Epidemiology and impact of frailty in patients with atrial fibrillation in Europe

BACKGROUND

Frailty is a medical syndrome characterised by reduced physiological reserve and increased vulnerability to stressors. Data regarding the relationship between frailty and atrial fibrillation (AF) are still inconsistent.

OBJECTIVES

We aim to perform a comprehensive evaluation of frailty in a large European cohort of AF patients.

METHODS

A 40-item frailty index (FI) was built according to the accumulation of deficits model in the AF patients enrolled in the ESC-EHRA EORP-AF General Long-Term Registry. Association of baseline characteristics, clinical management, quality of life, healthcare resources use and risk of outcomes with frailty was examined.

RESULTS

Among 10,177 patients [mean age (standard deviation) 69.0 (11.4) years, 4,103 (40.3%) females], 6,066 (59.6%) were pre-frail and 2,172 (21.3%) were frail, whereas only 1,939 (19.1%) were considered robust. Baseline thromboembolic and bleeding risks were independently associated with increasing FI. Frail patients with AF were less likely to be treated with oral anticoagulants (OACs) (odds ratio 0.70, 95% confidence interval 0.55-0.89), especially with non-vitamin K antagonist OACs and managed with a rhythm control strategy, compared with robust patients. Increasing frailty was associated with a higher risk for all outcomes examined, with a non-linear exponential relationship. The use of OAC was associated with a lower risk of outcomes, except in patients with very/extremely high frailty.

CONCLUSIONS

In this large cohort of AF patients, there was a high burden of frailty, influencing clinical management and risk of adverse outcomes. The clinical benefit of OAC is maintained in patients with high frailty, but not in very high/extremely frail ones.

Short- and long-term effects of the patient education strategy-learning and coping-in cardiac rehabilitation: a randomized controlled trial (LC-REHAB)

The objectives were to assess the short- and long-term effect of the patient education strategy 'Learning and Coping' (LC) in cardiac rehabilitation (CR) on health-related quality of life, patient education impact, cardiac risk factors and lifestyle. In total, 825 patients hospitalized with ischaemic heart disease or heart failure were randomized to either LC-CR or standard CR at three Danish hospitals. Teaching approach in LC-CR was situational, inductive and reflective, with experienced patients as co-educators and supplemental interviews. Teaching approach in standard CR was structured and deductive. Outcomes were assessed immediately after CR, and after 3 months (short term), and after 3 years (long term). Between-arm differences in favour of LC-CR were SF-12 'role emotional' (3.7, 95% CI: 0.6-6.8) and MDI depression score (0.9, 0.1-1.8) immediately after CR, exercise capacity (4 W, 1-9) at 3 months and SF-12 'role physical' (4.6, 0.1-9.0) (long term). Between-arm differences in favour of controls were waist circumference (-1.7 cm, -2.3 to -1.0) immediately after CR and HeiQ domain 'Constructive attitudes and approaches' (0.11, 0.04-0.18), triglycerides (-0.12 mmol/l, -0.21 to -0.02), systolic blood pressure (-3.12 mmHg, -5.66 to -0.58) at 3 months. Adding LC strategies to CR provides inconsistent short-term results but improves 'role physical' long term.

Effects of the patient education strategy 'Learning and Coping' in cardiac rehabilitation on readmissions and mortality: a randomized controlled trial (LC-REHAB)

We assessed the effects of the patient education strategy 'Learning and Coping' (LC) in cardiac rehabilitation (CR) on mortality and readmissions by exploring results from the LC-REHAB trial. In all, 825 patients with ischaemic heart disease or heart failure were randomized to the intervention arm (LC-CR) or the control arm (standard CR) at three hospitals in Denmark. LC-CR was situational and inductive, with experienced patients as co-educators supplemented with two individual interviews. Group-based training and education hours were the same in both arms. Outcomes were time to death or readmission, length of stay and absolute number of deaths or readmissions. No between-arm differences were found in time to death, first readmission, or length of stay. Within 30 days after completion of CR, the absolute number of all-cause readmissions was 117 in the LC arm and 146 in the control arm, adjusted odds ratio 78 (95% CI: 0.61-1.01), P = 0.06. This trend diminished over time. Adding LC strategies to standard CR showed a short term but no significant long-term effect on mortality or readmissions. However, the study was not powered to detect differences in mortality and morbidity. Thus, a risk of overseeing a true effect was present.

The prognostic value of the frontal QRS-T angle is comparable to cardiovascular autonomic neuropathy regarding long-term mortality in people with diabetes. A population based study

Cardiovascular autonomic neuropathy (CAN) is a well known prognostic marker in diabetes. A large angle between the QRS- and the T-wave vector (QRS-T angle) in the electrocardiogram (ECG) has recently been introduced as another marker of poor prognosis.

AIM

To assess and compare the long-term predictive power of the frontal plane QRS-T angle with CAN in people with diabetes.

METHODS

In 1992-93 people with diabetes in the municipality of Horsens, Denmark, were identified by the prescription method andan age and gender stratified sample of 240 individuals with diabetes were randomly selected. The presence of CAN was defined using the heart rate response to Valsalva manoeuvre. The QRS-T angle was read using the method described by Gandhi. In July 2015 vital statistics were obtained fromthe Danish Civil Registration System.

RESULTS

178 individuals accepted to participate in the study, of which 153 (86%) completed the Valsalva manoeuvre and had sinus rhythm. Total observation time was 21.5 (0.18) years, in which 99 (65%) individuals died. An elevated QRS-T angle and the presence of cardiovascular autonomic neuropathy were both found to be significant predictors of death. In Cox regression analyses, adjusting for the effect of gender, age, duration of diabetes, BMI, total-cholesterol, diabetes type, haemoglobin A1c, smoking status, hypertension and previous MI, an independent prognostic value was found for the QRS-T angle as well as the Valsalva ratio.

CONCLUSION

A large QRS-T angle and the presence of cardiovascular autonomic neuropathy are both strong and independent long-term predictors of all-cause mortality in people with diabetes.

