An optomechanogram for assessment of the structural and mechanical properties of tissues.

The structural and mechanical properties of tissue and the interplay between them play a critical role in tissue function. We introduce the optomechanogram, a combined quantitative and qualitative visualization of spatially co-registered measurements of the microstructural and micromechanical properties of any tissue. Our approach relies on the co-registration of two independent platforms, second-harmonic generation (SHG) microscopy for quantitative assessment of 3D collagen-fiber microstructural organization, and nanoindentation (NI) for local micromechanical properties. We experimentally validate our method by applying to uterine cervix tissue, which exhibits structural and mechanical complexity. We find statistically significant agreement between the micromechanical and microstructural data, and confirm that the distinct tissue regions are distinguishable using either the SHG or NI measurements. Our method could potentially be used for research in pregnancy maintenance, mechanobiological studies of tissues and their constitutive modeling and more generally for the optomechanical metrology of materials.

A preliminary investigation into a simple method for the determination of the mean ionisation energy of gas mixtures used in the NPL primary gas counting system.

The activity concentration of gaseous beta-emitting radionuclides such as (3)H, (85)Kr and, more recently, (11)C, is measured at NPL using a set of length-compensated proportional counters. The active gas is mixed with argon-methane (P-10) and passed to the counters. Adding gases to P-10 changes the mean ionisation energy, W, of the gas mixture. Estimation of the counting losses using the Monte Carlo model requires a knowledge of W. Unfortunately, only a limited amount of published data is available. This paper describes the initial experimental studies performed to enable the extension of the MC model based loss correction method to gases other than carbon dioxide in P-10. Preliminary measurements have been made to determine the W value for a gas mixture containing (85)Kr in nitrogen and P-10. The DC current through the counters is measured; the counters are also operated in the normal way with pulse amplifiers, discriminators and scalers. The value of W is derived from a knowledge of activity, counter current and mean beta energy.

Randomised controlled trial of exercise for low back pain: clinical outcomes, costs, and preferences.

OBJECTIVE: To evaluate effectiveness of an exercise programme in a community setting for patients with low back pain to encourage a return to normal activities. DESIGN: Randomised controlled trial of progressive exercise programme compared with usual primary care management. Patients' preferences for type of management were elicited independently of randomisation. PARTICIPANTS: 187 patients aged 18-60 years with mechanical low back pain of 4 weeks to 6 months' duration. INTERVENTIONS: Exercise classes led by a physiotherapist that included strengthening exercises for all main muscle groups, stretching exercises, relaxation session, and brief education on back care. A cognitive-behavioural approach was used. MAIN OUTCOME MEASURES: Assessments of debilitating effects of back pain before and after intervention and at 6 months and 1 year later. Measures included Roland disability questionnaire, Aberdeen back pain scale, pain diaries, and use of healthcare services. RESULTS: At 6 weeks after randomisation, the intervention group improved marginally more than the control group on the disability questionnaire and reported less distressing pain. At 6 months and 1 year, the intervention group showed significantly greater improvement in the disability questionnaire score (mean difference in changes 1.35, 95% confidence interval 0.13 to 2.57). At 1 year, the intervention group also showed significantly greater improvement in the Aberdeen back pain scale (4.44, 1.01 to 7.87) and reported only 378 days off work compared with 607 in the control group. The intervention group used fewer healthcare resources. Outcome was not influenced by patients' preferences. CONCLUSIONS: The exercise class was more clinically effective than traditional general practitioner management, regardless of patient preference, and was cost effective.

Economic implications of the prophylactic use of intraaortic balloon counterpulsation in the setting of acute myocardial infarction. The Randomized IABP Study Group. Intraaortic Balloon Pump.

