacroiliac region aided diagnosis of ligament damage and displacement of bone surfaces; and may aid in monitoring the progression of healing.

POTENTIAL RELEVANCE

Diagnostic ultrasound is readily available to most practitioners. Therefore the findings of this study show that diagnosis of sacroiliac injuries is possible in the field.

Application of industrial scale genomics to discovery of therapeutic targets in heart failure

In recent years intense activity in both academic and industrial sectors has provided a wealth of information on the human genome with an associated impressive increase in the number of novel gene sequences deposited in sequence data repositories and patent applications. This genomic industrial revolution has transformed the way in which drug target discovery is now approached. In this article we discuss how various differential gene expression (DGE) technologies are being utilized for cardiovascular disease (CVD) drug target discovery. Other approaches such as sequencing cDNA from cardiovascular derived tissues and cells coupled with bioinformatic sequence analysis are used with the aim of identifying novel gene sequences that may be exploited towards target discovery. Additional leverage from gene sequence information is obtained through identification of polymorphisms that may confer disease susceptibility and/or affect drug responsiveness. Pharmacogenomic studies are described wherein gene expression-based techniques are used to evaluate drug response and/or efficacy. Industrial-scale genomics supports and addresses not only novel target gene discovery but also the burgeoning issues in pharmaceutical and clinical cardiovascular medicine relative to polymorphic gene responses.

Detailed ultrasonographic mapping of the pelvis in clinically normal horses and ponies

OBJECTIVE

To map the equine pelvis using ultrasonography, validated by use of computed tomography (CT), magnetic resonance imaging (MRI), and measurements of frozen cadaver slices.

ANIMALS

6 ponies and 6 horses.

PROCEDURE

Ultrasonographic examination of the pelvis was performed on 6 clinically normal ponies. Measurements were obtained for imaged structures. Computed tomography, MRI, and measurements of frozen sections were performed after death and used to verify measurements. Linear regression determined the degree of correlation between measurements obtained ultrasonographically and the other modalities. Six clinically normal horses were then examined by use of ultrasonography. For each structure measured mean, SD, and range were calculated.

RESULTS

Data obtained from ponies revealed high correlations between ultrasonographic findings and those of CT, MRI, and frozen section measurements (r2 = 0.97, r2 = 0.99, and r2 = 0.99, respectively). Differences between structures measured on each side of the pelvis were not significant. Variation in size of structures was not associated with weight of horses. A correlation was not found between weight of horses and ponies and size of structure.

CONCLUSIONS AND CLINICAL RELEVANCE

Ultrasonography can be used to accurately measure and evaluate the musculoskeletal structures of the pelvis of horses. The use of CT, MRI, and measurements of frozen sections provided a means of validating the ultrasonographic measurements. Reference range values determined in our study can be used to evaluate horses with suspected pelvic disease.

Gene program for cardiac cell survival induced by transient ischemia in conscious pigs

Therapy for ischemic heart disease has been directed traditionally at limiting cell necrosis. We determined by genome profiling whether ischemic myocardium can trigger a genetic program promoting cardiac cell survival, which would be a novel and potentially equally important mechanism of salvage. Although cardiac genomics is usually performed in rodents, we used a swine model of ischemia/reperfusion followed by ventricular dysfunction (stunning), which more closely resembles clinical conditions. Gene expression profiles were compared by subtractive hybridization between ischemic and normal tissue of the same hearts. About one-third (23/74) of the nuclear-encoded genes that were up-regulated in ischemic myocardium participate in survival mechanisms (inhibition of apoptosis, cytoprotection, cell growth, and stimulation of translation). The specificity of this response was confirmed by Northern blot and quantitative PCR. Unexpectedly, this program also included genes not previously described in cardiomyocytes. Up-regulation of survival genes was more profound in subendocardium over subepicardium, reflecting that this response in stunned myocardium was proportional to the severity of the ischemic insult. Thus, in a swine model that recapitulates human heart disease, nonlethal ischemia activates a genomic program of cell survival that relates to the time course of myocardial stunning and differs transmurally in relation to ischemic stress, which induced the stunning. Understanding the genes up-regulated during myocardial stunning, including those not previously described in the heart, and developing strategies that activate this program may open new avenues for therapy in ischemic heart disease.

