Vasodilator agents and supracollicular transection fail to inhibit cortical spreading depression in the cat

It remains an open question as to whether cortical spreading depression (CSD) is the pathophysiological correlate of the neurological symptoms in migraine with aura. In the experimental animal, CSD is an electrophysiological phenomenon mainly mediated via NMDA receptors. However, according to case reports in humans, visual aura in migraine can be alleviated by vasodilator substances, such as amyl nitrite and isoprenaline. There is also circumstantial evidence that brainstem nuclei (dorsal raphe nucleus and locus coeruleus) may play a pivotal role in the initiation of aura. In this study, CSD was elicited in alpha-chloralose anesthetized cats by cortical needle stab injury and monitored by means of laser Doppler flowmetry. Topical application of isoprenaline (0.1-1%) and amyl nitrite (0.05%) onto the exposed cortex had no effect on the elicitation or propagation of CSD. Also, after supracollicular transection, subsequent CSDs showed no differences in the speed of propagation and associated flow changes. We conclude from these data that--given CSD probably exists in humans during migraine--spreading neurological deficits during migraine aura are independent of brainstem influence and have a primarily neuronal rather than vascular mechanism of generation.     

Benign intracranial hypertension: visual loss and optic nerve sheath fenestration.

Five patients with serious ocular complications of benign intracranial hypertension are described. Optic nerve sheath fenestration resulted in resolution of papilloedema with, in three instances, improvement in vision. Benign intracranial hypertension may not always be benign for vision and fenestration operations may prevent or reverse visual deterioration by an effect on the optic nerve rather than by reducing intra-cranial pressure.     

Percutaneous toxicity of ethylene glycol monomethyl ether and of dipropylene glycol monomethyl ether in the rat

The subacute percutaneous toxicity of dipropylene glycol monomethyl ether (DPM) in male rats dosed 5 days/week for 4 weeks under both occluded and unoccluded conditions has been assessed and compared to the percutaneous toxicity of ethylene glycol monomethyl ether (EGM). DPM caused no significant changes in the clinical chemistry, haematology, or pathology, whereas EGM caused changes in the haematology and clinical chemistry, and both testicular and bone marrow damage at doses of 1000 mg/kg per day.     

The relationship between blood pressure and personality in a large unselected adult sample

As part of a general health survey of a small New Zealand town, the Crow-Crisp Experiential Index, the State-Trait Anxiety Inventory, a shortened version of the Hostility and Direction of Hostility Questionnaire, and the Zung Self-rating Depression Scale were administered to 1173 subjects over the age of 15. Blood pressure was moderately correlated with age and Quetelet's Index, a measure of obesity. Low but significant correlations were found between Somatic Anxiety, Hysteria, and the Urge to Act-out Hostility scale. However, when effects of age were controlled for, in a series of multiple regression analyses, the correlations with psychometric test scores were no longer significant. This study confirms several previous reports that neuroticism, anxiety, depression, and hostility are of little significant in predicting levels of blood pressure in the general population.     

Effects of nerve growth factor on autonomic neurons in the chick embryo: A stereological study

Quantitative effects of nerve growth factor (NGF) on the sympathetic, Remak and ciliary ganglia in chicken embryos were investigated. Purified mouse beta NGF was injected (80 micrograms per day for three or four consecutive days) into the yolk sac at different stages (starting on days 6, 8, 10 and 13) of embryonic development. Ganglia were taken for fixation and embedding one day after the last NGF injection. The number of neurons belonging to the different size classes was determined by a computer aided stereological method based on unfolding of cell diameter frequencies. The volume of sympathetic ganglia was increased at all stages with a maximum of 8-fold occurring on day 10. The ganglion of Remak showed a 3-fold volume increase up to embryonic days 10 and 12. Ciliary ganglia did not exhibit any differences in volume or neuron size between the controls and the embryos injected with NGF. The number of neurons was increased in younger sympathetic and Remak ganglia in response to NGF, as was the recruitment of neurons to the larger size classes.     

Electrophysiologic evidence of increased distractibility after dorsolateral prefrontal lesions

Patients with left prefrontal lesions and control subjects showed enhanced event-related potentials (ERPs) to attended tone sequences presented in a dichotic attention task. ERP enhancements were comparable at short and long interstimulus intervals (ISIs), and did not depend upon whether attended stimuli were preceded by other attended stimuli or by distracting stimuli in the opposite ear. In contrast, patients with right prefrontal lesions showed absent ERP attention effects to contralateral (left ear) tones at all ISIs, and reduced attention effects to ipsilateral tones at long ISIs and when these were preceded by distracting sounds. The results are consistent with an asymmetric organization of dorsolateral prefrontal cortex, and indicate that increased distractibility may contribute to the attention disorders that follow prefrontal lesions.     

Chronic changes in brain Mg2+ concentration after forebrain ischemia in the rat

Brain Mg²⁺ ion concentrations, [Mg²⁺], were evaluated in three groups of animals subjected to either 8 minutes (n=10), or 12 minutes (n=10) of near-complete forebrain ischemia, or sham operation (n=10), from their³¹P NMR spectra. No significant differences were observed in [Mg²⁺] among sham operated animals prior to or at any time point after surgery. In the 8-min ischemia group, mean [Mg²⁺] were significantly lower at 48 (0.28 ± 0.06 mM, p=0.014) and 72 (0.29 ± 0.07 mM, p=0.005) hours post-ischemia when compared to their mean pre-ischemia levels (0.39 ± 0.08 mM). [Mg²⁺] was restored to preischemia values at 96 hours after induction of ischemia. In the 12 min ischemia group, [Mg²⁺] were lower at all time points post-ischemia when compared to their pre-ischemia levels. Our data shows that forebrain ischemia causes a chronic decline of cerebral Mg²⁺ concentration, and the observed reduction of this cation can be partially attributed to concurrent brain tissue alkalosis.     

Illness consequences after myocardial infarction: problems with physical functioning and return to work

Aim. This paper is a report of a study to explore health problems, physical and mental functioning, and physical activity in working‐age patients after myocardial infarction, in order to assess the possible effects of these factors on return to work. Background. A diagnosis of myocardial infarction may discourage patients from continuing an active working life. Enabling myocardial infarction patients to return to work has benefits for both individuals and society. Methods. A convenience sample was recruited of 88 patients, ≤65 years of age, who had suffered a myocardial infarction. Assessments of employment, health‐related quality of life and physical activity (footsteps per day) were conducted in 2005–2006, 4–6 months after myocardial infarction. To explore data and compare groups, t‐tests were applied. Logistic regression analyses were performed to identify variables that best predicted return to work. Results. Differences were identified between individuals who were employed after myocardial infarction and those who were not. Those not in work scored lower on variables related to the physical dimension of health‐related quality of life and on physical activity. Logistic regression revealed that a multivariate model including age, physical dimension of health‐related quality of life and footsteps per day predicted return to work in 68% of all cases (R² = 0·344). Conclusion. Low physical health and low physical activity after myocardial infarction negatively affect returning to work. These findings stress the importance of clinical assessment of myocardial infarction patients’ daily physical activity and physical functioning.