[As opposed to normal subjects, eyelid position doesn't interfere with postural behavior in blind subjects]. / Contrairement aux sujets normaux, la position des paupières n'interagit pas sur les stratégies de contrôle de l'équilibre chez les personnes non-voyantes.

AIM OF THE STUDY: A previous study has shown some behavioral differences in normal subjects depending on the position of the eyelids: the postural behavior was varying if the subject had the eyes open in darkness or the eyes closed. In this study, we explore the possible role of vision on this behavior. PATIENTS AND METHODS: The postural behavior of 12 blind and nine visually impaired participants was studied during undisturbed upright stance. RESULTS: In this sample, no difference was found in the conditions eyes open in the dark and eyes closed: the observed behavior in blind and visually impaired subjects is different compared to normal sighted subjects who show a visual preference even in total darkness when the eyes are open. Our two groups (blind and visually impaired) actually show a difference on the median frequency of the centre of gravity displacements. CONCLUSION: Our results suggest an adaptive mechanism of the central nervous system in healthy individuals to predominantly weigh visual cues when the eyelids remain open. Good visual acuity and time seem to be necessary for this process.

Neuroprotective natural antibodies to assemblies of amyloidogenic peptides decrease with normal aging and advancing Alzheimer's disease.

A number of distinct beta-amyloid (Abeta) variants or multimers have been implicated in Alzheimer's disease (AD), and antibodies recognizing such peptides are in clinical trials. Humans have natural Abeta-specific antibodies, but their diversity, abundance, and function in the general population remain largely unknown. Here, we demonstrate with peptide microarrays the presence of natural antibodies against known toxic Abeta and amyloidogenic non-Abeta species in plasma samples and cerebrospinal fluid of AD patients and healthy controls aged 21-89 years. Antibody reactivity was most prominent against oligomeric assemblies of Abeta and pyroglutamate or oxidized residues, and IgGs specific for oligomeric preparations of Abeta1-42 in particular declined with age and advancing AD. Most individuals showed unexpected antibody reactivities against peptides unique to autosomal dominant forms of dementia (mutant Abeta, ABri, ADan) and IgGs isolated from plasma of AD patients or healthy controls protected primary neurons from Abeta toxicity. Aged vervets showed similar patterns of plasma IgG antibodies against amyloid peptides, and after immunization with Abeta the monkeys developed high titers not only against Abeta peptides but also against ABri and ADan peptides. Our findings support the concept of conformation-specific, cross-reactive antibodies that may protect against amyloidogenic toxic peptides. If a therapeutic benefit of Abeta antibodies can be confirmed in AD patients, stimulating the production of such neuroprotective antibodies or passively administering them to the elderly population may provide a preventive measure toward AD.

Unspecific elevation of plasma troponin-T and CK-MB after coronary surgery.

OBJECTIVE: Biochemical markers of myocardial injury are frequently elevated after cardiac surgery. It is generally accepted that release unrelated to permanent myocardial damage explains a proportion of these elevations. However, little is known about the magnitude and temporal characteristics of this diagnostic noise. One way to address this issue would be to study a group without permanent myocardial injury. DESIGN: The unique release kinetics of troponin-T (permanent myocardial injury causes a sustained release of structurally bound troponin) were used to identify patients with no or minimal permanent myocardial injury. Blood was sampled from patients undergoing coronary artery bypass grafting (CABG) with cardiopulmonary bypass (CPB) before surgery, 3 and 8 h after unclamping the aorta, and each morning until postoperative day 4, for analysis of enzymes and troponin-T. From 302 consecutive patients a subgroup was identified that fulfilled the following criteria: (a) normalized troponin-T levels < or = postoperative day 4; (b) no ECG changes indicating myocardial injury. RESULTS: Seventy-seven patients fulfilled the criteria above and in this subgroup troponin-T (2.08 +/- 1.42 microg/l; range 0.35-8.99 microg/l) peaked at the 3 h recording and creatine kinase monobasic (CK-MB) (28.6 +/- 11.3 microg/l; range 11.9-86.0 microg/l) peaked at the 8 h recording after unclamping the aorta. CONCLUSION: Substantial early elevations of plasma CK-MB and troponin-T occurred in patients with no or minimal permanent myocardial injury after CABG. Unspecific release was most pronounced during the timeframe that is usually studied to evaluate myocardial protective strategies or to compare revascularization procedures.

Are overground or treadmill runners more likely to sustain tibial stress fracture?

BACKGROUND: Repetitive high bone strain and/or strain rates, such as those that occur during running, contribute to stress fractures as well as promoting maintenance of or increase in bone mass. Kinematic differences are known to exist between overground and treadmill running and these may be reflected in different bone strains and strain rates during the two running techniques. AIM: To measure in vivo strains and strain rates in human tibia during treadmill and overground running and determine if there are significant differences in strain and strain rate levels between the two running techniques. METHODS: A strain gauged bone staple was mounted percutaneously along the axial direction in the mid diaphysis of the medial tibia in three subjects, and in vivo tibial strains were measured during treadmill and overground running at 11 km/h. RESULTS: Axial compression strains (p<0.0001), tension strains (p<0.001), compression strain rates (p<0.0001), and tension strain rates (p<0.0001) were 48-285% higher during overground running than during treadmill running. CONCLUSIONS: On the basis of lower in vivo strains and strain rates, treadmill runners are at lower risk of developing tibial stress fractures, but less likely to achieve tibial bone strengthening, than overground runners.