Percutaneous ultrasound-guided pyelography aided diagnosis of ectopic ureter and hydronephrosis in a 3-week-old filly

Ultrasound-guided percutaneous pyelography has previously been used in dogs to diagnose ectopic ureter. To the authors' knowledge its use has never been reported in the horse. This paper reports the technique used in a three-week-old filly with a suspected ectopic ureter. Pyelography can be performed under sedation and is a relatively simple, safe procedure. The technique enables assessment of individual renal function through collection and analysis of urine from each renal pelvis.

Ultrasonographic evaluation of tarsocrural joint cartilage in normal adult horses

Ultrasonographic examination of the tarsus was performed on four clinically and radiographically normal limbs of adult horses. Particular attention was paid to the articular cartilage surfaces of the trochlear ridges of the talus and the distal intermediate ridge of the tibia. Two separate measurements of articular cartilage thickness were acquired from a longitudinal view at each site. Anatomy was confirmed with post mortem dissection. Ultrasonography was found to be a practical method for imaging the articular cartilage over the trochlear ridges of the talus and distal intermediate ridge of the tibia. The cartilage appeared as a hypoechoic band overlying the hyperechoic subchondral bone. The mean cartilage thickness over the lateral and medial trochlear ridges of the talus and the distal intermediate ridge of the tibia were 0.57 mm, 0.58 mm and 0.7 mm respectively. These measurements may have value for comparison to thickened cartilage and lesions of osteochondrosis and abnormally thinned cartilage of osteoarthritis. Ultrasound examination was not helpful in evaluating the proximal and distal intertarsal and tarsometatarsal joints, the close proximity of the articular surfaces obscured visualization of the articular cartilage.

Endoscopic treatment of suspected infectious intertubercular bursitis in a horse

A 9-year-old gelding was evaluated because of a 30-day history of mild intermittent left forelimb lameness. The only detectable abnormality was mild atrophy of the musculature of the proximal portion of the left forelimb. The cause of the lameness could not be determined. The horse was discharged from the hospital, but was reexamined 6 weeks later because of worsening of the lameness. At that time, the horse resisted flexion and extension of the left shoulder joint, and results of evaluation of an ultrasound-guided aspirate of fluid from the intertubercular bursa were suggestive of infection. Endoscopic examination of the bicipital bursa revealed synovial hypertrophy, particularly in the distal aspect of the bursa. The bursa was lavaged, and a synovial resector was used to remove inflamed synovium. The horse recovered and was healthy 4 months later. In this horse, endoscopy allowed adequate examination of the intertubercular bursa and was not technically difficult.

Cloning, chromosomal mapping, and regulatory properties of the human type 9 adenylyl cyclase (ADCY9)

The type 9 adenylyl cyclase (AC9) is a widely distributed adenylyl cyclase that was originally cloned from a mouse cDNA library. Here we report the cloning, chromosomal mapping, and regulatory properties of human AC9 (HGMW-approved symbol ADCY9). Although the human AC9 sequence shows 86% homology with mouse AC9, divergence at the C2a/C2b junction results in an alternative C2b amino acid sequence. In situ hybridization localized the human AC9 gene to both human and mouse chromosomes 16. AC9 mRNA is present in all tissues examined, with the highest levels found in skeletal muscle, heart, and brain. To characterize the regulatory properties of human AC9 in vivo, the enzyme was expressed in HEK-293 cells. Human AC9 is stimulated by beta-adrenergic receptor activation but is insensitive to forskolin, Ca2+ and somatostatin. In contrast to mouse AC9, the activity of human AC9 is unaffected by inhibitors of calcineurin. These data emphasize the importance of determining the regulatory properties of human adenylyl cyclases.

Functional importance of platelet-derived growth factor (PDGF) receptor extracellular immunoglobulin-like domains. Identification of PDGF binding site and neutralizing monoclonal antibodies

