Results of randomized controlled trials of low-versus high-osmolality contrast media

The authors reviewed 100 randomized controlled trials (RCTs) conducted in humans to compare safety or efficacy of new low-osmolality contrast media (LOM) with that of high-osmolality contrast media (HOM). Findings of the 43 RCTs judged to be of the highest quality suggest that the efficacy of LOM in imaging is equal or superior to that of HOM for all routes of administration. Heat sensation occurred less often with LOM for all routes and pain occurred less often with LOM for intraarterial routes. No differences were seen in nephrotoxicity or in frequency of nausea, vomiting, urticaria, bronchospasm, laboratory test abnormalities, or neurologic events. Greater cardiovascular changes were seen with HOM, including increased or decreased heart rate, increased left ventricular end-diastolic pressure, decreased systolic pressure, and QT prolongation, depending on route of administration. To demonstrate whether a reduction in clinically significant adverse outcomes truly occurs with LOM, trials will need to enlist larger numbers of patients and employ appropriate outcome measures. Future trials should stratify patients according to their risk of adverse reactions to provide better information about benefits of LOM in low- versus high-risk patients.     

Serum MBP immunoreactivity and immunoglobulin level as markers of tumour type

Summary Forty three patients, admitted to the department of Neurological Surgery for management of central nervous system tumours, were studied pre-operatively for serum myelin basic protein immunoreactivity as a marker of central nervous system lesion and for circulating immunoglobulins and complement (C₃) levels. Myelin basic protein concentration did not appear to correlate with tumour type or grade. Serum immunoglobulin levels were found to be within the normal range but the mean IgM level was significantly higher in the glioma group when compared with meningiomas.     

Informed Consent

There have been significant changes in the doctor patient relationship with the impact of technology in day-to-day practice. More and more patients are aware of their rights and are keen to make free choice and decision on their treatment. This helps them to choose the treatment of their choice from the options available and to select a physician of their choice. Doctor's decisions are being questioned regarding their correctness and there is a need to educate the patient, on what one offers by way of treatment. In some procedures and types of treatment, patient needs to be educated and informed of the merits and demerits of the treatment available. This will help the patient to make appropriate choice and also to accept some adverse outcome of treatment. Towards this end, all countries are looking afresh at the necessity of Informed Consent. Methods adopted by some countries are highlighted to help our physicians practice them in an appropriate way. A lot of remedial work needs to be done to minimize future litigation, as many doctors misunderstand their legal obligations and haven't caught up with the change in judge's thinking.     

Chloride losing diarrhoea and metabolic alkalosis in an infant with cystic fibrosis

A case of hypochloraemic metabolic alkalosis in an infant with chloride losing ileostomy drainage and cystic fibrosis is described. It is speculated that intestinal loss of chloride played a major role in the development of metabolic alkalosis.     

The role of pancreatic venous sampling in the localization of occult insulinomas

The palpation and enucleation of occult insulinomas (less than 15 mm) can be a difficult surgical problem even with good arteriographic localization. In the authors' limited experience, confirmation of arteriographic findings by pancreatic venous sampling provided little additional localizing information. However, if arteriography is negative or equivocal, venous sampling can indicate the segment of pancreas to be "blindly" resected if the adenoma is not palpable. Venous sampling may be misleading in polyendocrine syndromes because of the frequency of multiple adenomas and variable hormone production.     

The central organization of the vagus nerve innervating the stomach of the rat

We employed the neural tracers cholera toxin-horseradish peroxidase and wheat germ agglutinin-horseradish peroxidase to examine the organization of the afferent and efferent connections of the stomach within the medulla oblongata of the rat. The major finding of this study is that gastric motoneurons of the dorsal motor nucleus (DMN) possess numerous dendrites penetrating discrete regions of the overlying nucleus of the solitary tract (NTS). In particular, dendritic labelling was present in areas of NTS which also received terminals of gastric vagal afferent fibers such as the subnucleus gelatinosus, nucleus commissuralis, and medial nucleus of NTS. This codistribution of afferent and efferent elements of the gastric vagus may provide loci for monosynaptic vagovagal interactions. A small number of dendrites of DMN neurons penetrated the ependyma of the fourth ventricle and a few others entered the ventral aspect of the area postrema, thus making possible the direct contact of preganglionic neurons with humoral input from the cerebrospinal fluid and/or the peripheral plasma. Nucleus ambiguus neurons projecting to the stomach predominantly innervate the forestomach. The dendrites of these cells, when labelled, were generally short, and extended beyond the compact cluster of ambiguus neurons in a ventrolateral direction, parallel to the fascicles of vagal efferent fibers traversing the medulla.     

