Hypofractionated stereotactic body radiotherapy in spinal metastasis - with or without epidural extension.

AIMS: To evaluate clinical outcome and the effect of malignant epidural compression (MEC) in the treatment of spine metastasis with stereotactic body radiotherapy (SBRT). MATERIALS AND METHODS: Seventy-six lesions in 52 patients with spinal metastasis received SBRT during the period July 2010 to December 2012. MEC was detected in 20 patients (38.4%) and was separately contoured. The median dose prescribed to involved vertebra (planning target volume) was 24 Gy (range 24-27 Gy) in a median of three fractions (range 1-3). Uninvolved elements were prescribed 21 Gy in three fractions. In 59 lesions (77.6%), the entire vertebra was treated and in 17 lesions (22.4%) only the anterior elements were treated. All patients were treated with volumetric modulated arc therapy with image guidance on a Novalis Tx linear accelerator with the ExacTrac system. Dosimetric and clinical outcomes were compared in patients with or without MEC. RESULTS: At a median follow-up of 8.48 months (range 3-40 months), 1 year local control and overall survival was 94 and 68%, respectively. In patients with or without epidural extension, the median dose to the gross tumour volume (GTV; 95%) was 23.48 Gy (range 13.70-25.75) and 22.99 Gy (range 13.55-26.84), the median spinal cord Dmax was 17.36 Gy (range 8.47-21.63) and 15.71 Gy (range 8.39-23.33). The median GTV epidural (D95%) was 21.16 Gy (range 15.43-23.92). Complete pain relief was seen in 90% of patients with MEC and 93.75% without MEC (P=NS) and neurological improvement was seen in 60% of patients in both groups of patients. CONCLUSION: It is feasible to deliver a high dose of radiation (∼90% of the prescription dose) to the epidural component with volumetric modulated arc therapy SBRT and image guidance. It yielded high rates of pain control and local control in patients with spine metastases with or without MEC.

Effect of intra-aortic balloon pumping on nutrient coronary flow in normal and ischemic myocardium.

The effects of intra-aortic balloon pumping (IABP) on myocardial flow distribution were studied in 50 dogs. Cardiac output was controlled by right heart bypass. In each dog the following parameters were measured with and without IABP during normal coronary perfusion and after regional ischemia was induced by anterior descending coronary vein flow by timed collection, and endocardial/epicardial flow ratios by a previously reported thermal washout technique. In nonischemic myocardium, IABP significantly (p less than 0.05) increased mean coronary sinus flow 11.5 percent +/- 5.8 percent (S.D.) and the mean endocardial/epicardial ratio, 17.3 percent +/- 0.28 percent. In the regionally ischemic myocardium, IABP significantly (p less than 0.05) increased mean segmental coronary vein flow 13.9 percent +/- 1.23 percent but decreased the endocardial/epicardial ratio 29.9 percent +/- 1.1 percent. We conclude that in the dog, IABP enhances subendocardial blood flow in perfused but not in ischemic myocardium. Contrary to common suppositions, the increase in collateral blood flow with IABP preferentially supplies epicardial layers in segmental ischemic zones, but may be shunted from the subendocardium.

Topical myocardial cooling. An intensive laboratory investigation.

To better understand efficacy of topical cooling in myocardial protection, three groups of 12 dogs each were studied. Group 1 dogs had systemic cooling to 30 C; group 2 had cooling to 30 C and outside cooling of left ventricle; group 3 was cooled in the same way as group 2 was but also had inside of left ventricle topically cooled. Measurements were taken of left ventricular function curves, regional blood flow distribution to the subendocardium, sequential pH, PCO2, PO2, and lactate and serum glutamic oxaloacetic transaminase (SGOT) levels. Lower midseptal and subendocardial temperature (means, 11 and 7 C, respectively) in group 3 correlated with higher survival and greater preservation of left ventricular function. Lower levels of SGOT and lactate in coronary sinus efflux, and higher regional flow to subendocardium postoperatively, also correlated with minimal evidence of subendocardial necrosis in group 3 dogs. Rapid of cooling of subendocardium was noted as achieving maximum preservation of left ventricular function.

A method for revascularization of circumflex marginal coronary arteries.

The transverse sinus route for bypassing high marginal circumflex coronary arteries facilitates the operation and obviates potential kinking sites at the left atrial appendage and pericardial reflection over the pulmonary veins. The vein bypass emerges from the transverse sinus and closely parallels the marginal circumflex coronary vessels.