The biological effects of platelet-derived growth factor (PDGF) are mediated by alpha- and beta-PDGF receptors (PDGFR), which have an intracellular tyrosine kinase domain and an extracellular region comprising five immunoglobulin-like domains (D1-D5). Using deletion mutagenesis we mapped the PDGF binding site in each PDGFR to the D2-D3 region. In the case of alpha-PDGFR, 125I-PDGF AA and 125I-PDGF BB bound to the full-length extracellular domain, D1-D5, and D2-D3 with equal affinity (Kd = 0.21-0.42 nM). Identical results were obtained for 125I-PDGF BB binding to beta-PDGFR mutants D1-D5 and D2-D3, establishing that D1, D4, and D5 do not contribute to PDGF binding. Monoclonal antibodies (mAb) directed against individual PDGFR Ig-like domains were used to extend these observations. The anti-D1 mAb 1E10E2 and anti-D5 mAb 2D4G10 had no effect on alpha- or beta-PDGFR function, respectively. In contrast, mAb 2H7C5 and 2A1E2 directed against D2 of the alpha- and beta-receptor, respectively, blocked PDGF binding, receptor autophosphorylation and mitogenic signaling with IC50 values of 0.1-3.0 nM. An anti-D4 mAb 1C7D5 blocked beta-receptor autophosphorylation and signaling without inhibiting PDGF binding consistent with the observation that D4 is essential for PDGFR dimerization (Omura, T., Heldin, C.-H., and Ostman, A. (1997) J. Biol. Chem. 272, 12676-12682). mAbs identified here act as potent PDGFR antagonists that can be used as research tools and potentially as therapeutic agents for the treatment of diseases involving unwanted PDGFR signaling.

Current techniques in total knee replacement: results of a national survey

A postal questionnaire was sent to all Fellows of the British Orthopaedic Association to obtain a census of total knee replacement (TKR) preferences in the United Kingdom; 1162 questionnaires were sent and 721 replies received. There were 92 Fellows who had retired or filled in the forms incorrectly, and 32 no longer perform TKR. Thus, 597 responded correctly, giving a 62% response rate. This gives an extrapolated total of 34,677 TKRs being implanted per year in the UK, with an average of 34.3 being performed by each surgeon per year. Only 9% perform more than 90 per year. There were 41 different prostheses in current use among the respondents to our questionnaire, of which five prostheses constituted 61% of the total. Cemented prostheses were used by 95.2%. Resurfacing of the patella was always carried out by 32%, while 19% never resurface it; the most common reason for doing so being patellofemoral arthropathy at operation. Intramedullary alignment was used for the femoral component in 86%, 76% preferred extramedullary alignment for the tibial component. Regarding cementing technique, 43% use pulsatile lavage, 9% used a cement gun, 88% dry the bone and 56% seal the hole made by the femoral alignment device in the femur before cementing. All components were cemented simultaneously by 65% and one at a time by 31%. Metal-backed tibial prostheses are now used by 98% of surgeons, modular tibial components being preferred by 80%. Metal-backed patellar components were used by 13%. An onlay type of patella was preferred by 51%. This survey highlights the great diversity of surgical practice in the UK, which may reflect uncertainty regarding best practice in total knee replacement.

Effect of gamma carboxylation on prothrombinase inhibitory activity of catalytically inactive factor XA

Recombinant catalytically inactive factor Xa (factor rXai) is capable of assembly into inactive prothrombinase complexes, thus serving as a competitive inhibitor (Ki = 0.3nM) of active factor Xa. In order to study the role of gamma carboxylation in prothrombinase complex assembly, we have prepared differentially gamma carboxylated factor rXai and have measured the activities of these proteins in prothrombinase complex inhibition and in extension of plasma clotting. A factor rXai preparation containing 8 out of a possible maximum of 11 g carboxyglutamic acid (GLA) residues was found to be as active as chemically inactivated plasma factor Xa which was fully gamma carboxylated. Loss of a single additional g carboxyglutamic acid in the recombinant protein, however lead to a marked loss in activity. Factor rXai preparation with 8 GLA residues is also detected by a monoclonal antibody specific for a GLA dependent epitope. Thus assembly of the factor Va/Xa complex on phospholipid membranes does not require the presence of all of the g carboxyglutamic acid residues present in the plasma protein.