Outcomes of cup revision for ilio-psoas impingement after total hip arthroplasty: Retrospective study of 46 patients

BACKGROUND

Impingement of the ilio-psoas tendon on the acetabular component is a cause of pain after total hip arthroplasty (THA). Studies of cup revision for ilio-psoas impingement (IPI) are scarce and limited in size. We therefore conducted a large multicentre retrospective study with the following objectives: to assess the effectiveness of cup replacement in resolving the impingement syndrome, to determine the frequency and nature of complications after cup revision for IPI, and to identify pre-operative factors associated with good outcomes of cup revision for IPI.

HYPOTHESIS

Cup revision is effective in resolving the pain due to IPI in selected patients.

METHODS

This retrospective multicentre study included 46 patients who underwent cup revision because of IPI. Before the revision, 38 (83%) patients had prominence of the anterior cup rim (mean, 9.9±4.5mm (range, 2-22mm) by radiography and 35 (76%) had cup malposition (anteversion<10° and/or inclination>50°). Mean follow-up was 21months (range, 6months to 6 years) and no patient was lost to follow-up. Outcomes at last follow-up were assessed based on the Oxford Hip Score (OHS), patient satisfaction index, complications, and revisions.

RESULTS

At last follow-up, 39 (85%) patients were satisfied with the revision procedure, a significant improvement versus baseline was noted in the OHS (mean, 43±6; range, 25-48; P<0.001), and 41 patients were free of pain during hip flexion (P<0.001 versus baseline). Complications occurred in 3 (6.5%) patients, but only one complication was severe (deep infection). Recurrent groin pain was reported by 4 (8.7%) patients at last follow-up. None of the factors studied predicted the outcome of revision surgery.

DISCUSSION

Cup revision for IPI after THA is effective in relieving the groin pain in 80% of patients with anterior cup rim prominence and/or cup malposition. However, complications can occur. Tenotomy may be preferable when the diagnosis is in doubt and/or cup position is acceptable.

LEVEL OF EVIDENCE

IV, retrospective observational study.

Slipped capital femoral epiphysis management and the arthroscope

BACKGROUND

In situ pinning of slipped capital femoral epiphysis (SCFE) results in various degrees of deformity of the femoral head-neck junction. Repetitive trauma from cam-type femoroacetabular impingement (FAI) can lead to labral tears and injury to the articular cartilage causing loss of function. Arthroscopic osteoplasty is an alternative to open procedure and to Southwick/Imhäuser-type osteotomies in symptomatic selected cases.

SURGICAL TECHNIQUE

The amount of bone to be resected has to be carefully planned pre-operatively. Only gentle traction is applied on a well-padded perineal support. A spherical burr is used to gradually resect the prominence. Intra-operative fluoroscopy is very useful when checking adequate reshaping of the head-neck junction is obtained.

RESULTS

Arthroscopy often reveals acetabular cartilage lesions, labrum hyperhemia and fraying which rarely require repair. Arthroscopic osteoplasty provides satisfactory pain relief and, to a lesser extent, restores hip internal rotation.

CONCLUSION

Arthroscopic osteoplasty is more technically and time-demanding in post SCFE than idiopathic FAI. It requires strong arthroscopic skills and experience in hip arthroscopy. It stands as a reasonable alternative to open procedure or flexion osteotomies in symptomatic FAI post mild to moderate SCFE. It provides pain relief and to a lesser extent restores internal rotation of the hip.

Microinstability of the hip: A review

With the development of conservative hip surgery techniques, new entities such as microinstability have been identified. Microinstability is a painful supra-physiological mobility of the hip. It results from the association of architectural and functional abnormalities impairing joint stability. These risk factors concern hip joint bone architecture or peri-articular soft tissues. Bone abnormalities are identified on hip assessment parameters. Soft tissues also play a key role in the static and dynamic stability of the hip: the joint capsule, labrum, ligamentum teres and adjacent myotendinous structures affect joint coaptation; any abnormality or iatrogenic lesion concerning these structures may constitute a risk factor for microinstability. Diagnosis is based on interview, clinical examination and imaging. Findings of labral lesions or femoro-acetabular impingement do not rule out microinstability; they may be associated. Treatment is based first on physiotherapy for muscle reinforcement to improve joint coaptation. In case of failure, arthroscopic surgery is indicated for femoro-acetabular impingement and capsular plicature which is being evaluated. Periacetabular osteotomy or shelf acetabuloplasty may be indicated, according to the severity of joint bone architecture abnormality. Microinstability is a multifactorial entity. Lesions induced by microinstability may in turn become risk factors for aggravation. Diagnosis and indications for surgery are thus difficult to establish. Only full clinical examination and exhaustive imaging assessment allow microinstability and associated lesions to be identified.

Clinical results of endoscopic treatment without repair for partial thickness gluteal tears

INTRODUCTION

Various surgical treatments have been proposed for greater trochanteric pain syndrome (GTPS) related to gluteal tendinopathy with partial thickness tears. The clinical results of endoscopic debridement without repair of these gluteal tears are not well known. The objectives of this study were to determine if this procedure leads to: (1) reduction of pain, (2) functional improvement, (3) patient satisfaction (on scale of 0 to 10).

HYPOTHESIS

Endoscopic treatment without tendon repair provides short-term pain relief in patients with GTPS due to partial thickness gluteal tears.

MATERIAL AND METHODS

Seventeen patients (16 women, 1 man) with GTPS due to partial thickness gluteal tears that was present for at least 6 months and was refractory to conservative treatment were included in the analysis. The average age at the time of the procedure was 53.5years (17-71). Pain was evaluated with a visual analogue scale (VAS). Functional outcomes were defined using the Harris Hip Score and the UCLA activity score. Satisfaction was evaluated using a VAS and Odom's criteria.

RESULTS

The average follow-up was 37.6months (12-48). The average preoperative and follow-up values were respectively: (1) Pain: 7.2±1.1 (5-9) versus 3.3±1.9 (1-7) (P<0.001), (2) Harris score: 53.5±8.4 (36-68) versus 79.8±14.7 (45-96) (P<0.001). Seven patients (41.2%) were able to resume sports activities. The average satisfaction score for the surgery was 6.2±2.4 (0-9) at follow-up. Five patients had a poor outcome at the review: four still had pain and one had recurrence of the lateral snapping hip.

