Real-time cardiac MRI using DSP's.

A real-time cardiac magnetic resonance imaging (MRI) system has been implemented using digital signal processing (DSP) technology. The system enables real-time acquisition, processing, and display of ungated cardiac movies at moderate video rates of 20 images/s. A custom graphical user interface (GUI) provides interactive control of data acquisition parameters and image display functions. Images can be compressed into moving-picture experts group (MPEG) movies, but are displayed on the console without compression during the scan. Compared to existing real-time MRI systems, implementation with DSP's allows rapid parallel computations, fast data transfers, and greater system flexibility, including the ability to scale to multiple channels, at the expense of somewhat higher component cost.

Resistive homogeneous MRI magnet design by matrix subset selection.

A new technique for designing resistive homogeneous multicoil magnets for magnetic resonance imaging (MRI) is presented. A linearly independent subset of coils is chosen from a user-defined feasible set using an efficient numerical algorithm. The coil currents are calculated using a linear least squares algorithm to minimize the deviation of the actual magnetic field from the target field. The solutions are converted to practical coils by rounding the currents to integer ratios, selecting the wire gauge, and optimizing the coil cross-sections. To illustrate the technique, a new design of a short, homogeneous MRI magnet suitable for low-field human torso imaging is presented. Magnets that satisfy other constraints on access and field uniformity can also be designed. Compared with conventional techniques that employ harmonic expansions, this technique is flexible, simple to implement, and numerically efficient.

Plasma zinc response to a breakfast meal or fasting in elderly women.

The aim of this study was to determine whether the postprandial decline in plasma zinc concentration is altered by aging. Eleven women, between the ages of 65 and 82 yr, participated in two separate experimental protocols: a high carbohydrate breakfast trial and a fasting trial. Plasma zinc concentrations were measured from blood samples obtained at 8:00 AM (baseline fasting) and at 30-min intervals until 1:00 PM during each trial. Following the breakfast meal, plasma zinc concentrations declined 14% from 75 +/- 1 to 65 +/- 2 micrograms/dL (p < 0.05), reaching a nadir 2.7 +/- 0.2 h after the meal. This decline was significantly (p < 0.0001) greater than the 3.6% fall observed during the fasting trial. Postprandial changes in the plasma zinc concentrations were correlated with postprandial changes in serum glucose (r = -0.43, p < 0.001), serum insulin (r = -0.17, p < 0.01), and serum phosphorus (r = 0.32, p < 0.005). These data show that plasma zinc concentrations decline following food intake in elderly women in the same manner as previously described for younger adult women.

Microbial etiology of acute pneumonia in hospitalized patients.

The purpose of this study was to determine the microbial etiology of pneumonia by using strict criteria among a group of hospitalized patients. Patients with acute community-acquired or hospital-acquired pneumonia were studied in a systematic and comprehensive manner for bacterial, viral, chlamydial, mycobacterial, and fungal pathogens. A total of 198 patients with 204 episodes of pneumonia were evaluated. Despite 100 percent follow-up of all surviving patients, a specific etiologic agent could be found in only 103 episodes. Among 154 episodes of community-acquired pneumonia, a diagnosis was made in 79; the most common pathogen was from the genus Legionella, followed by various Gram-negative enteric bacteria, Gram-positive cocci, influenza A virus, and Mycoplasma pneumoniae. The etiologic agent was found in 24 of the 50 patients with hospital-acquired pneumonia; no pathogen predominated. We conclude that even when elaborate diagnostic studies are done, including many invasive procedures, the etiology can be determined in only about half of the patients with acute pneumonia. The pathogens of pneumonia in this study are not markedly different between community-acquired and hospital-acquired infection.

Effect of human semen on herpes-simplex virus-2.