Mechanism of platelet-derived growth factor (PDGF) AA, AB, and BB binding to alpha and beta PDGF receptor

The biological effects of platelet-derived growth factor (PDGF) are mediated by cell surface alpha and beta PDGF receptors, which, as a result of ligand binding, undergo dimerization in a manner consistent with PDGF being bivalent. In order to directly demonstrate PDGF bivalency and to define the binding of PDGF AB to isolated beta receptor, we developed solid-phase binding assays using purified recombinant extracellular domain of human PDGF receptors. PDGF AA, AB, and BB were prepared from the monomeric chains expressed in Escherichia coli, and each was purified to homogeneity; PDGF AB contained < 0.5% of either homodimer. The interactions of these isoforms with immobilized PDGF receptors were examined by several approaches. Scatchard analysis revealed high affinity binding (Kd = 0.5-1.0 nM) of radiolabeled PDGF AA and AB to alpha receptor and of PDGF BB to both receptor subtypes. Contrary to previous reports, PDGF AB also bound beta receptor with high affinity (Kd = 0.9 nM). When a B-chain-specific monoclonal antibody that recognizes the putative binding domain of PDGF BB was used for ligand detection, we found that PDGF AB binding to beta receptor occurred exclusively through the B-chain subunit, whereas binding to alpha receptor occurred through either subunit. In addition, site-directed mutagenesis was used to specifically inactivate the B chain of PDGF AB, which eliminated binding to the beta receptor without affecting alpha receptor binding. These results establish that PDGF is bivalent and that monovalent ligand retains high affinity receptor binding.

A novel monoclonal antibody dependent on domain 5 of the platelet-derived growth factor beta receptor inhibits ligand binding and receptor activation

Platelet derived growth factor (PDGF) induces activation of the protein tyrosine kinase domain of the PDGF receptor, resulting in receptor dimerization and the initiation of mitogenesis in responsive cells. In order to identify domains of the receptor involved in these processes, a panel of monoclonal antibodies (MAbs) against the extracellular region of the human PDGF receptor was developed and screened to identify which of these specifically block PDGF binding. One of these, MAb 2A1E2, binds PDGF beta receptor with high affinity and blocks PDGF BB binding in a whole cell binding assay with an IC 50 of 0.1 nM. Inhibition of binding results in the inhibition of ligand-induced receptor phosphorylation, dimerization and mitogenesis in cells expressing the PDGF beta receptor. MAb 2A1E2 has been mapped to the fifth Ig domain of the PDGF beta receptor, implying that this domain is important for ligand binding, dimerization and/or activation. The potency of MAb 2A1E2 for inhibiting PDGF BB binding indicates that this antibody is ideally suited to identify and characterize PDGF BB-induced biological responses.

Clinical diagnosis of tears of the rotator cuff

We have studied the reported clinical assessment of the presence and extent of a rotator cuff tear in 42 patients presenting to a special shoulder clinic. This pre-operative diagnosis was compared with the findings at operation. The clinical tests had a sensitivity of 91% and a specificity of 75%. It is important to exploit clinical examination before resorting to costly and sometimes harmful special investigations.

Apolipoprotein(a): expression and characterization of a recombinant form of the protein in mammalian cells

We have stably expressed a recombinant form of apo(a) in a human embryonic kidney cell line. The engineered protein (predicted mass of 250 kDa) contains 17 copies of the apo(a) domain, which resembles kringle 4 of plasminogen, followed by the plasminogen-like kringle 5 and protease-like domain of apo(a). The recombinant protein [r-apo(a)] was isolated from cell culture media by immunoaffinity chromatography, and its physical properties were studied. As is the case for apo(a) isolated from plasma-derived Lp(a), r-apo(a) is highly glycosylated (23% by weight), containing both N- and O-linked glycans, which results in an observed molecular mass of 500 kDa by SDS-PAGE. The high sialic acid content was reflected in a pI of 4.3 for the r-apo(a). Two subpopulations of r-apo(a) secreted by the permanent cell line were identified with respect to lysine-Sepharose binding; the majority of the r-apo(a) bound specifically to this matrix and was eluted with epsilon-aminocaproic acid (epsilon-ACA). When the r-apo(a) plasmid was used to transfect a human hepatoma cell line, lipoprotein particles were secreted containing the disulfide-linked complex of apoB-100 and the r-apo(a). The density of these particles was shown to be heterogeneous, with the majority of the r-Lp(a) floating in the density range of plasma-derived Lp(a).

