A rat model of leptomeningeal human neoplastic xenografts

Leptomeningeal (LM) cancer spread from either a primarybrain tumor or a systemic cancer is rapidlyfatal. Current therapies are ineffective and highly toxicto normal nervous system tissues. A xenograft modelof LM neoplasia in nude rats using adiversity of tumor cell types was established inorder to evaluate new treatment strategies and tostudy the pharmacokinetics and biological effects of treatmentsadministered into the subarachnoid space. Consistent leptomeningeal engraftmentand progressive tumor growth was seen after intrathecalinjection of 9 of 13 tumor cells lines,including 2 melanomas, 2 neuroblastomas, 2 medulloblastomas, 2gliomas, and 1 breast cancer. Clinical signs rangedfrom steady weight loss commencing from the dayafter tumor implantation to absence of any signsfor three weeks until the sudden occurrence ofmajor neurological deficits or death. Pathologic examination showedonly leptomeningeal tumor growth with some cell linesand severe parenchymal invasion with others. CSF cytologyconsistently demonstrated tumor cells in animals with LMdisease. Cranial magnetic resonance (MR) following intravenous (IV)administration of a contrast agent revealed enhancing lesionsone week following melanoma tumor implantation. Reliable ventricularpuncture was demonstrated by radiography following intraventricular (IVent)injection of an iodinated contrast material. IVent instillationof saline, albumin, or antibodies did not provokeclinical toxicity or an inflammatory response.     

Hyperoxemic retinal neuronal necrosis in the premature neonate

A cytologically distinctive type of acute hyperoxemic injury of retinal neurons occurs in premature neonates. Ganglion cells in the central well-vascularized neonate retina are susceptible to excessive oxygen and this is expressed morphologically by karyorrhexis of their nuclei. We observed retinal neuronal necrosis in neonates who had hyperoxemia of greater than 150 torr for two hours or longer in the first week of life. Neuronal necrosis was strikingly associated with immaturity as determined by gestational age and birth weight: of 30 involved neonates, all were below 2,000 g; of 47 autopsied premature infants with birth weights under 1,500 g who survived for at least two days, 26 (55%) had acute retinal necrosis. When gestational age was used as a measure of prematurity, the highest incidence occurred in the 24- to 27-week group where 13 of 21 (62%) were involved. Hyperoxemic karyorrhectic changes, most prominent in the ganglion cells of the macula, are distinct from the classic peripheral mesenchymal vascular abnormalities of retinopathy of prematurity.     

Neurophysiological and anatomical correlations in neonatal nonketotic hyperglycinemia

Electroencephalographic (EEG) and brainstem auditory evoked response (BAER) findings have not been previously described and correlated with the pathological findings in an autopsied case of neonatal nonketotic hyperglycinemia (NKH). A 38 week gestation male infant presented within two hours of age with stimulus-evoked myoclonus and seizures in the context of progressive coma. Electrographic studies demonstrated cortical myoclonus and electrical seizures exquisitely localized to the midline region as well as a suppression-burst background disturbance. These vertex spike discharges were elicited after tactile stimulation. Prolonged intra-axial latencies for waves III and V were recorded on the BAER on the second day of life. Spongy leukodystrophy was noted on gross and microscopic examination of the brain involving all myelinated tracts especially in the reticular activating system, cerebellar peduncles and optic tracts. Neuropathological confirmation of brainstem involvement emphasizes the role of the nonspecific diffuse somatosensory projection system in the generation of myoclonus and stimulus-evoked seizures in the comatose patient with NKH.     

Substantia nigra damage after flurothyl-induced seizures in rats worsens after post-seizure recovery: No exacerbation with hyperglycaemia

Abstract

The substantia nigra pars reticularis (SNPR) of rats is highly susceptible to both seizure- and ischaemia-mediated damage. Hyperglycaemic exacerbation of brain damage similar to that observed after global brain ischaemia may also occur in rats with status epilepticus. We tested the hypotheses that hyperglycaemia exacerbates seizure-induced SNPR damage in rats and that SNPR lesions develop rapidly post-seizure. Halothane-anaesthetized, paralysedand mechanically ventilated rats were prepared for haemodynamic and EEC monitoring. Halothane was discontinued’ and mechanical ventilation on 30% oxygen/70% nitrous oxide was continued for 1 h. Three treatment groups (20 rats each) were studied: (1) control, lactated Ringer’s solution; (2) equiosmolar control’ 40% mannitol; and (3) hyperglycaemia, 50% dextrose. Infusions were started 5 min before seizures were induced with flurothyl 3% administered for either 45 (n = 10) or 75 (n = 10) min. Immediately after seizures, half of the animals underwent cerebral perfusion-fixation with formalin and half were allowed to recover for 2 h post-seizure and then perfused. Brain histology was assessed by light microscopy and scored 0-5 (0 = no damage) for the percentage of eosinophilic neurons and vacuolation in the SNPR. Glucose administration decreased the severity of SNPR damage in rats subjected to 75 min of seizures and 2 h recovery (pathology scores: control, eosinophilic neurons = 3.6, vacuolation = 4.0; hyperglycaemia, eosinophilic neurons = 3.0, vacuolation = 2.75; p < 0.05). SNPR damage was worse after 2 h of recovery (pathology scores: 0 h recovery, eosinophilic neurons = 0.9, vacuolation = 0.1; 2 h recovery, eosinophilic neurons = 3.9, vacuolation = 3.8; p < 0.05). Hyperglycaemia did not exacerbate flurothyl-seizure-induced SNPR damage, and maturation of the lesions was observed at 2 h post-seizure. [Neurol Res 1993; 15: 333-338]     

