First Measurement of the Nuclear-Recoil Ionization Yield in Silicon at 100 eV.

We measured the nuclear-recoil ionization yield in silicon with a cryogenic phonon-sensitive gram-scale detector. Neutrons from a monoenergetic beam scatter off of the silicon nuclei at angles corresponding to energy depositions from 4 keV down to 100 eV, the lowest energy probed so far. The results show no sign of an ionization production threshold above 100 eV. These results call for further investigation of the ionization yield theory and a comprehensive determination of the detector response function at energies below the keV scale.

Free Volume and Swelling in Thin Films of Poly(N-isopropylacrylamide) End-Capped with n-Butyltrithiocarbonate.

The free volume in thin films of poly(N-isopropylacrylamid) end-capped with n-butyltriocarbonate (nbc-PNIPAM) is probed with positron annihilation lifetime spectroscopy (PALS). The PALS measurements are performed as function of energy to obtain depth profiles of the free volume of nbc-PNIPAM films. The range of nbc-PNIPAM films with thicknesses from 40 to 200 nm is focused. With decreasing film thickness the free volume increases in good agreement with an increase in the maximum swelling capability of the nbc-PNIPAM films. Thus in thin hydrogel films the sorption and swelling behavior is governed by free volume.

Obesity increases the likelihood of total joint replacement surgery among younger adults.

We conducted a retrospective review of medical charts of patients, aged 18 to 59 years old, who underwent either a total knee replacement (TKR) or total hip replacement (THR) from January 2002 to December 2004. Of the 204 study subjects, 52% had a TKR while 48% had a THR. Obesity was significantly associated with the need for a TKR or THR when comparing the study group to adults of similar age in the general population (P< 0.0001). Seventy-two percent (146) of the study group was obese and 21% (42) overweight (BMI 25.0 to 29.9 kg/m(2)) compared to only 26% (596) obese and 34% (732) overweight in the general population. Patients undergoing a TKR were significantly more likely to be obese (BMI>30 kg/m(2)) than those having a THR, 83% (89) compared to 59% (57) (P< .0006). Our findings support those previously observed in the elderly population. Primary and secondary prevention programs aimed at reducing obesity are strongly recommended.

Clomipramine and selegiline: do they influence impulse control?

Anxiety disorders in dogs are often accompanied by loss of impulse control and can result in inappropriate behaviour such as destructiveness, excessive barking and aggression. The reduction of these undesirable actions is the focus of behaviour therapy. Clomipramine and selegiline have been approved for the treatment of separation anxiety in dogs, but there are anecdotal reports that they produce inconsistent therapeutic effect. Hence, the aim of this study was to verify the efficacy of clomipramine and selegiline for regulating impulse control by using a rat model based on the delay of reward procedure. The principle is that the animal has to decide between an immediate small food reward, normally preferred by impulsive animals, and a delayed large food reward. In this study, acute effects of clomipramine (0.3-10.0 mg/kg), selegiline (0.3-3.0 mg/kg), and diazepam (1.0-3.0 mg/kg) on the impulsive behaviour of two breeding lines of rats with different anxiety-related behaviour were investigated. Neither clomipramine nor selegiline had an effect on impulse control in either breeding line. However, motor activity was decreased by clomipramine and increased by selegiline. Diazepam led to an increase in impulsive behaviour of one rat line concomitant with an increase in motor activity. The results of this rat model for studying impulsive behaviour suggest that a single administration of selegiline and clomipramine has no influence on impulsive behaviour.

The clients' experience of the community group: implications for nurse facilitators.

Community or large group meetings occur in many mental health units. Literature is available that describes the possible functions of such groups, but little is known about how they are actually experienced by the members, or the implications of this for nurse facilitators, especially in the current context of inpatient care. The aim of this study was to develop an understanding of the clients' experience of the daily community group in a unit that offered both an inpatient and a day patient service for adults experiencing mental health problems. The group meeting was intended to provide an opportunity for people to examine their relationships with others and discover new ways of coping with problems and stressors. The group had a changing membership, with all staff and clients present on the unit at the time expected to attend. The meeting lasted for an hour and had no predetermined agenda. Mental health nurses made up the majority of the staff membership. Semistructured interviews were conducted with four clients who had been attending the group for between 3 and 6 months. These were tape recorded, transcribed verbatim and then analysed using the phenomenological approach of Colaizzi. Three themes emerged from the data: 'Whose Responsibility?', 'Me vs. Them' and 'What Works?' These themes have implications for nurse facilitators, namely: their awareness that such issues are of importance; their ability to recognize how and when they are present; and their ability to effectively intervene.