This study was designed to evaluate the suggestion of inhibition of infectivity of HSV-2 by seminal fluid by examining relationships between HSV-2 and components of human semen. Viral infectivity was quantitated by TCID50 measurements of CPE in comparing viral inoculated aliquots of whole semen, seminal fluid, and control (EMEM) medium during incubation at 0, 5, and 24 hours. Statistical analysis of data from 15 experiments revealed inhibition by seminal fluid during 5 hours of incubation. After 24 hours viral infectivity was maintained significantly higher with whole semen than with other treatments, suggesting favorable spermatozoal interaction. Electron microscopy revealed no intimate ultrastructural relationship between the virion and the spermatozoon.

Effect of varying dietary zinc intake of weanling mouse pups during recovery from early undernutrition on growth, body composition and composition of gain.

Catch-up growth during recovery from undernutrition is characterized by rapid body weight gain often marked by disproportionately high fat gain. In this study dietary zinc intake of mouse pups during recovery from undernutrition affected composition of gain as well as growth. Mouse pups were undernourished during the suckling period and then fed 25% casein recovery diets containing 5, 10, 40 or 110 micrograms Zn/g diet. Pups given dietary zinc levels of 40 micrograms Zn/g ad libitum achieved recovery body weights and had normal body composition. However, previously undernourished pups given marginal levels of dietary zinc (10 micrograms Zn/g diet) had similar food intakes, similar final body weights, lower lean body mass gains and greater fat gains (males only) than controls. Pups fed low zinc diets (5 micrograms Zn/g diet) were unable to attain recovery body weight and had less protein gain than previously undernourished animals fed higher zinc-containing diets or healthy pups fed the same zinc levels. The results were consistently more pronounced in males. Thus dietary zinc deficiency during catch-up growth after undernutrition limited both recovery and protein gain, whereas marginal dietary zinc intake limited protein gain in mice.

Effect of varying dietary zinc intake of weanling mouse pups during recovery from early undernutrition on tissue mineral concentrations, relative organ weights, hematological variables and muscle composition.

Because growth is an early sign of zinc (Zn) deficiency in young animals, it is often assumed that the occurrence of normal growth indicates adequate Zn status. In an earlier study we found that both marginal (10 micrograms Zn/g) and low (5 micrograms Zn/g) dietary Zn intake resulted in altered composition of gain in mouse pups that had been previously undernourished (L) from d 10 to 21 of suckling and rehabilitated from d 21 to 40 with high protein recovery diets. Therefore we examined several tissues, organs and biochemical measures to identify other variables that might be sensitive to either marginal or low dietary Zn intake in mice. After undernutrition in the suckling animal, liver Zn concentrations were lower; they normalized when the pups were subsequently fed recovery diets irrespective of dietary Zn intake (5-110 micrograms Zn/g). Bone Zn was 30% lower in pups fed low Zn, and 30% higher in pups given Zn-supplemented recovery diets (110 micrograms Zn/g) compared with controls (40 micrograms Zn/g). Thus bone Zn concentration was highly correlated with dietary Zn intake and lower liver Zn was highly correlated with undernutrition. Most organs of L pups recovered in proportion to body weight; the exceptions were brain, kidney and gastrocnemius muscle. At d 21 or 40, brain weight was most conserved and kidney weight was stunted during either protein or Zn deprivation. Gastrocnemius muscle weight in L pups was stunted to a much greater degree than other tissues, although proximate analysis showed muscle composition was similar among groups. These data support previous reports that adequate dietary Zn is essential for optimal recovery from early undernutrition.

Association of adenovirus type 16 with Reye's-syndrome-like illness and pneumonia.

Thirty-eight antigenically distinct viruses have been described as adenoviruses, though only about one third have been commonly associated with human illnesses. In mid-January 1981, adenovirus 16, one of the more rarely encountered ones, was isolated from three patients in separate hospitals in the Little Rock, Arkansas, area, even though it had not previously been isolated there. We report the details of these cases, which included a Reye's-syndrome-like illness and fatal viral pneumonia. The reports indicate a new and more important clinical role for adenovirus 16 infection.

