Kaposi's sarcoma presenting as linitis plastica

A 31-yr-old woman presenting with abdominal complaints and fever was found to have linitis plastica on upper gastrointestinal series. Endoscopic studies confirmed these findings; however, pathology revealed the diagnosis to be Kaposi's sarcoma. We believe this to be the first case report of linitis plastica presenting as Kaposi's sarcoma.

Digital subtraction cavernosography: method to detect venous leakage

Cavernosography has become an important diagnostic test for detecting venous leakage as a cause of vasculogenic impotence. Digital subtraction cavernosography (DSC) was carried out on 21 patients with a history of venous leakage resulting in impotence. The DSC technique was compared to conventional cineradiography. Major venous leaks were easily identified in 16 patients. DSC was able to detect minor leaks missed by cineradiography in 2 patients. DSC seems to be a reliable technique that is easy to perform. It should be done in conjunction with pharmacologically induced erection.

Hippocampal mu-receptors mediate opioid reinforcement in the CA3 region

Dependence on reinforcing chemicals is manifested when drug-seeking and drug-taking behaviors come to dominate the response repertoire. Clinical observations suggest that the craving and compulsive drug-seeking that characterize drug dependence are aroused by memories of the reinforcing drug experience. If so, a brain structure intimately associated with memory--the hippocampus--would be a plausible substrate for drug reinforcement effects. We report here that drug-naive rats rapidly learn to self-administer the opioid peptide dynorphin A in the CA3 region of hippocampus, and that this behavior is blocked by co-administration of the non-selective opiate antagonist naloxone. Subsequent studies demonstrated that coadministration of mu-, but not kappa- or delta-opioid antagonists also blocked self-administration behavior. We conclude that mu-receptors in the CA3 region of hippocampus may be important target sites for opioid dependence.

Review of human and animal cases of coccidioidomycosis diagnosed in Canada

The first Canadian case of coccidioidomycosis in a human was reported in 1952 and 11 more cases since then. This study provides details of other cases of coccidioidomycosis that have been diagnosed in Canada. Based on clinical details, isolation of Coccidioides immitis, detection of a specific antibody (F band) for coccidioidomycosis by macro- or microimmunodiffusion tests, concurrently used with the complement fixation procedure, and histopathological findings, 116 more cases of this disease were verified. The great majority (94%) of these cases were diagnosed in the western Canadian provinces of British Columbia, Alberta, Saskatchewan and Manitoba, and the others in Quebec, Ontario and Nova Scotia (5, 1, and 1 cases, respectively). Available information indicates that the C. immitis infections were contracted during visits to endemic areas in the United States (Arizona, California and New Mexico), Mexico, and Bolivia. Pulmonary infections were the most common type of coccidioidomycosis (93%) followed by the disseminated or meningeal types C. immitis infections occurred in individuals with or without predisposing factor(s) and were more common in males than in females. The exoantigen procedure was very useful and reliable in the accurate and rapid identification of suspected C. immitis isolates. Two cases of coccidioidomycosis were reported in animals in Ontario, Canada.

Naloxone blockade of amphetamine place preference conditioning

Amphetamine and naloxone were examined in place conditioning, in order to study possible interactions between endogenous opioids and catecholamines in reinforcement. After initial preferences were determined, animals were conditioned with amphetamine alone (1.0 mg/kg SC), naloxone alone (0.02, 0.2 or 2.0 mg/kg SC) or combinations of amphetamine plus naloxone. A reliable, long-lasting preference for the compartment associated with amphetamine was observed, reflecting the reinforcing properties of this drug. No preference or aversion was observed in animals that received saline in both compartments. Naloxone (0.02, 0.2 and 2.0 mg/kg) produced a dose-dependent place aversion; while the lowest dose had effects similar to saline, the higher doses produced significant place aversions. Naloxone, at all three doses examined, prevented the ability of amphetamine to produce a place preference. Thus, the lowest dose of naloxone, having no effects alone in place conditioning was still able to block the reinforcing effects of amphetamine. These results suggest that the reinforcing effects of amphetamine are dependent on activation of opiate receptors, and provide further evidence that interactions between endogenous opioids and catecholamines may be important in reinforcement.

