Isoluminance and contingent color aftereffects

In the typical induction of the orientation-contingent color aftereffect (CCAE), the stimuli are composed of elements that differ in both color and luminance. Three experiments are reported that show that chromatic contrast between stimulus elements is insufficient for the induction of the orientation-CCAE and that luminance contrast is necessary. These experiments expand on previous research concerned with the role of luminance contrast in the induction of orientation-CCAEs by eliminating alternative explanations.

Simultaneous PET and MR imaging

We have developed a prototype PET detector which is compatible with a clinical MRI system to provide simultaneous PET and MR imaging. This single-slice PET system consists of 48 2 x 2 x 10 mm3 LSO crystals in a 38 mm diameter ring configuration that can be placed inside the receiver coil of the MRI system, coupled to three multi-channel photomultipliers housed outside the main magnetic field via 4 m long and 2 mm diameter optical fibres. The PET system exhibits 2 mm spatial resolution, 41% energy resolution at 511 keV and 20 ns timing resolution. Simultaneous PET and MR phantom images were successfully acquired.

Ibogaine interferes with the establishment of amphetamine place preference learning

The ability of ibogaine, injected 24 hr before amphetamine, to modify the establishment of amphetamine-induced place preference learning was assessed. A single injection of ibogaine blocked the establishment of amphetamine place preference after 1 or 2 conditioning trials, but it was less effective after 4 trials. The reduced effectiveness of ibogaine across multiple conditioning trials appears to be the result of the development of tolerance to ibogaine.

Ibogaine interferes with the establishment of amphetamine place preference learning

The ability of ibogaine, injected 24 hr before amphetamine, to modify the establishment of amphetamine-induced place preference learning was assessed. A single injection of ibogaine blocked the establishment of amphetamine place preference after 1 or 2 conditioning trials, but it was less effective after 4 trials. The reduced effectiveness of ibogaine across multiple conditioning trials appears to be the result of the development of tolerance to ibogaine.

Compartment model for measuring myocardial oxygen consumption using [1-11C]acetate

Although [1-11C]acetate has been validated as a PET tracer for myocardial oxygen consumption (MVO2) in animals and humans, mono- and biexponential fitting of the tissue time-activity curve yields only estimates of MVO2. This study attempts to develop and validate a simple tracer kinetic model in vivo for estimation of regional MVO2.

METHODS

Twenty-seven experiments were performed in 12 anesthetized dogs with [1-11C]acetate and serial PET images under different MBF and MVO2 (baseline, ischemia, xylazine, dobutamine and dipyridamole). Estimates of MVO2 were obtained from dynamic [1-11C]acetate PET and model fitting. MBF was measured by radiolabeled microspheres, and MVO2 was calculated by the Fick method using arterial and coronary blood samples.

RESULTS

The proposed model fitted equally well for all study conditions with a multiple correlation coefficient of 0.985 +/- 0.026. Estimated MVO2 correlated linearly with measured MVO2 (y = 0.033 + 0.690x, r = 0.92, s.e. of estimates = 0.020).

CONCLUSION

This study indicates that MVO2 can be assessed with PET and [1-11C]acetate over a wide range with a simple tracer kinetic model.

Pavlovian conditioning and multiple chemical sensitivity

Pavlovian conditioning processes may contribute to some symptoms of multiple chemical sensitivity (MCS). This review summarizes the potential relevance of the literature on conditional taste and olfactory aversions, conditional sensitization, and conditional immunomodulation to understanding MCS. A conditioning-based perspective on MCS suggests novel research and treatment strategies.

Contingent color aftereffects: reassessing old conclusions

Although there is considerable evidence supporting an associative interpretation of contingent color aftereffects, there are data that appear inconsistent with this interpretation. New findings from seven experiments are presented indicating that, contrary to earlier claims, contingent color aftereffects are observed after induction with (1) single orthogonal black bars on colored backgrounds, (2) geometric forms, and (3) two orthogonal grids of the same color. The results of these experiments are relevant to an associative interpretation of contingent color aftereffects, as well as to assessing alternative interpretations of the phenomenon.

Palliative radiotherapy

Palliative radiation therapy can be useful in controlling the pain associated with tumors for which definitive therapy is not an option. The patient's quality of life is improved while side effects, hospitalization, and cost of treatment are minimized. Palliative radiation therapy should be considered as part of the oncologist's armamentarium; however, further investigations are warranted to develop appropriate protocols based on patient response.

