Cardiac conduction abnormalities and atrial arrhythmias associated with salicylate toxicity

Cardiac side effects from aspirin are uncommon; however, severe acid-base imbalance, pulmonary edema, ventricular ectopic activity and cardiopulmonary arrest have been reported in patients with toxic serum salicylate concentrations. We saw a patient with salicylate toxicity who developed a variety of sinus and atrioventricular nodal conduction disturbances and atrial arrhythmias with a relatively low toxic serum salicylate concentration. The cardiac rhythm returned to normal as the serum salicylate concentration decreased, and results of subsequent electrophysiologic testing and Holter monitoring were normal. A low serum albumin level may have resulted in altered salicylate binding in this patient, thereby increasing the availability of unbound (active) drug for toxic effects.     

Isozyme variation in Simulium (Edwardsellum) damnosum s.l. (Diptera: Simuliidae) from Kenya

Isozyme variation of the Simulium damnosum sibling species complex was studied by cellulose acetate electrophoresis (CAE) from four Kenyan river systems. Two enzymes, PGM and HK, were diagnostic and differentiated the larvae collected in Western and Nyanza provinces from the larvae collected at Mt. Kenya. Allele frequency differences of the enzyme PGI allowed about 75% separation of the geographically distinct populations.     

Hypertension in neuroblastoma induced by imipramine

Hypertension is a well-known finding in some patients with neuroblastoma. However, it has not previously been described in association with the use of Imipramine. We report the occurrence of severe hypertension (blood pressure 190/160) in a 4-year-old girl with neuroblastoma who was given Imipramine to control a behavior disorder. It was determined later that this patient's tumor was recurring at the time of her hypertensive episode. Since she had no blood pressure elevation at initial diagnosis and none following discontinuation of the Imipramine (when she was in florid relapse), we believe that this drug rather than her underlying disease alone caused her hypertension. The mechanism for this reaction is believed to be increased levels of vasoactive catecholamines due to interference of their physiologic inactivation by Imipramine. From this experience, we urge extreme caution in the use of tricyclic antidepressants in children with active neuroblastoma.     

Monoclonal antibody for avian thymic hormone.

Avian thymic hormone (ATH), a parvalbumin with immunomodulating properties, was used as antigen for development of a hybridoma cell line. Hybridoma screening by enzyme-linked immunosorbent assay (ELISA) led to the culture, purification, and characterization of an hybridoma, designated 4A6, which secretes IgG1 that is specific for ATH. The monoclonal antibody (MAb) was characterized by techniques involving indirect competitive and non-competitive ELISA, Western Blot analysis, and immunohistological staining. The MAb was highly specific for ATH with no cross-reactivity to other chicken tissue extracts or commercially available parvalbumins.     

Techniques for high-resolution MR imaging of atherosclerotic plaque

Atherosclerotic cardiovascular disease is the most common cause of death in the United States. Investigation of atherosclerotic plaque morphology and composition is important because the findings may be useful in predicting prognosis or response to therapy. This study presents high-resolution magnetic resonance (MR) imaging techniques developed on a 1.5-T whole-body imager with a custom-built surface coil, for characterizing the composition and morphology of plaque removed at carotid endarterectomy. The initial comparison of MR imaging and histologic results showed good correlation. In conjunction with MR angiography, these techniques could be used in in vivo imaging to define the size, location, and contents of atherosclerotic plaque at the carotid bifurcation.     

Senile plaques,amyloid β-protein,and acetylcholinesterase fibres: laminar distributions in Alzheimer's disease striate cortex

Summary The laminar distributions of senile plaques and amyloid -protein (AP) within the striate cortex of patients with Alzheimer's disease (AD) were studied with enhanced Bielschowsky (roughly equivalent to the Campbell technique) and immunohistochemical methods. The laminar distribution of acetylcholinesterase (AChE) fibres within the striate cortex of both AD patients and control patients was studied with an enzyme histochemical method. Quantification of Bielschowsky-stained plaque numbers along intersect lines drawn parallel to laminar boundaries revealed a significant aggregation of plaques at the interface of layers IVc and V. Lines drawn through layer VI intersected significantly fewer plaques than lines through other laminae. Immunoperoxidase staining for AP revealed a similar distribution fo senile plaques, and additional, prominent, diffuse deposits of AP within layers I and IVc. AChE fibres were markedly depleted in the striate cortex of AD cases. In control cases, AChE fibres were, like AP immunoreactivity, concentrated within layers I and IVc. The results indicate that enhanced silver methods may not reveal the complete distribution of AP. The codistribution of AP-immunoreactive diffuse amyloid deposits and AChE fibres to the same cortical laminae is consistent with the possibility that these deposits may be formed from degenerating cholinergic elements. The formation of a line of senile plaques at the interface of two cortical laminae within the striate cortex, in an anatomically analogous situation to a similar line of plaques within the dentate gyrus, suggests that formation of well-defined plaques may be accelerated by the interaction of specific neuronal systems.Supported by a Fellowship from the British Columbia Health Care Research Foundation to TGB. This work is part of the PhD. dissertation of Dr. Beach (University of British Columbia, 1991)     

Should results of ultrasound Doppler studies be reported in units of frequency or velocity?