Distinguishing between scar and recurrent herniated disk in postoperative patients: value of contrast-enhanced CT and MR imaging

Twenty patients with failed back surgery syndrome were analyzed prospectively with MR imaging. In addition, 10 of these patients were analyzed with high-dose contrast-enhanced CT or gadopentetate dimeglumine-enhanced MR imaging. Imaging results were compared with surgical and pathologic findings in all cases. In the 10-patient subset, abnormal epidural soft-tissue specimens were also assessed with light and electron microscopy for vascular density, size of the extracellular space, and collagen orientation and thickness. The average vascular density of epidural fibrosis on light microscopy was found to be 1.19%; the average size of the extracellular space on electron microscopy was 4.29%. Scar 4 months of age or less had a larger extracellular space than did older scar; high- (grade 4 or 5) intensity scar had a larger extracellular space than did less intense scar on long TR/short TE images. Scar 1 year old or less enhanced more intensely on CT than did older scar. The MR signal intensity and CT enhancement characteristics of epidural scar were also found to differ according to epidural location. The percentage of scar that was hyperintense on long TR/TE images was as follows: anterior, 82%; lateral recess, 70%; lateral, 47%; and posterior, 20%. However, no relationship was found between the degree of CT enhancement of scar and vascular density. Gap junction status and extracellular space size, therefore, are more important than vascular density in predicting the degree of enhancement. The accuracy of contrast-enhanced CT and unenhanced MR in separating scar from herniated nucleus pulposus is 80%. This accuracy is related to the partial overlap in imaging characteristics of scar and recurrent herniated nucleus pulposus.

Speech recognition measures with noise suppression hearing aids using a single-subject experimental design

Research aimed at quantifying the benefits a hearing aid user might expect from noise suppression hearing aids purported to improve hearing in the presence of background noise have yielded widely varying results. We suggest this may in part be due to the inappropriate use of experimental approaches based on group design and inferential statistical analysis. Included in this paper is our rationale for employing a single-subject experimental design to investigate subject performance with two commercially available hearing-aid noise suppression systems. Preliminary results with two subjects indicate that both the Siemens Automatic Signal Processing (ASP) and Zeta Noise Blocker (ZNB) noise suppression systems markedly improve listener scores on the low predictability sentence material of the SPIN Test. We conclude these two noise suppression systems may improve performance as the listening situation becomes contextually more difficult, and that single-subject experimental designs could be a valuable addition to applied behavioral research with hearing aids.

Opiate antagonists and self-stimulation: extinction-like response patterns suggest selective reward deficit

The present study investigated the response decrement patterns produced by opiate antagonists on intracranial self-stimulation behavior, in order to determine if these drugs affect the reinforcement value of the stimulation or interfere with the ability of the animal to respond. Male rats lever-pressed in 60-min sessions on a continuous reinforcement schedule for self-stimulation of the nucleus accumbens. Naloxone (2.0 and 20 mg/kg) and naltrexone (2.0 and 20 mg/kg) suppressed self-stimulation only after a significant delay, in an extinction-like response decrement pattern, mimicking the effects of reductions in current intensity (75% and 50% of baseline). The increasing behavioral effects characteristic of the extinction pattern were observed despite the fact that testing began after the time point at which maximal suppression of self-stimulation occurs with these drugs, and when brain concentrations of these drugs were declining. Since normal responding was observed for several minutes after the beginning of the session, the results may explain why long sessions are necessary to observe suppression of self-stimulation by opiate antagonists. The extinction-like pattern produced by these drugs suggests that opiate antagonists suppress self-stimulation by reducing the reinforcement value of the stimulation, rather than by interfering with the ability of the animal to respond. These findings are consistent with a role for endogenous opioid peptides in brain stimulation reward.

Effects of opiate antagonists and their quaternary analogues on nucleus accumbens self-stimulation

Naloxone and naltrexone were compared with their quaternary analogues naloxone methobromide and naltrexone methobromide for efficacy in suppressing intracranial self-stimulation behavior. These quaternary analogues effectively block opiate receptors in the periphery, but since they do not readily cross the blood-brain barrier they have little effect on central receptors. Rats with electrodes in the nucleus accumbens were trained to self-stimulate in daily 60-min sessions. Naloxone (0.2, 2.0 and 20 mg/kg) and naltrexone (20 mg/kg) potently suppressed self-stimulation behavior. In contrast, neither naloxone methobromide (0.2 and 20 mg/kg) nor naltrexone methobromide (20mg/kg) had any significant effects on this behavior. These results suggest that blockade of peripheral opiate receptors alone is insufficient to suppress self-stimulation, and therefore support the idea that opiate antagonists suppress self-stimulation by blockade of central receptors that mediate reinforcement.