Neurotropic properties of pseudorabies virus: uptake and transneuronal passage in the rat central nervous system

Uptake, replication, and transneuronal passage of a swine neurotropic herpesvirus (pseudorabies virus, PRV) was evaluated in the rat CNS. PRV was localized in neural circuits innervating the tongue, stomach, esophagus and eye with light microscopic immunohistochemistry. In each instance, the distribution of PRV-immunoreactive neurons was entirely consistent with that observed following injection of cholera toxin-horseradish peroxidase conjugate (CT-HRP). Injections of the tongue resulted in retrograde transport of PRV and CT-HRP to hypoglossal motor neurons, while preganglionic neurons in the dorsal motor vagal nucleus or somatic motor neurons in the nucleus ambiguus were labeled following injections of the stomach or esophagus, respectively. At longer times after infection, viral antigens were found in astrocytes adjacent to infected neurons and their efferent axons and second-order neuron labeling became apparent. The distribution of second-order neurons was also entirely dependent upon the site of PRV injection. Following tongue injection, second-order neurons were observed in the trigeminal complex, the brain-stem tegmentum and in monoaminergic cell groups. Injection of the stomach or esophagus led to second-order neuron labeling confined to distinct subdivisions of the neucleus of the solitary tract and monoaminergic cell groups. Comparative quantitative analysis of the number of PRV immunoreactive neurons present in the diencephalon and brain stem following injection of virus into both the eye and stomach musculature of the same animal demonstrated that retrograde transport of PRV from the viscera was more efficient and occurred at a much faster rate than anterograde transport of virus. These data demonstrate projection-specific transport of PRV in the nervous system and provide further insight into the means through which this neurotropic virus infects the nervous system.     

The organization of vagal innervation of rat pancreas using cholera toxin-horseradish peroxidase conjugate

The present study was initiated to address the current controversy concerning the parasympathetic innervation of the pancreas, using a more sensitive tracer. The location of retrogradely labeled neurons within the dorsal motor nucleus of the vagus (DMV) was examined 48 h following injections of cholera toxin-horseradish peroxidase (CT-HRP) into designated areas of the rat pancreas. The brainstem and spinal cord were searched for any additional labeled neurons located outside of the DMV. Separate groups of animals were used for control injections into the adipose tissue of the greater omentum, the spleen, abdominal musculature, and the diaphragm. In addition, CT-HRP was dripped over the surfaces of the abdominal viscera in another group of animals. These control cases were designed to indicate whether diffusion of the neural tracer away from injection sites had occurred and had resulted in labeling of neurons which did not innervate the injected areas. Following injection of CT-HRP into the right lobe of the pancreas, labeled neurons were found primarily within the medial region of the left DMV. Injection of CT-HRP into the left lobe of the pancreas resulted in retrogradely labeled neurons predominantly within the medial region of the right DMV. Following injections into the entire pancreas, neural labeling was seen bilaterally within the DMV and was concentrated within the medial regions, with a slightly higher degree of labeling within the right DMV. No labeled neurons were seen within the nucleus ambiguus or other areas of the brainstem or spinal cord following pancreatic injections. Furthermore, no afferent labeling within the nucleus of the solitary tract (NTS) was observed, although a very small number of neurons within the nodose ganglia were labeled. The dendrites of backfilled DMV neurons could be seen extending across the midline to the contralateral DMV as well as dorsally into certain subnuclei of the NTS, and to the borders of the area postrema and the fourth ventricle. These results indicate that both the motor and sensory innervation of the rat pancreas are more restricted than has been previously suggested.     

Dendritic architecture of nucleus ambiguus motoneurons projecting to the upper alimentary tract in the rat.

The motor innervation for palatal, pharyngeal, laryngeal, and esophageal muscles originates within the nucleus ambiguus. Although the viscerotopic organization of the upper alimentary tract in the nucleus ambiguus has been extensively studied, little information concerning the dendritic arborization of nucleus ambiguus motoneurons is available. The neural tracer cholera toxin-horseradish peroxidase, which is particularly effective at revealing dendrites of retrogradely labeled neurons, was used to determine the dendritic architecture and organization of nucleus ambiguus motoneurons. In 72 rats, cholera toxin-horseradish peroxidase in volumes of 1.0-18 microliters was directly applied under pressure to the musculature of various sites along the upper alimentary tract. Motoneurons innervating the soft palate, pharynx, cricothyroid muscle, and cervical esophagus were all found to have extensive dendrites that extended into the adjacent reticular formation with a distinct pattern for each muscle group. In contrast, the dendrites of motoneurons innervating the thoracic and subdiaphragmatic esophagus were confined to the compact formation of the nucleus ambiguus. Dendritic bundling within the confines of the nucleus ambiguus was prominent following injection of tracer into the soft palate, pharynx, and esophagus. The bundles were primarily oriented in a rostrocaudal direction. These data suggest that the extensive extranuclear dendritic arborization of motoneurons innervating the soft palate, pharynx, larynx, and cervical esophagus provide a wide ranging target for multiple central afferents that may be involved in the differential control of muscles that participate in multiple complex motor functions. The lack of extensive extranuclear dendrites of motoneurons innervating the distal esophagus suggest that they receive focused central afferents. The prominent bundling of dendrites within the nucleus ambiguus may provide for synchronization of motoneurons innervating a specific muscle and perhaps for synchronization of motoneurons innervating different muscles acting in sequence.