A computational model for the overall pattern of ocular dominance.

In layer IV of the primary visual cortex, in both the macaque monkey and the cat, geniculocortical terminals representing the two eyes are segregated into alternating zones known as ocular dominance bands. Viewed tangentially, in the monkey these bands take the form of a series of branching parallel stripes that run roughly perpendicular to the border of striate cortex. In the cat, the overall ocular dominance pattern consists of irregularly branching, beaded bands that exhibit no predominant orientation. If the striking differences in the appearance of these two patterns reflect important differences in the basic rules governing cortical ocular dominance, then this poses a problem for attempts to formulate general principles of visual cortical organization. However, it has been suggested that the differences in the appearance of the ocular dominance patterns in these two species could result simply from known differences in the boundary conditions of their geniculocortical pathways. This article describes the formulation and testing of a single computational model that accurately predicts the quite dissimilar ocular dominance patterns in cats and monkeys. This model also generalizes to predict the different ocular dominance patterns observed in young and old three-eyed frogs, supporting the notion that the overall pattern of ocular dominance is governed by a common set of rules. The significance of these results is discussed in terms of previous models, which have focused largely on local processes underlying the development of ocular dominance segregation. Although the present model is not a developmental one, it does shed some light on potential mechanisms for establishing retinotopy in striate cortex and on possible developmental relationships between the geniculostriate pathway and intrinsic modularity of the striate cortex.     

Absence of a pharmacokinetic interaction between enalapril and frusemide.

Single doses of enalapril maleate 10 mg and frusemide 80 mg do not significantly affect the pharmacokinetics of each other when taken concomitantly. Their concomitant use may be associated with more adverse effects than with the individual entities.     

Oral premedication in children

Preoperative and postoperative sedation, postoperative analgesia and vomiting were assessed following four different oral premedications in 143 children aged 1-10 years, weighing 10-30 kg, and undergoing elective adenotonsillectomy or inguinal surgery. Diazepam, diazepam combined with droperidol, trimeprazine and trimeprazine combined with droperidol were compared in a double-blind trial in conjunction with a standardised inhalational anaesthetic technique employing an intraoperative narcotic. Trimeprazine produced significantly more preoperative sedation (P less than 0.001) and was associated with enhanced postoperative analgesia (P less than 0.01). The incidence of postoperative vomiting was significantly less in the group receiving trimeprazine (P less than 0.001). The addition of droperidol to diazepam and trimeprazine only marginally improved the performance of those drugs but significantly prolonged postoperative recovery times. This was more marked when droperidol was combined with trimeprazine.     

Characterization and evolutionary aspects of a transcript encoding a neuropeptide precursor of Lymnaea neurons, VD1 and RPD2.

We isolated and characterized a cDNA clone encoding the major prohormone of VD1 and RPD2, two electrotonically coupled identified neurons in the central nervous system of the freshwater snail, Lymnaea stagnalis. The VD1/RPD2 prohormone may be cleaved to generate a set of 4 different neuropeptides, called epsilon, delta, alpha 1 and beta peptides, as well as a single aspartate. Since VD1 and RPD2 probably are involved in O2 perception and modulation of cardio-respiratory functions, it is thought that the neuropeptides synthesized and released by these neurons coordinate the adaptive physiological and behavioural processes that occur in response to changes in O2 availability. Comparison of the Lymnaea VD1/RPD2 precursor with two related precursors, prohormones R15-1 and R15-2, identified from neuron R15 in the marine mollusc Aplysia californica revealed a similar pattern of organization of the preprohormones. The overall homology is rather low, however, detailed comparisons show a highly differential pattern of conservation of peptide regions on the precursors.     

Magnesium deficiency as a cause of acute intractable seizures

Summary Clinical and experimental investigations have shown that magnesium depletion causes a marked irritability of the nervous system, eventually resulting in epileptic seizures. Although magnesium deficiency as a cause of epilepsy is uncommon, its recognition and correction may prove life-saving. Two case reports are presented which emphasize the importance of recognizing hypomagnesaemia in patients with acute intractable seizures.     

Antennular projections to the midbrain of the spiny lobster. I. Sensory innervation of the lateral and medial antennular neuropils

The organization of sensory afferents in the antennular nerve (AN) of the spiny lobster and the central arborization of the afferents in the lateral and medial antennular neuropils (LAN, MAN) were analyzed by backfilling the AN with biocytin. The MAN receives primarily thick afferents (diameter ≥ 10 μm) with a consistent pattern of arborization from the medial of the three major divisions of the AN. The LAN, in contrast, receives many thin to medium-sized afferents (diameter ≤ 0.3–5 μm), in addition some with diameters ≥ 5 μm, from the lateral and dorsal divisions of the AN. In contrast to the consistent pattern of arborization in the MAN, afferents projecting to the LAN arborize in widely different patterns. Serially arranged, orthogonal side branches that are suggestive of topographical representation of the serially arranged sensilla on the antennule contribute to the stratification of the LAN. Together with existing electrophysiological data, these morphological findings are consistent with the idea that the MAN receives primarily mechanosensory (largely statocyst) input, as previously thought, but that the LAN receives chemosensory as well as mechanosensory input. The chemosensory input to the LAN would represent a novel pathway for processing chemosensory input from the antennule.     

Subacute sclerosing panencephalitis in The Netherlands--1976-1990.

Since 1976, when general immunization against measles was introduced in the Netherlands, all new cases of subacute sclerosing panencephalitis (SSPE) were registered and detailed data about immunization, epidemiology and disease progression were collected on them. Up to 1991, 99 new patients have been registered of which 81 were born in this country and 18 elsewhere. From 1981 onwards, the incidence of SSPE among those born in the Netherlands decreased gradually from 13 cases per year to one case per year. This decrease is attributed to the large scale of immunization against measles. Three SSPE patients had been immunized against measles, all of them without a history of clinical measles. Epidemiology and risk factors of SSPE did not differ from those reported in other countries. An exceptional cluster of four patients in one town, who had measles in the same year, is reported. Progression of SSPE appeared to be age related. A total of 28 patients was treated with Inosiplex; no significant effect on survival in stage 3 of the disease was found.     

Die präoperative Evaluierung und Vorbereitung Die Sicht des Anästhesisten

Die Anaesthesiologie - Nicht zuletzt aus Kostengründen müssen auch die präoperativ veranlaßten Untersuchungen nach einem rationalen Konzept, adaptiert an das individuelle...