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A mathematical analysis of ghosting artifacts often seen in interleaved echo-planar images (EPI) is presented. These artifacts result from phase and amplitude discontinuities between lines of k-space in the phase-encoding direction, and timing misregistrations from system filter delays. Phase offsets and time delays are often measured using "reference" scans, to reduce ghosting through postprocessing. From the expressions describing ghosting artifacts, criteria were established for reducing ghosting to acceptable levels. Subsequently, the signal-to-noise ratio (SNR) requirements for estimation of time delays and phase offsets, determined from reference scans, was evaluated to establish the effect of estimation error on artifact reduction for interleaved EPI. Artifacts resulting from these effects can be reduced to very low levels when appropriate reference scan estimation is used. This has important implications for functional MRI (fMRI) and applications involving small changes in signal intensity.

Background: The ability of the myocyte to maintain an ionic concentration gradient is perhaps the best indication of myocardial viability. We studied the relationship of 23Na MRI intensity to viability and explored the potential of fast-imaging techniques to reduce 23Na imaging times in rabbits and dogs., Methods and Results: Eighteen rabbits underwent in situ coronary artery occlusion and reperfusion. The hearts were then either imaged following isolation and perfusion with cardioplegic solution (n = 6), imaged in vivo (n = 6), or analyzed for 23Na content and relaxation times (n = 12). Normal rabbits (n = 6) and dogs (n = 4) were imaged to examine the effect of animal size on 23Na image quality. 23Na imaging times were 7, 11, and 4 minutes for isolated rabbits, in vivo rabbits, and in vivo dogs, respectively. Infarcted, reperfused regions, identified by triphenyltetrazolium chloride staining, showed a significant elevation in 23Na image intensity compared with viable regions (isolated, 42 +/- 5%, P < .02; in vivo, 95 +/- 6%, P < .001), consistent with increased tissue sodium content. Similarly, 23Na MR spectroscopy showed that [Na+] was higher in nonviable than viable myocardium (isolated, 99 +/- 4 versus 61 +/- 2 mmol/L; in vivo, 91 +/- 2 versus 38 +/- 1 mmol/L; P < .001 for both). Image signal-to-noise ratios were higher in dogs than rabbits despite shorter imaging times, primarily due to larger voxels., Conclusions: Following acute infarction with reperfusion, a regional increase in 23Na MR image intensity is associated with nonviable myocardium. Fast gradient-echo imaging techniques reduce 23Na imaging times to a few minutes, suggesting that 23Na MR imaging has the potential to become a useful experimental and clinical tool.

Progress in research on hypertension, heart failure, aging, post-infarct remodeling, and the molecular basis of cardiovascular diseases in general has been greatly facilitated in recent years by the development of specialized small-mammal models by selective breeding and/or genetic alteration. Routine noninvasive evaluation of cardiac function and perfusion in these animals models, however, is difficult using existing methods. In principle, MRI can be used for this purpose, but in practice this is difficult because of problems related to RF coils, cardiac gating, and imaging pulse sequences. In this article, solutions to these problems are described that have allowed us to use MRI to routinely image the hearts of rats and rabbits. Specifically described are four RF coils, cardiac gating schemes, and an imaging pulse sequence specially designed for cardiac imaging in these animals on a 4.7 T Omega chemical-shift imaging (CSI) spectrometer. These techniques can be used to obtain, within 2 min, eight double-oblique short-axis images of the rat at different cardiac phases with 200 x 400 microm in-plane resolution and a slice thickness of 2 mm. Moreover, myocardial tissue tagging can be performed with tag thicknesses and separations comparable to those used routinely in humans. The technical information is presented in sufficient detail to allow researchers at other sites to reproduce the results. This information should facilitate the use of MRI for the noninvasive examination of cardiac function and perfusion, which can be combined with other established techniques for the study of cardiovascular disease in specialized animal models.

