Cortical-striatal gene expression in neonatal hippocampal lesion (NVHL)-amplified cocaine sensitization

Cortical-striatal circuit dysfunction in mental illness may enhance addiction vulnerability. Neonatal ventral hippocampal lesions (NVHL) model this dual diagnosis causality by producing a schizophrenia syndrome with enhanced responsiveness to addictive drugs. Rat genome-wide microarrays containing >24 000 probesets were used to examine separate and co-occurring effects of NVHLs and cocaine sensitization (15 mg/kg/day × 5 days) on gene expression within medial prefrontal cortex (MPFC), nucleus accumbens (NAC), and caudate-putamen (CAPU). Two weeks after NVHLs robustly amplified cocaine behavioral sensitization, brains were harvested for genes of interest defined as those altered at P < 0.001 by NVHL or cocaine effects or interactions. Among 135 genes so impacted, NVHLs altered twofold more than cocaine, with half of all changes in the NAC. Although no genes were changed in the same direction by both NVHL and cocaine history, the anatomy and directionality of significant changes suggested synergy on the neural circuit level generative of compounded behavioral phenotypes: NVHL predominantly downregulated expression in MPFC and NAC while NVHL and cocaine history mostly upregulated CAPU expression. From 75 named genes altered by NVHL or cocaine, 27 had expression levels that correlated significantly with degree of behavioral sensitization, including 11 downregulated by NVHL in MPFC/NAC, and 10 upregulated by NVHL or cocaine in CAPU. These findings suggest that structural and functional impoverishment of prefrontal-cortical-accumbens circuits in mental illness is associated with abnormal striatal plasticity compounding with that in addictive disease. Polygenetic interactions impacting neuronal signaling and morphology within these networks likely contribute to addiction vulnerability in mental illness.

A neurobiological basis for substance abuse comorbidity in schizophrenia

It is commonly held that substance use comorbidity in schizophrenia represents self-medication, an attempt by patients to alleviate adverse positive and negative symptoms, cognitive impairment, or medication side effects. However, recent advances suggest that increased vulnerability to addictive behavior may reflect the impact of the neuropathology of schizophrenia on the neural circuitry mediating drug reward and reinforcement. We hypothesize that abnormalities in the hippocampal formation and frontal cortex facilitate the positive reinforcing effects of drug reward and reduce inhibitory control over drug-seeking behavior. In this model, disturbances in drug reward are mediated, in part, by dysregulated neural integration of dopamine and glutamate signaling in the nucleus accumbens resulting form frontal cortical and hippocampal dysfunction. Altered integration of these signals would produce neural and motivational changes similar to long-term substance abuse but without the necessity of prior drug exposure. Thus, schizophrenic patients may have a predilection for addictive behavior as a primary disease symptom in parallel to, and in many, cases independent from, their other symptoms.

Droperidol: efficacy and side effects in psychiatric emergencies

BACKGROUND

As admission criteria to inpatient units become more focused on patient safety and behavioral instability, primary treatment often requires use of medications that need to be quick, safe, and effective for control of agitation. This article reviews the evidence that droperidol may serve as the optimal medication for this task.

DATA SOURCES

A comprehensive MEDLINE search of English-language literature was conducted using the search term droperidol concerning the use of droperidol in psychiatric emergencies. Cross-referencing of those articles was conducted to include pertinent articles in the non-psychiatric and European literature regarding safety and early development of the drug.

STUDY FINDINGS

As evidenced in the animal and clinical literature, studies demonstrate the efficacy and rapidity of onset of droperidol and its relative safety compared with the most widely used antiagitation drug, haloperidol. Evidence for this use of droperidol is particularly compelling for situations in which intramuscular administration is necessary.

CONCLUSION

Droperidol, while not in widespread use, may prove to be the superior typical neuroleptic for psychiatric emergencies. Increased clinical utilization and study of droperidol for this use is warranted.