Cellular investigations of behavioral reinforcement

Using the hippocampal-slice preparation, we attempted to demonstrate operant conditioning of pyramidal cell activity using local micropressure applications of transmitters and drugs as reinforcement; the same injections administered independently of bursting provided a control for direct pharmacological stimulation or facilitation of firing. The results suggested that the spontaneous bursting of individual CA1 pyramidal neurons may be reinforced with activity-contingent injections of dopamine and cocaine, whereas, CA3-bursting responses may be reinforced with contingently-applied dynorphin A. We sought to confirm these indications of cellular reinforcement at the behavioral level in studies of hippocampal self-administration (despite the fact that the hippocampus has been ignored as a brain site for chemical self-administration experiments). The results suggested that dynorphin A is a powerful reinforcer of hippocampal self-administration behavior when injected in the CA3 field; experiments still in progress suggest that dopamine can reinforce self-administration behavior when injected in the CA1 field. Successful prediction of new behavioral data from operant-conditioning data at the cellular level helps to validate the cellular data by providing suggestive evidence of interrelationship between cellular and behavioral operant conditioning processes.

Naloxone suppression of self-stimulation is independent of response difficulty

The action of the opiate antagonist naloxone on relatively easy (nose-poke) and relatively difficult (lever-press) self-stimulation behaviors was compared, in order to determine if opiate antagonists suppress self-stimulation by interfering with the ability of the animal to respond, or by reducing the reinforcement value of the stimulation. Naloxone (0.2, 2.0 and 20 mg/kg) significantly suppressed both nose-poking and lever-pressing self-stimulation rates, and the degree of suppression was virtually identical for both tasks at all doses examined. If naloxone had interfered with the ability of the animal to respond, then lever-pressing--which requires more motor output than nose-poking--should have been more suppressed than nose-poking. The results suggest that opiate antagonists do not interfere with the ability of the animal to respond, and are therefore consistent with the hypothesis that these drugs reduce the reinforcement value of the stimulation.

BAM-18: analgesia, hyperalgesia and locomotor effects

BAM-18, a proenkephalin A-derived opioid peptide, is widely distributed throughout rat CNS and displays high affinity for both mu and kappa opioid receptors. In the present study, BAM-18 was tested in two analgesia paradigms, tail-flick and hot-plate. Injections were centrally administered through a chronically implanted unilateral cannula in the lateral ventricle. In the tail-flick, low doses of BAM-18 (5 micrograms) produced a hyperalgesia while high doses of BAM-18 (50 micrograms) produced an analgesic response. Naloxone (10 mg/kg, s.c.) reversed the BAM-18-induced analgesia and unmasked a persistent hyperalgesia. Morphine-induced (1 microgram) analgesia was completely reversed by 5 micrograms BAM-18. In the hot-plate test, high doses of BAM-18 produced analgesia, with no hyperalgesia observed at any dose. Naloxone reversed the BAM-18-induced analgesia. The locomotor effects of BAM-18 did not differ from those of morphine except in effective dose (50 micrograms vs. 5 micrograms, respectively). Opioid and non-opioid effects of BAM-18 are discussed and compared with other endogenous peptides.

Determinants of low serum concentrations of salicylates in patients with Kawasaki disease

The mechanisms leading to the previously reported difficulties in achieving therapeutic serum concentrations of salicylates in Kawasaki disease were studied in eight children, once during the acute (febrile) phase and again during the nonfebrile (subacute) phase of the disease. Salicylate bioavailability was impaired during the acute phase of the disease (47.7% +/- 6.6%), and increased significantly thereafter to 75.1% +/- 9.3%. During the febrile phase there was a significant correlation between salicylate bioavailability and steady-state serum concentrations. Salicylate renal clearance was significantly higher during the febrile phase (14.45 +/- 2.5 mL/kg.h), compared with the nonfebrile phase (7 +/- 1.6 mL/kg.h, P less than 0.05). The change in salicylate clearance could be explained by decreased protein binding in the acute phase (82.5% +/- 1.9%) with substantially more free salicylates caused by significantly lower serum albumin concentrations. Changes in urine metabolites during the acute and subacute phases were consistent with the changes in dose administered (100 mg/kg in the acute phase vs 10 mg/kg in the subacute phase). The pattern of metabolites excreted in the urine of children with Kawasaki disease receiving 100 mg/kg was similar to that in children with juvenile rheumatoid arthritis receiving the same dose.

