Exotic earthworms can profoundly alter soil carbon (C) and nitrogen (N) dynamics in northern temperate forests, but the mechanisms explaining these responses are not well understood. We compared the ...soil microbial community (SMC) composition (measured as PLFAs) and enzyme activity between paired earthworm-invaded and earthworm-free plots in northern hardwood forests of New York, USA. We hypothesized that differences in SMCs and enzyme activity between plots would correspond with differences in soil C content and C:N ratios. Relative abundance of several bacterial (mostly gram-positive) PLFAs was higher and that of two fungal PLFAs was lower in earthworm compared to reference plots, largely because of earthworm incorporation of the organic horizon into mineral soil. In surface mineral soil earthworms increased arbuscular mycorrhizal fungi (AMF) and gram-positive bacterial PLFAs, and decreased fungal (mostly saprotrophic) and several bacterial (gram-negative and non-specific) PLFAs. Earthworms also increased the activities of cellulolytic relative to lignolytic enzymes in surface mineral soil, and the relationships between enzyme activities and components of the SMC suggest a substrate-mediated effect on the SMC and its metabolism of C. A highly significant relationship between components of the SMC and soil C:N also suggests that earthworms reduce soil C:N through functional and compositional shifts in the SMC. Finally, changes in AMF abundances were linked to phosphatase activity, suggesting that earthworms do not necessarily inhibit P-acquisition by AMF-associated plants in our study system. We conclude that the combined influence of earthworm-related changes in physical structure, accessibility and chemistry of organic matter, and relative abundance of certain groups of fungi and bacteria promote C metabolism, in particular by increasing the activities of cellulolytic vs. lignolytic enzymes.
•Earthworms increased abundance of many bacterial relative to most fungal indicators.•Abundance of arbuscular mycorrhizal fungi increased by earthworms.•Earthworms increased activities of cellulolytic compared to lignolytic enzymes.•Changes in enzyme activities contribute to more complete carbon metabolism.•Soil microbial community composition correlated with enzyme activity and soil C:N.
Instability in carotid vulnerable plaque can generate cerebral micro-emboli, which may be related to both stroke and eventual cognitive abnormality. Strain imaging to detect plaque vulnerability ...based on regions with large strain fluctuations, with arterial pulsation, may be able to determine the risk of cognitive impairment. Plaque instability may be characterized by increased strain variations over a cardiac cycle. Radiofrequency signals for ultrasound strain imaging were acquired from the carotid arteries of 24 human patients using a Siemens Antares with a VFX 13-5 linear array transducer. These patients underwent standardized cognitive assessment (Repeatable Battery for the Assessment of Neuropsychological Status RBANS). Plaque regions were segmented by a radiologist at end-diastole using the Medical Imaging Interaction Toolkit. A hierarchical block-matching motion tracking algorithm was used to estimate the cumulated axial, lateral and shear strains within the imaging plane. The maximum, minimum and peak-to-peak strain indices in the plaque computed from the mean cumulated strain over a small region of interest in the plaque with large deformations were obtained. The maximum and peak-to-peak mean cumulated strain indices over the entire plaque region were also computed. All strain indices were then correlated with RBANS Total performance. Overall cognitive performance (RBANS Total) was negatively associated with values of the maximum strain and the peak-to-peak for axial and lateral strains, respectively. There was no significant correlation between the RBANS Total score and shear strain and strain indices averaged over the entire identified plaque for this group of patients. However, correlation of maximum lateral strain was higher for symptomatic patients (r = -0.650, p = 0.006) than for asymptomatic patients (r = -0.115, p = 0.803). On the other hand, correlation of maximum axial strain averaged over the entire plaque region was significantly higher for asymptomatic patients (r = -0.817, p = 0.016) than for symptomatic patients (r = -0.224, p = 0.402). The results reveal a direct relationship between the maximum axial and lateral strain indices in carotid plaque and cognitive impairment.