Magnetic resonance imaging-guided core needle biopsy and needle localized excision of occult breast lesions.

BACKGROUND: Breast magnetic resonance imaging (MRI) has been reported to be twice as sensitive and three times more specific in detecting breast cancer. We report a series of MRI-guided stereotactic breast biopsies (SCNBB) and needle localized breast biopsies (NLBB) to evaluate MRI as a localization tool. METHODS: Forty-one breast lesions were identified in 39 patients who subsequently had SCNBB or NLBB. Suspicious areas of enhancement were stereotactically biopsied with 16-G core biopsy needles or localized with 22-G wires for excision under laser guidance. RESULTS: Forty-one breast lesions were identified from 1,292 breast MRIs. SCNBB identified three malignancies and two areas of atypia. Two additional cancers were found after NLBB. In patients having NLBB alone, five cancers and two areas of atypia were identified. CONCLUSIONS: In this initial series, breast MRI-guided SCNBB and NLBB were valuable tools in the management of patients with suspicious abnormalities seen only on MRI.

Splenic imaging with ultrasmall superparamagnetic iron oxide ferumoxtran-10 (AMI-7227): preliminary observations.

PURPOSE: Ferumoxtran-10 (ultrasmall superparamagnetic iron oxide; Combidex, AMI-7227) is a long-circulating MR contrast agent with reticuloendothelial uptake known to enhance tissue T1 and T2 relaxation rates. The purpose of this study was to assess the effect of ferumoxtran-10-enhanced MRI in evaluating focal splenic lesions. METHOD: Eighteen patients underwent MR evaluation of the spleen. Two of these patients with exophytic normal splenic tissue (splenules) and 13 of these patients with 24 focal splenic lesions (7 cysts, 2 hemangiomas, 7 metastases, 1 infarct, 7 lymphoma) were assessed by T1-weighted gradient echo and T2-weighted fast SE MRI following intravenous administration of ferumoxtran-10 (1.1 mg of Fe/kg). Qualitative analysis involving improved lesion detection and/or characterization, additional information from postcontrast images affecting staging, and patient management was performed. Quantitative measurements of lesion-to-spleen contrast-to-noise ratio were also performed. RESULTS: Additional information was provided by ferumoxtran-10-enhanced images in 15 of 18 patients. In 8 of 15 (53%) patients, improved lesion detection (i.e., number of lesions) was obtained on contrast-enhanced images. Improved lesion visualization (i.e., conspicuity) was noted in 11 of 15 (73%) of patients. In 10 of 15 (67%) patients, postcontrast imaging provided additional information leading to lesion characterization. Staging of disease and patient management were affected in 5 of 15 (33%) and 6 of 15 (40%) patients, respectively. CONCLUSION: Ferumoxtran-10 is a promising contrast agent for the evaluation of focal splenic lesions.

MR-guided minimally invasive procedures.

This article outlines the integration of breast MR imaging minimally invasive therapy for breast tumors. Technical obstacles discussed include accurate determination of margins, DCIS, and localization methods. Treatment methods such as cryotherapy, interstitial hyperthermia, and focused ultrasound are discussed. Other subjects include the amount of minimally-invasive therapy performed to date and the ethical dilemma of clinical trials.

Issues in bidding for contracts for occupational therapy services.

There is an increasing number of occupational therapists in Canada who are involved in bidding for contracts to deliver occupational therapy services. Occupational therapists working in an institutional or community-based setting may not have had the responsibility of developing a proposal or a marketing plan for bidding purposes. However, the responsibility of developing a bid to compete for a service delivery contract often rests on occupational therapists who are sole practitioners in a private practice setting. The purpose of this paper is to highlight issues in the literature such as service delivery plans, marketing strategies and costing of services that can assist the occupational therapist in the development of a contractual bid. A specific clinical example, school therapy services, has been used to illustrate how these strategies can be applied to practice. Success in contractual bids appears to be primarily influenced by cost of the service, the expertise of the service provider, ability to provide coordinated care, ease of access for clients, and inclusion of methods to measure client outcome.

Integration of breast MRI in clinical trials.

Clinical trials are the mechanism for implementing new treatment methods into clinical practice. A number of organizations have been developed to facilitate the initiation, implementation, and data analysis for clinical trials. Imaging is important for patient selection and establishment of endpoints, yet imaging expertise has been underrepresented in most clinical trial groups. The integration of breast MRI in clinical trials is an important step toward the establishment of this method of imaging in routine practice. In addition, these data will be important in justifying the expense of MRI to payer organizations. The potential roles of breast MRI in clinical trials are reviewed. These breast MRI applications are linked with some of the studies that are under development. It is important for the MRI community to be aware of the importance of clinical trials in the future clinical establishment of breast MRI. J. Magn. Reson. Imaging 2001;13:830-836.

