ABO blood types: influence on infarct size, procedural characteristics and prognosis

Introduction

Patients with non-O blood groups have higher plasma von Willebrand factor (vWF) levels than those with type O. vWF mediates platelet adhesion, aggregation and thrombosis. These considerations likely explain the prior observations that non-O patients have higher rates of arterial and venous thromboembolic events. However, the effect of blood group status on size of MI, procedural findings and outcomes after PCI for MI have not been reported.

Methods

We analyzed 1198 patients who underwent percutaneous coronary intervention for acute myocardial infarction between 10/03 and 8/06, and who had ABO blood group status and clinical follow-up.

Results and conclusions

Patients with O blood type were slightly older (62 ± 13 vs. 60 ± 13years; p = 0.017) had a higher prevalence of hypercholesterolemia (67% vs. 58%; p = 0.002), and had a higher burden of atherosclerosis with more vascular disease (17% vs. 13%; p = 0.017) and higher prevalence of previous PCI (22% vs. 17%; p = 0.025). Non-O blood group patients had larger infarcts as measured by median peak troponin (33 vs. 24; p = 0.037), total CK (721 vs. 532; p = 0.012) and CK-MB (101 vs. 68; p = 0.010). At PCI, non-O patients had increased visible thrombus and reduced TIMI flow pre-procedure. However, there were no differences in procedural success, in-hospital blood transfusion or occurrence of MACE at 1year follow-up. Our data demonstrate that non-O compared to O blood groups patients have higher thrombus burden despite less extensive atherosclerosis. Nevertheless, outcomes at 1year were similar.     

Human fetal bone cells associated with ceramic reinforced PLA scaffolds for tissue engineering

Fetal bone cells were shown to have an interesting potential for therapeutic use in bone tissue engineering due to their rapid growth rate and their ability to differentiate into mature osteoblasts in vitro. We describe hereafter their capability to promote bone repair in vivo when combined with porous scaffolds based on poly(l-lactic acid) (PLA) obtained by supercritical gas foaming and reinforced with 5 wt.% beta-tricalcium phosphate (TCP). Bone regeneration was assessed by radiography and histology after implantation of PLA/TCP scaffolds alone, seeded with primary fetal bone cells, or coated with demineralized bone matrix. Craniotomy critical size defects and drill defects in the femoral condyle in rats were employed. In the cranial defects, polymer degradation and cortical bone regeneration were studied up to 12 months postoperatively. Complete bone ingrowth was observed after implantation of PLA/TCP constructs seeded with human fetal bone cells. Further tests were conducted in the trabecular neighborhood of femoral condyles, where scaffolds seeded with fetal bone cells also promoted bone repair. We present here a promising approach for bone tissue engineering using human primary fetal bone cells in combination with porous PLA/TCP structures. Fetal bone cells could be selected regarding osteogenic and immune-related properties, along with their rapid growth, ease of cell banking and associated safety.     

Hemodynamics of the sternocleidomastoid measured with frequency domain near-infrared spectroscopy towards non-invasive monitoring during mechanical ventilation

Mechanical ventilation (MV) is used to assist spontaneous breathing in critically ill patients in the intensive care unit (ICU). MV is a cornerstone of critical care medicine but it is now known that inspiratory muscle dysfunction due to injury, disuse, and/or atrophy during MV plays a major role in outcomes for these patients. For example, prolonged MV is strongly correlated with dysfunction of the sternocleidomastoid (SCM), an accessory inspiratory muscle that has been linked to weaning failure from MV. Hemodynamic monitoring of the SCM may provide an important non-invasive and real-time means to monitor MV. In this work, we first conducted multi-layer Monte Carlo simulations to confirm the ability of near infrared light to detect changes in the oxygenation of the SCM over wide ranges of skin tones and adipose layer thicknesses. We then optimized a custom digital frequency domain near-infrared spectroscopy (FD-NIRS) system for continuous 10 Hz measurements of the SCM at 730 nm and 850 nm. A healthy volunteer study was conducted (N=10); subjects performed sets of isometric neck flexions of the SCM. Substantial changes in oxyhemoglobin + oxymyoglobin (oxy[Hb + Mb]), deoxyhemoglobin + deoxymyoglobin (deoxy[Hb + Mb]), and total hemoglobin + myoglobin (total[Hb + Mb]) were observed during sustained and intermittent isometric flexions. There were notable sex differences observed in the magnitude of hemodynamic changes (∼2x larger changes in males for oxy[Hb + Mb] and deoxy[Hb + Mb]). The magnitude of hemodynamic changes when taking into account µ_s′ changes during flexions was ∼ 2-2.5x larger as compared to assuming constant scattering (CS), which is a common assumption used for continuous wave (CW) NIRS methods. This study suggests that FD-NIRS provides improved accuracy for hemodynamic monitoring of the SCM compared to CW-NIRS, and that FD-NIRS may provide value for SCM monitoring during MV.     