CONCLUSION

Endoscopic treatment without repair of partial thickness gluteal tears is a treatment option with modest clinical results for GTPS patients refractory to conservative treatment.

LEVEL OF EVIDENCE

IV, retrospective study.

Experimental evidence on the mechanism of dissociative electron attachment to formic acid

Two mechanisms for dissociative electron attachment in HCOOH, the formation of HCOO(-)+H, were proposed in the literature: (i) via a direct electron attachment into a σ* resonance, augmented by dipole binding of the incident electron [G. A. Gallup et al., Phys. Rev. A 79, 042701 (2009)], and (ii) with the 1.8 eV π* resonance as a doorway state, linked to the products by symmetry lowering-distortion of the temporary anion, primarily the C-H bond, from the planar symmetry [T. N. Rescigno et al., Phys. Rev. Lett. 96, 213201 (2006)]. The later mechanism implies a reduction of the cross section upon deuteration of the hydrogen bonded to the C atom, whereas the former mechanism would leave the cross section unaffected. Our experimental absolute cross sections for the four isotopomers of formic acid show that deuteration on the C atom reduces the cross section value only marginally (by 12%) compared to deuteration on the O atom (reduction by a factor of 16), and thus favor mechanism (i).

De-escalation exchange of loosened locked revision stems to a primary stem design: complications, stem fixation and bone reconstruction in 15 cases

INTRODUCTION

Femoral stem revision with a locked stem after total hip arthroplasties treats severe bone defects by favoring spontaneous bone reconstruction. Initially, once reconstruction was obtained, the temporary implant was to be replaced by a standard primary component. The use of locked stems has increased, but repeat revision with a short stem which is also called "de-escalation" has not been extensively studied.

HYPOTHESIS

Repeat revision of a locked stem with a short stem is not associated with any specific morbidity and does not affect the quality of reconstruction obtained, or fixation of the subsequent standard length primary design stem.

PATIENTS AND METHODS

Fifteen patients whose locked femoral stem was exchanged due to thigh pain and/or radiographic images showing failed osteointegration were analyzed. These 15 patients were all followed-up and evaluated by the Postel Merle d'Aubigné score. Progression of bone defects was evaluated using the Hofmann cortical index.

RESULTS

There were no difficulties extracting the locked stem and a standard length primary stem was inserted with no associated procedures or bone complications in any of the cases. At a mean follow-up of 55 months (36-84months), thigh pain had disappeared and the Postel Merle d'Aubigné score had increased from 12.6±2.9 (7-16) to 16.5±0.9 (15-18) (P=0.0001). The use of a locked femoral stem resulted in bone reconstruction in all cases, the Hofmann index increased from 30.5%±17.9% (12-71%) before insertion of the locked stem to 43.6%±25.6% (19-90%) at exchange (P<0.05). Bone reconstruction was durable after the exchange with a stable Hofmann index 43.7%±26.2% (17-92%) at the final follow-up (P=0.9). No recurrent loosening occurred.

DISCUSSION

Revision of a loosened locked femoral stem with a standard design primary stem does not result in any specific increased morbidity, or modify bone reconstruction obtained with the locked stem and results in stable fixation of a new standard length stem.

LEVEL OF EVIDENCE

IV: retrospective or historical series.

Assessment of arthroscopic management of femoroacetabular impingement. A prospective multicenter study

INTRODUCTION

Surgical treatment of femoroacetabular impingement can be performed under arthroscopic control, to limit associated morbidity. Encouraged by recent good reports, arthroscopy is replacing alternative techniques for this indication.

HYPOTHESIS

Arthroscopy enables femoroacetabular impingement to be corrected with a low rate of associated morbidity.

AIM OF STUDY

To assess the indications for and quality of the technique and its impact on preliminary results and complications. To investigate preoperative prognostic factors.

PATIENT AND METHODS

One hundred and eleven hips in 110 patients (78 male, 32 female; mean age, 31 years) were operated on under arthroscopic control for femoroacetabular impingement, by six senior surgeons. Sixty-five patients showed no radiographic sign of osteoarthritis, and 36 showed grade-1 early osteoarthritis on the Tönnis scale.

RESULTS

Mean WOMAC score rose from 60.3 preoperatively to 83 (p<0.001) at a mean 10 months' FU (range, 6-18 mo). Seventy-seven percent of patients were satisfied or very satisfied with their result. Patients with early osteoarthritis had significantly lower WOMAC and satisfaction scores than those free of osteoarthritis. Operative crossover to open surgery occurred in only one case. Five patients (4%) had revision: total hip replacement or resurfacing. There were seven complications (6%): three cases of heterotopic ossification, one of crural palsy, one of pudendal palsy, one of labium majus necrosis, and one non-displacement stress fracture of the femoral head/neck junction (managed by non-weight-bearing). There was no palsy of the territory of the lateral cutaneous nerve of the thigh.

DISCUSSION

Results confirmed the efficacy and low associated morbidity of arthroscopy in the management of femoroacetabular impingement. Short-term functional results matched those of the literature. Planning and assessment seem not yet to be fully standardized. Preoperative osteoarthritis on X-ray was associated with poorer functional results. This attitude does not seem to be indicated for hips showing evolved osteoarthritis (>grade 1).