Hematoma-directed ultrasound-guided breast biopsy.

OBJECTIVE AND SUMMARY BACKGROUND DATA: The standard technique for removal of nonpalpable breast lesions is needle localization breast biopsy. Because traumatic hematomas can often be seen with ultrasound, the authors hypothesized that iatrogenically induced hematomas could be used to guide the excision of nonpalpable lesions using ultrasound. METHODS: Twenty patients with nonpalpable breast lesions detected by magnetic resonance imaging only were enrolled in this single-institution trial, approved by the institutional review board. A hematoma consisting of 2 to 5 mL of the patient's own blood was injected into the breast to target the nonpalpable lesion. Intraoperative ultrasound of the hematoma was used to direct the excisional biopsy. RESULTS: The average age of women was 53.8 +/- 10 years. Ninety-five percent of lesions detected by magnetic resonance imaging were localized by hematoma injection. All the hematomas used to recognize targeted lesions were identified at surgery by ultrasound and removed without complication. Eight (40%) of the lesions were malignant, with an average tumor size of 12 +/- 6 mm (range 4-25). The remaining 12 lesions (60%) comprised papillomas, sclerosing adenosis, radial scar, fibroadenoma, and areas of atypical ductal hyperplasia. CONCLUSION: The results of this pilot study show the effectiveness of hematoma-directed ultrasound-guided breast biopsy for nonpalpable lesions seen by magnetic resonance imaging. This new procedure is potentially more comfortable for the patient because no wire or needle is left in the breast. It is technically faster and easier because ultrasound is used to visualize directly the location of the hematoma at surgery and to confirm lesion removal in the operating room by specimen ultrasound. The hematoma can be placed several days before biopsy, easing scheduling, and without fear of the migration that may occur with needle localization. This method may have ready application to mammographically detected lesions.

Efficacy and safety of mangafodipir trisodium (MnDPDP) injection for hepatic MRI in adults: results of the U.S. Multicenter phase III clinical trials. Efficacy of early imaging.

The efficacy of contrast-enhanced magnetic resonance imaging (MRI) for detecting and characterizing, or excluding, hepatic masses was assessed in 404 patients, following the intravenous administration of mangafodipir trisodium (MnDPDP) injection, a hepatic MRI contrast agent. An initial contrast-enhanced computed tomography (CT) examination was followed by unenhanced MRI, injection of MnDPDP (5 micromol/kg IV), and enhanced MRI at 15 minutes post injection. Agreement of the radiologic diagnoses with the patients' final diagnoses was higher for enhanced MRI and for the combined unenhanced and enhanced MRI evaluations than for unenhanced MRI alone or enhanced CT using the clinical diagnosis as the gold standard. Mangafodipir-enhanced MRI uniquely provided additional diagnostic information in 48% of the patients, and patient management was consequently altered in 6% of the patients. MnDPDP-enhanced MRI was comparable or superior to unenhanced MRI and enhanced CT for the detection, classification, and diagnosis of focal liver lesions in patients with known or suspected focal liver disease.

Safety and efficacy of mangafodipir trisodium (MnDPDP) injection for hepatic MRI in adults: results of the U.S. multicenter phase III clinical trials (safety).

The short-term safety of mangafodipir trisodium (MnDPDP) injection was studied in 546 adults with known or suspected focal liver lesions. An initial contrast-enhanced computed tomography examination was followed by unenhanced magnetic resonance imaging (MRI), injection of MnDPDP (5 micromol/kg), and enhanced MRI. Adverse events were reported for 23% of the patients; most were mild to moderate in intensity, did not require treatment, and were not drug related. The most commonly reported adverse events were nausea (7%) and headache (4%). The incidence of serious adverse events was low (nine events in six patients) and not drug related. Injection-associated discomfort was reported for 69% of the patients, and the most commonly reported discomforts included heat (49%) and flushing (33%). Changes in laboratory values and vital signs were generally transient, were not clinically significant, and did not require treatment. There were no clinically significant short-term risks from exposure to MnDPDP.

Biologically variable ventilation increases arterial oxygenation over that seen with positive end-expiratory pressure alone in a porcine model of acute respiratory distress syndrome.

