Effects of amiodarone in a swine model of nortryptiline toxicity

Objectives

Antiarrhythmics can have devastating effects in cardiotoxic poisonings. Amiodarone is recommended for treatment of wide complex tachycardia, but its hemodynamic effects in wide complex tachycardia induced by tricyclic antidepressant poisoning are unknown. The objective of this study was to compare the effects of sodium bicarbonate, amiodarone, and normal saline in treating wide complex tachycardia secondary to nortriptyline poisoning.

Methods

This unblended randomized controlled animal study involved 18 anesthetized, intubated pigs with arterial and venous lines. Nortriptyline (2 mg/mL) was infused at 20 mg/min until the onset of toxicity, defined as a systolic blood pressure ≤50 mmHg or QRS ≥120 ms. At that point, the pigs were randomized into three groups of six. Group I received 0.9% normal saline, 10 ml/kg. Group II received hypertonic sodium bicarbonate, 1 mEq/kg. Group III received amiodarone, 15 mg/kg. The pigs were observed until death or survival at 60 minutes.

Results

After treatment, the changes in QRS were as follows: Group I, −2.0 ms; Group II, −33.0 ms; Group III, −21.7 ms. ANOVA demonstrated no significant difference between the groups (p = 0.28). Mean arterial pressures 10 minutes after treatment were as follows: Group I, 19.4 mmHg; Group II, 23.7 mmHg; Group III, 12.5 mmHg. Based on ANOVA, there was no significant difference between any of the groups (p = 0.50).

Conclusions

In this model of nortriptyline poisoning, the administration of amiodarone to correct wide complex tachycardia did not have a harmful effect.     

Impaired mismatch negativity generation in prodromal subjects and patients with schizophrenia

BACKGROUND: Mismatch negativity (MMN) specifically the response to tone duration deviants has consistently been shown to be reduced in schizophrenia suggesting dysfunction in auditory sensory memory. As part of a multidimensional approach to the early recognition of psychosis, MMN was investigated as a possible risk factor for later development of psychosis in subjects with a prodromal syndrome. Forty-three prodromal subjects, 31 neuroleptic-free inpatients with schizophrenia and 33 healthy controls were studied. A prodromal state was defined by a cluster 'Cognitive Disturbances' as defined by the 'Bonn Scale for the Assessment of Basic Symptoms' (BSABS), which was found highly predictive of first-episode schizophrenia. To elicit MMN, a three-tone auditory oddball paradigm with 10% 'duration deviants' and 10% 'frequency deviants' was used. RESULTS: MMN amplitudes to tone duration deviants were significantly reduced in the patients with schizophrenia compared to controls. The putatively prodromal subjects also showed a slight, though non-significant reduction of the MMN amplitude that was intermediate between normal controls and patients with schizophrenia, and with a larger within-group variance. CONCLUSION: These results support the view that abnormalities in temporal processing are particularly pronounced in patients with schizophrenia. Prodromal subjects are a heterogeneous group with regard to outcome and time until transition to a first psychotic episode. Follow-up of these putatively prodromal subjects will show whether MMN amplitudes further reduce over time in those developing psychosis and if a reduction is state-dependent.     

Latent infection as a source of disseminated disease caused by organisms of the Mycobacterium avium complex in simian immunodeficiency virus-infected rhesus macaques

Whether infection with Mycobacterium avium complex (MAC) among patients with acquired immune deficiency syndrome results from recent exposure to virulent strains or reactivation of latent infection acquired years earlier is unknown. To address this question, tissue samples from 47 simian immunodeficiency virus (SIV)-infected and 63 SIV-uninfected rhesus macaques were cultured. MAC was cultured from 14 SIV-uninfected macaques (22.2%) and 32 SIV-infected macaques (68.1%); median bacterial burdens were 33.3 and 998.7 cfu/g, respectively. Genetically distinct strains of MAC were identified for 13 SIV-uninfected macaques (20.6%) and 15 SIV-infected macaques (31.9%). A genetically identical MAC strain (K128A) was identified for 25 SIV-infected macaques (53.2%) and 1 SIV-uninfected macaque (1.6%). Multivariate analysis identified infection with SIV/Delta(B670), diagnosis of an SIV-related tumor or opportunistic infection, and birth on site as risks for MAC infection. SIV-uninfected and SIV-infected macaques yielding unique strains of MAC were considered to have latent and reactivation infection, respectively, whereas animals infected with strain K128A were considered to have recent infection, demonstrating that both mechanisms occur among rhesus macaques.     