Descriptive epidemiology of mechanical hip pathology in adults under 50 years of age. Prospective series of 292 cases: Clinical and radiological aspects and physiopathological review

Two hundred and ninety-two patients, aged between 16 and 50 years and presenting with mechanical hip pathology, were included in a prospective multicenter study. The descriptive study concerned the clinical examination and analysis of three X-ray views (AP pelvic, Lequesne false profile and lateral axial view). The series comprised 62% males, mean age 35 years, with 53% right side and 22% bilateral involvement. Initial trauma was reported in 19% of cases, and direct familial history of hip pathology in 20%. Seventy percent of the patients played sports, 30% were high-level athletes, and 17% played combat sports. The physical impingement sign was present in 18% to 65% of cases depending on the variant studied. On imaging (n=241), 62% of hips showed osteoarthritis, with 25% at the evolved stage. In the series, as a whole, there was a 35% rate of dysplasia, 63% of impingement and 5% of normal X-ray results. The radiologic impingement aspects were 58% cam-type, 19% pincer-type and 23% mixed. Twenty-two percent of dysplasia cases showed signs of associated impingement. Pain experienced exclusively in flexion/internal rotation/adduction on examination showed little sensitivity (20%) but considerable specificity (86%) for the main diagnosis of impingement. The links between impingement and dysplasia are discussed, and an integrative schema of all risk factors is put forward.

Delayed, transient sciatic nerve palsy after primary cementless hip arthroplasty: a report of two cases

Delayed sciatic nerve palsy is uncommon after primary hip replacement. Two kinds of sciatic palsy have been reported with regard to the time of onset: early palsy related to wound haematoma or lumbosacral nerve elongation which occurs between surgery and 18 days, is more frequent than delayed palsy, occurring between 10 and 32 months, which is usually caused by cement extrusion or heat produced by cement polymerisation. We present two cases of delayed, transient sciatic nerve palsy arising at three weeks and four months after primary cementless arthroplasty, respectively, without haematoma and with a normal lumbar spine. These palsies were possibly caused by excessive tension from minor limb lengthening of 2 cm to 4 cm required to achieve leg-length equality. As the initial symptoms were limited to calf pain and mild numbness in the foot, surgeons should be aware of this mode of onset, particularly when it is delayed after hip replacement. Both patients recovered fully by 12 months after surgery so we did not undertake surgical exploration of the nerve in either patient.

[Polyethylene liner replacement: behavior and morbidity in 68 cases]

PURPOSE OF THE STUDY

Isolated acetabular polyethylene exchange is advocated as an advantage of metal-backed cups, since the acetabular bone stock can be spared and operative time is shorter. The purpose of this study was to determine whether this is true.

MATERIAL AND METHODS

A consecutive serie of 68 THA revisions involving replacement of the polyethylene liner was analyzed retrospectively (liner replacement alone for 37 hips and liner replacement plus femoral component revision for 31). The posterolateral approach was used for the revision in all cases. This series was compared with a control series of revisions involving the acetabular component with revision of the femoral component in patients matched for age, sex, and BMI.

RESULTS

Operative time and hospital stay were significantly shorter when the revision involved the polyethylene liner alone. In 19 hips, a limited zone of osteolysis was observed around the liner before replacement. At last follow-up, new zones of osteolysis were noted in two hips and aggravation in five, one of which required revision because of acetabular loosening. Episodes of dislocation were observed in nine hips (2 anterior and 7 posterior) of which three underwent revision because of recurrence. These dislocations occurred after liner replacement (n=4) or combined liner and femoral component replacement (n=5). Dislocations were more frequent after multiple hip operations and when the cup inclination was less than 40 degrees . Ten revisions were required for: an unclipped liner (n=2), recurrent dislocation (n=3), acetabular loosening (n=1), infection which was cured after a one-stage procedure (n=1). At seven years, survival was comparable between liner replacement alone (82+/-10%), combined liner replacement and femoral component revision (84+/-11%), and femoral component and acetabular component revision (82+/-11%).

DISCUSSION

Changing the cup liner can limit morbidity compared with a more complex revision, but liner replacement alone is insufficient in the event of acetabular osteolysis. It would be preferable to combine osteolysis debridement with a graft or a complete revision. The survival rate after liner replacement is comparable with that observed after more complex revision but the risks of dislocation or unclipped insert are significant. For this reason, liner replacement alone should only be proposed if the cup is correctly aligned and if the new liner can be solidly clipped into the metal back. In addition, this simplified procedure should not be attempted after multiple hip operations.

Treatment of failed arthroscopic acetabular labral debridement by femoral chondro-osteoplasty: a case series of five patients

Femoroacetabular impingement is recognised as being a cause of labral tears and chondral damage. We report a series of five patients who presented with persistent pain in the hip after arthroscopy for isolated labral debridement. All five had a bony abnormality consistent with cam-type femoroacetabular impingement. They had a further operation to correct the abnormality by chondro-osteoplasty of the femoral head-neck junction. At a mean follow-up of 16.3 months (12 to 24) all had symptomatic improvement.

Fiabilité limitée du plan pelvien antérieur pour l’implantation assistée par informatique de la cupule d’une prothèse totale de hanche

PURPOSE OF THE STUDY

The anterior pelvic plane, also called the Lewinnek plane, is commonly used as the reference plane to guide imageless computer assisted surgery for total hip arthroplasty (THA) because this plane is considered to be globally vertical in the standing position. To our knowledge, no study has evaluated this hypothesis or the potential variations in orientation as a function of gender, position of the subject, or THA insertion. The purpose of this work was to examine these different hypotheses in a radio-clinical study.

MATERIAL AND METHODS

The orientation of the anterior pelvic plane was measured in relation to the vertical plane on plain lateral x-rays of the pelvis in the standing position. X-rays were studied for 106 patients: 1) 82 patients with a THA (40 with at least one dislocation, 42 with a stable hip selected randomly, 19 with a standing lateral x-ray before and after arthroplasty) and 24 control subjects for whom lateral images were obtained in the supine and standing positions to assess potential position-related changes in orientation.

RESULTS

The orientation of the anterior pelvic plane was not affected by gender or age. The anterior pelvic plane formed an angle greater than 5 degrees with the vertical plane in 38% of patients and more than 10 degrees in 13%. The orientation of the anterior pelvic plane was not significantly different between the study groups (control versus THA) nor between the THA groups (stable versus dislocated). The supine position modified significantly the orientation of the anterior pelvic plane which changed on average from 1.20 degrees to -2.25 degrees ; the change was greater than 7 degrees in twelve subjects. Implantation of a THA did not modify signi-ficantly the orientation of the anterior pelvic plane in the standing position for the 19 subjects [the variations were small (-1 degrees to 7 degrees on average, range -21 degrees to 8 degrees ) but greater than 5 degrees for 7 of 19 subjects].