Unusual membrane bound intranuclear inclusions in human fibroblasts infected with herpes simplex.

Examination of brain tissue taken at autopsy from a 55-year old male showed the presence of herpes simplex viral antigen by immunofluorescence techniques. A suspension of this tissue was inoculated into cultures of human diploid fibroblasts. After 72 h, viral particles at different stages of development were seen inside the nuclei. Envelopment of the viral particles seemed to occur in association with the nuclear membranes, endoplasmic reticulum, cytoplasmic vacuoles and plasma membranes. Severely altered nuclear membranes, with as many as 4 to 8 layers of nuclear envelope, emphasized the common occurrence of membrane reduplication associated with herpes simplex infection. Unusual membrane-bound, dense, rounded inclusions, 100 to 500 nm in diameter, were present in the nucleus. These inclusions apparently were formed between the inner and outer lamellae of the nuclear membrane.

Rapid definitive diagnosis of Legionnaires' disease.

We describe a sporadic case of Legionnaires' disease in which the diagnosis was made by direct immunofluorescence of material obtained by percutaneous aspiration of the involved lung via a needle. Employment of this technique among selected patients with suspected Legionnaires' disease would provide for more rapid diagnosis and more prompt initiation of definitive therapy for some patients.

Location of brown recluse venom attachment sites on human erythrocytes by the firritin-labeled antibody technique.

Brown recluse spider (loxosceles reclusa) venom has been demonstrated by a ferritin-labeled antibody technique to attach to human erythrocyte cell membranes. The number of individual attachment sites per cell is proportional to the concentration of the venom used to sensitize the erythrocytes. Structural changes in the red cell membrane are associated with the venom attachment. These sites may be related to the red cell hemolysis which sometimes occurs in the human as a result of the spider bite.

Inhibition of human complement components by Loxosceles reclusa venom.

Venom from the brown recluse spider, Loxosceles reclusa, was capable of inactivation human C1-C7 in vitro. This inactivation occurred if venom was added to fresh adult human serum, human cord serum, or functionally pure specific human components. Optimal incubation conditions for the inactivation of each component were determined and were found generally to be in the range of 25 or 37 degrees C for 30-60 min. The alternative complement pathway did not appear to be involved, since C1, C4, and C2 were readily inactivated, and inactivation took place in sera depleted of factor B of the properdin system. Venom-induced inactivation appeared to require few, if any, serum cofactors, because, with the possible exception of C2, functionally pure components, as well as those in sera, were readily inactivated.

Identification and neutralization of biological activities associated with venom from the brown recluse spider, Loxosceles reclusa.

Venom from the brown recluse spider, Loxosceles reclusa, reacted with human erythrocytes to form venom-sensitized erythrocytes. These cells were agglutinated specifically by high dilutions of adsorbed rabbit antivenin or were lysed by normal blood group compatible human sera. The specific rabbit antivenin prevented venom from attaching to erythrocytes, from interacting with serum complement, and from producing dermonecrotic lesions in rabbits. Results of experiments involving heat inactivation and adsorption to erythrocytes provide circumstantial evidence to suggest that the three biological activities of venom could be associated with a single component or few components with similar properties. The component interacting with serum complement is immunologically distinct from a factor in cobra venom which possesses similar biological activities.

Amyotrophic lateral sclerosis. Inclusion bodies in a case of the classic sporadic form.

Postmortem light and electron microscopic studies of a 52 year old black male who died 17 months after the onset of upper and lower motor neuron signs showed: (1) degeneration of cortico-spinal tracts, (2) loss of spinal neurons and gliosis and (3) cellular inclusions with neurotubules, neurofilaments and granular material. Although these cellular inclusions resemble Lafora bodies, they differ in that, to the authors' knowledge, the latter were not reported to have microtubules. Review of the literature revealed no previous report of these inclusions in cases of amyotrophic lateral sclerosis. Tissue cultures of cord, hindbrain and cerebrum did not show cytopathic effect during a three-week observation period.