Early identification of permanent myocardial damage after coronary surgery is aided by repeated measurements of CK-MB.

OBJECTIVE: ECG diagnosis of myocardial infarction after cardiac surgery is associated with major pitfalls and enzyme diagnosis is interfered by unspecific elevation unrelated to permanent myocardial injury. Sustained release of troponin-T is a marker of permanent myocardial injury if renal function is maintained. However, early identification of perioperative myocardial infarction is desirable and therefore the usefulness of creatine kinase monobasic (CK-MB) kinetics to detect myocardial injury early after coronary surgery was investigated. DESIGN: Two hundred and eighty-six patients undergoing coronary surgery were studied with respect to release of enzymes and troponin-T preoperatively and postoperatively 3 and 8 h after unclamping the aorta, and every morning postoperative days 1-4. RESULTS: CK-MB peak was found at 3 h (n = 145), 8 h (n = 103) and 16-20 h after unclamping (n = 38). Depending on when the CK-MB peak was recorded different demographic and perioperative characteristics were found. A sustained release of troponin-T was characteristic for the group with the CK-MB peak at 16-20 h after unclamping. CONCLUSION: If CK-MB is measured only once it may be advisable to do it on the first postoperative morning as these measurements provided the best discrimination between patients with and without sustained elevation of troponin-T. However, repeated sampling provides additional information that aids in the early identification of permanent myocardial injury particularly in patients with borderline elevations of CK-MB.

Heart rescue in acute left main coronary artery occlusion with CABG using initial retrograde perfusion.

Acute occlusion of the left main coronary artery (LMCA) is a rare and almost invariably fatal condition. Here, we report on heart salvage in two such cases with CABG aided by emergent retrograde reperfusion as the initial operative step. Both cases were extremely unusual. The first patient had twice survived LMCA occlusion; the second also had right coronary artery occlusion. We will also review the literature on acute LMCA occlusion and coronary venous retroperfusion.

Aortic valve replacement with pericardial valves in patients with small aortic roots. Clinical results in a consecutive series of patients receiving 19 and 21 mm prostheses.

OBJECTIVE: To determine how second generation pericardial valves perform in patients with small aortic roots. DESIGN: Ninety patients who underwent isolated aortic valve replacement (AVR) with 19 or 21 mm Mitroflow or Carpentier-Edwards (Perimount) valves between 1989 and 1996 were studied. Mean age was 78 years. Concomitant coronary bypass surgery was performed in 41%. RESULTS: Thirty-day mortality was 5.6%. Ninety-seven percent had acceptable transprosthetic mean pressure gradients (25 mmHg or less) 1 week after surgery. Follow-up was 100% complete and 76% of the patients were alive after a mean of 5 years. There was no structural valve failure or valve thrombosis. One patient required reoperation for perivalvular leak. Four patients had transient ischemic attacks and seven had strokes. These figures are, however, within the expected range for the age. CONCLUSION: Second generation pericardial valves perform well in elderly patients with small aortic roots. Postoperative hemodynamics are acceptable, valve durability of up to 8 years adequate, and the clinical results good, considering the age of the patients.

Perioperative myocardial infarction in cardiac surgery--risk factors and consequences. A case control study.

OBJECTIVE: The aim of the study was to analyze risk factors and clinical outcome in patients sustaining perioperative myocardial infarction (PMI) after cardiac surgery. DESIGN: A retrospective, case control study was conducted, in which 42 patients fulfilling both Q-wave criteria and enzyme criteria for PMI, or autopsy diagnosis, from a cohort of 1147 operated on during the same time period were compared with matched controls. A follow-up by telephone interview was conducted, on average 24 months after the operation. RESULTS: Unstable angina, peripheral vascular disease, short stature and low body weight were more prevalent in the PMI group. Intraoperative remarks of poor quality coronary vessels and incomplete revascularization were more frequent in the PMI group; 30-day mortality was 24% in the PMI group vs 0% in the control group (p < 0.01). The postoperative course was more complicated and protracted in the PMI group. At follow-up, the control group managed significantly better with regard to freedom from angina and the need for nitroglycerine. However, 24 of the 30 survivors in the PMI group reported an improved quality of life after surgery. CONCLUSIONS: We found that PMI was mainly associated with coronary surgery and that unstable angina was the most important preoperative risk factor for PMI. Poorer conditions for revascularization may explain some of the infarcts and could also contribute to the impaired long-term outcome in the PMI group.

Minimal access aortic valve surgery.