Expression of human plasminogen cDNA in a baculovirus vector-infected insect cell system

A cDNA that encodes the human plasminogen (HPg) amino acid sequence has been inserted adjacent to the polyhedrin promoter in the genome of the baculovirus, Autographa californica nuclear polyhedrosis virus, which was then used to infect cultured cells of the farm armyworm, Spodoptera frugiperda. Under the conditions of cell growth employed, recombinant (rec)-HPg was secreted into the medium after 24 h postinfection (p.i.), at which point virtually no rec-HPg antigen remained inside the cells. At 48 h p.i., a maximal level of intact rec-HPg was present in the medium, which underwent substantial proteolytic digestion after that time. The rec-HPg produced by this expression system possessed a molecular weight equivalent to that of plasma [Glu1]-plasminogen. In addition, the rec-HPg adsorbed to Sepharose-lysine, and was eluted with epsilon-aminocaproic acid (EACA). The recombinant protein also interacted with polyclonal antibodies generated to plasma HPg, as well as with a monoclonal antibody directed against a distinct region (kringle 1-3) of the plasma HPg molecule. Finally, the insect-expressed rec-HPg was activatable to plasmin (HPm) by urokinase. The results demonstrate that this expression system produces a full-length functional single-chain rec-HPg, which can be isolated intact from the culture medium, with some consideration for the temporal events that occur in secretion and longer-term degradation of the protein. The fact that this rec-HPg was converted to HPm with a plasminogen activator, and that it interacted with anti-plasma HPg polyclonal and monoclonal antibodies, as well as with the ligand, EACA, indicates that the molecule retains many of its important functional properties and is folded in an integral manner.

Regulation of apolipoprotein E synthesis and mRNA by diet and hormones

Rats were fasted or fasted and refed simple purified diets so the effects of individual carbohydrates or fats could be studied. Freshly isolated hepatocytes from these animals were used to measure both apoE synthesis and mRNA levels so any changes in apoE synthesis that might occur without changes in its mRNA could be detected. Some of these experiments were done with both sexes. Both fasting and fasting and refeeding a 60% glucose fat-free diet significantly increased spoE synthesis. However, cyclic AMP is not likely to rapidly mediate the effect of fasting since dibutyryl cAMP slightly lowered (rather than increased) apoE synthesis and mRNA when injected into rats for 4.5 h. Dietary fat had no effect either in the absence of carbohydrate or when consumption of carbohydrate was constant in pair-fed rats. ApoE mRNA levels remained normal for 4 days in primary hepatocytes cultured in medium that had only amino acids as an energy source. Added hormones or fructose had no significant effect. Thus, only fasting and fasting and refeeding glucose were able to significantly change apoE synthesis or mRNA levels. Synthesis of apoE may be regulated to increase when apoE is secreted with very low density lipoprotein or when apoE in secreted high density lipoprotein is needed to acquire cholesteryl esters for the synthesis of bile salts and acids by liver.

Rhesus monkey apolipoprotein(a). Sequence, evolution, and sites of synthesis

Human lipoprotein(a) is a low density lipoprotein-like lipoprotein whose concentration in plasma is correlated with atherosclerosis. The characteristic protein component of lipoprotein(a) is apolipoprotein(a) (apo(a)) which is disulfide-linked to apolipoprotein B-100. Sequencing of rhesus monkey apo(a) cDNA suggests that this protein, like human apo(a), is highly similar to plasminogen. Sequence data suggests that a plasminogen-like protease activity and kringle 1-, 2-, 3-, and 5-like domains are unnecessary for apo(a) function, but a highly repeated kringle four-like domain is important. Liver is the major site of apo(a) RNA synthesis; reduced amounts of message were also found in testes and brain. Co-expression with apoB-100 and plasminogen in rhesus tissues is not mandatory.

The apolipoprotein(a) gene resides on human chromosome 6q26-27, in close proximity to the homologous gene for plasminogen

Apolipoprotein(a) [apo(a)], the glycoprotein associated with the lipoprotein(a) [Lp(a)] subfraction of plasma lipoproteins, has been shown to exhibit heritable molecular weight isoforms ranging from 400-700 kDa. Increased serum concentrations of Lp(a) correlate positively with the risk of atherosclerosis. Variations in Lp(a) plasma levels among individuals are inherited as a codominant quantitative trait. As part of an effect to define the basis of these variations and further clarify the expression of the protein, we have determined the chromosomal location of the human apo(a) gene. Blot hybridization analysis of DNA from a panel of mouse-human somatic cell hybrids with an apo(a) cDNA probe revealed a complex pattern of bands, all of which segregated with chromosome 6. In situ hybridization yielded a single peak of grain density located on chromosome 6q26-27. Apo(a) cDNA sequences exhibit striking homology to those of the plasma protease plasminogen, and, therefore, we have reexamined the chromosome assignment of the plasminogen gene. We conclude that both the apo(a) and plasminogen genes reside on human chromosome 6q22-27, consistent with a gene duplication mechanism for their evolutionary origin. The results are of significance for the genetic control of apo(a) expression and genetic influences predisposing to atherosclerosis.