An MR line scan protocol has been used to measure relaxation parameters (T1 and T2) in isolated, blood perfused rabbit hearts at various blood oxygenations. Hearts were retrogradely perfused at 37 degrees C with a cardioplegic solution (modified St. Thomas' solution) containing sheep red blood cells and adenosine (1 mM) to maximally vasodilate the coronary vascular bed. Arresting the hearts eliminated motion complications and minimized arteriovenous oxygenation differences. The authors have found that under conditions of stable flow, there is a strong correlation between T2 in myocardial septa and hemoglobin (Hb) saturation, while tissue T1 is virtually independent of blood oxygenation. These effects are believed to be due to the paramagnetic agent deoxyhemoglobin.

A T1-weighted imaging pulse sequence for contrast-based studies of myocardial perfusion is presented and evaluated in phantoms and in vivo. The sequence is similar to spoiled gradient-recalled echo sequences except that nonselective preparatory RF pulses drive magnetization to steady state prior to image acquisition. Steady state is thus obtained in both tissue and blood resulting in a stable, homogeneous, and dark pre-contrast baseline. Tip angles and timings are chosen so that pixel intensity approximates a linear relation to 1/T1. The dynamic range of signal response to contrast agent concentration is greater than that of an inversion-recovery fast low angle shot sequence. The sequence proposed should be useful for myocardial perfusion studies.

The effect of gradient system performance on segmented k-space gradient echo imaging is presented. Three cases were investigated. First, an ideal system that has infinite slew rates and unlimited maximum gradient strengths was considered. Second, a "high speed" imaging system (2.3 (G/cm), 23 (G/cm)/ms) was considered. These two cases were compared with a "conventional" imaging system (1(G/cm), 1.67 (G/cm)/ms). It was found that substantial increases in SNR can be achieved (approximately 45%) by using high speed versus a conventional gradient system, for a TR of 6 ms. For trapezoidal gradient waveforms, there exists an optimum maximum gradient strength for a given slew rate, and any increase in gradient strength above this optimum will not be utilized by an optimized sequence. These studies have shown that increasing TR without decreasing the bandwidth is not a good way to increase SNR for constant scan time.

Contrast between tagged and nontagged myocardium was investigated using rapid gradient echo segmented k-space CINE MRI. The transient behavior of magnetization was measured in stationary and moving phantoms using gradient recalled acquisition in steady-state GRASS and spoiled GRASS (SPGR) sequences with TR approximately 7 ms and TE approximately 2.5 ms. Bloch equation simulations were used to compute theoretical results. Understanding the transient behavior of magnetization is important because tags only persist in the myocardium during the nonequilibrium transition to steady state. The transition to steady state for both SPGR and GRASS is reproducible after one heartbeat, and including unprocessed data from the first heartbeat leads to image artifacts. In a moving phantom, simulations and experimental results showed that GRASS and SPGR are essentially equivalent. Tag-tissue contrast in SPGR was very sensitive to imaging tip angle. The optimum tip angle for the scanning parameters used in this study was 11 degrees.

Purpose: To validate cine magnetic resonance (MR) image tagging measurements of a deforming object by means of a precise photographic method., Materials and Methods: A piece of silicone rubber that acted as a phantom was stretched in a cyclical fashion inside a plastic clamp driven by a respirator pump. Deformation as a function of time was measured with a rapid gradient-echo cine tagging sequence and with sequential stroboscopic photographs. Deformations from 1.0 to 1.2 (0% to 20% stretch) in the readout direction were measured over a 7-cm region of the phantom, which had a maximum standard error of +/- 0.001 with photography and a maximum standard error of +/- 0.003 with MR imaging., Results: The deformation versus time values measured with MR imaging had a standard error of 0.002 about a straight line fit to the photographic deformation versus time data. These results demonstrate that the MR imaging deformation estimates were accurate and precise., Conclusion: The validated tagging method can now be used to evaluate MR imaging motion estimation techniques.