Hydrocephalus in weanling mice induced by a temperature-sensitive mutant of vesicular stomatitis virus

Hydrocephalus developed in weanling Swiss-Webster mice after intracerebral (IC) inoculation of a naturally selected temperature-sensitive (ts) mutant of vesicular stomatitis virus (VSV). This spontaneous ts mutant was isolated from a persistent infection (pi) of mouse L cells with VSV, and named VSV-tspi 364 (complementation Group I). High doses of the mutant virus induced hydrocephalus in 87% of the mice. Infected mice were clinically asymptomatic, except for a few with transient hind-limb paralysis and proximal muscle weakness. After inoculation, mice were killed every other day for the first two weeks, and weekly thereafter for two months. Virological studies showed replication in the brain in the first nine days post-inoculation (DPI). Neutralizing antibody titers increased rapidly after 15 DPI, and elevated titers were measured at 30 DPI. Pathologically, there was patchy ependymal cell necrosis in the aqueduct and lateral ventricles, as early as the second DPI. Mild meningoencephalitis and severe ependymal cell necrosis with focal aqueductal stenosis were present iun the first two weeks of infection. Hydrocephalus began as early as 10 DPI and became severe at 28 DPI. This represents the first animal model for hydrocephalus following IC inoculation of a spontaneous ts mutant of a rhabdovirus. In our study, inoculation of mice with wild-type VSV and with other spontaneous and chemical ts mutants of VSV IC as well as with tspi 364 by other routes did not cause hydrocephalus.     

Cerebellar glutamine synthetase in children after hypoxia or ischemia.

BACKGROUND: Glutamate has been implicated in the pathophysiology of acute hypoxic-ischemic encephalopathy. Glutamine synthetase is an enzyme found in astrocytes that converts glutamate to its nontoxic analogue, glutamine. The present study tests the hypothesis that brain glutamine synthetase activity increases in response to acute hypoxic-ischemic insults and not in response to chronic hypoxia-ischemia or non-hypoxic-ischemic neurological disease. SUMMARY OF REPORT: Frozen sections of cerebellum from children who died with acute or chronic hypoxic-ischemic insults or chronic non-hypoxic-ischemic neurological disease were spectrophotometrically assayed for glutamine synthetase activity by an observer who was blinded to the clinical group assignment of each specimen. Enzyme activity was elevated in specimens from children with acute hypoxic-ischemic insults (mean 6.5; range 5.4-7.2 units/g wet tissue wt) as compared with those from patients with chronic hypoxia-ischemia (mean 2.8; range 0.7-10.2 units/g wet tissue wt) or with non-hypoxic-ischemic neurological disease (mean 2.6; range 1.3-3.9 units/g wet tissue wt). This difference was not due to differences in the degree of histological astrocytosis or edema among the specimens. Statistical analysis by the Kruskal-Wallis one-way analysis of variance by ranks test indicates that the three data groups do not come from one population (p less than 0.05). CONCLUSIONS: These results support the notion that glutamine synthetase activity increases in response to acute hypoxic-ischemic nervous system injury in children and that other compensatory mechanisms prevail in the case of chronic hypoxic-ischemic insults.     

Risk factors associated with kernicterus in the newborn infant: importance of benzyl alcohol exposure

The prevalence of kernicterus in our neonatal intensive care unit (NICU) decreased from more than 2/1000 live births in 1980 to none in 1984. To clarify predictors of kernicterus, we examined the medical records of infants born during that time who died between 2 and 28 days of age. Infants were divided into three groups: those with kernicterus, all born before June 10, 1982 (n = 29); contemporaneous controls (n = 28); and infants born after June 10, 1982 (n = 32). Benzyl alcohol was not used after June 10, 1982. Kernicteric infants were more likely than contemporaneous controls to have seizures (p less than 0.001). Indices of pulmonary disease, arterial partial pressure of carbon dioxide and end-expiratory pressure on the ventilator were higher after 1982. However, exposure to benzyl alcohol was not different in kernicteric infants and contemporaneous controls, suggesting that benzyl alcohol exposure was not the explanation for the decrease in the prevalence of kernicterus in our NICU.     

Central pontine myelinolysis after liver transplantation

Eight adults and 3 children out of 85 patients who had neuropathologic examination after death following orthotopic liver transplantation showed central pontine myelinolysis (CPM). Four patients also had extrapontine myelinolysis. Eight patients had significant serum sodium changes. In 5, the fluctuation occurred perioperatively and 4 had a clinical picture consistent with CPM, although no patient had this as an antemortem diagnosis. We emphasize the role of hepatic dysfunction as a cause of CPM and recommend careful monitoring of electrolytes in the perioperative period of patients undergoing liver transplantation.