Effect of using stencil masks made by focused ion beam milling on permalloy (Ni81Fe19) nanostructures.

Focused ion beam (FIB) milling is a common fabrication technique to make nanostencil masks which has the unintended consequence of gallium ion implantation surrounding milled features in silicon nitride membranes. We observe major changes in film structure, chemical composition, and magnetic behaviour of permalloy nanostructures deposited by electron beam evaporation using silicon nitride stencil masks made by a FIB as compared to stencil masks made by regular lithography techniques. We characterize the stenciled structures and both types of masks using transmission electron microscopy, electron energy loss spectroscopy, energy dispersive x-ray spectroscopy, magnetic force microscopy and kelvin probe force microscopy. All these techniques demonstrate distinct differences at a length scale of a 1-100 nm for the structures made using stencil mask fabricated using a FIB. The origin of these differences seems to be related to the presence of implanted ions, a detailed understanding of the mechanism however remains to be developed.

Novel method for rapid assessment of antibiotic resistance in Escherichia coli isolates from environmental waters by use of a modified chromogenic agar.

We validated a novel method for screening Escherichia coli resistance to antibiotics in environmental samples using modified Difco MI agar (Becton Dickinson) impregnated with selected antibiotics (tetracycline, ampicillin, cephalexin, and sulfamethoxazole), termed MI-R. This method combines an existing rapid assessment technique for E. coli enumeration with clinical reference data for breakpoint analysis of antibiotic resistance and was developed to address issues encountered when clinical methods are used with environmental samples. Initial trials conducted using strains of E. coli with resistance to the selected antibiotics showed that this method was reproducible and accurate with respect to antibiotic resistance. Trials using wastewater effluent demonstrated the precision of the method, and the levels of resistance found in effluent were directly comparable to the levels of antibiotic resistance determined using the more traditional CLSI (formerly NCCLS) disk susceptibility test. All wastewater isolates growing on MI-R plates were confirmed to be resistant using the CLSI disk susceptibility test. Bacterial resistance to ampicillin (38% +/- 4% overall), sulfamethoxazole, tetracycline (21% +/- 3% overall), and ciprofloxacin (6% +/- 1%) were found in wastewater effluent. A successful trial was also conducted with water collected from the Brisbane River, Australia. The levels of antibiotic resistance in E. coli ranged from 0 to 47% for ampicillin, from 0 to 24% for tetracycline, from 0 to 63% for sulfamethoxazole, and from 0 to 1% for ciprofloxacin, with the highest incidence of resistance associated with wastewater treatment plant discharges. This method has great potential for rapid and representative assessment of antibiotic resistance in E. coli and could allow increased sample analysis, resulting in greater confidence in spatial analysis in environmental studies.

Enhanced surveillance for meningococcal disease in Queensland in 1999.

Enhanced surveillance of invasive meningococcal disease commenced in Queensland in 1999. There were 93 cases, an incidence of 2.8/100,000 population. Most (87%) cases were laboratory confirmed, but 12 per cent were probable cases without laboratory confirmation. The highest age-specific attack rates were in the under 1, 1 to 4 and 15 to 24 year age groups. Most of the serologically characterised isolates were group B (70%), followed by group C (24%). There were 12 deaths, resulting in a case fatality rate of 13 per cent. Those who died were more likely to have group C than group B disease (OR 5.04, CI 1.05-25.14). Only 14 per cent of cases that saw a general practitioner (GP) prior to hospitalization received parenteral antibiotics, 23 per cent of the 35 cases referred to hospital by a GP received pre-hospital parenteral antibiotics and 33 per cent of cases were notified to health authorities within 24 hours of hospital admission. Thirty per cent were notified two or more days after hospitalization, delaying the start of public health action. Enhanced surveillance has demonstrated a need to promote the use of pre-hospital parenteral antibiotics by GPs and a need to encourage more timely reporting of cases to health authorities.

Dynamic three-dimensional echocardiographic reconstruction of congenital cardiac septation defects.

Dynamic three-dimensional echocardiographic reconstructions of 27 cardiac septation defects were performed in 19 sedated infants and children. Using a subxiphoid rotational scanning approach, complete visualization of the entire shape and breadth of the defect was attained in 11 of 16 ventricular septal defects and 9 of 11 atrial septal defects. This technique enabled the operator to cut slices from the three-dimensional block of echocardiographic data in order to present septation defects in a region- or lesion-oriented fashion. Poor baseline two-dimensional image quality and certain small septation defects that were readily obscured by nearby structures led to inadequate three-dimensional reconstructions. The application of dynamic three-dimensional echocardiography for assessment of cardiac septation defects uniquely provided (1) the ability to present en face views of atrial and ventricular septal defects; and (2) a means by which intracardiac anatomy can be displayed in a region- and lesion-oriented fashion for interventional and surgical planning purposes.

Evaluation of patterns of perfusion and metabolism in dobutamine-responsive myocardium.

