Analysis of the evolution of focal cerebral ischemia in the rat using the eigenimage filter.

The eigenimage filter was used to evaluate the results of a MRI study of cerebral ischemia in a rat model. This linear filter segments a desired feature in an image sequence from other features which may interfere with its observation. The animals were imaged temporally, after occlusion of the middle cerebral artery, to investigate the evolution of the ischemic process. The temporal evolution of ischemia was evaluated by analysis of the "eigenimages," calculated T2 and T1 map images, and images for the angles between signature vectors defined in the eigenimage technique. The eigenimages and angle map images demonstrated an improved visibility of the lesion at all time points, as compared to the original images and T2 and T1 map images. The eigenimages also demonstrated signal intensity changes within the area of ischemia. These changes are speculated to be related to variations in local cerebral blood flow resulting in varying degrees of tissue damage. The eigenimage intensities and the angles between signature vectors demonstrated time-related changes similar to the T2 and T1 values. Since the eigenimage filter and angle calculations are not dependent upon physical models (like T2 and T1), and the errors associated with these models, they may be preferable as methods for tissue characterization.     

Temporal evolution of ischemic damage in rat brain measured by proton nuclear magnetic resonance imaging

We studied the effect of focal cerebral ischemia on the "state" of brain water using proton nuclear magnetic resonance imaging. Focal cerebral ischemia was induced in five halothane-anesthetized rats via tandem occlusion of the left common carotid artery and the left middle cerebral artery. The proton transverse relaxation time, the proton density, and the water diffusion coefficient were measured at various times from the same region of brain tissue from 1.5 to 168 hours after occlusion. Early measurements indicated significant changes in the transverse relaxation time (p = 0.004) and water diffusion coefficient (p = 0.002) of ischemic brain tissue compared with a homologous region from the contralateral hemisphere. However, the transverse relaxation time, proton density, and water diffusion coefficient in ischemic brain tissue showed different temporal evolutions over the study period. Diffusion coefficient weighting was superior to relaxation time and proton density weighting for the visualization of early cerebral ischemia. Our data suggest that nuclear magnetic resonance imaging is sensitive in detecting changes in proton-associated parameters during early cerebral ischemia and confirm significant changes (p less than or equal to 0.01) in the temporal evolution of transverse relaxation times, proton densities, and diffusion coefficients following middle cerebral artery occlusion.     

Transient interference of right hemispheric function due to automatic emotional processing

We examined the effects of emotional stimuli on right and left hemisphere detection performance in a hemifield visual discrimination task. A group of 18 healthy subjects were asked to discriminate between upright and inverted triangles (target). Targets were randomly presented in the left or right visual hemifield (150 ms target duration). A brief emotional picture (pleasant or unpleasant; 150 ms stimulus duration) or neutral picture selected from the International Affective Picture System was randomly presented either in the same (47%) or the opposite (47%) spatial location to the subsequent target. Emotional or neutral stimuli offset 150 ms prior to the subsequent target. Subjects were instructed to ignore the pictures and respond to the targets as quickly and accurately as possible. Independent of field of presentation, emotional stimuli prolonged reaction times (P < 0.01) to LVF targets, with unpleasant stimuli showing a greater effect than pleasant stimuli. The current study shows that brief emotional stimuli selectively impair right hemispheric visual discrimination capacity. The findings suggest automatic processing of emotional stimuli captures right hemispheric processing resources and transiently interferes with other right hemispheric functions.     

Genetic variants of GPX1 and SOD2 and breast cancer risk at the Ontario site of the Breast Cancer Family Registry.

There are several genes that code for enzymes, including various forms of superoxide dismutase and glutathione peroxidase, that protect the cell against oxidative damage that, in turn, can lead to carcinogenesis. There are a few common genetic polymorphisms in these genes that lead to altered proteins. Three that have been identified are SOD2 Val-9Ala, GPX1 Pro198Leu, and the GPX1 GCG repeat (three alleles with four, five, or six repeats). The SOD2 variant has been associated with increased breast cancer risk in two studies. The GPX1 variants have not been studied with respect to breast cancer, but Pro198Leu has been associated with lung cancer. We conducted a case-control study of these three polymorphisms in incident, invasive breast cancer in Caucasian women under 55. There were 399 cases and 372 controls genotyped, of whom 488 were premenopausal, 208 postmenopausal, and 75 of unknown menopausal status. We were unable to replicate the previously observed association with SOD2 Val-9Ala and also found no association between breast cancer and GPX1 Pro198Leu. However, the allele of GPX1 containing four GCG repeats was significantly associated with breast cancer risk in premenopausal women (odds ratio, 1.55; 95% confidence interval, 1.04-2.30 for carriers versus noncarriers). There is a significant trend of increasing risk with increasing number of alleles with four GCG repeats (P = 0.03). This variant has not previously been reported to be associated with breast cancer.     

