Rapid digital filtering

Image filtering with the larger, and potentially most valuable, digital filters is very time-consuming, thus precluding use of these filters in routine clinical applications. A recently developed algorithm for spatial-domain filtering is described, and its speed is compared with those of conventional methods with and without an array processor. Using the new Chebyshev method, a 64 by 64 pixel image can be filtered on a standard 16-bit minicomputer with filters of size 3 by 3 to 23 by 23 in 1.4-9.2 sec. The conventional spatial-domain algorithm requires 3.8-71 sec. With an array processor, filtering is accomplished in 0.19-0.54 sec. Filtering in the frequency domain requires 34 sec without an array processor and 0.12 sec with one. Thus with this new Chebyshev algorithm, clinically practical digital filtering can be performed with large filters even without an array processor.     

The effects of West Nile virus on major histocompatibility complex class I and II molecule expression by Lewis rat Schwann cells in vitro

The expression of major histocompatibility complex (MHC) class I and II molecules by Lewis rat Schwann cells after infection with West Nile virus (WNV) in vitro was examined by fluorescence microscopy and flow cytometry. WNV enhanced the expression of MHC class I molecules and induced the expression of MHC class II molecules by Schwann cells. Irradiated medium from WNV-infected Schwann cell cultures upregulated class I molecule expression on dissociated Schwann cell cultures but did not induce the expression of class II molecules. This finding has implications for virally triggered autoimmune diseases of nervous tissue.     

Unemployment and child abuse

The employment state of men living in the homes of children at the time that child abuse was diagnosed was determined. The series included a wide range of abuse, including non-accidental injury, failure to thrive, neglect, and emotional deprivation. Two cohorts of children seen during 1974-9 and 1980-5 were compared; these periods were chosen because a large increase in unemployment began in Sheffield in 1980. Although the proportion of the men without work was significantly increased during the second period, this increase could not be ascribed to the rise in either long term or short term unemployment among those who had previously been in regular employment. It was accounted for by a rise in the proportions of single parent families and families in which the resident man had never had regular employment. This may reflect an increase in pregnancies among young mothers. There was no evidence to support the belief that the loss of a job in otherwise stable families leads to an increase in child abuse.     

Delineating the sites and progression of in vivo atrophy in multiple system atrophy using fluid-registered MRI.

We describe the pattern and progression of atrophy delineated using fluid registration of serial magnetic resonance imaging scans in a case of multiple system atrophy (MSA). The in vivo findings were consistent with those found at postmortem, including significant supratentorial atrophy concurrent with an unusual degree of cognitive impairment for MSA.     

Intravenous Phenylephrine Preconditioning of Cardiac Grafts From Non–Heart-Beating Donors

Background. Hypoxia and warm ischemia produce severe injury to cardiac grafts harvested from non–heart-beating donors. To potentially improve recovery of such grafts, we studied the effects of intravenous phenylephrine preconditioning.Methods. Thirty-seven blood-perfused rabbit hearts were studied. Three groups of non–heart-beating donors underwent intravenous treatment with phenylephrine at 12.5 (n = 8), 25 (n = 7), or 50 μg/kg (n = 7) before initiation of apnea. Non–heart-beating controls (n = 8) received saline vehicle. Hypoxic cardiac arrest occurred after 6 to 12 minutes of apnea, followed by 20 minutes of warm in vivo ischemia. A 45-minute period of ex vivo reperfusion ensued. Nonischemic controls (n = 7) were perfused without antecedent hypoxia or ischemia.Results. Phenylephrine 25 μg/kg significantly delayed the onset of hypoxic cardiac arrest compared with saline controls (9.6 ± 0.5 versus 7.7 ± 0.4 minutes; p = 0.00001), yet improved recovery of left ventricular developed pressure compared with saline controls (57.1 ± 5.3 versus 41.0 ± 3.4 mm Hg; p = 0.04). Phenylephrine 25 μg/kg also yielded a trend toward less myocardial edema than saline vehicle (p = 0.09).Conclusions. Functional recovery of nonbeating cardiac grafts is improved by preconditioning. We provide evidence that the myocardium can be preconditioned with phenylephrine against hypoxic cardiac arrest.(Ann Thorac Surg 1997;63:1664–8)     

A method of simultaneous dual-radionuclide cardiac imaging with technetium 99m and thallium 201. I: Analysis of interradionuclide crossover and validation in phantoms

Background  

Simultaneous dual-radionuclide technetium 99m/thallium 201 scintigraphy can potentially produce perfectly aligned stress and rest images in less time than conventional protocols. However, interradionuclide crossover limits diagnostic accuracy. Accordingly, we evaluated^99mTc and²⁰¹Tl crossover in line and heart phantoms.