Quantitative distribution of 131I-labelled monoclonal antibodies administered by the intra-ventricular route.

In a preliminary study in one patient [111In]DTPA was injected into the lateral ventricle and at the same time [99mT]DTPA into the lumbar sac. The 111In distributed freely throughout the CSF but the concentration of 99mTc in the ventricles remained consistently low. In the second phase of the study three patients with tumours confined to the neuraxis were treated with 20-50 mCi 131I-labelled monoclonal antibodies administered into the lateral ventricle via Ommaya reservoirs. Quantitative distribution of radio-labelled antibody was assessed at intervals up to 8 days post injection. In each case there was rapid distribution to all parts of the neuraxis with 38-68% of total CNS counts remaining in the head and 13-39% in each of the upper and lower half spine areas. The t1/2 for total CNS counts were 31.5, 19.8 and 15.5 h. There was no clear evidence of tumour localization and no neurological toxicity. These patients demonstrate that radiolabelled monoclonal antibodies can be given safely via Ommaya reservoirs and that in order to obtain optimal distribution throughout the CSF this should be the preferred method of administration. Further trials in patients with minimal disease are warranted.

Immunohistochemical localisation of a gastrin-releasing peptide-like material in area postrema, nucleus of the solitary tract and vagal motor nucleus in the brainstem of rat.

The presence of an endogenous gastrin-releasing peptide (GRP)-like peptide in the hindbrain of rat was demonstrated immunohistochemically using antisera directed against the N-terminus and C-terminus of GRP. N-terminal and C-terminal-like immunoreactive material were distributed throughout the nucleus of the solitary tract (NTS), dorsal motor nucleus of the vagus (DMV) and tractus solitarius (TS), as well as in areas postrema (AP) and substantia gelatinosa separating AP from NTS. Positive immunostaining was localised to a dense network of nerve fibres which project longitudinally along the neuraxis. Immunolabelled cell bodies were observed rostral to the obex, principally in the mediolateral subnucleus of NTS. These immunopositive neurones project their axons caudally and longitudinally towards the commissural subnucleus of the NTS. Immunolabelled cell bodies also were found in AP; they projected their axons caudally and ventrally towards NTS. Positive immunostaining was blocked by pre-adsorbing antisera with either GRP (1 nmol/ml) or bombesin (3 nmol/ml), but was unaffected by substance P (30 nmol/ml) and spared by capsaicin pretreatments which deplete sensory nerves of their peptide content. The results indicate that NTS neurons containing a GRP-like peptide connect the rostral and caudal regions of the dorsal vagal complex by way of longitudinal nerve tracts descending NTS and TS. Some neurons in AP also contain a GRP-like peptide and appear to connect with the dorsal vagal complex.

Evidence of high concentrations of melatonin in lateral ventricular cerebrospinal fluid of sheep.

In this study we examined the cerebrospinal fluid (CSF) for regional differences in the concentration of melatonin. Cerebrospinal fluid samples were collected at hourly intervals from either the lateral ventricle or the cisterna magna of nine Merino ewes and were compared against jugular plasma. The study revealed that the CSF of the cisterna magna and the lateral ventricle had temporal patterns of melatonin that were similar to those found in jugular plasma. However, the concentrations of melatonin within the CSF obtained from the lateral ventricle were one order of magnitude higher than those of the jugular plasma, as verified by gas chromatography and mass spectrometry, while the melatonin concentrations within the CSF obtained from the cisterna magna were comparable to those of the jugular plasma. The data from this study suggest that there may be regional differences in the concentration of melatonin within the CSF and indicate that this medium is an important route of transport for melatonin from the pineal gland to putative target tissues.

Vasopressin content of cerebrospinal fluid and fluid perfusing cerebral ventricles after the stimulation of preganglionic fibres of superior cervical ganglia in rats.

The subject of the study was the determination of the content of vasopressin (AVP) in the cerebrospinal fluid (CSF) and of the release of this neurohormone into the fluid perfusing the cerebral ventricles. The content of AVP in CSF taken from the cerebellomedullary cistern of rats under urethane anesthesia was 27 +/- 2.97 pg/ml. AVP was released into the fluid perfusing the cerebral ventricles at the rate of 6.83 +/- 0.7 pg/ml per 30 min. Electric stimulation of preganglionic fibres to the superior cervical ganglia did not cause any alterations in AVP release into the fluid perfusing the cerebral ventricles, which evidences lack of effect of the sympathetic system on the release of this neurohormone into the cerebral ventricles.