DISCUSSION

Most teams use the anterior pelvic plane to guide computer-assisted navigation, considering that this plane is vertical in the standing position. Our findings show however that this is not true for 38% of subjects with a margin of error of 10 degrees , i.e. about half of the anatomic anteversion of the acetabulum. Moving to the standing position would produce a significant variation in the orientation of the anterior plane of the pelvis. This is a source of error which has not been integrated into most imageless navigation systems. Similarly variations in the position of the pelvis from the standing to sitting and supine positions which can produce impingement or dislocation have not been taken into consideration.

CONCLUSION

Variations in the orientation of the anterior pelvic plane in relation to the vertical would suggest that this plane is not a reliable reference. To our knowledge, there is no reliable reference which can be easily identified during the operation which would take into account variations in the position of the pelvis. We thus believe it would be preferable to attempt to operate without a reference plane, relying on a more kinematic approach to guide computer-assisted implantation of the THA cup.

Seed size and seedling growth: differential response of Australian and British Fabaceae to nutrient limitation

Seed size is widely held to exert an important influence over plant establishment, but while large seeds are often assumed to be at an advantage in nutrient-limited conditions, there is in fact, little consistent evidence to support this hypothesis. Here, we examined the interspecific relationship between seedling growth and seed size for Australian and British Fabaceae species in nutrient solutions deficient in nitrogen, phosphorus, potassium or all nutrients combined (distilled water). The British species showed no consistent link between mean seed mass and seedling growth in nutrient-limited conditions. By contrast, all four nutrient-deficient treatments yielded a significant relationship for the Australian species. Linear regression showed that growth under balanced nutrient conditions was positively associated with growth without nutrients, although in fewer cases for the British species. We suggest that habitat-specific differences in regeneration conditions and/or evolutionary history may influence the role that seed size plays in dictating how seedlings of different species respond to nutrient shortage. We recommend caution in attempts to link traits like seed size to wider patterns of plant community ecology.

[Bilateral Moore hemiarthroplasty: 36 years of good tolerance without loosening or osteolysis]

We report an illustrative case of bilateral Moore arthroplasty with the clinical and radiographic results at 36 years follow-up. The femoral prostheses were implanted for necrosis of the femoral head when the patient was 46 years old. At implantation the patient's physical activity level was high (Devane 4) and remained so until retirement at age 65 years. His activity level remained high (Devane 3) to the age of 82 years when the patient suffered a Vancouver B1 periprosthetic fracture on the left. At this date, both arthroplasties were free of loosening an osteolysis. Plate fixation with wiring led to fracture healing. The Postel Merle d'Aubigné score was 17 before the fracture and 16 at healing (with a pain score of 6 both before and after). Radiographically, acetabular cartilage tolerance was excellent. This case illustrates the excellent clinical outcome obtained with the Moore hemiarthroplasty at more than 35 years despite less than satisfactory initial fixation and the absence of resurfacing. The fact that this prosthesis does not have a polyethylene element prevented the development of osteolysis which could have been expected with such a long postoperative period in this a highly active patient. Favorable factors (good abductor lever arm, adapted head diameter, resistance of the acetabular cartilage in a young subject with femoral head necrosis) may have played a role in this particular case since the excellent and sustained outcome was observed on both sides. This exceptional longevity provides useful information for better determining precise indications for head cups for the treatment of necrosis of the femoral head.

Bias of QT dispersion

BACKGROUND

Prolonged QT dispersion (QTD) is associated with an increased risk of arrhythmic death but its accuracy varies substantially between otherwise similar studies. This study describes a new type of bias that can explain some of these differences.

MATERIAL

One dataset (DiaSet) consisted of 356 subjects: 169 with diabetes, 187 nondiabetic control persons. Another dataset (ArrSet) consisted of 110 subjects with remote myocardial infarction: 55 with no history of arrhythmia and 55 with a recent history of ventricular tachycardia or fibrillation.

METHODS

12-lead surface ECGs were recorded with an amplification of 10 mm/mV at a paper speed of 50 mm/s. The QT interval was measured manually by the tangent-method. The bias depends on the magnitude of the measurement errors and the measurable part of the bias increases with the number of the repeated measurements of QT.

RESULTS

The measurable bias was significant for both datasets and decreased for increasing QTD in the DiaSet (P < 0.001) and in the ArrSet (P = 0.11). The bias was 2.5 ms and 1.9 ms at QTD = 38 ms and 68 ms, respectively, in the ArrSet, and 7.5 ms and 2.8 ms at QTD = 19 ms and 55 ms, respectively, in the DiaSet.

CONCLUSIONS

This study shows that random measurement errors of QT introduces a type of bias in QTD that decreases as the dispersion increases, thus reducing the separation between patients with low versus high dispersion. The bias can also explain some of the differences in the mean QTD between studies of healthy populations. Averaging QT over three successive beats reduces the bias efficiently.

Dépose par laparotomie des composants d’une prothèse totale de hanche compliquée de migration intra-pelvienne avec complication urinaire

We present the first report of transabdominal removal of femoral and acetabular components of a severely loosened hip prosthesis protruding into the pelvis. In a 73-year-old woman post-operative development of urinary tract complications emphasize importance of careful assessment of the prosthetic relations with the vascular and nervous structures as well as pelvic organs before removal of the hip prosthesis. Angio-computed tomography is the most contributive exploration to assess vascular relations. In patients with particular clinical presentations or with threatened structures in the vicinity of the prosthesis, this examination must be completed by complementary opacifications (urinary and gastrointestinal tracts, joints). Ureteral catheterization may be needed if the structures are close or if there is a suspected modification of the urinary tract (retraction, mass effect). In present case, we did not opacify the urinary tract before laparatomy despite the presence of urinary signs preoperatively. A suspected ureterovaginal fistula was discovered. But they where also a ureteral lesions which can result from difficult dissection in contact with infected tissues. In this patient, urinary complications led to nephrectomy after temporary pyelostomy for urine bypass. At last follow-up, the urinary tract infection was controlled but reimplantation was not attempted because of insulin dependent diabetes mellitus and poor general condition. The spontaneous course of this infection with prosthesis loosening recalls the importance of regular surveillance of total hip replacements.