Comparative hemodynamic properties of vein and mammary artery in coronary bypass operations.

To understand better the observed differences in bypass flows between vein and internal mammary artery (IMA) grafts, a technique was devised for anastomosing both vein and IMA to the same anterior descending coronary artery in 14 patients. In the stable postperfusion state, flows in the two bypass conduits were simultaneously recorded as well as pressure relationships in both grafts and the left ventricle. The supply/demand ratio for left ventricular performance was calculated with respect to the diastolic pressure-time index/tension-time index (DPTI/TTI) for each bypass independently and simultaneously and then compared. The DPTI/TTI ratio was nearly two times greater with the vein bypass than with the IMA. This difference was further confirmed by the flow studies, in which blood flow through the vein ranged 2 to 3 times higher than IMA flow to the same coronary bed. By present criteria the DPTI/TTI ratio for IMA grafts to the left ventricle was inadequate in the majority of patients studied, and atrial pacing markedly lowered the DPTI/TTI ratio of the IMA. The choice of vein or IMA as a bypass is a critical determinant of the resultant bypass-left ventricular DPTI/TTI ratio. Vein bypasses exhibited far superior hemodynamic capability in the resting state, and the effect of atrial pacing on the DPTI/TTI ratio in IMA-vein-left ventricle bypasses confirms this point.

Prognostic considerations in the management of left ventricular aneurysms.

This report summarizes a four-year experience with 60 patients who had left ventricular aneurysm (LVA) resection and bypass of all significantly diseased coronary arteries, with an operative and late mortality of 3.3 and 8.3%, respectively. Their cardiac catheterizations were reviewed, and the only values that seemed to reflect prognosis were preoperative cardiac index and the presence of absence of septal motion. The lower the cardiac index, the less likely the patient was to do well postoperatively. There were now survivors who had lacked septal motion by left anterior oblique ventriculogram. Patients without septal motion are therefore no longer considered surgical candidates. If septal motion is present, resection of LVA carries no more risk than myocardial revascularization without LVA.

Factors predictive of perioperative myocardial infarction during coronary operations.

The diagnosis of perioperative myocardial infarction (PMI) in our patients was based upon electrocardiography, vectorcardiography, and postoperative enzyme changes. A group of 303 patients operated on between January and September, 1972, formed the basis of this study. Three groups were identified from among these patients. Group A was composed of 90 consecutive patients in whom MI was excluded by all criteria. Group B comprised 25 patients with proved MI and yielded the 8% incidence of MI among our patients. Group C included 34 patients with triple-vessel disease who did not sustain MI. Significantly more patients sustaining MI had preinfarction angina and severe coronary artery disease. The incidence of MI was also higher in patients with diffuse disease and those in whom the lesions could not be totally bypassed. A statistical correlation with longer pump runs and periods of anoxia was obtained. There was some suggestion that the preoperative location of the hypokinetic segment determined the site of MI in patients.

Beri-beri: the major cause of infant mortality in Karen refugees.

During a prospective evaluation of malaria prophylaxis in pregnancy in a refugee population on the north-western border of Thailand from 1987 to 1990, an extremely high infant mortality rate (18%) was documented despite good access to health care. Infantile beri-beri was recognized as the main cause of death accounting for 40% of all infant mortality. Thereafter, severe vitamin B1 deficiency in infants was diagnosed and treated promptly. The impact of this was assessed prospectively from 1993 to 1996 in a second cohort study. The case fatality of infantile beri-beri fell from almost 100% to 7%. The overall infant mortality rates declined from 183 to 78 per 1000 live births. Post-neonatal deaths fell by 79% (95% CI 65-87%) while neonatal mortality remained unchanged. Mortality resulting from acute respiratory infections did not change (15 and 11 per 1000, respectively), whereas mortality attributable to beri-beri decreased from 73 to 5 per 1000 (P < 0.0001). Before its recognition approximately 7% of all infants in this population died from infantile beri-beri. This lethal but preventable syndrome may be more common than hitherto recognized, particularly in refugee populations, in this populous region.

Research priorities for rice pest management in tropical Asia: a simulation analysis of yield losses and management efficiencies.