Glutamate and post-traumatic stress disorder: toward a psychobiology of dissociation

Dissociative cognitive and perceptual alterations commonly occur at the time of traumatization and as an enduring feature of post-traumatic stress disorder (PTSD). After stress exposure, dissociative symptoms are a predictor of the development of PTSD. Recent preclinical data suggest that stress stimulates the cortico-limbic release of glutamate. The glutamate that is released during stress in animal models influences behavior, induces a variety of changes in neural plasticity that may have long-lasting effects on brain function and behavior, and contributes to neural toxicity. Antagonist of the N-methyl-D-aspartate (NMDA) subtype of glutamate receptor also stimulates transient cortico-limbic glutamate release in animals. Further, some of the effects of NMDA antagonists in animals are blocked by drugs that attenuate glutamate release. Clinical studies suggest that NMDA antagonists may transiently stimulate glutamate release and produce symptoms resembling dissociative states in humans. A recent study suggests that a drug that reduces glutamate release also attenuates the perceptual effects of the NMDA antagonist, ketamine, in humans. Because of the possible contributions of hyperglutamatergic states to the acute and long-lasting consequences of traumatic stress exposure, the therapeutic and neuroprotective potential of drugs that attenuate glutamate release should be explored in traumatized individuals with dissociative symptoms.

Cognitive effects of neonatal hippocampal lesions in a rat model of schizophrenia

Lesioning the ventral hippocampus of neonatal rats has been proposed as an experimental model of schizophrenia. This lesion causes a syndrome of hyperresponsivity to the stimulant effects of amphetamine, impaired grooming and disrupted social interactions, effects that emerge during adolescence, much like schizophrenia. Persisting cognitive effects of neonatal ventral hippocampal lesions were assessed in the current study, because the hippocampus is critically important for a variety of cognitive functions and cognitive impairment and because it is an important feature of schizophrenia. Spatial learning and working memory were assessed in the radial-arm maze, which is sensitive to the adverse effects of hippocampal lesions made in adults. Lesioned rats showed pronounced deficits in radial-arm maze choice accuracy that persisted throughout training. Deficits were seen during the prepubertal period as well as in adulthood. Even though the lesioned rats performed more poorly, they were significantly less sensitive to the amnestic effects of the nicotinic antagonist mecamylamine and the muscarinic antagonist scopolamine. No significant effects of nicotine or amphetamine were seen in either the lesioned or control groups. The long-lasting deficits in spatial learning and working memory resulting from neonatal ventral hippocampal lesions show that, unlike frontal cortical lesions during the same age, the effects of hippocampal lesions are not overcome during development. The resistance to the amnestic effects of nicotinic and muscarinic acetylcholine (ACh) antagonists suggests that the hippocampus is a critical site for the action of these drugs. Neonatal hippocampal lesions may provide a good model of the cognitive impairments of schizophrenia and may be useful to assess novel drug effects to counteract the cognitive deficits in schizophrenia.

The PLDD registry

The rapid acceptance of minimally invasive surgery in the United States has largely occurred without statistical proof of its superiority over traditional methods. All players in the healthcare field now see the need for valid outcome studies supporting the efficacy of new treatment techniques. Percutaneous laser disc decompression (PLDD) will gain wide acceptance only if it is statistically shown to be a safe and effective alternative treatment of a lumbar disc herniation. To that end, a central PLDD registry has been developed and implemented into clinical practice at several centers. This article reviews healthcare trends that motivated the creation of this data repository and discusses the history of its development. The currently used PLDD evaluation form is outlined and its utility is discussed. Most importantly, preliminary PLDD results and complications based on the data received are presented and analyzed.

Progressive multifocal leukoencephalopathy in acquired immune deficiency syndrome

Progressive multifocal leukoencephalopathy occurred in two homosexual men affected with acquired immune deficiency syndrome (AIDS). Both patients received HLA-matched platelet transfusions in an attempt to increase their immune status, but we were unsuccessful in altering their fatal clinical course.