Repression of pentose phosphate pathway dehydrogenase synthesis and mRNA by dietary fat in rats

We have studied the effects of polyunsaturated fatty acid and its metabolism on the activity, relative synthesis and mRNA levels for rat hepatic glucose-6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6PGD). Rats were meal-fed high carbohydrate diets containing either no fat, 5% safflower oil or 5% safflower oil + eicosa-5,8,11,14-tetraynoic acid (TYA). Hepatocytes were isolated and used as a source of RNA, de novo radiolabeled protein and postmitochondrial supernatant for enzyme assay. Dietary safflower oil, as a source of linoleic acid, repressed G6PD activity, synthesis and mRNA levels two- to threefold without significantly changing the amount of carbohydrate consumed. Similar but smaller changes were observed for 6PGD. Dietary fat + TYA (an analogue of arachidonate that inhibits normal metabolism of linoleic acid) prevented the fat-dependent lowering of G6PD and 6PGD activity, synthesis and mRNA levels. Our results suggest that a metabolite of linoleic acid regulates the activity of two lipogenic enzymes, G6PD and 6PGD, by lowering gene expression or mRNA processing or stability.

cDNA sequence of human apolipoprotein(a) is homologous to plasminogen

Lipoprotein(a) is an LDL-like lipoprotein whose concentration in plasma is correlated with atherosclerosis. The characteristic protein component of lipoprotein(a) is apolipoprotein(a) which is disulphide-linked to apolipoprotein B-100. Sequencing of cloned human apolipoprotein(a) complementary DNA shows that it is very similar to human plasminogen. It contains a serine protease domain and two types of plasminogen-like kringle domains, one of which is present in 37 copies.

Effect of dietary cholesterol on apolipoprotein E synthesis in the rabbit

Female New Zealand White rabbits were fed either rabbit chow or rabbit chow plus 1% (w/w) cholesterol for 14 days. The chow-fed rabbits had normal plasma lipoprotein profiles on agarose gel electrophoresis, 59 +/- 5 mg of cholesterol and 5.5 +/- 0.4 mg of apolipoprotein E (apoE) per dl of serum. The cholesterol-fed rabbits had significant amounts of beta-VLDL in their serum, 1870 +/- 140 mg of cholesterol and 96 +/- 12 mg of apoE per dl of serum. Relative rates of apoE synthesis were determined by incubating hepatocytes in culture medium containing [3H]leucine for 15 min at 37 degrees C and expressing the radioactivity incorporated into immunoprecipitable apoE as a percentage of the radioactivity incorporated into total protein. Hepatocytes from cholesterol-fed rabbits had twice the relative rate of apoE synthesis (1.05 +/- 0.18%) of hepatocytes from chow-fed rabbits (0.55 +/- 0.07%). This increase in synthesis could be a major contributor to the 17-fold increase in serum apoE levels in the cholesterol-fed rabbit.

Mammary transfer of vitamin A alcohol and ester in lactating dairy cows

The effect of intravenous injection of vitamin A alcohol and vitamin A ester on the vitamin A concentration of bovine milk was studied. Holstein cows received either an intravenous injection of 1 million international units (IU) of vitamin A alcohol, 1 million international units of vitamin A palmitate, or served as controls. Blood serum and milk were sampled at intervals prior to and following injection. Mean concentrations of vitamin A in milk at time 0 were 59.0, 52.0, and 58.4 mug/100 ml for the control, alcohol, and palmitate treatments. Mean contrations of vitamin A in milk, expressed as mug/100 ml or mug/g fat of cows receiving vitamin A alcohol at +195, +451, and +678 min postinjection, were greater than concentrations for either control cows or cows receiving palmitate. Partition of milk Vitamin A at +195 min postinjection for cows injected with vitamin A alcohol showed 4.1% of the recovered vitamin A in the alcohol and 95.9% in the ester form. Injection of vitamin A palmitate had little effect on milk vitamin A concentration. Vitamin A in serum (mug/100 ml) at 195 min after vitamin A alcohol injection was higher (100.4) than for either control (84.0) or cows injected with vitamin A palmitate (89.0).