Melatonin: a clock-output,a clock-input

In mammals, the circadian system is comprised of three major components: the lateral eyes, the hypothalamic suprachiasmatic nucleus (SCN) and the pineal gland. The SCN harbours the endogenous oscillator that is entrained every day to the ambient lighting conditions via retinal input. Among the many circadian rhythms in the body that are driven by SCN output, the synthesis of melatonin in the pineal gland functions as a hormonal message encoding for the duration of darkness. Dissemination of this circadian information relies on the activation of melatonin receptors, which are most prominently expressed in the SCN, and the hypophyseal pars tuberalis (PT), but also in many other tissues. A deficiency in melatonin, or a lack in melatonin receptors should therefore have effects on circadian biology. However, our investigations of mice that are melatonin-proficient with mice that do not make melatonin, or alternatively cannot interpret the melatonin message, revealed that melatonin has only minor effects on signal transduction processes within the SCN and sets, at most, the gain for clock error signals mediated via the retino-hypothalamic tract. Melatonin deficiency has no effect on the rhythm generation, or on the maintenance of the oscillation. By contrast, melatonin is essential for rhythmic signalling in the PT. Here, melatonin acts in concert with adenosine to elicit rhythms in clock gene expression. By sensitizing adenylyl cyclase, melatonin opens a temporally-restricted gate and thus lowers the threshold for adenosine to induce cAMP-sensitive genes. This interaction, which determines a temporally precise regulation of gene expression, and by endocrine-endocrine interactions possibly also pituitary output, may reflect a general mechanism by which the master clock in the brain synchronizes clock cells in peripheral tissues that require unique phasing of output signals.     

Head injuries in children: a chronicle of a quarter of a century

Children aged 0–15 years hospitalized in Geneva for head trauma during the last quarter of a century are reviewed. More than half of the severely injured children were not from Geneva area. New methods of management have been introduced progressively. The cases are divided in four successive time periods and classified according to their pathology. A continuous improvement in mortality is obvious, decreasing from 29.4% to 2.2%, but climbing again to 15.2% in the last period, probably due to more severe pathologies. For the Geneva area the mortality decreased progressively from 10.4/100 000 to 3.5/100 000 annually, due to better organization and management, but also to a drop in the incidence of severe cases from 35.5–13.5/100 000 per year. A decrease in the number of traffic accidents is responsible for this. However, the number of handicapped children has not changed.     

Impact of a family-centred approach on a couple living with a brain tumour: a case study

The diagnosis of a malignant brain tumour can be devastating for both patients and their families. Despite neurological and cancer treatment advances, there has been little progress in extending life expectancy for these patients. Cassileth et al. (1985) suggest that of all types of cancer, brain tumours cause the most psychosocial repercussions for the family. The brain tumour clinical nurse specialist (CNS) is in a strategic position to intervene with families along the continuum of care by using a family-oriented approach which can facilitate their adaptation to this health problem. The present case study will describe the illness experience of one couple where a member had a brain tumour. The process of assessment, interventions and outcomes will be highlighted. The CNS utilized the Calgary Family Assessment Model (CFAM) (Wright & Leahey, 1984) and Calgary Family Intervention Model (CFIM) (Wright & Leahey, 1994) to guide her work with this family. An example of an intervention was the illness narrative approach. In this approach the concepts of illness experience, perceptions, beliefs and support were used as part of the therapeutic modality which served to enhance the coping strategies of the couple and decreased their crisis situation. This collaborative style of nursing promoted the well-being throughout the illness trajectory of both the family and the CNS.     

Ictal bradycardia in a patient with a hypothalamic hamartoma: a stereo-EEG study

Little is known about bradycardia and cardiac asystole which occur during partial epileptic seizures, especially whether they relate to ictal involvement of well-defined cortical areas. Several reports based on simultaneous electrocardiographic and intracranial depth electroencephalographic monitoring have shown that either the fronto-orbital cortex or the amygdalohippocampal complex could be responsible for such cardiac variations. We performed stereo-EEG recordings in a patient with refractory localization-related epilepsy associated with a hypothalamic hamartoma. We found that other cortical areas, such as the frontocentral region and the temporal neocortex, can contribute to the genesis of ictal bradyarrhythmia. Second, the lesion per se, although located within the hypothalamus, is not involved with this phenomenon.     

Gambling: a dependence without a drug

This paper reviews the research literature on excessive and persistent gambling with particular emphasis on the reasons why such behaviour has come to be classified among the addictions. The characteristics of gamblers who seek help from mental health agencies are discussed in relation to the diagnostic criteria for ‘pathological gambling’ given in DSM III-R.⁵ Although there have been few controlled treatment evaluations the range of therapeutic approaches employed in Australia, the U.S.A. and the U.K. are reviewed. A variety of theoretical models have been proposed to explain the psychological and physiological processes that may underlie the progression of this behavior from an infrequent leisure habit to a costly, all-engrossing, addictive-like preoccupation. These models are critically reviewed in the light of existing empirical findings. The evidence that excessive gambling shows features of dependence despite the absence of a psychoactive agent is evaluated. The concluding section of the paper explores the potential theoretical and clinical benefits inherent in classifying this behavioural excess as an addiction.     

Axon-glia transfer of a protein and a carbohydrate

We have investigated the transfer of a fluorescent protein, the fluorescein isothiocyanate derivative of bovine serum albumin (FITC-BSA), and a fluorescent carbohydrate, FITC-dextran, from the crayfish medial giant axon (MGA) to the periaxonal glial cells. The dialyzed tracer was injected into one of the two MGAs, and, after a transfer period of 15-60 min, the tissue was fixed for histological examination of fluorescence distribution. With each tracer, the periaxonal sheath of the injected MGA was specifically labeled. Similar results were obtained with several different fixatives. During the transfer period, there was no appreciable change in the resting potential or conducted action potential of the MGA or in the resting potentials of the adaxonal glial cells. Polyacrylamide gel electrophoresis indicated that the axoplasmic and sheath fluorescence was produced by the intact tracers. These results suggest that "foreign" macromolecules can be exchanged from crayfish axons to glia under physiological conditions. Such transfers may indicate a substantial intercellular traffic of molecules or a means whereby neurons can eliminate waste materials.     

Radiological Follow-up of a Cerebral Tuberculoma with a Paradoxical Response Mimicking a Brain Tumor

We report a case of a paradoxical response of a tuberculoma in the brain mimicking a brain tumor. A 76-year-old woman presented with a 2 week history of headache, dysarthia, and orthopnea. Brain magnetic resonance images (MRI) revealed two rim-enhancing lesions on the pons and occipital lobe, and chest computed tomography showed randomly distributed miliary nodules. The tentative diagnosis was tuberculosis (TB) of the brain and lung. She complained of right hemiparesis and worsening general weakness after taking the anti-TB medication. On the monthly follow-up images, the enhanced lesions were enlarged with increased perfusion and choline/creatinine ratio, suggesting a high grade glioma. A surgical resection was completed to diagnose the occipital lesion, and the tuberculoma was pathologically confirmed by a positive TB-polymerase chain reaction. The anti-TB medication was continued for 13 months. A follow-up MRI showed decreased size of the brain lesions associated with perilesional edema, and the clinical symptoms had improved. Brain tuberculoma could be aggravated mimicking brain malignancy during administration of anti-TB medication. This paradoxical response can be effectively managed by continuing the anti-TB drugs.     

Reflections on a Nurse Becoming a Psychoanalyst

An increasing number of nurses have become psychoanalysts in the past few years. The author discusses the process of psychoanalysis and issues related to this expanded role for nurses from her own personal experience in analytic training.