ABSTRACT A simulation study was conducted to assess the current and prospective efficiency of rice pest management and develop research priorities for lowland production situations in tropical Asia. Simulation modeling with the RICEPEST model provided the flexibility required to address varying production situations and diverse pest profiles (bacterial leaf blight, sheath blight, brown spot, leaf blast, neck blast, sheath rot, white heads, dead hearts, brown plant-hoppers, insect defoliators, and weeds). Operational definitions for management efficacy (injury reduction) and management efficiency (yield gain) were developed. This approach enabled the modeling of scenarios pertaining to different pest management strategies within the agroecological contexts of rice production and their associated pest injuries. Rice pests could be classified into two broad research priority-setting categories with respect to simulated yield losses and management efficiencies. One group, including weeds, sheath blight, and brown spot, consists of pests for which effective pest management tools need to be developed. The second group consists of leaf blast, neck blast, bacterial leaf blight, and brown plant-hoppers, for which the efficiency of current management methods is to be maintained. Simulated yield losses in future production situations indicated that a new type of rice plant with high-harvest index and high-biomass production ("New Plant Type") was more vulnerable to pests than hybrid rice. Simulations also indicated that the impact of deployment of host resistance (e.g., through genetic engineering) was much larger when targeted against sheath blight than when targeted against stem borers. Simulated yield losses for combinations of production situations and injury profiles that dominate current lowland rice production in tropical Asia ranged from 140 to 230 g m(-2). For these combinations, the simulated efficiency of current pest management methods, expressed in terms of relative yield gains, ranged from 0.38 to 0.74. Overall, the analyses indicated that 120 to 200 x 10(6) tons of grain yield are lost yearly to pests over the 87 x 10(6) ha of lowland rice in tropical Asia. This also amounts to the potential gain that future pest management strategies could achieve, if deployed.

Rice Pest Constraints in Tropical Asia: Characterization of Injury Profiles in Relation to Production Situations.

A protocol for characterizing patterns of rice cropping practices and injuries due to pathogens, insects, and weeds was developed and used in six sites in tropical Asia covering a wide range of environments where lowland rice is cultivated. The data collected in a total population of 456 individual farmers' fields were combined to site-specific weather data and analyzed using non-parametric multivariate techniques: cluster analyses with chi-square distance and correspondence analyses. The main results are: (i) patterns of cropping practices that are common across sites can be identified; (ii) conversely, injury profiles that are common across sites can be determined; (iii) patterns of cropping practices and injury profiles are strongly associated at the regional scale; (iv) weather patterns are strongly associated with patterns of cropping practices and injury profiles; (v) patterns of cropping practices and injury profiles allow for a good description of the variation in actual yield; and (vi) patterns of cropping practices and injury profiles provide a framework that accurately reflects weather variation and site diversity, and reliably accounts for variation in yield. The mean estimated yield across sites (4.12 t ha-1) corresponds to commonly cited averages in the region and indicates the potential for increased productivity with better management practices, especially an improved water supply. Injuries due to pests are secondary compared with other yield-limiting factors. Injury profiles were dominated by stem rot and sheath blight (IN1); bacterial leaf blight, plant hoppers, and leaf folder (IN2); and sheath rot, brown spot, leaf blast, and neck blast (IN3). IN1 was associated with high (mineral) fertilizer inputs, long fallow periods, low pesticide use, and good water management in (mostly) transplanted rice crops of a rice-rice rotation. IN2 was associated with direct-seeded rice crops in an intensive rice-rice rotation, where fertilizer and pesticide inputs are low and water management is poor, or where fertilizer and pesticide inputs are high and water management is adequate. IN3 corresponds to low input, labor intensive (hand weeding and transplanting) rice crops in a diverse rotation system with uncertain water supply. Weed infestation was an omnipresent constraint. This study shows the potential for developing pest management strategies that can be adapted throughout the region, rather than being site-specific.

Segmental ventricular adjustments to brief periods of ischemia in the dog.

The changes in left ventricular segmented contractile force induced by brief periods of ischemia (15-90 s) and subsequent reperfusions were analyzed in anesthetized dogs. Segmental coronary artery occlusion (left anterior descending or left circumflex) produced a decrease in segmental ventricular function in the occluded area and an increase in contractile force in the myocardial segment away from the occluded area. With reperfusion, a transient overshoot in contractile force above preischemic control levels was observed in the occluded segment. This overshoot was shown not to be dependent on adrenergic mechanisms but appears to indicate changes in calcium permeability.