Visual evoked potentials in sarcoidosis

The visual evoked potential to pattern reversal was recorded in 50 patients with sarcoidosis. Abnormalities of latency and amplitude were found in 15 patients (30%), including all 4 patients with clinically evident brain disease and 4 of 17 patients with overt ocular disease. Twenty-nine patients had no clinical evidence of ocular or neurologic disease, and 7 of them (24%) had abnormalities of the VEP, implying subclinical sarcoid lesions in structures at the base of the brain.

Syringoencephalomyelia (syringocephalus)

This is the fourth recorded patient with extension of syringomyelia into the brain rostral to the mesencephalon verified at autopsy. A syrinx was demonstrated from the low thoracic segments of the spinal cord to the cervico-medullary junction, where a fibrovascular malformation and dural-arachnoid adhesions deformed the pyramids. Cavities in the spinal cord were continuous, with rostral glial-lined cavities in both corticospinal tracts through a system of sponge-like tubes. The rostral extent of these cavities on the right was the centrum semi-ovale above the neostriatum; on the left, the cavities extended to the diencephalon. A classical lateral-dorsal syringobulbia in the right medulla accompanied the syringoencephalomyelia (syringocephalus).

50ppm MnBK subclinical neuropathy in rats

40 rats were subjected daily for 6 months to an atmosphere containing 50ppm MnBK. 32 of the rats presented with demyelination of the sciatic nerve and 2 of these with axonal hypertrophy.

Myokymia and impaired muscular relaxation with continuous motor unit activity

We have studied two cases of the syndrome of myokymia and impaired muscular relaxation with continuous motor unit activity. Both patients complained of muscle twitching, weakness, stiffness, and hyperhydrosis during their illness. Myokymia was present over the entire body in both. On repetitive testing of muscle strength each patient showed initial fatigue followed by increasing strength as he continued his efforts. Both patinets improved on phenytoin therapy at high blood levels. Nerve conduction velocities were decreased. Electromyograms showed continuous electrical activity at rest which persisted during sleep and spinal anaesthesia but was diminished by curare. Intravital staining with methylene blue in one case demonstrated sprouting and beading of motor nerve terminals with multiple innervation of muscle fibres. The neurophysiological and pathological findings in these two cases indicate an abnormality of peripheral nerve in this disorder.

Evaluation of cerebral infarction by computed tomography with special emphasis on microinfarction

Computed tomography has proved to be the most effective mode of evaluating cerebral infarction in 143 documented cases. This was especially true when multiple focal infarcts were present. The incidence of contrast enhancement in acute infarcts was 88%. Concomitant acute and old infarcts were observed in 20% of cases. In the acute stage of stroke, radionuclide studies are preferable to contrast angiography since the latter may aggravate the pre-existing focal ischemia. Follow-up CT and radionuclide scans were extremely useful in confirming the diagnosis and demonstrating various postinfarction sequelae.

Role of gluten, prednisone, and azathioprine in non-responsive coeliac disease

A case of severe "non-responsive" coeliac disease has been shown to be sensitive to gluten whilst under prednisone therapy, but not without prednisone. This adds an additional dimension to the criteria for diagnosis of coeliac disease. Cases of non-responsive coeliac disease may require both prednisone and gluten exclusion to induce a remission. In this patient, azathioprine induced and sustained a remission when unacceptably high doses of prednisone had failed, and may prove to be a valuable immunosuppressive in non-responsive coeliac disease.

Physiological aspects of visual perception. I. Functional aspects of visual cortex

The first part of the Bennett Lecture for 1975 is a description of the dissociation of visual perception in the macaque monkey by ablation of area 17 on the one hand, and of areas 18 and 19 on the other. Bilateral removal of area 17, with careful preservation of a great part of areas 18 and 19, and of the inferior pulvinar, resulted in loss of binocular fixation, loss of visual recognition of still objects, and loss of visuosocial behavior such as grimacing and vocalization. There remained excellent visuospatial orientation and reaching for moving peripheral visual targets. Removal of areas 18 and 19, with isolation of area 17 from the remainder of cortex, was accomplished in two animals and left intact the ability to distinguish and sort out still objects by vision, with intact fixation, and visuosocial behavior. Spatial orientation was then easily confused by movement.