Cardiovascular autonomic neuropathy in insulin-dependent diabetes mellitus: prevalence and estimated risk of coronary heart disease in the general population

OBJECTIVES

The aim of the study was to estimate the prevalence of cardiovascular autonomic neuropathy (CAN) in Type 1 diabetes mellitus in the general population and to assess the relationship between CAN and risk of future coronary heart disease (CHD).

METHODS

The Type 1 diabetes mellitus population in the municipality of Horsens, Denmark, was delineated by the prescription method and a random sample of 120 diabetics aged 40-75 years was recruited. Type 1 diabetes mellitus was registered if fasting C-peptide was below 0.30 nmol L(-1). The E/I ratio was calculated as the mean of the longest R-R interval in expiration divided by the shortest in inspiration during deep breathing at 6 breaths min(-1) and taken to express the degree of CAN. A maximal symptom-limited exercise test was carried out and the VA Prognostic Score, indicating risk of cardiovascular death or non-fatal myocardial infarction, was computed. Additionally, the 10-year risk of CHD was calculated using the Framingham model.

RESULTS

A total of 84 people responded, of whom 71 had Type 1 diabetes mellitus. The E/I ratio was measured in 69 people. The prevalence of CAN expressed as an E/I ratio below the normal 5th percentile was 38%. The E/I ratio was significantly reduced in old age, long duration of diabetes, female gender, high fasting blood glucose, triglyceride, systolic blood pressure and urinary albumin excretion. A high risk of future CHD calculated using the Framingham model was associated with a low E/I ratio (r = -0.39, P = 0.001). Exercise capacity, rise in systolic blood pressure and heart rate were positively correlated with the E/I ratio. A high VA Prognostic Score was correlated with a low E/I ratio (r = - 0.58, P < 0.0005). The risks estimated by the two models were significantly correlated (r = 0.60, P < 0.0005).

CONCLUSION

The prevalence of CAN in the 40-75-year-old Type 1 diabetes mellitus population is estimated to be 38%. CAN is associated with exercise test parameters and a coronary risk factor profile indicating a high risk of future CHD.

[Testing a computer-assisted bending machine for manufacturing orthodontic treatment elements]

The use of suitable orthodontic devices producing desired defined force systems is of importance for successful orthodontic treatment. Bending loops can be difficult and time-consuming. Computerised fabrication would enable very precise reproduction of individual loops. A bending machine has now been developed within the framework of a computer-assisted treatment concept. In this study, a prototype machine was used to fabricate U-, T- and delta loops made of stainless steel, cobalt chromium and titanium molybdenum wire. The various geometric parameters of each loop were measured to determine how precisely they had been produced. Furthermore, the force system of each loop were experimentally investigated during simulated activation in an orthodontic measurement and simulation system. The results indicate that the geometric parameters had an average error of 2.8 degrees for angles and 0.9 mm for lengths. Owing to the fabrication errors, loops of the same type produced different force systems. Overall, the new bending machine can fabricate different types of loop, but the requirements of very precise fabrication are currently not met. This fact, together with further limitations in terms of configuration, means that the machine cannot be used routinely at present. However, the machine can nevertheless be considered a good basis for further development.

Inverting enantioselectivity by directed evolution of hydantoinase for improved production of L-methionine

Using directed evolution, we have improved the hydantoinase process for production of L-methionine (L-met) in Escherichia coli. This was accomplished by inverting the enantioselectivity and increasing the total activity of a key enzyme in a whole-cell catalyst. The selectivity of all known hydantoinases for D-5-(2-methylthioethyl)hydantoin (D-MTEH) over the L-enantiomer leads to the accumulation of intermediates and reduced productivity for the L-amino acid. We used random mutagenesis, saturation mutagenesis, and screening to convert the D-selective hydantoinase from Arthrobacter sp. DSM 9771 into an L-selective enzyme and increased its total activity fivefold. Whole E. coli cells expressing the evolved L-hydantoinase, an L-N-carbamoylase, and a hydantoin racemase produced 91 mM L-met from 100 mM D,L-MTEH in less than 2 h. The improved hydantoinase increased productivity fivefold for >90% conversion of the substrate. The accumulation of the unwanted intermediate D-carbamoyl-methionine was reduced fourfold compared to cells with the wild-type pathway. Highly D-selective hydantoinase mutants were also discovered. Enantioselective enzymes rapidly optimized by directed evolution and introduced into multienzyme pathways may lead to improved whole-cell catalysts for efficient production of chiral compounds.

Assessing cardiovascular autonomic neuropathy in diabetes mellitus: how many tests to use?

The aim was to evaluate the relative importance of an established battery of five function tests used in the assessment of cardiovascular autonomic neuropathy (CAN) in diabetes employing spectral analysis of heart rate variability (HRV) as the reference test. In a population-based sample of 178 diabetic persons and 194 non-diabetic controls, five function tests (E/I ratio, Valsalva, 30:15 ratio, Orthostatic-BP, and sustained Handgrip) and power spectral analysis of a 24-h Holter recording were carried out. The high-frequency power during nighttime (LnHF(NIGHT)) was taken to express the parasympathetic function and the daytime low-frequency power (LnLF(DAY)) to express the sympathetic function. The readings were log transformation when appropriate, age-corrected, and standardized to units of standard deviation. Combinations of the three mainly parasympathetic tests and the two mainly sympathetic tests were computed by averaging the standardized readings. A high value of the mean sum of squares in LnHF(NIGHT) or LnLF(DAY) - explained in regression analysis - was assumed to represent the better test or combination of tests. The three parasympathetic function tests each correlated significantly to LnHF(NIGHT). The E/I ratio had a correlation to LnHF(NIGHT) similar to the combination of the three parasympathetic tests and the combination of all five function tests, whereas Valsalva and 30:15 ratio had a significantly poorer association. Sustained Handgrip-correlated significantly poorer to LnLF(DAY) compared to Orthostatic BP and the combination of the two sympathetic tests explained a significantly smaller part of the variation in LnLF(DAY) and LnHF(NIGHT) than did the combination of all five tests. This study indicates that: (1) no information is gained by adding the sympathetic function tests to the parasympathetic tests, (2) the most informative test is the E/I ratio, (3) and knowledge about the degree of CAN as defined by reduced HRV is not significantly increased when the four other function tests assessed are added to the E/I ratio.