OBJECTIVES: We compared biologically variable ventilation (BVV) (as previously described) (1) with conventional control mode ventilation (CV) in a model of acute respiratory distress syndrome (ARDS) both at 10 cm H2O positive end-expiratory pressure. DESIGN: Randomized, controlled, prospective study. SETTING: University research laboratory. SUBJECTS: Farm-raised 3- to 4-month-old swine. INTERVENTIONS: Oleic acid (OA) was infused at 0.2 mL/kg/hr with FIO2 = 0.5 and 5 cm H2O positive end-expiratory pressure until PaO2 was < or =60 mm Hg; then all animals were placed on an additional 5 cm H2O positive end-expiratory pressure for the next 4 hrs. Animals were assigned randomly to continue CV (n = 9) or to have CV computer controlled to deliver BVV (variable respiratory rate and tidal volume; n = 8). Hemodynamic, expired gas, airway pressure, and volume data were obtained at baseline (before OA), immediately after OA, and then at 60-min intervals for 4 hrs. MEASUREMENTS AND MAIN RESULTS: At 4 hrs after OA injury, significantly higher PaO2 (213+/-17 vs. 123+/-47 mm Hg; mean+/-SD), lower shunt fraction (6%+/-1% vs. 18%+/-14%), and lower PaCO2 (50+/-8 vs. 65+/-11 mm Hg) were seen with BVV than with CV. Respiratory system compliance was greater by experiment completion with BVV (0.37+/-0.05 vs. 0.31+/-0.08 mL/cm H2O/kg). The improvements in oxygenation, CO2 elimination, and respiratory mechanics occurred without a significant increase in either mean airway pressure (14.3+/-0.9 vs. 14.9+/-1.1 cm H2O) or mean peak airway pressure (39.3+/-3.5 vs. 44.5+/-7.2 cm H2O) with BVV. The oxygen index increased five-fold with OA injury and decreased to significantly lower levels over time with BVV. CONCLUSIONS: In this model of ARDS, BVV with 10 cm H2O positive end-expiratory pressure improved arterial oxygenation over and above that seen with CV with positive end-expiratory pressure alone. Proposed mechanisms for BVV efficacy are discussed.

Biologically variable or naturally noisy mechanical ventilation recruits atelectatic lung.

Biologically variable mechanical ventilation (Vbv)-using a computer-controller to mimic the normal variability in spontaneous breathing-improves gas exchange in a model of severe lung injury (Lefevre, G. R., S. E. Kowalski, L. G. Girling, D. B. Thiessen, W. A. C. Mutch. Am. J. Respir. Crit. Care Med. 1996;154:1567-1572). Improved oxygenation with Vbv, in the face of alveolar collapse, is thought to be due to net volume recruitment secondary to the variability or increased noise in the peak inspiratory airway pressures (Ppaw). Biologically variable noise can be modeled as an inverse power law frequency distribution (y approximately 1/f(a)) (West, B. J., M. Shlesinger. Am. Sci. 1990;78:40-45). In a porcine model of atelectasis-right lung collapse with one-lung ventilation-we studied if Vbv (n = 7) better reinflates the collapsed lung compared with conventional monotonously regular control mode ventilation (Vc; n = 7) over a 5-h period. We also investigated the influence of sigh breaths with Vc (Vs; n = 8) with this model. Reinflation of the collapsed lung was significantly enhanced with Vbv-greater Pa(O(2)) (502 +/- 40 mm Hg with Vbv versus 381 +/- 40 mm Hg with Vc at 5 h; and 309 +/- 79 mm Hg with Vs; mean +/- SD), lower Pa(CO(2)) (35 +/- 4 mm Hg versus 48 +/- 8 mm Hg and 50 +/- 8 mm Hg), lower shunt fraction (9.7 +/- 2.7% versus 14.6 +/- 2.0% and 22.9 +/- 6.0%), and higher respiratory system compliance (Crs) (1.15 +/- 0.15 ml/cm H(2)O/kg versus 0.79 +/- 0.19 ml/cm H(2)O/kg and 0.77 +/- 0.13 ml/cm H(2)O/kg)-at lower mean Ppaw (15.7 +/- 1.4 cm H(2)O versus 18.8 +/- 2.3 cm H(2)O and 18.9 +/- 2.8 cm H(2)O). Vbv resulted in an 11% increase in measured tidal volume (VT(m)) over that seen with Vc by 5 h (14.7 +/- 1.2 ml/kg versus 13. 2 ml/kg). The respiratory rate variability programmed for Vbv demonstrated an inverse power law frequency distribution ( y approximately 1/f(a)) with a = 1.6 +/- 0.3. These findings provide strong support for the theoretical model of noisy end-inspiratory pressure better recruiting atelectatic lung. Our results suggest that using natural biologically variable noise has enhanced the performance of a mechanical ventilator in control mode.