In this study we evaluated the clinical response of 12 patients with malignant melanoma and renal cell carcinoma (RCC) following administration of recombinant human interleukin-2 (rhIL-2) by continuous infusion. Serum samples taken before, during and following sequential courses of IL-2 were assayed for the presence of tumour necrosis factor alpha (TNF-alpha) IL-1 alpha, IL-6 and interferon gamma (IFN-gamma) and the presence or changes in these cytokines were examined with respect to clinical response data: our results did not show any direct correlation between the parameters measured and clinical outcome. In addition, peripheral blood mononuclear cells (PBMC) derived from 3 RCC patients were cultured in a serum-free environment and the resulting supernatants assayed for the production of these cytokines and compared to the corresponding serum levels. During one or more courses of treatment only 1 patient, who had metastatic bone disease, demonstrated detectable serum TNF-alpha; serum IL-6 levels were elevated in a proportion of all patients studied and a sustained IL-6 response occurred in a patient who had complete disease remission; IL-1 alpha was detected in the serum of 3 RCC patients; IFN-gamma could not be detected in any serum sample tested. Cytokine levels in sera and supernatants derived from 3 RCC patients were compared but no correlation was found: TNF-alpha and IL-6 were shown to be present at much higher concentrations in supernatants when compared to sera whereas the levels of IL-1 alpha were almost undetectable. This lack of correlation is probably due to the presence of "interfering" proteins in sera which either depress or enhance the ability to detect cytokines in sera using enzyme immunoassays.

The immunological and haematological effects of continuous infusion of recombinant human interleukin-2 (rhIL-2) in 6 patients with metastatic melanoma and 6 with disseminated renal cell carcinoma are reported. In patients with malignant melanoma dacarbazine was given before IL-2; in renal cell carcinoma IL-2 alone was given. In malignant melanoma, 1 complete (CR) and 1 partial response (PR) were seen; 2 patients had stable disease (SD) and 2 progressive disease (PD). In renal cell carcinoma 4 patients had SD and 2 PD. Toxicity of IL-2 therapy was minimal. All patients showed increased cytotoxicity, that was not major histocompatibility complex restricted, towards target cells sensitive and insensitive to natural killer cells. These activities varied between individual patients and were less marked in cases of renal cell carcinoma. Cellular proliferative responses increased in all patients, being consistently higher following the first course of therapy, as did HLA-DR, CD16 and CD25 activation marker expression. Hypersegmentation of neutrophils and eosinophilia were commonly observed, and in renal cell carcinoma these changes were accompanied by abnormal lymphocyte morphology.

To determine their efficacy as barriers to the passage of lipid-enveloped viruses, wound dressings were exposed to known concentrations of Semliki Forest virus (SFV) at their inner surfaces for varying periods of time. The dressings were tested such that their outer surfaces were maintained in either a dry or a wet environment. Out of a total of 120 dressings each tested at four time points under wet conditions, virus was found to have penetrated on only one occasion. Similarly, virus penetration was noted in only a single test out of 442 carried out on 59 dressings under dry conditions. The dressings under test thus proved highly effective barriers to passage of a lipid enveloped virus.