Primary lymphoma of the calcaneus

Primary non-Hodgkin's lymphoma (NHL) of bone is a rare condition. Presented herein is a case of primary NHL of the calcaneus illustrating many of the classic features of the disease. Emphasized in this report are the nonspecific clinical and conventional radiographic features of primary NHL of bone, which may mimic inflammatory, neuropathic, infectious, or other neoplastic conditions of the extremities. The importance of early cross-sectional radiologic studies, such as magnetic resonance imaging, lies in the early characterization of the mass-like features and local extent of such lesions, helping to raise the suspicion of neoplastic disease.

Fetal ascites associated with ABO incompatibility: case report and review of the literature

We report a pregnancy complicated by anti-B isoimmunization that resulted in fetal ascites, anemia, hepatomegaly, and polyhydramnios. A previous pregnancy in the same patient was complicated by neonatal ABO incompatibility. A review of the obstetric literature suggests that ABO incompatibility may cause severe fetal anemia, especially in patients with type O blood or a previous history of ABO incompatibility of the newborn.

Magnetic resonance imaging of the musculoskeletal system. Part 5. The wrist

Musculoskeletal radiology has been transformed with the advent of magnetic resonance imaging. Magnetic resonance imaging provides visualization of the complex anatomy of the wrist and delineation of numerous pathologic processes, which are difficult to visualize with conventional imaging modalities. With the use of sophisticated pulse sequences and a dedicated extremity coil, magnetic resonance imaging allows evaluation of osseous and ligamentous injuries, arthritides, tumors, and tumor-like conditions. Magnetic resonance imaging techniques will be emphasized and anatomy and various pathologic conditions pertaining to the wrist will be reviewed.

Disruption of tolerance to the ataxic effect of ethanol by an extraneous stimulus

According to a conditioning analysis, pharmacological conditional responses (CRs) contribute to tolerance. We previously reported that, as expected on the basis of this model, tolerance to the hypothermic effect of ethanol is attenuated by "external inhibition," for instance, by presentation of a novel stimulus (a strobe). However, results of more recent research indicate that novel stimuli augment the hypothermic effect of ethanol in rats receiving the drug for the first time. It is possible, therefore, that a novel stimulus apparently attenuates ethanol tolerance because it augments ethanol-hypothermia, rather than because it functions as an external inhibitor. Two experiments were designed to evaluate external inhibition of tolerance to another effect of ethanol-ataxia. Although the initial ataxic effect of the drug (unlike the hypothermic effect) is not enhanced by a novel stimulus, the stimulus reinstated ethanol-induced ataxia in tolerant rats. The results demonstrate external inhibition of ethanol tolerance in a preparation not confounded by the effects of the novel stimulus on initial responding to ethanol.

Ibogaine fails to interrupt the expression of a previously established one-trial morphine place preference

1. Ibogaine, a proposed anti-addictive agent, has been found to interfere with the acquisition of a weak morphine-induced place preference. The present series of experiments determined if ibogaine would interfere with the expression of a previously established morphine (5 mg/kg) place preference. 2. A single injection of 40 mg/kg of ibogaine 24 h, 12 h or 4 h prior to the preference test (Experiment 1) or 80 mg/kg of ibogaine 24 hr prior to the preference test (Experiment 3) did not interfere with the expression of a morphine conditioned place preference. 3. Furthermore, two injections of 40 mg/kg of ibogaine 48 h and 24 h or 24 h and 4 h prior to testing (Experiment 2) did not interfere with the expression of a morphine place preference. 4. Ibogaine appears to be incapable of attenuating the expression of a previously established one-trial morphine place preference.