Ultrastructural characteristics of GD3 ganglioside-positive immature glia in rat forebrain white matter.

Immunocytochemistry and electron microscopy were used to examine the ultrastructural features of immature neuroectodermal cells of the rat forebrain in their early stages of differentiation. We used a monoclonal antibody (AbR24) to GD3 ganglioside, which binds to cells of the subventricular zone (SVZ). R24 also labels immature cells in developing white and gray matter (LeVine and Goldman: J. Neurosci. in press, '88, and accompanying paper). Sections of developing cingulum and white matter adjacent to the cingulum were examined at E18, P4, and P10 by using a preembedding immunocytochemical technique with PAP reagents. Labeled cells seen earliest were large, with high nuclear to cytoplasmic ratios and few cytoplasmic organelles. With time, smaller forms appeared, with prominent Golgi apparatus and processes containing microtubules. Labeled cells with similar characteristics but which contained cytoplasmic vacuoles were also observed. The results indicate a series of ultrastructural transformations that are consistent with oligodendrocyte differentiation.

Core and paracores; some new chemoarchitectural entities in the mammalian neuraxis.

A study of the recent neuromorphological, neurophysiological and neuroethological literature, and data from the current research in our own laboratory have led us to a new classification of entities in the mammalian neuraxis. This classification comprises the core and the median and lateral paracores. The core of the neuraxis may be considered as a caudally extended limbic system. It extends throughout the central nervous system and, as its name implies, most of it is situated close to the ventricular cavity. This entity is characterized by the presence of (1) numerous diffuse grisea, (2) enormous amounts of thin, unmyelinated, varicose axons, many of which are arranged in diffuse fibre systems, (3) large numbers of different neuromediators, particularly neuropeptides, and (4) large numbers of neurons which concentrate estrogen and androgen hormones. Ethophysiological studies have shown that the core region contains numerous loci from which on stimulation quite characteristic behavioral patterns, like eating, drinking, fear, attack, reproductive behavior etc., can be elicited. The core region appears to be involved most directly in the organization of behavior and is of paramount importance for the regulation of processes aimed at the survival of the individual (organism) and of the species. The median and lateral paracores represent extensions of the core at the level of the brain stem. The median paracore includes the raphe nuclei, whereas the (bilateral) lateral paracore is constituted by a ventrolaterally extending lamella of tissue. Both paracores contain sets of monoaminergic cells giving rise to networks of fibres that pervade virtually all grisea of the neuraxis, i.e. the serotoninergic neurons in the median paracore and the catecholaminergic cells in the lateral paracore. The lateral paracore contains a series of grisea, including the substantia nigra, the ventral tegmental area, the nucleus reticularis parvocellularis, the tegmental pedunculopontine nucleus and the catecholaminergic cell groups A1, A2, A5, A7 and C1 and C2. It harbours a large bundle of loosely arranged, thin fibres, which forms a direct caudal continuation of the hypothalamic medial forebrain bundle. This lateral paracore bundle contains numerous catecholaminergic and peptidergic fibres. Three typical core centres, viz. the nucleus centralis amygdalae, the bed nucleus of the stria terminalis and the lateral hypothalamic area contribute substantially to this bundle. The lateral paracore contains, just like the core region, a large number of functionally defined centres related to integrated somatomotor and visceromotor responses. It is postulated that non-synaptic interneuron

Eicosanoids in human ventricular cerebrospinal fluid following severe brain injury.

Recent evidence has shown that a variety of prostaglandins and leukotrienes can be produced in brain tissue after injury in animals. It has also been speculated that increases in brain prostaglandins occur in humans following injury. Ventricular cerebrospinal fluid (CSF) samples have been obtained from children with static lesions (controls) as well as children with acute brain injury and eicosanoids measured by immunologic techniques. Metabolites of prostacyclin (6-keto-PGF1 a) and thromboxane A2 (thromboxane B2) were the major eicosanoids found in CSF, and levels of these compounds were increased 3-10 times in acutely injured patients. Prostaglandin E2 was also found in lower amounts, although in one case its level was very high. Prostaglandin D2 was also present, but in low amounts. No leukotrienes were found in CSF samples that were purified by HPLC prior to immunoassay. Elevated levels of hydroxyeicosatetraenoic acids (HETEs) were observed in those samples stored frozen, but these metabolites were most probably due to autooxidation of arachidonic acid in CSF. Arachidonic acid concentration in CSF was typically found to be in the range of 10-200 ng/ml, but was found to be 5-10 fold higher in one severely injured patient. Thus, elevated free arachidonic acid and various oxygenated metabolites were observed in CSF following brain injury.

