Effects of magnetic resonance imaging on cardiac pacemakers and electrodes

In phantom studies we investigated the effects of magnetic resonance imaging (MRI) on pacemakers and electrodes. Twenty-five electrodes were exposed to MRI in a 1.5T scanner with continuous registration of the temperature at the electrode tip. Eleven pacemakers (five single chamber and six dual chamber) were exposed to MRI. Pacemaker output was monitored to detect malfunction in VOO/DOO and VVI/DDD modes. A temperature increase at the electrode tip of up to 63.1 degrees C was observed during 90 seconds of scanning. In seven electrodes the temperature increase exceeded 15 degrees C. Although no pacemaker malfunctions were observed in asynchronous pacing mode (VOO/DOO), inhibition and rapid pacing were observed during spin-echo imaging if the pacemakers were set to VVI or DDD mode. Pacemaker function was not impaired during scanning with gradient-echo sequences. Next to pacemaker dysfunction, electrode heating has to be considered a possible adverse effect when exposing patients with pacemakers to MRI.     

Short-term preoperative radiotherapy results in down-staging of rectal cancer: a study of 1316 patients

OBJECTIVE: The incidence of back pain in children in our country is unknown. Several causes can produce this symptom, but it is necessary to rule out pathologies that require specific treatments. The goal of this work was to study the incidence and the etiology of back pain in children in our country. PATIENTS AND METHODS: We present a prospective study done in our Orthopedic Department during a period of 7 months. Twenty-two patients were referred with back pain of at least two months duration. The incidence was 2.9% compared to the total number of patients. The average age ranged from 7 to 17 years. RESULTS: A careful history and a radiological examination diagnosed 50% (11 cases) of the causes of backache in the present study. An idiopathic etiology was the most frequent cause and represented 9 patients (41%). In the remaining 12 cases (59%) pathological causes that required special treatment were identified including 2 cases of Scheuermann disease, 4 cases of painful scoliosis, 3 spondylolysis with spondylolisthesis, 2 cases of discitis, 1 benign neoplasm and 1 psychogenic cause. CONCLUSIONS: We recommend conservative management with the use of medication for relief of pain and physical therapy in the idiopathic cases. In the remaining cases, the specific treatment of the disease can improve the back pain.     

Apoptosis in the failing human heart

BACKGROUND: Loss of myocytes is an important mechanism in the development of cardiac failure of either ischemic or nonischemic origin. However, whether programmed cell death (apoptosis) is implicated in the terminal stages of heart failure is not known. We therefore studied the magnitude of myocyte apoptosis in patients with intractable congestive heart failure. METHODS: Myocardial samples were obtained from the hearts of 36 patients who underwent cardiac transplantation and from the hearts of 3 patients who died soon after myocardial infarction. Samples from 11 normal hearts were used as controls. Apoptosis was evaluated histochemically, biochemically, and by a combination of histochemical analysis and confocal microscopy. The expression of two proto-oncogenes that influence apoptosis, BCL2 and BAX, was also determined. RESULTS: Heart failure was characterized morphologically by a 232-fold increase in myocyte apoptosis and biochemically by DNA laddering (an indicator of apoptosis). The histochemical demonstration of DNA-strand breaks in myocyte nuclei was coupled with the documentation of chromatin condensation and fragmentation by confocal microscopy. All these findings reflect apoptosis of myocytes. The percentage of myocytes labeled with BCL2 (which protects cells against apoptosis) was 1.8 times as high in the hearts of patients with cardiac failure as in the normal hearts, whereas labeling with BAX (which promotes apoptosis) remained constant. The near doubling of the expression of BCL2 in the cardiac tissue of patients with heart failure was confirmed by Western blotting. CONCLUSIONS: Programmed death of myocytes occurs in the decompensated human heart in spite of the enhanced expression of BCL2; this phenomenon may contribute to the progression of cardiac dysfunction.     

Analogue micropowered log-domain tone controller for auditoryprostheses

A micropower tone-control circuit comprising two first-order log-domain filters and a subtractor built with MOS transistors in weak inversion is described. The tone-controller is capable of providing bass cut/boost and treble cut operations. This circuit is being used in new designs of a conventional (acoustic) hearing-aid and cochlear implant     

Vibrating cylinder in a cylindrical duct filled with an incompressible fluid of low viscosity

Summary The dynamic interaction of an elastically supported rigid cylinder and a surrounding incompressible fluid in a coaxial cylindrical duct is studied. Attention is focussed on a fluid of low viscosity so that conventional approaches lead to uncertain results. Here a singular perturbation analysis is performed which overcomes the difficulties. As a quantitative result, the complex-valued eigenvalue of the vibrating body in the fluid is computed.     

An image processing IC for backprojection and spatial histogrammingin a pipelined array

The first VLSI digital signal processor that performs both high-precision image backprojection and spatial histogram calculations at raster-scan rates as high as 30 MHz is described. Realized in 1 μm CMOS technology, this 13.3 mm×13.3 mm chip is designed to handle images as large as 1024×1024 12 b pixels. Loadable coefficients and a unified architecture allow this IC to be used with a variety of computed-tomography scanners for image reconstructions, including fan- and parallel-beam reconstruction. This chip also computes the forward Radon transform, which is a spatial histogram, permitting it to be used for iterative reconstruction algorithms. The bit lengths in the fixed-point architecture assure 12 b reconstruction accuracy     

"Cadism": Odd man out.

Comments that L. B. Silverstein's (see record 1992-05293-001) article on child care and maternal employment contributes unfounded and damaging misbeliefs regarding fathers. The dad-as-cad myth suggests intentional malevolence or at least blatant failure by fathers to care for others, and suggests that their failure to share equally in child care and household management is the primary cause of marital conflict. W. B. Johnson and D. Hayes propose a research agenda for fathering that originates in a coherent model of male development in the context of ever-changing environmental demands. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Border crossing for hospital care and its implications for the use of statewide data

A major concern of researchers using state data sets for population-based analyses and market share studies in the health care sector is the potential bias caused by 'border crossing'--patients receiving care out of state. By using the Health Care Financing Administration (HCFA) discharge abstract files for 1987 and 1988, we found that 'border crossing' is not a serious problem for the two large states we examined. Only 4.4% of New York patients and 2.15% of California patients received care out of state. At the county and zip code level, 'border crossing' is more frequent but tends to be concentrated in areas adjacent to other states. Even excluding all zips with more than 10% of patients crossing the 'border' results in a small loss of patients (2.2% for New York and 1.0% for California).