Neural correlates of chromostereopsis: An evoked potential study

Chromostereopsis is an illusion of depth arising from colour contrast: ocular chromatic aberrations usually make red appear closer to the viewer than blue. Whereas this phenomenon is widely documented from the optical and psychophysical point of view, its neural correlates have not been investigated. To determine the cortical processing of this colour-based depth effect, visual evoked potentials (VEPs) to contrasts of colour were recorded in 25 subjects. Chromostereopsis was found with the stimuli combining spectra extremes. VEP amplitude but not latency effects were observed to colour depth cues, suggesting an underlying, depth-specific slow negative wave, located using source modelling first in occipito-parietal, parietal, then temporal areas. The component was larger over the right hemisphere consistent with RH dominance in depth processing, likely due to context-dependent top-down modulation. These results demonstrate that the depth illusion obtained from contrast of colour implicates similar cortical areas as classic binocular depth perception.     

Cardiovascular risk factors in young snuff-users and cigarette smokers

We studied cardiovascular risk factors in 21 young men who were habitual snuff-users, and compared them with the same risk factors in 18 non-tobacco-users and 19 cigarette smokers of the same age and body mass index. Both snuff-users and smokers showed increased levels of alcohol and coffee consumption and a decreased level of physical exercise compared to non-users. Both groups of tobacco-users showed increased serum insulin levels compared to the control group at similar blood glucose concentrations. In contrast to the smokers, snuff-users showed no significant elevation of diastolic blood pressure, haemoglobin concentrations, white cell count, serum cholesterol or triglyceride levels. Snuff users had higher plasma fibrinogen levels than non-users (P = 0.07). The use of snuff by young men appears to have less impact than smoking on cardiovascular risk factors, with the possible exception of elevated serum insulin and plasma fibrinogen levels.     

Digital imaging of the chest

During the past several years, image acquisition in nuclear medicine, computed tomography, ultrasonography, subtraction angiography, and magnetic resonance has been by digitization. Despite these advances, research in the development of digital imaging in conventional radiography has lagged behind. Although studies with a variety of digital techniques have been carried out on several fronts, we still do not possess a method that has captured the imagination of the majority of radiologists and other physicians to a point where it could replace conventional screen-film imaging. This article reviews the current status and general principles of the technology, focusing on the four digital radiographic techniques that have shown the greatest promise - film digitization, an image intensifier - based system, photostimulable phosphor plates, and a scanned projection system. The physical aspects of each of the four systems and the clinical results that have been reported to date, as well as the advantages and disadvantages of each system, are presented.     

The effect of antibody against TNF alpha on cytokine response in Jarisch-Herxheimer reactions of louse-borne relapsing fever

Severe Jarisch Herxheimer reaction (J-HR) precipitated by antibiotic treatment of louse-borne relapsing fever (LBRF) is associated with a transient, marked rise in circulating tumour necrosis factor alpha (TNF alpha), interleukin 6 (IL-6) and interleukin 8 (IL-8). Ovine polyclonal anti-TNF alpha antibody fragments (Fab) were used in a randomized double blind placebo controlled trial in an attempt to prevent this reaction. Within 4 h after penicillin, in controls (n = 29), a several- fold rise in cytokines occurred, concomitant with a fall in spirochaetes and maximal clinical manifestations of the J-HR. An intravenous infusion of anti-TNF alpha Fab, 30 min before penicillin in 20 patients reduced peak plasma levels of IL-6 and IL-8 (but not IL-1 beta) compared with controls (p = 0.01 and < 0.001, respectively) and the incidence of the J-HR, indicating some neutralization of TNF alpha. An apparent fall in TNF alpha reflected interference of anti-TNF alpha in the immunoassay.      

Blastomycosis in a young African man presenting with a pleural effusion

Blastomyces dermatitidis is a dimorphic fungus endemic to northwestern Ontario, Manitoba and some parts of the United States. The fungus is also endemic to parts of Africa. Pulmonary and extrapulmonary findings of a 24-year-old African man who presented with weight loss, dry cough and chronic pneumonia not resolving with antibiotic treatment are presented. The unusual occurrence of pulmonary blastomycosis associated with skin lesions and a moderate pleural effusion is reported.     

A selective cyclooxygenase 2 inhibitor suppresses the growth of H-ras-transformed rat intestinal epithelial cells

BACKGROUND & AIMS: Constitutive expression of cyclooxygenase 2 (COX-2) has been found in 85% of colorectal cancers. Ras mutations are found in 50% of colorectal adenocarcinomas. The aim of this study was to determine the role of COX-2 in ras-induced transformation in rat intestinal epithelial (RIE) cells. METHODS: Cell growth was determined by cell counts. The expression of COX-2 was examined by Northern and Western analyses. For tumorigenicity assays, cells were inoculated into dorsal subcutaneous tissue of athymic nude mice. DNA-fragmentation assays were performed to detect apoptosis. RESULTS: The expression of COX-2 was increased in RIE-Ras cells at both messenger RNA (9-fold) and protein (12-fold) levels. Prostaglandin I2 levels were elevated 2.15-fold in RIE-Ras cells. Serum deprivation further increased COX-2 expression 3.8-fold in RIE-Ras cells. Treatment with a selective COX-2 antagonist (SC58125) inhibited the growth of RIE-Ras cells through inhibition of cell proliferation and by induction of apoptosis. SC-58125 treatment reduced the colony formation in Matrigel by 83.0%. Intraperitoneal administration of SC-58125 suppressed RIE-Ras tumor growth in nude mice by 60.3% in 4 weeks. SC-58125 treatment also induced apoptosis in RIE-Ras cells as indicated by increased DNA fragmentation. CONCLUSIONS: Overexpression of COX-2 may contribute to tumorigenicity of ras-transformed intestinal epithelial cells. Selective inhibition of COX-2 activity inhibits growth of ras-transformed intestinal epithelial cells and induces apoptosis. (Gastroenterology 1997 Dec;113(6):1883-91)     

Liver transplant recipients: portable duplex US with correlative angiography

Twenty patients, aged 4 months to 58 years, were evaluated for liver transplantation by duplex sonography, and 15 transplantations were completed; 42 postoperative examinations were performed. Sonographic findings were correlated with seven preoperative and five postoperative angiographic evaluations. Preoperative duplex US findings included tumors, portal vein occlusion, varices, biliary obstruction, and variant vascular anatomy. Postoperative findings included hepatic artery occlusion, portal vein occlusions (one with cavernous transformation), portal vein stenosis, biliary obstruction, intrahepatic and extrahepatic fluid collections, and air in the portal vein due to ischemic bowel. Use of angiography allowed confirmation of the vascular abnormalities and demonstrated evidence of rejection in patients with normal Doppler waveforms. Duplex sonography is a valuable portable technique for evaluating these patients and can be used in triage of patients requiring angiography.