Increased QT dispersion in patients with insulin-dependent diabetes mellitus

AIM

To compare the QT dispersion in unselected patients with insulin-dependent diabetes mellitus to non-diabetic control subjects and to assess the association between the QT dispersion and cardiac autonomic neuropathy, ischaemic heart disease, blood pressure level and nephropathy.

METHODS

42 patients with insulin-dependent diabetes mellitus and 80 control subjects aged 40-57 years participated. The QT interval was measured in a resting 12-lead electrocardiogram (ECG) and the QT dispersion defined as the difference between the maximum and minimum QT interval. Bazett's formula was used to correct for heart rate (QTc). The degree of cardiac autonomic neuropathy was assessed by five function tests and ischaemic heart disease was defined by a previous myocardial infarction, ECG abnormalities or a positive exercise test.

RESULTS

Compared to control subjects, diabetic patients had a longer QTc interval (433 vs. 416 ms; P=0.002) and a higher QT dispersion (36 vs. 30 ms; P=0.02). In the diabetic group, the QTc interval was prolonged in patients with autonomic neuropathy (449 vs. 420 ms; P=0.007) and the QT dispersion was increased in patients with ischaemic heart disease (51 vs. 33 ms; P=0.004). No association was found to urinary albumin excretion rate or blood pressure.

CONCLUSION

The QT dispersion as well as the QTc interval is increased in patients with insulin-dependent diabetes mellitus. The association between QT dispersion and ischaemic heart disease indicates that abnormalities in cardiac repolarisation may be caused by complications to diabetes rather than diabetes in itself.

Microbial hydantoinases--industrial enzymes from the origin of life?

Hydantoinases are valuable enzymes for the production of optically pure D- and L-amino acids. They catalyse the reversible hydrolytic ring cleavage of hydantoin or 5'-monosubstituted hydantoins and are therefore classified in the EC nomenclature as cyclic amidases (EC 3.5.2.). In the EC nomenclature, four different hydantoin-cleaving enzymes are described: dihydropyrimidinase (3.5.2.2), allantoinase (EC 3.5.2.5), carboxymethylhydantoinase (EC 3.5.2.4), and N-methylhydantoinase (EC 3.5.2.14). Beside these, other hydantoinases with known metabolic functions, such as imidase and carboxyethylhydantoinase and enzymes with unknown metabolic function, are described in the literature and have not yet been classified. An important question is whether the distinct hydantoinases, which are frequently classified as L-, D-, and non-selective hydantoinases depending on their substrate specificity and stereoselectivity, are related to each other. In order to investigate the evolutionary relationship, amino acid sequence data can be used for a phylogenetic analysis. Although most of these enzymes only share limited sequence homology (identity < 15%) and therefore are only distantly related, it can be shown (i) that most of them are members of a broad set of amidases with similarities to ureases and build a protein superfamily, whereas ATP-dependent hydantoinases are not related, (ii) that the urease-related amidases have evolved divergently from a common ancestor and (iii) that they share a metal-binding motif consisting of conserved histidine residues. The difference in enantioselectivity used for the classification of hydantoinases on the basis of their biotechnological value does not reflect their evolutionary relationship, which is to a more diverse group of enzymes than was assumed earlier. This protein superfamily probably has its origin in the prebiotic conditions of the primitive earth.

Parasympathetic function during deep breathing in the general population: relation to coronary risk factors and normal range

OBJECTIVES

To examine the association between the parasympathetic function assessed by deep breathing-induced heart rate variability (HRV) and coronary risk factors and to establish a reference range for deep breathing-induced HRV.

DESIGN

Cross-sectional population-based study.

SETTING

The municipality of Horsens, Denmark.

SUBJECTS

One hundred and ninety-four individuals aged 40-67 years without diabetes, atrial fibrillation or a pacemaker randomly selected from the population.

MAIN OUTCOME MEASURES

During deep breathing at 6 respiratory cycles min-1, an ECG was taken and in three consecutive cycles the longest R-R interval during expiration (E) and the shortest during inspiration (I) were selected. The mean ratio (E/Iratio) and the mean difference in instantaneous heart rate (E/Idiff) were taken as expressions of the parasympathetic function.

RESULTS

In multivariate analysis, E/Idiff was reduced with increasing age (P < 0.0005) and left ventricular mass (P = 0.008), with ECG sign of probable previous myocardial infarction (P = 0.020) and the use of cardiac medication (P = 0.018) and positively correlated to heart rate (P = 0.030). The E/Iratio was diminished with increasing age (P = 0.001), left ventricular mass (P = 0.003), waist-hip ratio (P = 0.044), with ECG sign of probable previous myocardial infarction (P = 0.012) and use of cardiac medication (P = 0.020), but no association was found with heart rate (P = 0.92). In both E/Idiff and E/Iratio, no correlation was found to lipids, blood pressure or alcohol consumption. In the group not on cardiac medication, without left ventricular hypertrophy or ECG sign of probable myocardial infarction, E/Idiff and E/Iratio were still independently correlated to age and left ventricular mass. In this group, equations defining the age-corrected 5th percentile were calculated.

CONCLUSIONS

The parasympathetic function as assessed by deep breathing-induced HRV in the general population is reduced in older people, and in individuals on cardiac medication, with left ventricular hypertrophy or ECG signs of myocardial infarction. Even in healthy persons the parasympathetic function is inversely associated with age and left ventricular mass. Values of E/Idiff above (4.39-0.033 x age)2 and readings of E/Iratio above 1 + exp (-1.12-0.0198 x age) can be regarded as normal.