OBJECTIVE: We report our experience with minimal access aortic valve surgery and discuss the three approaches used. METHODS: From June 1996 to October 1997, 18 patients underwent minimally invasive aortic valve surgery through three different incisions: right parasternal minithoracotomy (three cases), upper ministernotomy (11 cases), and transverse sternotomy (four cases). No special surgical instrumentation was used. Aortic valve replacement was carried out in 17 patients and aortic valve repair in one patient. The patients ranged in age from 42 to 86 years (mean 64 years). Concomitant procedures involving the aortic root and the ascending aorta were performed in five patients. RESULTS: There was no mortality and no complications related to the procedure or the access. There was no instability or paradoxical movement of the chest wall. One patient was reoperated for postoperative bleeding. All patients were discharged from hospital within the usual time. No attempts were made to discharge them earlier, even if they recovered quickly. CONCLUSIONS: Of the three incisions used, the upper ministernotomy seemed to be the safest and easiest to perform. Through this incision, both the aorta and the right atrium could be cannulated, the right ventricle was accessible, and concomitant procedures on the ascending aorta could be carried out. The drawback of minimal access aortic valve surgery in general is that it is difficult to de-air the heart and more difficult to master intra- and postoperative complications should they occur.

Are electrocardiographic Q-wave criteria reliable for diagnosis of perioperative myocardial infarction after coronary surgery?

OBJECTIVE: A major assumption in cardiovascular medicine is that Q-waves on the electrocardiogram indicate major myocardial tissue damage. The appearance of a new Q-wave has therefore been considered the most reliable criterion for diagnosis of perioperative myocardial infarction (PMI) in cardiac surgery. In a study, originally intended to evaluate troponin-T as a marker of PMI, analysis of our data aroused the need to address the reliability of Q-wave criteria for diagnosis of PMI. METHODS: In 302 consecutive patients undergoing coronary surgery, Q-wave and other electrocardiogram (ECG) criteria were compared with biochemical markers of myocardial injury and the postoperative course. All ECGs were analysed by a cardiologist blinded to the biochemical analyses and the clinical course. RESULTS: The incidence of positive Q-wave criteria was 8.1%. Combined biochemical (CK-MB > or = 70 microg/l) and Q-wave criteria were found in 1.0%. Patients with new Q-waves did not have CK-MB or troponin-T levels significantly different from those without Q-waves. More than 25% of the Q-waves were associated with plasma troponin-T below the reference level (< 0.2 microg/l) on the fourth postoperative day. Q-wave criteria alone did not influence the postoperative course. In contrast, biochemical markers correlated with clinical outcome. CONCLUSIONS: The majority of Q-waves appearing after coronary surgery were not associated with major myocardial tissue damage, and according to troponin-T one-fourth of the Q-waves were not associated with myocardial necrosis. Furthermore, the appearance of Q-waves had little influence on short term clinical outcome. Therefore, the use of Q-wave criteria as the gold standard for diagnosis of PMI may have to be questioned.

Phenotypic alterations in circulating monocytes induced by open heart surgery using heparinized and nonheparinized cardiopulmonary bypass systems.

In this study of 31 patients with coronary bypass surgery, we used flow cytometry to compare heparin-coated and noncoated cardiopulmonary bypass systems on leukocyte activation. We found significant differences between the groups during bypass, with activation of the complement system, measured as elevated levels of C3a desArg, upregulation of granulocyte beta2 integrin (CD11b), and a loss of circulating monocytes when noncoated systems were used. In both groups an early increase in the monocyte cell surface CD62L expression was obvious while the percentage of human leukocyte antigen (HLA)-DR positive monocytes did not alter. The morning after the operation, leukocytosis was present, together with a highly significant reduction in the monocyte expression of CD11b and HLA-DR, indicating the recruitment to the peripheral blood of cells with altered phenotypes. This alteration in phenotype on potent inflammatory cells may be one part of the impaired function of the immunological system reported after major surgery.

Periprosthetic leaks and valve dehiscence: alternative methods of repair.

BACKGROUND AND AIMS OF THE STUDY: Reoperations for periprosthetic leaks (PL) and valve dehiscence (VD) are associated with high mortality and substantial recurrence rate. Standard methods of repair are often not feasible due to friability of the annulus tissue or lack of space to locate the sutures. We have therefore used a variety of unconventional methods to close the leaks securely. CLINICAL MATERIAL AND METHODS: The clinical records of 25 patients reoperated for PL and VD between 1989 and 1995 were reviewed. Eighteen patients had aortic and seven mitral PL. Patients with mechanical heart valves were more frequently reoperated than those with bioprostheses (2.1% versus 0.7%). The PL was repaired in 16 cases, and the prosthesis was exchanged in nine cases with VD or large leaks. Six of the latter nine patients had active prosthetic endocarditis. A variety of surgical techniques was used to repair the leaks, including placing sutures from outside the aortic wall, through the atrial and ventricular septum, through the free left atrial wall and closure by single or double patch technique. RESULTS: Hospital mortality was 4% (1/25 patients) and one-year mortality 12.5%. None of the patients except one with active prosthetic endocarditis needed a second reoperation. CONCLUSIONS: If PLs are difficult to close with standard surgical technique, the alternative methods described might be useful. These methods can also be used during primary valve replacements where leaks remain.