Gradient of arginine vasopressin concentration but not angiotensin II concentration between cerebrospinal fluid of anterior 3rd ventricle and cisterna magna in dogs.

Dogs were chronically implanted with two devices for cerebrospinal fluid (CSF) sampling from (a) the anterior part of the 3rd ventricle and (b) the cisterna magna. In conscious dogs arginine vasopressin (AVP) concentration of CSF samples collected at different occasions were 2-3 times higher in the CSF of the 3rd ventricle as compared to the AVP concentration of the cisterna magna. Inhalation anesthesia stimulated AVP release into the CSF at both sites by a factor of about 2, the gradient between 3rd ventricle and cisterna magna CSF of 2-3 remained for AVP in simultaneously collected samples. In contrast, angiotensin II-like immunoreactivity of CSF was not significantly different at both sites, neither in the conscious dogs nor during anesthesia. It is concluded that the main amount of AVP enters the CSF at the 3rd ventricular level.

Molecular size distribution of somatostatin-like immunoreactivity in the cerebroventricular fluid of neurosurgical patients.

The molecular size distribution of somatostatin-like immunoreactivity (SLI) in the cerebroventricular fluid of patients with Parkinson's disease, dystonic syndromes, multiple sclerosis, basal and midline tumors, epilepsy and pain syndromes was investigated by separation with a Sephadex G-50f column and subsequent radioimmunoassay of the eluate. Marked heterogeneity of SLI was observed in most of the pools investigated. The most conspicuous feature of the elution profiles was the preponderance of the peak coeluting with synthetic somatostatin-14, whereas the peaks comigrating with synthetic somatostatin-28 and attributable to precursor-like SLI represented only minor or trace amounts of total immunoreactivity. These findings are consistent with the greater biological activity of somatostatin-14 in the human central nervous system, whereas somatostatin-28 appears to represent the more active form in the pituitary and in the intestinal mucosa. Solely in the case of brain tumor patients, some differences could be seen, resulting in an approximately equal distribution of somatostatin-14 and somatostatin-28 in two pools of ventricular fluid and by the detection of a degradation product of somatostatin-14 in another one. These observations could be explained by a lowered barrier function as a consequence of increased intracranial pressure in case of brain tumors, which is well in accordance with a markedly elevated total protein content being a sign of a lowered barrier function.

Computed tomography number correlations for metrizamide computed tomographic ventriculography.

The authors describe a method that permits the determination of the precise intraventricular iodine concentration after metrizamide computed tomographic ventriculography. There is an observed linear relationship between computed tomography number (Hounsfield units) and iodine concentration. This relationship may be used to provide the basis for a method of evaluating ventricular fluid dynamics. This, in turn, is useful for the determination of the indications for a shunting procedure and for the evaluation of shunt function in a patient with an existing shunt.

Comparative aspects of the area postrema: fine-structural considerations help to determine its function.

The area postrema is a circumventricular organ of the fourth ventricle of the mammalian brain. Although there are distinct gross anatomical differences in the appearance of this organ between "lower" mammals such as rodents and lagomorphs and "higher" mammals such as carnivores and primates, its fine structure is remarkably similar in all species studied. There are many suggestions in the literature for a specific function for this area of the brain, ranging from its being a chemoreceptive trigger zone for the emetic response to its being a regulatory nucleus for the sleep cycle. The present report describes some comparative studies on the ultrastructure of this organ. This information is discussed in relation to what is known about the neurochemistry of the area postrema and its connections with other brain regions and visceral structures. A suggestion is offered that our current knowledge of the area postrema is consistent with its performing many of its proposed functions in the context of a regulatory ("fine-tuning") center for many autonomic functions.

Elevation of sodium levels in the cerebral ventricles of anaesthetized dogs triggers the release of an inhibitor of ouabain-sensitive sodium, potassium-ATPase into the circulation.