Intraaortic balloon counterpulsation (IABP) has been shown to improve coronary artery patency and reduce the rates of recurrent myocardial ischemia and its sequelae in selected patients when used within 24 hours of acute myocardial infarction. The economic implications of prophylactic IABP use are unknown. We obtained hospital bills for 102 patients enrolled in the Randomized IABP Trial (56%) and converted charges to costs using each hospital's Medicare cost report. In-hospital costs for patients who had 48 hours of IABP were compared with those of patients who did not. The costs of angiographic and clinical complications were determined. Small differences in clinical and angiographic characteristics existed between patients in the economic substudy and the overall population, but overall angiographic and clinical outcomes were comparable. Costs for patients who had IABP versus control patients were similar: mean $22,357 +/- $14,369 versus $19,211 +/- $8,414, median (25th and 75th percentiles) $17,903 ($15,787, $22,147) versus $17,913 ($15,144, $21,433), p = 0.45. Hospital costs were higher with the development of recurrent ischemia: mean $23,125 +/- $7,690 versus $20,416 +/- $12,449, median $21,069 ($17,896, $26,885) versus $17,492 ($14,892, $20,998) p = 0.02. Patients who had an adverse clinical event (death, stroke, reinfarction, and emergency revascularization) also had higher hospital costs: mean $25,598 +/- $10,024 versus $19,790 +/- $12,045, median $21,877 ($18,380, $28,049) versus $17,364 ($14,773, $20,779), p = 0.002. The prophylactic use of IABP in patients at high risk of infarct artery reocclusion within 24 hours of acute myocardial infarction provides sustained clinical benefit without substantially increasing hospital costs.

Use of the perfusion balloon as a primary dilation device.

The development of more user-friendly and versatile perfusion balloon catheters has increased the use of prolonged dilations as a primary catheter treatment for coronary artery disease. In a multicenter randomized trial, the use of these devices to prolong initial inflation durations resulted in improved angiographic outcomes when compared with conventional short dilations. This benefit was most apparent in stenoses with complex morphology. Use of the perfusion balloon as a primary device is also appealing because of its ability to reduce anginal pain and hemodynamic changes during balloon inflation. Clinical experience suggests that primary use of the perfusion balloon may improve patient stability during procedures in which the treated segment jeopardizes a large percentage of the functional myocardium. An observational series has demonstrated the excellent outcomes which can be achieved in selected patients using a strategy of primary perfusion angioplasty with stent bailout when needed. Selection of a perfusion balloon rather than a conventional balloon as a primary device has the potential to decrease overall balloon usage approximately 25%, but the economic benefit of this strategy will depend on the cost of the perfusion balloon relative to a conventional balloon. Retrospective analyses suggest that perfusion angioplasty as a primary treatment strategy compares favorably with directional atherectomy for left anterior descending lesions. The use of coronary stents has not been directly compared to perfusion angioplasty as a primary treatment for coronary lesions, but use of a perfusion balloon as an initial device may have broader applicability, lower cost and less technical demands on the operator compared to stent deployment. In conclusion, when overall applicability, clinical outcome and cost are considered, the primary strategy of prolonged dilation with a perfusion balloon should have an important role in coronary intervention.

Determination of red-cell mass in assessment and management of anaemia in babies needing blood transfusion.

A new method for the rapid determination of red-blood-cell mass (RCM) in infants needing blood transfusion is described. RCM is estimated from the fall in the baby's fetal haemoglobin level resulting from transfusion of a known mass of adult-haemoglobin-containing red cells. In severe blood loss and refractory anaemias in preterm infants, in addition to the red-cell deficit, the plasma volume is low, leading to a falsely high haematocrit of about 0.30, which conceals a deficiency of 50-70% in circulating red cells. Red-cell transfusion in such infants based on haematocrit often fails to restore RCM to normal, leading to repeated transfusions. The frequency of transfusions may be reduced by giving enough red cells fully to correct the deficiency based on RCM estimation.

Ultrasonic assessment of fetal growth in the nonhuman primate (Macaca mulatta).

Serial ultrasound measurements of fetal growth were made during uncomplicated pregnancy in 28 time-mated rhesus monkeys. Gestational sac (GS) size, crown-rump length (CRL), biparietal diameter (BPD), head circumference (HC), head area (HA), abdominal circumference (AC), abdominal area (AA), and femur length (FL) were measured. Average longitudinal growth curves for each parameter were obtained from individual fetal growth curves. Data analysis indicated that the linear model was optimal for GS, CRL, HA, AA, and FL. The linear-quadratic model was optimal for AC, and the linear-cubic model was optimal for BPD and HC.