OBJECTIVES: We investigated the patterns of perfusion and metabolism in dysfunctional myocardium whose contractility improved with dobutamine. BACKGROUND: Clinical studies have suggested that dobutamine echocardiography can identify hibernating myocardium, but laboratory studies suggest that reduced perfusion limits the response to dobutamine. METHODS: Twenty-five patients with coronary disease and ventricular dysfunction underwent low (5 and 10 micrograms/kg body weight per min) and high dose (maximum of 50 micrograms/kg per min) dobutamine echocardiography and positron emission tomography (PET) using nitrogen-13 (N-13) ammonia and fluorine-18 fluorodeoxyglucose (FDG) for imaging of perfusion and metabolism. Wall motion and tracer uptake were scored in 16 left ventricular segments. RESULTS: Perfusion and metabolism were normal in 56.4%, mildly reduced in 29.1% and mismatched (reduced perfusion, preserved FDG uptake) in 14.5% of dysfunctional segments viable on PET. Wall motion improved with dobutamine in 89 dysfunctional segments (62 at low dose, 27 only at peak dose), and 86 of these (97%) were viable on PET. Improvement in wall motion with dobutamine was more common in segments with normal perfusion and metabolism (56.5%) than in those with mildly reduced tracer uptake (28.5%, p < 0.001) and those with mismatch (32%, p = 0.03). All the segments with a biphasic response were supplied by vessels with > or = 70% stenosis, and 88% had normal perfusion and metabolism. CONCLUSIONS: The majority of viable segments with rest dysfunction had normal perfusion and metabolism, suggesting that myocardial stunning was common. Improvement of wall motion at low and high doses of dobutamine was highly correlated with myocardial viability on PET and was more common in myocardium with normal perfusion. A biphasic response to dobutamine identified segments with normal perfusion and metabolism supplied by severely diseased vessels.

A systematic approach to echocardiographic image acquisition and three-dimensional reconstruction with a subxiphoid rotational scan.

Rotational scanning from the subxiphoid position is an image acquisition technique used for reconstruction of dynamic three-dimensional echocardiographic images in infants and small children. The orientation of the heart within the three-dimensional data set is variable and dependent on the image plane at which rotational scanning was initiated. We describe an image acquisition technique that standardizes the orientation of the heart within the three-dimensional data set, thereby permitting a systematic approach to the reconstruction of three-dimensional renderings. Thirteen infants and small children with congenital heart disease were studied by this approach. Illustrative examples are provided. The average time required to derive a three-dimensional rendering was 37 +/- 9 minutes. We conclude that subxiphoid rotational scanning by a systematic approach to image acquisition and reconstruction can be applied successfully to the derivation of three-dimensional renderings of congenital cardiac defects.

Evaluation using dobutamine stress echocardiography in patients with insulin-dependent diabetes mellitus before kidney and/or pancreas transplantation.

The purpose of this study was to examine the ability of dobutamine stress echocardiography to stratify patients with juvenile onset, insulin-dependent diabetes mellitus who are being considered for kidney and/or pancreas transplantation, into high-or low-risk groups for future cardiac events. Fifty-three such patients underwent dobutamine stress echocardiography before kidney and/or pancreas transplantation. Cardiac events, including cardiac death, nonfatal myocardial infarction, unstable angina, pulmonary edema, and need for coronary revascularization, occurring between the time of the dobutamine stress echocardiogram and the last patient follow-up contact were retrospectively identified. Twenty patients 938%) had an abnormal dobutamine stress echocardiogram. Eleven patients had 15 cardiac events over a mean (+/- SD) follow-up period of 418 +/- 269 days. Event rates were 45% among those with an abnormal, versus 6% among those with a normal dobutamine stress echocardiogram (p = 0.002). The result of the dobutamine stress test independently predicted prognosis in a multivariate analysis (p = 0.003, odds ratio = 12.7). We conclude that dobutamine stress echocardiography accurately stratifies patients with juvenile onset, insulin-dependent diabetes being considered for kidney and/or pancreas transplantation for risk of future cardiac events.

Color coding of digitized echocardiograms: description of a new technique and application in detecting and correcting for cardiac translation.

Color coding is a new software application for digitized echocardiograms that displays a reference image of end diastole throughout the cardiac cycle. With color-coded digitized echocardiograms, we determined the frequency of, and corrected for cardiac translation in 21 bicycle stress echocardiograms in patients who were known to be without significant coronary artery disease or wall motion abnormalities. Translation was present in 4%, 40%, and 74% of rest, postexercise, and peak exercise images, respectively, and was noted most frequently in the apical views, 59% of four-chamber views and 40% of two-chamber views. Interobserver and intraobserver agreement for detection of translation was 81% and 86%, respectively. Translation was corrected by shifting digitized images to eliminate transverse displacement of the mitral valve anulus and restore normal basal-to-apical shortening. Ventricular contraction was assessed as normal in 92% of the images in which correction for translation was performed. In the remaining images, poor image quality (3%) and apparent wall motion abnormalities (5%) prevented the studies from being graded as normal. We conclude that color coding of digitized echocardiograms is a useful new technique that can be applied to detect and correct for cardiac translation.

Treatment of idiopathic seborrhea in a dog.

A spayed Cocker Spaniel with idiopathic chronic generalized seborrhea responded poorly to treatment, consisting of medicated baths and intermittent use of lincomycin and triamcinolone acetate, over a 5 1/2-year period. At 7 years of age, the animal became refractory to triamcinolone injections. Oral vitamin A therapy was not beneficial, but oral use of 13-cis-retinoic acid (Accutane: Roche), at 0.25 mg/kg BID, resulted in recovery within a month.