The present studies are designed to determine whether a ouabain-sensitive inhibitor of Na+,K+-stimulated ATPase is released into the circulation when the Na+ levels are elevated in the cerebral ventricles in pentobarbital anaesthetized dogs. Na+-pump activity was estimated in the plantar and dorsal branches of the lateral saphenous veins by using the 86Rb-uptake method. Infusion of the cerebral ventricles with the artificial cerebrospinal fluid (CSF) containing normal Na+ (0.15 mol/l) for over 120 min resulted in significant increases in only ouabain-sensitive 86Rb-uptake. In contrast, when the ventricles were perfused with the CSF containing high Na+ (0.3 mol/l) for similar periods, there were significant reductions in the ouabain-sensitive as well as in ouabain-insensitive 86Rb-uptake by the blood vessels. Similar blood vessels from a separate group of dogs were incubated for 120 min in the plasma samples collected from the above groups in which normal or hypertonic Na+ solutions were infused. The data showed that ouabain-sensitive 86Rb-uptake (but not the insensitive component) was significantly inhibited only in those vessels which were incubated in the plasma samples that were obtained at 120 min after perfusion of the cerebral ventricles with CSF containing high Na+ (0.3 mol/l). These studies have provided direct evidence which would suggest that the elevation of Na+ levels in the cerebral ventricles would precipitate the release of an inhibitor of the ouabain-sensitive Na+-pump into the circulation, perhaps due to an activation of Na+-sensitive and/or osmo-sensitive sites in the circumventricular organs.(ABSTRACT TRUNCATED AT 250 WORDS)

Vascular-induced intrauterine growth retardation: relations between birth weight and the development of biochemical parameters in young rabbits.

The development of biochemical parameters (cellular DNA and protein) in relation to birth weight was studied in the rabbit, a perinatal brain developer. To induce intrauterine growth retardation and to increase the number of low-birth-weight rabbits, experimental ischemia, in half the fetuses of each doe, was achieved by total ligation of approximately 30% of uteroplacental vessels during the last third of gestation. Following natural delivery, the rabbit pups were raised until 60 days of age, at which time the brains were removed and dissected into cerebral hemispheres, cerebellum and brain stem. The amount of DNA (representing cell number) and protein (suggesting cell size) was estimated in each brain region. A significant correlation was found between low birth weight and reduced DNA in the cerebellum and reduced protein in the cerebral hemispheres. These persistent deficiencies could be related to some lasting handicaps, especially motor incoordination, as an expression of cerebellar dysfunction.

Immunohistological studies of masked indoleamine cells in the area postrema of the rat.

Masked indoleamine cells (MICS) in the area postrema and adjacent areas in the rat were immunohistochemically studied (the peroxidase-antiperoxidase method) using a serotonin antiserum. After pretreatment with nialamide (200-300 mg/kg), immunoreactive MICS could be observed. They were small cells (about 12 micron in diameter) with several processes and were distributed in nearly all parts of the area postrema and also in the nucleus tructus solitarii. Following a single intraventricular injection of 75 micrograms 5,6-dihydroxytryptamine, the immunoreactivity of these cells conspicuously decreased for several days. The submicroscopical structure of the cells was investigated using immunoelectron microscopy. Immunoreactive products were observed in the cytoplasm as particles with a diameter of 25-40 nm and high electron density, but these were not found in the nucleus or cell organelles.

A procedure for small-volume brain grafting; vasopressin cells in neonatal and adult Brattleboro rats.

A simple and reliable technique is described for the transplantation of fetal vasopressin (VP) neurons in the third ventricle of the brain of homozygous Brattleboro neonates. Small-volume grafting is introduced by microdissection of paraventricular and supraoptic areas and by pelleting the minced tissue for insertion into the transplantation cannula. Morphological and immunocytochemical evaluation yielded results in both neonatal and adult host brain that were similar to those described for anterior hypothalamic grafts in adult Brattleboro brain. The present protocol circumvents some of the general problems encountered when the use of small grafts is imperative, and is also applicable to the implantation of pelleted cell suspensions.

Effects of carbamazepine and anti-depressant drugs on endogenous catecholamine levels in the cerebroventricular compartment of the rat.

Concentrations of endogenous norepinephrine, dopamine and epinephrine in cerebroventricular perfusates were used to evaluate the effects of drugs on the availability of extracellular catecholamines in the intact rat brain. Administration of the antidepressant drugs imipramine, desmethylimipramine or tranylcypromine resulted in marked increases of both norepinephrine and dopamine concentrations while epinephrine levels were not affected. Treatment with a similar dose of carbamazepine - an anticonvulsant drug with antidepressant activity - resulted in a significant increase in dopamine concentrations without apparent effect on either norepinephrine or epinephrine. It is suggested that at the applied dose, carbamazepine may act to modify the uptake, release or metabolism of dopamine in brain areas adjacent to the cerebroventricular space without affecting the other catecholamines.