Evaluating sex chromosome content of sorted human sperm samples with use of dual-color fluorescence in situ hybridization

OBJECTIVE: Although most methods for selecting the sex of offspring by sorting spermatozoa are ineffective at shifting the ratio of Y- to X-containing cells, some commercial sources continue to offer such services. Our objective was to evaluate commercially “sorted” samples with use of dual-color fluorescence in situ hybridization and to identify variations in assessment by comparing motile and total sperm populations, donors, observers, and fluorescence in situ hybridization probes.STUDY DESIGN: Cryopreserved sperm from seven anonymous donors were processed as for insemination. Sperm cells from each total sample or motile subfraction were prepared for fluorescence in situ hybridization by incubation with disulfide-reducing agents to expand sperm nuclei. Two sets of X and Y chromosome–specific, fluorophore-labeled deoxyribonucleic acid probes were used. At least 400 nuclei from each preparation were classified independently by three blinded observers. Hybridization efficiency, aneuploidy, and sex chromosome content were evaluated in subsets of five unsorted, five female-oriented, and five male-oriented samples. Total and motile subfractions were compared with eight samples. Fluorescence in situ hybridization probes were compared in five paired unsorted samples.RESULTS: No differences were detected between washed samples and paired motile subfractions. No differences in hybridization and aneuploidy were detected between groups of sorted samples. The Y/X ratio was significantly different between the sorted groups. However, male-oriented samples had a lower Y/X ratio than female-oriented samples did. Observer and probe choice accounted for small but significant variations that did not alter conclusions about the Y/X ratio for sorted samples.CONCLUSION: In a series of 10 sorted samples from one commercial source, dual-color fluorescence in situ hybridization demonstrated a small but significant shift in the sex chromosome ratios among samples. However, this shift was opposite to that expected by the orientation of the sorted samples. (Am J Obstet Gynecol 1997;176:1172-80.)     

Implementing the National Local Public Health System Performance Assessment: evaluation of a readiness process in Kentucky.

The objectives of the study described in this article were to test training and resource materials for preparing Kentucky public health agency staff to lead the National Local Public Health System Performance Assessment and to identify barriers encountered in implementation. Readiness supports provided to five Kentucky district and county health departments that led the system assessment process in 12 counties were evaluated using training pre- and posttests, performance assessment posttests, observations, and interviews. The training and materials provided in this study appeared to be the minimum needed for these Kentucky health departments. Training sequences need to allow time for independent study of assessment processes, and training in using and interpreting the assessment instrument should be included. Partner orientation materials targeted for nonpublic health partners would be useful. In Kentucky, barriers to completing the assessment included questions about its purpose and benefits and the lack of a self-identified local public health system. Formal training of health department staff, committed leadership, and adequate personnel resources can help overcome these barriers. The health departments that brought together system partners for the performance assessment considered it a valuable community-building educational event.     

The effects of cyclophosphamide on neurotransmission in the urinary bladder of Suncus murinus, the house musk shrew

This study has shown that cyclophosphamide treatment of the insectivore Suncus murinus, causes a down regulation in both muscarinic and P2X receptors, together with a reduced responsiveness to exogenous histamine (0.3 mM) in the urinary bladder. Electrical field stimulation (70 V, 0.3 ms, 0.5-16 Hz, 10 s every 5 min) of bladders from both control and cyclophosphamide-treated animals showed identical responses. Since post-junctional alterations have been revealed by the reduced responsiveness to exogenous carbachol (0.1 microM-3 mM) and beta,gamma-methylene ATP (0.3-300 microM), it would appear that in the bladders of cyclophosphamide-treated animals there is also a pre-junctional effect, increased transmitter release compensating for the down regulation of the receptors. As the pattern of neurotransmission of the bladder of suncus more closely resembles that of human detrusor than other commonly studied laboratory animals, this insectivore appears to be a useful animal model for the study of bladder neurotransmission in pathophysiological conditions.