The exotic earthworm invasion in hardwood forests of the northern United States is associated with many ecosystem-level changes. However, less is known about the effects of the invasion on the ...composition of the soil microbial community through which ecosystem-level changes are mediated. Further, earthworm effects on soil microbial community composition have not been well studied in the field. To evaluate changes in bacterial and fungal abundance associated with the earthworm invasion we quantified bacterial and fungal biomass by microscopic counts in paired earthworm-invaded (earthworm) and earthworm-free (reference) plots in five forest stands in central New York (USA). Earthworms significantly increased the ratio of bacteria to fungi on an area basis (per m
2), by more than two times in mid-summer and early autumn. While this effect was associated primarily with the lack of the fungal-dominated organic horizon in earthworm plots, a higher ratio of bacteria to fungi in the surface 5
cm mineral soil also contributed as it developed between spring and mid-summer. Earthworm reduction of fungal biomass was confirmed by substantially lower growth of fungal hyphae into mesh sand bags in earthworm compared to reference plots. Burrowing activity by the earthworm
Lumbricus terrestris increased the ratio of bacteria to fungi over the short-term within earthworm plots, introducing small-scale spatial heterogeneity associated with burrows. Our study suggests that the exotic earthworm invasion in these northern hardwood forests markedly increased the ratio of bacteria to fungi by eliminating the fungal-rich organic horizon, and was associated localized increases in bacterial vs. fungal abundance in mineral soil, setting the stage for future research into linkages between the earthworm invasion, bacterial and fungal abundance, and ecosystem processes.
► Earthworms increased bacteria: fungi in northern hardwood forest soil. ► Growth of hyphae into mesh bags was reduced by earthworms. ► Effects at a landscape scale were related mostly to elimination of the organic horizon. ► Bacteria:fungi in mineral soil showed within-season and burrow-associated effects. ► Earthworms likely affect nutrient processing by changing fungal translocation.
Purpose: Locoregional tumor control for locally advanced cancers with radiation therapy has been unsatisfactory. This is in part associated with the phenomenon of tumor hypoxia. Assessing hypoxia in ...human tumors has been difficult due to the lack of clinically noninvasive and reproducible methods. A recently developed positron emission tomography (PET) imaging-based hypoxia measurement technique which employs a Cu(II)-diacetyl-bis(
N
4-methylthiosemicarbazone) (Cu-ATSM) tracer is of great interest. Oxygen electrode measurements in animal experiments have demonstrated a strong correlation between low tumor pO
2 and excess
60Cu-ATSM accumulation. Intensity-modulated radiation therapy (IMRT) allows selective targeting of tumor and sparing of normal tissues. In this study, we examined the feasibility of combining these novel technologies to develop hypoxia imaging (Cu-ATSM)-guided IMRT, which may potentially deliver higher dose of radiation to the hypoxic tumor subvolume to overcome inherent hypoxia-induced radioresistance without compromising normal tissue sparing.
Methods and Materials: A custom-designed anthropomorphic head phantom containing computed tomography (CT) and positron emitting tomography (PET) visible targets consisting of plastic balls and rods distributed throughout the “cranium” was fabricated to assess the spatial accuracy of target volume mapping after multimodality image coregistration. For head-and-neck cancer patients, a CT and PET imaging fiducial marker coregistration system was integrated into the thermoplastic immobilization head mask with four CT and PET compatible markers to assist image fusion on a Voxel-Q treatment-planning computer. This system was implemented on head-and-neck cancer patients, and the gross tumor volume (GTV) was delineated based on physical and radiologic findings. Within GTV, regions with a
60Cu-ATSM uptake twice that of contralateral normal neck muscle were operationally designated as ATSM-avid or hypoxic tumor volume (
hGTV) for this feasibility study. These target volumes along with other normal organs contours were defined and transferred to an inverse planning computer (Corvus, NOMOS) to create a hypoxia imaging-guided IMRT treatment plan.