Circuit-specific alterations of N-methyl-D-aspartate receptor subunit 1 in the dentate gyrus of aged monkeys

Age-associated memory impairment occurs frequently in primates. Based on the established importance of both the perforant path and N-methyl-D-aspartate (NMDA) receptors in memory formation, we investigated the glutamate receptor distribution and immunofluorescence intensity within the dentate gyrus of juvenile, adult, and aged macaque monkeys with the combined use of subunit-specific antibodies and quantitative confocal laser scanning microscopy. Here we demonstrate that aged monkeys, compared to adult monkeys, exhibit a 30.6% decrease in the ratio of NMDA receptor subunit 1 (NMDAR1) immunofluorescence intensity within the distal dendrites of the dentate gyrus granule cells, which receive the perforant path input from the entorhinal cortex, relative to the proximal dendrites, which receive an intrinsic excitatory input from the dentate hilus. The intradendritic alteration in NMDAR1 immunofluorescence occurs without a similar alteration of non-NMDA receptor subunits. Further analyses using synaptophysin as a reflection of total synaptic density and microtubule-associated protein 2 as a dendritic structural marker demonstrated no significant difference in staining intensity or area across the molecular layer in aged animals compared to the younger animals. These findings suggest that, in aged monkeys, a circuit-specific alteration in the intradendritic concentration of NMDAR1 occurs without concomitant gross structural changes in dendritic morphology or a significant change in the total synaptic density across the molecular layer. This alteration in the NMDA receptor-mediated input to the hippocampus from the entorhinal cortex may represent a molecular/cellular substrate for age-associated memory impairments.

Individual differences in reactivity to the rewarding/aversive properties of drugs: assessment by taste and place conditioning

The ability of individual differences in the strength of conditioned taste avoidance (CTA) to predict strength of place conditioning produced by the same drug was assessed. In Phase 1, rats were assigned to High CTA and Low CTA groups on the basis of their intake of saccharin solution previously paired with morphine, amphetamine, lithium, or fenfluramine. In Phase 2, the rats received place conditioning training with the same drug used during Phase 1. The rats that displayed the strongest amphetamine-induced CTA also displayed the strongest amphetamine-induced place preference, suggesting that a common mechanism mediates both effects. On the other hand, the strength of the CTA was unrelated to the strength of the place preference or place aversion produced by morphine, lithium, or fenfluramine.

[CAA 19-9 and carcinoembryonic antigen in gallbladder cancer]

The aim of this work was to assess the diagnostic yield of serum tumoral markers, Ca 19-9 and carcinoembryonic antigen, in patients with gallbladder cancer. We studied 54 patients of whom 33 had gallbladder cancer and in 21 the tumor was removed previously and were presently free of disease. Twenty one patients with cholelithiasis were used as controls. Ca 19-9 was over 37 U/ml in 22 (65%) patients with cancer, in two patients free of disease and in two controls. The sensitivity and specificity of Ca 19-9 was 0.66 and 0.90 respectively. Carcinoembryonic antigen was over 2.5 ng/ml in 25 patients with cancer (56%) and its sensitivity and specificity was 0.75 and 0.71 respectively. Using a cutoff point of 4 ng/ml, these figures were 0.51 and 0.9 respectively. The better predictive capacity was given by a Ca 19-9 over 37 U/ml or a carcinoembryonic antigen over 4 ng/ml. It is concluded that, although the sensitivity and specificity of these markers was adequate in this work, one must bear in mind that studied patients had advanced tumors.

An associative interpretation of the indirect McCollough effect

Following an induction procedure in which a coloured grid is alternated with a square of a complementary colour, subjects report colour after-effects on both the grid orientation present during induction and the orthogonal non-induced grid orientation. The after-effect reported on the induced grid orientation is called the McCollough effect (ME). The after-effect reported on the non-induced grid orientation is called the indirect ME. There is evidence that the ME represents an instance of Pavlovian conditioning. The present results support a conditioning interpretation of the indirect ME and are inconsistent with interpretations of the indirect ME that attribute the phenomenon to special orthogonal coding mechanisms within the visual system.

Tolerance to naloxone-induced suppression of intake: learning and cross-tolerance to cholecystokinin in rats

Experiments were conducted to evaluate the contribution of conditioning to tolerance to the meal-suppressive effect of naloxone (Nx) in rats. The results indicated (a) Nx suppresses consumption in a dose-dependent manner; (b) tolerance to this suppression of intake is "contingent" (the rat must eat in conjunction with drug administration for tolerance to develop); (c) tolerance is displayed only in the context of environmental cues previously associated with Nx; (d) Nx-tolerant rats overeat when presented with cues previously associated with the drug; (e) Nx-tolerant rats display cross-tolerance to cholecystokinin. The results are consistent with C.X. Poulos and H. Cappell's (1991) "homeostatic" theory of tolerance, as well as with the results of other experiments indicating that conditioning contributes to tolerance to many effects of various drugs.