1. The washout of (22)Na, (45)Ca and (58)CoEDTA(-) has been observed in arterially perfused rabbit interventricular septa both in the presence and absence of intoxicating doses of the aglycone, 3 acetylstrophanthidin (ACS).2. The washout of (22)Na from paced septa (21.0/min) was rapid with approximately 99% of the exchange occurring in 30 min.3. Septa labelled with (22)Na and washed out in the presence of 10(-5)m-ACS were quiescent, exhibited marked contracture and a slowed (22)Na exchange with 99% of the initial (22)Na leaving the tissue in approximately 200 min.4. Comparison of the washout of the extracellular marker (58)CoEDTA(-) from paced and intoxicated septa revealed no differences, suggesting that regions of the extracellular space had not become inexchangeable as a result of the contracture that these septa exhibited.5. Simultaneous measurements of the distribution of (22)Na and (58)CoEDTA(-) in the presence of 10(-5)m-ACS revealed an apparent cellular Na concentration of 54.8+/-10.4 (s.e.). This was considerably in excess of the maximum amount of Na contributing to the slowest component of Na efflux from intoxicated septa. Origins of this discrepancy are considered.6. The slowest component of (22)Na efflux from intoxicated septa could be markedly stimulated by increasing the external Ca concentration from a nominal 1.5 to 16 mm. The magnitude of stimulation was 44.3+/-7.8% (s.e.). Increases in the concentration of Mg from 1.0 to 16.0 mm were without effect on the (22)Na efflux.7. Application of 10(-5)m-ACS produced marked depolarization of the membrane to new stable levels that lay between -10 and -20 mV.8. Washout of ACS after several hours of intoxication resulted in a partial decline in contracture tension, an acceleration of Ca efflux, little change in (22)Na efflux and a repolarization of the cell membrane.9. Some of the Na and Ca movements reported in this paper have been interpreted by supposing that there is, in this preparation, a coupled exchange of three Na ions for a single Ca ion.

Data from the ongoing Los Angeles Health Study were analyzed to determine women's behavior and behavioral intentions regarding three modes of breast cancer detection behavior: breast self-examination (BSE), physician examination of the breasts, and mammography. Two questions were addressed: Are women who engage in one type of breast surveillance behavior likely to engage in all three? What are the social characteristics of women who engage in these breast cancer detection behaviors?The data indicated that women who had had a recent professional (physician) breast examination did not necessarily practice monthly BSE. Only 82 of a sample of 540 women had had mammography; thus, it was not possible to relate this type of surveillance to the other two types. However, 93 percent of the women interviewed indicated they would obtain a mammography examination if their physicians recommended it. There were few differences among the sociodemographic subgroups with respect to BSE and professional examination, with the exception that black women were more likely to report practicing monthly BSE than were white or Hispanic women.

Panel data are presented from the Los Angeles Health Survey, in which 1 year of symptom experience is analyzed. Of the 1,210 individuals originally in the panel, 769 reported at least one symptom in reinterviews conducted every 6 weeks during the study year. The dependent variable in the analysis is whether or not the individual decided to seek medical attention for his symptoms. Hierarchical multiple regression was used to organize the independent variables into five groups: 1) need; 2) social structure; 3) organization of care; 4) general social network patterns and health orientations; and 5) social network influences and personal beliefs specific to the symptoms. Of the 57 per cent of the variance explained by the entire set of independent variables, need factors accounted for 12 per cent and network influences and personal beliefs specific to the symptom accounted for 42 per cent. In spite of the amount of variance explained in this analysis, the allocation of the explained variance among the predictor variables raises some disturbing questions regarding our ability to understand the decision to use health services.

Naval oranges, Valencia oranges, and grapefruit, representative of the California and Arizona citrus crop, were collected over three consecutive growing seasons, and the nutritional composition of their juices was determined. Measured as per cent of the U.S. RDAs, folic acid, magnesium, vitamin A (oranges only), vitamin B6, thiamin, and ascorbic acid are all supplied in greater proportion than the calories present, while niacin and calcium are supplied in approximately proportionate amounts.

A simple, direct, and rapid method is given for the analysis of citrus oils for the fungistat biphenyl by high-speed liquid chromatography. The method is extended to orange juice and various "dry flavors" by an extraction procedure. Analytical limits are less than 1 ppm without need for any cleanup or concentration steps.

