International workshop on: Patient decision making in coronary artery disease: Present role and future prospectives of echocardiography

International workshop on: Patient decision making in coronary artery disease: Present role and future prospectives of echocardiography     

Immunocytochemical Evidence that Glutamate is a Neurotransmitter in the Cochlear Nerve: A Quantitative Study in the Guinea-pig Anteroventral Cochlear Nucleus

The large so-called type I afferents of the cochlear nerve carry the majority of the auditory input from the cochlea to the cochlear nuclei in the brainstem. These fibres are excitatory and previous studies have suggested they may use glutamate as their neurotransmitter. In the present investigation therefore, antibodies to glutamate and to the glutamate precursor, glutamine, were applied to resin sections of perfusion-fixed brains and of in vitro brain slices subjected to depolarizing levels of potassium before fixation to study glutamate handling and synaptic release. Ultrathin sections were labelled by the immunogold technique, and the immunoreactivity was quantified by recording the density of gold particles over the various tissue profiles. Non-primary, presumably inhibitory, terminals and glial processes were used as reference structures. The cochlear primary terminals proved to be strongly immunoreactive for glutamate. The density of glutamate labelling was higher in primary terminals than in non-primary ones, and lowest in glial processes. The ratio between the mean glutamate and glutamine labelling densities was also higher in primary terminals than in non-primary ones, and lowest in glial processes in each case. In the primary terminals, the glutamate immunoreactivity was higher over vesicle-containing regions than over vesicle-free regions, whilst glutamine was evenly distributed throughout. The in vitro brain slices showed a potassium-induced, partly calcium-dependent depletion of glutamate from the primary terminals but not from the non-primary ones. These observations strongly support the conclusion that glutamate is a neurotransmitter of type I cochlear afferents.     

Diffuse Cerebral Air Embolism Treated With Hyperbaric Oxygen: A Case Report

A 54-year-old woman presented for cardiac evaluation of atypical chest pain. Workup included coronary angiography and a left ventriculogram, during which air was inadvertently injected, resulting in the development of an acute right hemisphere syndrome. Right carotid angiography was immediately performed, yielding only a delayed diffuse venous phase without focal vessel cutoffs. Within 60 minutes, the patient underwent hyperbaric oxygen therapy for the suspected cerebral air emboli. After removal from the chamber for technical reasons, she had a generalized tonic-clonic seizure, and further hyperbaric oxygen therapy was withheld. Initial computed tomography imaging obtained approximately 8 hours after symptom onset showed signs of early right hemispheric edema. Subsequent magnetic resonance imaging studies were markedly abnormal and suggestive of diffuse bilateral but predominantly right-sided parietal lobe edema with mildly positive diffusion-weighted imaging. Follow-up magnetic resonance imaging at 6 months was normal, and the patient's neurological examination returned to normal.     

Behavioral and biochemical studies of dopamine receptor sensitivity in differentially housed mice

Group housed and individually housed mice were compared in (1) the motor activity responses to direct and indirect dopamine (DA) agonists, (2) in vivo presynaptic autoreceptor sensitivity and (3) in vitro binding of ³H-spiperone. Relative to group housed mice, individually housed mice showed an increased motor activity response to amphetamine, 1.25 and 0.625 mg/kg. Using two in vivo measures of presynaptic DA receptor sensitivity, the antagonism of spontaneous locomotor activity and the antagonism of dihydroxyphenylalanine (DOPA) accumulation by apomorphine (APO), individually housed mice showed greater activity counts and higher DOPA accumulations than group housed mice. Levels of tyrosine were significantly greater in individually housed mice. Significant effects of housing were also noted with the motor activity response to APO, 0.075–0.300 mg/kg, following pretreatment with reserpine, an in vivo measure of postsynaptic receptor sensitivity. However, there was no effect of housing on the number or affinity of ³H-spiperone binding sites in the striatum. These results are discussed in terms of the presynaptic activity of catecholaminergic neurons and the postsynaptic receptor sensitivity to APO in individually housed mice.     

Fertilization and early embryolgoy: Can Matrigel substitute for Vero cells in promoting the in-vitro development of mouse embryos?

The influences of Vero cells and the basement membrane substratumfor these cells (Matrigel^®) on the rate of hatched blastocystformation from mouse zygotes in vitro were compared. Zygotesobtained from C57BL/6xBALB/c F1 females pretreated with pregnantmare's serum gonadotrophin/human chorionic gonadotrophin matedwith BDF1 males were cultured (120 h) in human tubal fluid mediumsupplemented 0.5% with bovine serum albumin. The rates of earlyhatching and hatched blastocyst formation at 96 and 120 h ofculture were expressed as the percentage of 2-cell embryos visualizedafter the initial 24 h. The rate of total blastocyst formationdid not differ between treatment groups. However, <10% ofembryos cultured for 96 h in medium alone advanced to the hatchingstage compared with 35–40% of blastocysts cultured withVero cells or with Matrigel alone. Similarly, by 120 h of culture,only 20% of embryos cultured in medium alone developed to hatchingor hatched blastocysts compared with >70% for those embryosco-cultured with Vero cells or with Matrigel. In conclusion,Vero cells improved the rate of development of mouse embryosto hatched blastocysts during serum-free culture. Similar improvementswere seen in the presence of Matrigel alone; Matrigel is thebasement membrane substratum used for the Vero cells. Furtherstudies on the means whereby Matrigel promotes early embryonicdevelopment (e.g. appropriate combination of basement membrane-associatedgrowth factors) may lead to a safe, defined medium preparationfor the stimulation of in-vitro development of human embryos.