[Hereditary chronic pancreatitis. Report of a case]

Childhood hereditary pancreatitis is a rare entity of uncertain etiology, characterized by recurrent episodes of acute pancreatitis, abdominal pain and other unspecific symptoms. Among several therapeutic alternatives, pancreatojejunostomy is presently the treatment of choice. We report a 17 years old male with chronic hereditary pancreatitis that was treated with pancreatojejunostomy drainage.

Distribution of the excitatory amino acid receptor subunits GluR2(4) in monkey hippocampus and colocalization with subunits GluR5-7 and NMDAR1

Ionotropic excitatory amino acid (EAA) receptors are divided pharmacologically into three categories termed NMDA, AMPA/kainate, and high affinity kainate receptors. Each of these receptor subtypes is composed of a specific subset of subunits termed GluR1-4 (AMPA/kainate), GluR5-7, KA1-2 (high affinity kainate), and NMDAR1, 2 A-D (NMDA). Although colocalization of NMDA and non-NMDA receptors has been previously demonstrated electrophysiologically in rat, comprehensive analyses of subunit specific colocalization patterns have not been possible until the advent of appropriate antibodies. The present study investigates such immunocytochemical colocalization of several EAA receptor subunits within individual cells as well as dendritic spines in the monkey hippocampus. Double-label immunohistochemical experiments using antibodies which are specific for GluR2(4), GluR5-7, and NMDAR1 demonstrated that virtually all projection neurons in each subfield of the hippocampus contain subunits from the AMPA/kainate, kainate, and NMDA receptor families. In addition, confocal microscopy has demonstrated that individual spines may contain subunits representative of multiple EAA receptor families. Furthermore, detailed regional, cellular, and ultrastructural distribution patterns of the EAA receptor subunits GluR2 and GluR4 in monkey hippocampus are presented based on the use of a monoclonal antibody (mAb), 3A11, which was generated against the putative extracellular N-terminal domain of GluR2. Since this antibody recognizes only GluR2 in Western blots, and GluR2 as well as GluR4 in fixed transiently transfected cells, it has been designated anti-GluR2(4). Immunocytochemical labeling with mAb 3A11 revealed pyramidal cell somata and dendrites in each field of the hippocampus, as well as granule cells and polymorphic hilar cells in the dentate gyrus. Small cells with the morphologic characteristics of astroglia were also immunolabeled for GluR2(4) within the alveus and fimbria. Immunoreactivity at the ultrastructural level was localized to postsynaptic densities on dendritic spines and shafts and within the somatodendritic cytoplasm in all major hippocampal regions, as well as in a subset of dentate granule cell axons within the mossy fiber projection.

Learning and tolerance to the intake suppressive effect of cholecystokinin in rats

Experiments were conducted to evaluate the contribution of conditioning to tolerance to the meal suppressive effect of cholecystokinin (CCK). The results indicate that (a) tolerance was contingent (the rat had to eat in conjunction with drug administration for tolerance to the meal suppressive effect to develop), (b) tolerance was displayed only in the context of environmental cues previously associated with CCK, (c) CCK-tolerant rats overate when presented with cues previously associated with the peptide, and (d) CCK tolerance displayed latent inhibition. The results are consistent with C.X. Poulos and H. Cappell's (1991) homeostatic theory of tolerance, as well as with the results of other experiments indicating that conditioning contributes to tolerance to many effects of a variety of drugs.

Morphine-induced taste avoidance is attenuated with multiple conditioning trials

Morphine has paradoxical effects in learning experiments. The drug can serve as a reinforcer in several situations; yet rats avoid tastes paired with morphine, much as they avoid tastes paired with an emetic drug such as lithium chloride (LiCl). The results of the present experiment indicate that, in contrast with LiCl-induced taste avoidance, the strength of morphine-induced avoidance is nonmonotonically related to the duration of training. Although taste avoidances produced by both drugs are readily established, the morphine-induced avoidance (unlike the LiCl-induced avoidance) weakens with continued flavor-drug pairings. These results, together with prior findings, suggest that there are distinctive features of morphine-induced taste avoidance.