"Relatively spared zones" in leprosy: a clinicopathological study of 500 patients

In this study, clinically all forms of lesions like macules, plaques, and nodules were found in all the "relatively spared zones," except groins. Histopathology confirmed that the disease process was established and the acid-fast bacilli were not present as a part of bacteremic settlement. Hence, it appears that practically no area on the surface of skin is immune to invasion by M. leprae. However, as the incidence of lesions and AFB in these regions is relatively less, especially over axilla and groin, these areas can be considered as relatively spared zones but not completely resistant to development of lesions of leprosy.     

Process dissociation between contextual retrieval and item recognition

We employed a source memory task in an event related fMRI study to dissociate MTL processes associated with either contextual retrieval or item recognition. To introduce context during study, stimuli (photographs of buildings and natural landscapes) were transformed into one of four single-color-scales: red, blue, yellow, or green. In the subsequent old/new recognition memory test, all stimuli were presented as gray scale photographs, and old-responses were followed by a four-alternative source judgment referring to the color in which the stimulus was presented during study. Our results suggest a clear-cut process dissociation within the human MTL. While an activity increase accompanies successful retrieval of contextual information, an activity decrease provides a familiarity signal that is sufficient for successful item recognition.     

Atrial and ventricular rat coronary arteries are differently supplied by noradrenergic, cholinergic and nitrergic, but not sensory nerve fibres

The present immunohistochemical study set out to determine the extent of perivascular innervation in the rat heart, using markers for noradrenergic sympathetic fibres (tyrosine hydroxylase = TH), cholinergic parasympathetic fibres (vesicular acetylcholine transporter = VAChT), nitrergic fibres (neuronal NO synthase = nNOS), and peptidergic sensory fibres (calcitonin gene-related peptide = CGRP). For each of these antigens, the vascular innervation density was assessed separately in the atria, the basal and the apical parts of the ventricles, and was correlated to the inner vascular diameter. The four major findings are: (1) Each of these neurochemically defined populations shows an individual distribution pattern significantly different from the others with respect to correlation with vascular diameter and occurrence along atrial versus ventricular vessels. (2) Among autonomic efferent axons, nNOS-containing fibres are far less numerous than cholinergic and noradrenergic fibres. (3) Autonomic efferent axons (noradrenergic, cholinergic, nitrergic) are much more abundant around atrial than ventricular vessels, whereas perivascular CGRP-immunoreactive sensory nerve fibres are equally distributed in the various parts of the heart. (4) Noradrenergic and cholinergic axons preferentially innervate small-diameter vessels (negative linear correlation between index of innervation and vascular diameter), whereas the supply with CGRP-immunoreactive sensory nerve fibres does not change with vascular diameter. Collectively, the present study shows individual distribution patterns for each of the neurochemically defined populations of perivascular axons along the atrial and ventricular coronary arteries, indicating a highly differentiated nervous regulation of atrial versus ventricular, and large-diameter versus resistance vessels.     

Spinal epidural epitheloid hemangioma--case report and review of the literature

Epitheloid hemangiomas are benign vascular lesions composed of epitheloid endothelial-cell-lined channels. We report an unusual case of a purely extradural non-osseous spinal epitheloid hemangioma presenting with quadriparesis. A 5-year-old boy presented with neck pain and quadriparesis following a trivial fall. MRI revealed a mixed intensity extradural lesion compressing the cervico-thoracic spinal cord posteriorly. At surgery the lesion consisted of vascular granulation tissue admixed with blood clots without abnormal vessels. Bone was normal. Histopathology revealed it to be an epitheloid hemangioma. The case and relevant literature is reviewed.