Molecular evolution of hydantoinases

The complete amino acid sequence of the hydantoinase from Arthrobacter aurescens DSM 3745 has been derived by automated Edman degradation. This is the first ever reported amino acid sequence of a non-ATP-dependent hydantoinase, which hydrolyzes 5'-monosubstituted hydantoin derivatives L-selectively. A homology search performed in protein and nucleic acid databases retrieved only distantly related proteins. All of these are members of the recently described protein superfamily of amidohydrolases related to ureases (Holm and Sander, Proteins 28: 72-82, 1997). Phylogenetic analysis revealed that the novel hydantoinase forms a new branch separate from other hydantoin cleaving enzymes like dihydropyrimidinases (EC 3.5.2.2) and allantoinases (EC 3.5.2.5). Our results suggests that the enzymes of this protein superfamily have evolved from a common ancestor and therefore are the product of divergent evolution. We show further that the enclosed gene families developed very early in evolution, probably prior to the formation of the three domains, Archaea, Eukarya and Bacteria. Hydantoinases related to ATP-dependent N-methylhydantoinases (EC 3.5.2.14) or 5-oxoprolinases (EC 3.5.2.9) do not belong to this superfamily.

The diurnal variation in blood pressure should be calculated from individually defined day and night times

The aim of this study was to compare the nocturnal fall in BP parameters calculated from individually defined periods of day and night to values computed from collectively fixed day/night definitions. Day and night periods were defined according to 3 different methods: (i) the individually defined time of getting up and going to bed obtained from participant diaries (MethodIND); (ii) the mean time of rising and retiring in the group (MethodMEAN); and (iii) a daytime period from 07.00-22.00 h as recommended by The Scientific Committee (Method722). The ambulatory BP was recorded every 30 min over 24 h. One hundred and eighty-seven persons aged 40-66 years participated. With MethodIND, the BP load, systolic, diastolic and mean BPs were higher in the daytime and lower in the night-time compared to the results using Method722 and MethodMEAN. The nocturnal BP fall using MethodIND was larger than the fall calculated from every possible fixed division in the period from 3 h before till 3 h after the group mean time of getting up and going to bed (p < 0.001). The lowest frequency of non-dipping, defined as a nightly fall in systolic and diastolic BP below 10%, was observed using MethodIND (10%). Compared to MethodIND, 11% were misclassified as non-dippers by Method722 and 8% by MethodMEAN. We conclude that the diurnal blood pressure variation based on individually defined periods of day and night is larger than the variation based on any collectively fixed day/night definition. It is recommended that assessment of the nocturnal change in BP be based on individually defined periods of day and night.

Substrate-dependent enantioselectivity of a novel hydantoinase from Arthrobacter aurescens DSM 3745: purification and characterization as new member of cyclic amidases

A hydantoinase from Arthrobacter aurescens DSM 3745 has been purified to homogeneity with a yield of 77% using a three-step purification procedure. The active enzyme is a tetramer consisting of four identical subunits, each with a molecular mass of 49670 Da as determined by mass spectrometry. The N-terminal amino acid sequence of the enzyme indicates sequence identities to cyclic amidases involved in the nucleotide metabolism as the D-hydantoinase from Agrobacterium radiobacter (53%), the D-selective dihydropyrimidinase from Bacillus stearothermophilus (38%), the allantoinase from Rana catesbeiana (26%), as well as to the catalytic subunit of the urease from Helicobacter pylori (50%). However, all studies based on substrate-dependent growth, induction and catalytic behavior documented the novelty of the bacterial hydantoinase and that its physiological role is not related to any of these enzymes or known metabolic pathways. Its substrate specificity differs from hydantoinases listed in Enzyme Nomenclature and is rather more predominant for the cleavage of aryl- than for alkyl-hydantoin derivatives. It is shown that the stereoselectivity of this enzyme depends on the substrate used for bioconversion: although it is strictly L-selective for the cleavage of D,L-5-indolylmethylhydantoin, it appears to be D-selective for the hydrolysis of D,L-methylthioethylhydantoin. Due to these findings we conclude that this novel bacterial hydantoinase should be classified as a new member of the EC-group 3.5.2 of cyclic amidases.

Prevalence and prediction of silent ischaemia in diabetes mellitus: a population-based study

OBJECTIVES

The aim of the study was to estimate the prevalence of silent ischaemia in diabetic subjects in the population, to compare the prevalence of silent ischaemia in diabetics and non-diabetics and to attempt to predict the presence of silent ischaemia in diabetic subjects.

METHODS

A random sample of 120 users of insulin and 120 users of oral hypoglycaemic agents aged 40-75 years living in the Danish municipality of Horsens were asked to participate in the study. Corresponding to the youngest half of the sample two non-diabetic controls were randomly selected from the Central Population Register. ST-depression of horizontal or descending character of at least 0.1 mV measured 80 ms after the J-point on either exercise ECG or Holter ECG was considered indicative of myocardial ischaemia. Angina pectoris was considered present if the Rose questionnaire was positive, or chest pain was registered simultaneously with ECG evidence of ischaemia. Individuals with ischaemia, but without angina pectoris, were defined as persons with silent ischaemia.

RESULTS

Seventy-four percent of the invited group were included. The observed prevalence of silent ischaemia in diabetics was 13.5% (95% CI = 8.5-19.8%). No association was found between silent ischaemia and gender (P = 0.83) or diabetes type (P = 0.67). In the group of diabetics who had controls, the prevalence was 11.4%, and among the controls the prevalence was 6.4% (OR = 1.87, one-sided P = 0.079). Systolic blood pressure was highly predictive of silent ischaemia in the diabetic subjects (P = 0.005). No predictive value could be shown for other variables.

CONCLUSION

This is the first population-based study of silent ischaemia in diabetes. The prevalence of silent ischaemia in diabetic subjects was 13.5%. The frequency of silent ischaemia did not differ significantly between diabetics and non-diabetics. Systolic blood pressure was predictive of silent ischaemia in diabetes.