Results: A study of the accuracy of target volume mapping showed that the spatial fidelity and imaging distortion after CT and PET image coregistration and fusion were within 2 mm in phantom study. Using fiducial markers to assist CT/PET imaging fusion in patients with carcinoma of the head-and-neck area, a heterogeneous distribution of
60Cu-ATSM within the GTV illustrated the success of
60Cu-ATSM PET to select an ATSM-avid or hypoxic tumor subvolume (
hGTV). We further demonstrated the feasibility of Cu-ATSM-guided IMRT by showing an example in which radiation dose to the
hGTV could be escalated without compromising normal tissue (parotid glands and spinal cord) sparing. The plan delivers 80 Gy in 35 fractions to the ATSM-avid tumor subvolume and the GTV simultaneously receives 70 Gy in 35 fractions while more than one-half of the parotid glands are spared to less than 30 Gy.
Conclusion: We demonstrated the feasibility of a novel Cu-ATSM-guided IMRT approach through coregistering hypoxia
60Cu-ATSM PET to the corresponding CT images for IMRT planning. Future investigation is needed to establish a clinical-pathologic correlation between
60Cu-ATSM retention and radiation curability, to understand tumor re-oxygenation kinetics, and tumor target uncertainty during a course of radiation therapy before implementing this therapeutic approach to patients with locally advanced tumor.
In this paper, we explore two parameters or strain indices related to plaque deformation during the cardiac cycle, namely, the maximum accumulated axial strain in plaque and the relative lateral ...shifts between plaque and vessel wall under in vivo clinical ultrasound imaging conditions for possible identification of vulnerable plaque. These strain indices enable differentiation between calcified and lipidic plaque tissue utilizing a new perspective based on the stiffness and mobility of the plaque. In addition, they also provide the ability to distinguish between softer plaques that undergo large deformations during the cardiac cycle when compared to stiffer plaque tissue. Soft plaques that undergo large deformations over the cardiac cycle are more prone to rupture and to release micro-emboli into the cerebral bloodstream. The ability to identify vulnerable plaque, prone to rupture, would significantly enhance the clinical utility of this method for screening patients. We present preliminary in vivo results obtained from ultrasound radio frequency data collected over 16 atherosclerotic plaque patients before these patients undergo a carotid endarterectomy procedure. Our preliminary in vivo results indicate that the maximum accumulated axial strain over a cardiac cycle and the maximum relative lateral shift or displacement of the plaque are useful strain indices that provide differentiation between soft and calcified plaques.
We hypothesized that during exercise at maximal O2 consumption (VO2max), high demand for respiratory muscle blood flow (Q) would elicit locomotor muscle vasoconstriction and compromise limb Q. Seven ...male cyclists (VO2max 64 +/- 6 ml.kg-1.min-1) each completed 14 exercise bouts of 2.5-min duration at VO2max on a cycle ergometer during two testing sessions. Inspiratory muscle work was either 1) reduced via a proportional-assist ventilator, 2) increased via graded resistive loads, or 3) was not manipulated (control). Arterial (brachial) and venous (femoral) blood samples, arterial blood pressure, leg Q (Qlegs; thermodilution), esophageal pressure, and O2 consumption (VO2) were measured. Within each subject and across all subjects, at constant maximal work rate, significant correlations existed (r = 0.74-0.90; P < 0.05) between work of breathing (Wb) and Qlegs (inverse), leg vascular resistance (LVR), and leg VO2 (VO2legs; inverse), and between LVR and norepinephrine spillover. Mean arterial pressure did not change with changes in Wb nor did tidal volume or minute ventilation. For a +/-50% change from control in Wb, Qlegs changed 2 l/min or 11% of control, LVR changed 13% of control, and O2 extraction did not change; thus VO2legs changed 0.4 l/min or 10% of control. Total VO2max was unchanged with loading but fell 9.3% with unloading; thus VO2legs as a percentage of total VO2max was 81% in control, increased to 89% with respiratory muscle unloading, and decreased to 71% with respiratory muscle loading. We conclude that Wb normally incurred during maximal exercise causes vasoconstriction in locomotor muscles and compromises locomotor muscle perfusion and VO2.
Background. This retrospective study compared clinical outcomes and resource utilization in patients having off-pump coronary artery bypass grafting (OPCAB) versus conventional coronary artery bypass ...grafting (CABG). Angiographic patency was documented in the OPCAB group.