Corticosteroids-salicylate interaction in a case of juvenile rheumatoid arthritis

In an 11-year-old child with juvenile rheumatoid arthritis (JRA), the addition of prednisone caused a significant decrease in salicylate serum concentrations. A pharmacokinetic assessment suggested that these changes were not the result of altered compliance or impaired absorption of salicylate but rather an increase in salicylate clearance induced by the corticosteroid.

High-pass filter settings affect the detectability of MLRs in humans

Auditory middle latency responses (MLRs) have been recorded in 217 patients ranging in age from 6 days to 20 years. The probability of obtaining MLR components Na and Pa was higher with a high-pass filter setting of 15 Hz, 12 dB/octave as compared to 3 Hz, 6 dB/octave. This effect was found at all ages tested. Age-related latency effects were apparent with 3 Hz but not 15 Hz filtering.

Development of the middle latency response in an animal model and its relation to the human response

Although the clinical use of the middle latency response (MLR) in adults is fairly straightforward, its use is complicated by maturational changes that continue throughout the first decade of life. In order to telescope the time period of this long developmental course, we have approached the study of MLR maturation using the gerbil as an animal model. The course of MLR obtained over the temporal lobe development was characterized in the Mongolian gerbil ranging in age from 10 days to 3 months of life. The adult gerbil MLR consists of two positive peaks (A and C) at 11 and 25 ms, respectively, and a negative component (B) at 16 ms. These components emerge in a systematic fashion as a function of age. The present work supports a strong age effect of increased MLR detectability in the gerbil, similar to findings reported for humans. Wave A was infrequently detected in young animals, but when present, it occurred at adult latencies. The latency of waves B and C decreased systematically with age. The amplitude of all components increased with age, similar to findings in humans. The fact that adult-like thresholds were obtained shortly after birth indicates that when present, MLRs may be a good index of hearing threshold. Effects of stimulating across a wide range of intensities were described. The gerbil model appears appropriate for the study of development of the central auditory system function.

Changing a state mental health system through litigation: the Arizona experiment

Litigation may be a viable means to change mental health systems for the chronically mentally ill. Court orders achieved in the 1970s have been ignored or proven inefficient over the years. However, in Arizona, a strategy was designed by a team of lawyers and psychiatrists to deal with failures seen elsewhere in court actions seeking adequate services for chronically mentally ill patients. This novel approach produced a favorable court outcome and triggered a chain reaction at the executive and legislative levels to reform radically the system of care for the chronically mentally ill in Arizona.

Reinforcement delay of one second severely impairs acquisition of brain self-stimulation

The effect of delayed reinforcement on the acquisition of lateral hypothalamic self-stimulation was investigated. Brain stimulation reinforcement minimizes cues associated with reinforcement delivery (secondary reinforcement) and, by eliminating consummatory responses, permits precise temporal control of the interval between the operant response and reinforcement. Different groups were trained in daily 1-h sessions for brain stimulation reinforcement at one of 4 delay intervals (1, 2, 3 or 6 s). Responses made during the delay interval were not reinforced and reset the delay timer. Control groups (IMMEDIATE) were reinforced immediately, but were required to space responses--according to a delayed reinforcement of low rates (DRL) schedule--for an interval corresponding to one of the delay of reinforcement intervals. The DRL schedule equalized opportunities for reinforcement and non-reinforcement. At all intervals, rats trained with delayed reinforcement had significantly lower bar-press rates than controls trained with immediate reinforcement under DRL. When reinforcement schedules were switched (DELAY groups now get IMMEDIATE and vice versa), response rates rapidly shifted to levels appropriate to the new schedule. The pre-switch results indicate that delays even as short as 1 s markedly impede the acquisition of self-stimulation behavior. The post-switch results suggest that delay of reinforcement, like stimulation intensity, may determine the strength of hypothalamic reinforcement and hence final levels of performance.