There is a current tendency to report the results of ultrasound Doppler studies in units of velocity instead of Doppler frequency. This is probably motivated by the intuitive feeling that blood flow studies should naturally be reported in cm/s and the notion that "velocity" is a normalizing factor for Doppler ultrasound studies. In order to determine velocity, the Doppler angle theta or angle formed by the ultrasound beam and flow velocity vector, must be known. It is not possible, using currently available systems, to obtain an accurate estimate of this angle. The physics related to the Doppler equation are reviewed in this paper along with examples to illustrate the origin and magnitude of errors that could arise when reporting in units of velocity. Guidelines are provided for thinking about and reporting results of Doppler studies in units of velocity. An understanding of the Doppler equation and its use in clinical studies are promoted in this paper to enhance the diagnostic usefulness of Doppler ultrasound studies and to reduce serious errors which could lead to faulty information dictating patient management.     

Development of attraction to estrous females in male dogs

In simultaneous choice tests male beagles were allowed to visit a caged female in estrus, or caged, spayed female not in estrus. Males were tested periodically from 1-3 to 22-24 months of age. The 3 subject groups were normal males (Group N), males castrated 4-7 days postpartum and injected with testosterone propionate (TP) until they were 3 months old (Group TPTC), and males castrated 4-7 days but given no hormone treatment, i.e., untreated castrates (Group UC). A statistically reliable preference for visiting the estrous rather than the nonestrous female first appeared in N males at 4-6 months, in TPTC males at 1-3 months, and in UC males at 10-12 months. In N males attraction to the estrous female (measured by time spent visiting her) increased progressively from 4-6 to 16-18 months. In the same period concentration of plasma testosterone rapidly increased, reached a peak at 10-12 months, and then declined. UC males exhibited no significant increase in attraction to the estrous female from 10-12 months (when a preference first appeared) to 22-24 months. They then received 10 injections of TP after which their visiting time to the estrous female was equal to that of N males. TPTC males exhibited a precocious preference for the estrous female at 1-3 months, while they were receiving TP, and there was no decrease in strength of attraction in the following 9 months during which time no hormone was administered. Between 10-12 and 13-15 months, still without exogenous androgen, visiting to the estrous female began to increase and continued to do so until 19-21 months.     

Elevated abeta42 in skeletal muscle of Alzheimer disease patients suggests peripheral alterations of AbetaPP metabolism

The levels of amyloid-beta40 (Abeta40) and Abeta42 peptides were quantified in temporalis muscles and brain of neuropathologically diagnosed Alzheimer disease (AD) and of nondemented individuals. This was achieved by using a novel analytical approach consisting of a combination of fast-performance liquid chromatographic (FPLC) size exclusion chromatography developed under denaturing conditions and europium immunoassay on the 4.0- to 4.5-kd fractions. In the temporalis muscles of the AD and nondemented control groups, the average values for Abeta42 were 15.7 ng/g and 10.2 ng/g (P = 0.010), and for Abeta40 they were 37.8 ng/g and 29.8 ng/g (P = 0.067), respectively. Multiple regression analyses of the AD and control combined populations indicated that 1) muscle Abeta40 and muscle Abeta42 levels were correlated with each other (P < 0.001), 2) muscle Abeta40 levels were positively correlated with age (P = 0. 036), and 3) muscle Abeta42 levels were positively correlated with Braak stage (P = 0.042). Other forms of the Abeta peptide were discovered by mass spectrometry, revealing the presence of Abeta starting at residues 1, 6, 7, 9, 10, and 11 and ending at residues 40, 42, 44, 45, and 46. It is possible that in AD the skeletal muscle may contribute to the elevated plasma pool of Abeta and thus indirectly to the amyloid deposits of the brain parenchyma and cerebral blood vessels. The increased levels of Abeta in the temporalis muscles of AD patients suggest that alterations in AbetaPP and Abeta metabolism may be manifested in peripheral tissues.