Cigarette smoking among nurses remains a public health concern despite a recent decline in current smoking prevalence. We recruited 149 registered nurses into a no-cost, targeted, self-help smoking cessation program supplemented by a supportive worksite environmental module. The study was designed to expand understanding of nurses' smoking and to measure program effectiveness. Follow-ups were conducted at one, six and 12 months post-intervention to assess self-reported smoking status (92% objectively validated) and predictors of cessation. Point prevalence abstinence at these time points (22.5%, 21.5% and 19.5%), continuous abstinence (12.7%), and an ever-quit rate of 57% (i.e., quit for at least 48 hours), compare favorably to population quit rates and to rates reported for other self-help programs. Logistic regression analyses were utilized to identify predictors of short-term cessation [time before needing a cigarette, concern regarding the health hazards of smoking, working in a critical care setting, use of targeted weight manual] and long-term cessation [dosage (inverse relationship), use of standard American Lung Association maintenance manual, working with dying patients, and M.D.s' opposition to upgrading nursing service (inverse relationship)].

A method has been developed for rapidly determining the amounts of alpha-carotene, beta-carotene, and cryptoxanthin in orange juice. The procedure includes extraction, saponification, and high-speed liquid chromatography. Limits of detection for the 3 carotenoids are 0.04, 0.02, and 0.04 mug/ml, respectively.

A survey of smoking behavior was conducted on 1,569 registered nurses in six unrelated acute care hospitals in Los Angeles in 1984-1985. Smoking prevalence, higher than for other health professionals but lower than for women in the United States or in other recently surveyed samples of nurses, was closely linked to the ethnicity and the age distribution of the nurses surveyed. Patterns for black and white nurses, who account for the majority of nurses nationally, were similar to those found in other recent studies of registered nurses. Among Asian nurses, however, prevalence was lower, age of initiation was higher, and the mean number of cigarettes smoked daily was lower than for other nurses. Smoking prevalence for younger nurses was lower than for other nurses, and these nurses were more likely to report themselves as never having smoked. Smoking patterns among nurses remain a significant public health concern.

A method is presented for the quantitative analysis of o-phenylphenol residues in citrus oils, encapsulated flavors, and dried meal. The method utilizes high-speed liquid chromatography for the determination after specific sample preparations for each material. These preparations include hexane extraction of acidified basic extracts or steam distillation and extraction. The limit of the analysis is less than 1 ppm with an analysis time of less than 45 min.

Hamman's syndrome occurs rarely in the setting of labor and delivery. In this report 187 cases of Hamman's syndrome, with and without objective evidence of pneumothorax, are summarized and the literature reviewed. Most of the women were primiparous, and first and second stages of labor were of normal duration (18.3 and 4.1 hour, respectively). Average fetal size (7 pounds, 14 ounces) was also found to be within normal limits. Signs, symptoms, and pathophysiology are reviewed and treatment discussed.

A representative sample of women living in metropolitan Los Angeles were asked what they heard and what they believed about mammography and whether they would obtain a mammogram if their doctor advised it. Forty percent of these women said they had not heard of mammography even after the procedure was described. Few of those who had heard of mammography had negative feelings about it. Further, 93 percent of the overall sample said they would obtain a mammogram if their physician recommended it.

Human, diploid fibroblasts from an 84-year-old donor (AlPos) were used to study the effect of 20, 40 and 80 micrograms/100 ml concentrations of lead on in vitro senescence. The results showed that there was a significant decrease in the number of total population doublings due to the treatment with lead. However, there was no significant difference between the effects of the three concentrations of lead. As far as nucleolar number is concerned in the case of the controls as well as in the lead-treated cells the number remained constant with aging in vitro. When the areas and dry mass of cells, nuclei and nucleoli were examined in controls and lead-treated groups at early and late doublings the results showed that in general no significant changes were noted with the exception of the 40 micrograms/100 ml lead treatment which caused a significant increase in these parameters with aging in vitro. The results are discussed and compared to those from a previous study [17] in which embryonic, IMR-90 cells were treated in a similar way. It is concluded that the fibroblasts from the 84-year-old donor AlPos are even more vulnerable than the embryonic cells to the effects of lead as indicated by the drastic curtailment of the in vitro lifespan exhibited in the case of treatment even with the lowest concentration of lead.(ABSTRACT TRUNCATED AT 250 WORDS)