Limitations of the keyhole technique for quantitative dynamic contrast-enhanced breast MRI

The effect of keyhole data acquisition on quantitative analysis of dynamic MRI was examined. Experiments were performed retrospectively on raw data obtained from clinical dynamic contrast-enhanced breast imaging procedures. The effects of keyhole phase-encoding acquisition and type of reconstruction algorithm on the accuracy of derived quantitative parameters was assessed. Results indicate that the minimum keyhole size used should be restricted by the approximate minimum size of the expected lesions. Furthermore, reconstruction algorithms that offer improved image resolution do not circumvent this restriction.     

Neuronal activity in the globus pallidus of multiple system atrophy patients.

The pathophysiological changes in neural activity that characterize multiple system atrophy (MSA) are largely unknown. We recorded the activity of pallidal neurons in 3 patients with clinical and radiological features of MSA who underwent unilateral microelectrode-guided pallidotomy for disabling parkinsonism. Findings in these patients were compared with 4 control patients with a clinical diagnosis of Parkinson's disease (PD). The position, firing rates, and firing patterns of single neurons in the pallidal complex were analyzed in both MSA and PD patients. The mean spontaneous firing rate of neurons in the internal segment of the globus pallidus internus (GPii) was significantly lower in MSA than in PD patients. There were no significant differences between MSA and PD patients, however, in firing rates of neurons in the external globus pallidus (GPe) or in the external segment of GPi (GPie). In addition, no significant differences in firing pattern were found between MSA and PD patients. In conclusion, this study has shown that firing rates of neurons in GPii but not in GPie and GPe are different in MSA patients compared with that in PD patients, a finding that may reflect the poor clinical results of pallidotomy reported in patients with MSA.     

Leukotriene generation and clinical implications.

Since the elucidation of the structure of the cysteinyl leukotrienes (LTs) > 20 years ago, considerable progress has been made in our understanding of the role of these molecules in health and disease, particularly regarding bronchial asthma. This study will review the biochemistry of the 5-lipoxygenase pathway for LT generation. It will discuss the early evidence that LTs, the cysteinyl LTs in particular, have the biological properties expected for molecules that participate in the pathogenesis of bronchial asthma and the evidence for their formation in the airways of asthmatic individuals. It will briefly review tile evidence that LT-modifying drugs are effective in the management of bronchial asthma and will discuss novel developments in our understanding of the proinflammatory properties of the LTs including their role as autocrine mediators of leukocyte responses. The pharmacogenomics of 5-lipoxgenase and LTC4 synthase in bronchial asthma will be discussed.     

A double-blind combination study of clonazepam with sertraline in obsessive-compulsive disorder.

This double blind, randomized, parallel, placebo-controlled study investigates whether clonazepam accelerates and/ or increases the overall response in patients with obsessive compulsive disorder (OCD) who are treated with sertraline. Thirty-seven patients were randomized with 20 in the sertraline and clonazepam group and 17 in the sertraline and placebo groups. Male and female outpatients, age 18-65 years, met criteria for a primary diagnosis of obsessive compulsive disorder according to DSM-IV, as determined by the structured clinical MINI interview. Appropriate safety and efficacy parameters were measured throughout the study. The determination of efficacy was based primarily on changes from baseline to the last observation taken through week 12. Analysis revealed no significant difference between groups at endpoint on the main scale.     

Standardization and quantification of radionuclide solid gastric-emptying studies.

The purposes of this investigation were to standardize and validate a simple quantitative method for performing radionuclide solid gastric emptying that can be used for any dual-head gamma-camera and to establish reference values. METHODS: After eating a solid meal (egg sandwich) labeled with a radionuclide, 20 healthy volunteers (9 male, 11 female) underwent a 90-min gastric-emptying study performed with a triple-head gamma-camera. Two sets of 3 simultaneous projections were acquired sequentially for 30 s each: anterior, right posterior oblique (RPO), left posterior oblique (LPO), posterior, left anterior oblique (LAO), and right anterior oblique (RAO), and this sequence was repeated continuously for 90 min. Time-activity curves were generated using a gastric region of interest for each of the views as well as the conjugate-view geometric mean (GM) data for the anterior/posterior, LAO/RPO, and RAO/LPO combinations. Quantitative parameters were determined: percentage gastric emptying (%GE) at 90 min, half-time (min) based on an exponential fit, and clearance rate (%/min) based on a linear fit. Reference values were determined on the basis of a 95% confidence interval of the t distribution. The results were statistically analyzed and compared. RESULTS: The %GE reference values were greater for the anterior/posterior GM (>or=33%) than for the LAO (>or=31%) and anterior (>or=30%) GMs. The 3 %GE GM methods, the 3 exponential-fit GM methods, and the 3 linear-fit GM methods had high correlation coefficients (r >or= 0.874), and with only a single exception, there was no statistical difference among them. The LAO method and LAO/RPO GM mean method correlated strongly (r = 0.900) and had similar mean values (52% vs. 51%) and reference values (29% vs. 30%). All 3 methods of GM quantification also correlated strongly, and there was no significant difference among them. CONCLUSION: We have described and validated a simple method for radionuclide solid gastric emptying that can be used with a dual-head gamma-camera. We recommend the anterior/posterior GM method and have established reference values (>or=33%).     

An unusual association with Raynaud's phenomenon

A 36-yr-old lady with a year of typical Raynaud's and polyarthralgiahad a normal examination other than cold peripheries and bloodpressure of     

Noxious stimuli excite neurons in nucleus submedius of the normal and arthritic rat

Anatomical studies have revealed the existence of an ascending pathway originating in the spinal cord and medullary dorsal horn, relaying in nucleus submedius (Sm) in medial thalamus and terminating in ventrolateral orbital cortex. It has been suggested that this pathway may be involved in the transmission of nociceptive information. In the present study extracellular recordings were obtained from neurons in Sm of anesthetized arthritic and normal rats. Mechanical and thermal stimuli were delivered to various regions of the body to determine the types of somatic stimuli which could activate Sm neurons. Over 40% of the 146 neurons studied responded to somatic stimuli. In the normal rats only high intensity mechanical and thermal stimuli were effective in inducing responses. In the arthritic rats lower intensity mechanical stimuli, joint movements and high intensity thermal stimuli were effective. Such stimuli produce nociceptive reactions in the freely moving arthritic rat. Almost all the responses were excitatory and generally lasted the entire duration of the 15-s stimuli employed. In some cases after-discharges were present. The receptive fields of the neurons were in almost all cases large and bilateral. These findings support the hypothesis that Sm may be involved in mediating the affective-motivational aspects of pain.