A survey of tobacco-related knowledge, attitudes and behaviours of primary care providers in Mississippi

Rationale  Relative to other regions in the USA, Mississippi has a high prevalence of tobacco use and tobacco-related disease. This study assessed the tobacco-related knowledge, attitudes and intervention behaviours of family doctors, dentists and nurse practitioners in the state of Mississippi.
Methods  The Provider Attitude Survey, an 85-item measure of tobacco-related knowledge, attitudes and intervention behaviours was mailed to all members of Mississippi's Family Medicine, Dentistry and Nurse Practitioner professional organizations ( N  = 2043).
Results  Over one-third ( n  = 802, 39.2%) of eligible providers responded. Just 24.3% had received training in tobacco cessation and 33.7% were aware of the Public Health Service clinical practice guideline. Over 90% indicated that it was their role to prevent tobacco use; felt rewarded when they helped patients quit; and were bothered and upset by the health effects of tobacco. Doctors assisted more patients than nurses or dentists. Doctors and nurses reported more self-efficacy, motivation and preparedness for treating tobacco use than dentists. Providers with training performed more interventions and reported more self-efficacy, preparedness and fewer barriers than those without training. Training was associated with greater increases in self-efficacy, preparedness and intervention behaviours for dentists than for the other groups.
Conclusions  Despite a high prevalence of tobacco use and tobacco-related disease in Mississippi, primary care providers in Mississippi provide tobacco cessation interventions at an unacceptably low frequency relative to other regions. Training is likely to increase the frequency of intervention behaviours.     

Deep hypothermia and circulatory arrest in adults

Brain protection during cardiopulmonary bypass has been the subject of intense research. Deep hypothermic circulatory arrest (DHCA) continues to be used for that goal during complex aortic arch and large intracranial aneurysm surgeries. The anesthetic management for adult patients undergoing these types of procedures requires specific knowledge and expertise. Based on our experience and review of the current literature, the authors highlight the key areas of the anesthetic plan, discussing the risk factors associated with adverse neurologic outcome as well as the rationale for decisions regarding specific monitors and medications. In the conclusion an anesthetic protocol for adult patients undergoing DHCA is suggested.     

Effect of Alendronate on Risk of Fracture in Women With Low Bone Density but Without Vertebral Fractures: Results From the Fracture Intervention Trial

Context.— Alendronate sodium reduces fracture risk in postmenopausal women who have vertebral fractures, but its effects on fracture risk have not been studied for women without vertebral fractures. Objective.— To test the hypothesis that 4 years of alendronate would decrease the risk of clinical and vertebral fractures in women who have low bone mineral density (BMD) but no vertebral fractures. Design.— Randomized, blinded, placebo-controlled trial. Setting.— Eleven community-based clinical research centers. Subjects.— Women aged 54 to 81 years with a femoral neck BMD of 0.68 g/cm² or less (Hologic Inc, Waltham, Mass) but no vertebral fracture; 4432 were randomized to alendronate or placebo and 4272 (96%) completed outcome measurements at the final visit (an average of 4.2 years later). Intervention.— All participants reporting calcium intakes of 1000 mg/d or less received a supplement containing 500 mg of calcium and 250 IU of cholecalciferol. Subjects were randomly assigned to either placebo or 5 mg/d of alendronate sodium for 2 years followed by 10 mg/d for the remainder of the trial. Main Outcome Measures.— Clinical fractures confirmed by x-ray reports, new vertebral deformities detected by morphometric measurements on radiographs, and BMD measured by dual x-ray absorptiometry. Results.— Alendronate increased BMD at all sites studied (P<.001) and reduced clinical fractures from 312 in the placebo group to 272 in the intervention group, but not significantly so (14% reduction; relative hazard [RH], 0.86; 95% confidence interval [CI], 0.73-1.01). Alendronate reduced clinical fractures by 36% in women with baseline osteoporosis at the femoral neck (>2.5 SDs below the normal young adult mean; RH, 0.64; 95% CI, 0.50-0.82; treatment-control difference, 6.5%; number needed to treat [NNT], 15), but there was no significant reduction among those with higher BMD (RH, 1.08; 95% CI, 0.87-1.35). Alendronate decreased the risk of radiographic vertebral fractures by 44% overall (relative risk, 0.56; 95% CI, 0.39-0.80; treatment-control difference, 1.7%; NNT, 60). Alendronate did not increase the risk of gastrointestinal or other adverse effects. Conclusions.— In women with low BMD but without vertebral fractures, 4 years of alendronate safely increased BMD and decreased the risk of first vertebral deformity. Alendronate significantly reduced the risk of clinical fractures among women with osteoporosis but not among women with higher BMD.      