Methods. From April 1997 through November 1999, OPCAB was performed in 200 consecutive patients, and the results were compared with those in a contemporaneous matched control group of 1,000 patients undergoing CABG. Patients were matched according to age, sex, preexisting disease (renal failure, diabetes, pulmonary disease, stroke, hypertension, peripheral vascular disease, previous myocardial infarction, and primary or redo status. Follow-up in the OPCAB patients was 93% and averaged 13.4 months.
Results. Hospital death (1.0%), postoperative stroke (1.5%), myocardial infarction (1.0%), and re-entry for bleeding (1.5%) occurred infrequently in the OPCAB group. There were reductions in the rates of transfusion (33.0% versus 70.0%; p < 0.001) and deep sternal wound infection (0% versus 2.2%; p = 0.067) in the OPCAB group compared with the CABG group. Angiographic assessment of 421 grafted arteries was performed in 167 OPCAB patients (83.5%) prior to hospital discharge. All but five were patent (98.8%) (93.3% FitzGibbon A, 5.5% FitzGibbon B, 1.2% FitzGibbon O). All 163 internal mammary artery grafts were patent. Off-pump coronary artery bypass grafting reduced postoperative hospital stay from 5.7 ± 5.3 days in the CABG group to 3.9 ± 2.6 days (p < 0.001), with a decrease in hospital cost of 15.0% (p < 0.001).
Conclusions. Off-pump coronary artery bypass grafting reduces hospital cost, postoperative length of stay, and morbidity compared with CABG on cardiopulmonary bypass. Off-pump coronary bypass grafting is safe, cost effective, and associated with excellent graft patency and clinical outcomes.
We previously compared the effects of increased respiratory muscle work during whole body exercise and at rest on diaphragmatic fatigue and showed that the amount of diaphragmatic force output ...required to cause fatigue was reduced significantly during exercise (Babcock et al., J Appl Physiol 78: 1710, 1995). In this study, we use positive-pressure proportional assist ventilation (PAV) to unload the respiratory muscles during exercise to determine the effects of respiratory muscle work, per se, on exercise-induced diaphragmatic fatigue. After 8-13 min of exercise to exhaustion under control conditions at 80-85% maximal oxygen consumption, bilateral phrenic nerve stimulation using single-twitch stimuli (1 Hz) and paired stimuli (10-100 Hz) showed that diaphragmatic pressure was reduced by 20-30% for up to 60 min after exercise. Usage of PAV during heavy exercise reduced the work of breathing by 40-50% and oxygen consumption by 10-15% below control. PAV prevented exercise-induced diaphragmatic fatigue as determined by bilateral phrenic nerve stimulation at all frequencies and times postexercise. Our study has confirmed that high- and low-frequency diaphragmatic fatigue result from heavy-intensity whole body exercise to exhaustion; furthermore, the data show that the workload endured by the respiratory muscles is a critical determinant of this exercise-induced diaphragmatic fatigue.
Abstract
Objective: We sought to determine subsequent pregnancy outcomes in a cohort of women with a history of unexplained recurrent miscarriage (RM) who were not receiving medical treatment.
Study ...design: This was a prospective cohort study, of women with a history of three unexplained consecutive first trimester losses, who were recruited and followed in their subsequent pregnancy. Control patients were healthy pregnant patients with no previous adverse perinatal outcome.
Results: A total of 42 patients with a history of unexplained RM were recruited to the study. About nine (21.4%) experienced a further first trimester miscarriage, one case of ectopic and one case of partial molar pregnancy. About 74% (23/31) of the RM cohort had a vaginal delivery. There was one case of severe pre-eclampsia. The RM group delivered at a mean gestational age of 38 + 2 weeks and with a mean birthweight of 3.23 kg. None of the neonates were under the 10th centile for gestational age. Overall, there was no significant difference in pregnancy outcomes between the two cohorts.
Conclusion: Our study confirms the reassuring prognosis for achieving a live birth in the unexplained RM population with a very low incidence of adverse events with the majority delivering appropriately grown fetuses at term.
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