The effects of high Mg2+-to-Ca2+ ratios on frequency potentiation in hippocampal slices of young and aged rats

In some central systems, excitatory postsynaptic potential (EPSP) amplitude increases substantially during repetitive synaptic stimulation ("frequency potentiation"), as does the probability of spike generation. An apparently analogous phenomenon at the neuromuscular junction ("frequency facilitation") depends on residual Ca2+ in nerve terminals. However, the mechanisms of central frequency potentiation are not completely defined and it is therefore not clear whether the patterns of Ca2+-dependent synaptic plasticity are fully analogous in central and peripheral systems. In addition, an age-related deficit in hippocampal frequency potentiation has been previously described, and the degree of sensitivity of this deficit to Mg2+-to-Ca2+ balance could yield important insights into its nature. In these studies, we used the hippocampal slice preparation to examine the effects of varying Mg2+-to-Ca2+ ratios in the artificial cerebrospinal fluid (ACF) on frequency potentiation in aged and young rats. Extracellular and intracellular methods were used to assess the responses of hippocampal CA1 neurons during orthodromic stimulation of the monosynaptic Schaffer-commissural pathway. In experiment 1, frequency potentiation of the hippocampal population spike during 7-Hz stimulation was found to be significantly greater in an ACF with a high Mg2+-to-Ca2+ ratio (2.7) than in an ACF with a normal Mg2+-to-Ca2+ ratio (0.5), for both young and aged rat slices. Aged slices exhibited less frequency potentiation than young in both media. In experiment 2, the field EPSP and population spike were monitored concurrently, and the differences in Mg2+-to-Ca2+ ratio between the high Mg2+-to-Ca2+ ACF ratio (2.0) and normal Mg2+-to-Ca2+ ACF ratio (1.0) were reduced, to determine whether aged and young brains differed in sensitivity to smaller variations in Mg2+-to-Ca2+ balance. Under these conditions, the effects of high Mg2+-to-Ca2+ ratios on frequency potentiation (at 7 Hz) were found to be most pronounced in aged rat slices, particularly for potentiation of the spike. No effects were seen of age or Mg2+-to-Ca2+ ratios on presynaptic fiber volley amplitudes. Field EPSP (but not spike) amplitudes were reduced with aging, in an input-output (I/O) stimulation series at control frequency (0.2 Hz). However, the high Mg2+-to-Ca2+ ACF ratio of (2.0), which improved field EPSP frequency potentiation, did not decrease control field EPSP amplitudes in the I/O series. Therefore, the effects of high MG2+-to-Ca2+ ACF ratio on brain frequency potentiation seem to be mediated in part by mechanisms other than the classical reduction of release probability.(ABSTRACT TRUNCATED AT 400 WORDS)     

The Use of Transesophageal Echocardiography to Guide Sternal Division for Cardiac Operations Via Mini-Sternotomy

A bstract Cardiac surgery utilizing the mini-sternotomy technique offers many advantages, including lessened pain and hospitalization. Mid-line upper sternotomy (or mini-sternotomy) can provide adequate exposure of the ascending aorta, the aortic root, the right atrial appendage and the dome of the left atrium. Inherent in providing adequate exposure is the level at which the sternum is "T'd" off. The lower aspect of the sternotomy is "I'd" off at the second, third, or fourth intercostal space depending on the patient's anatomy. We describe a technique that uses transesophageal echocardiography to determine the precise location for "T'ing" off the sternotomy, rather than approximating the sternotomy site by physical exam and chest radiograph. This technique will reliably delineate the sternotomy site, irrespective of a patient's body size and habitus.