Study of the formulation optimization and reusability of a MAGAT gel dosimeter

PURPOSE

This study aims to optimize the formulation of a methacrylic acid gelatine and tetrakis (hydroxymethyl) phosphonium chloride (MAGAT) gel dosimeter to achieve acceptable dosimetric characteristics and the lowest final costs. This study also evaluates the reusability of the dosimeter.

METHODS

The MAGAT gel dosimeter formulation was optimized. Tetrakis (hydroxymethyl) phosphonium chloride (THPC) concentrations (2, 5, 8, 10, 20, and 65 mM), methacrylic acid (MA) concentrations (2.0, 2.5, 3.0, 3.5, and 4.0% w/w) and gelatin concentrations (4.36, 6.45, 8.36, and 10.45% w/w) were evaluated to provide an adequate dosimetric response. The final dosimeter formulation linearity and dose rate dependence were evaluated. The reutilization methodology of the optimized gel formulation, but containing 2 mM of THPC, which was previously irradiated with a dose of 2 Gy, is also presented.

RESULTS

The optimized mass concentration of the dosimeter consists of 88.60% deionized water, 8.36% gelatin, 3.00% of MA and 0.04% THPC (5 mM). It presents a linear response for doses up to 10 Gy with a 1.16 Gy^-1 s^-1 sensitivity. A maximum sensitivity variation of less than 4.0% was found when varying the dose rate of the radiation beams from 300 to 500 cGy/min. It was possible to reuse the dosimeter, however the sensitivity decreased by 15% from the first to the second irradiation.

CONCLUSIONS

A low-cost MAGAT gel dosimeter with optimized formulation that responds to radiation in a dose range of 0 to 10 Gy with small dose-rate dependence is presented. The MAGAT gel can be reused after a 2 Gy irradiation.

Avaliação de parâmetros dosimétricos de uma fonte de Braquiterapia em regiões próximas à fonte

Neste trabalho foram determinadas as funções dosimétricas de uma fonte clínica de braquiterapia de alta taxa de dose de Irídio-192 em distâncias próximas à fonte. O fator geométrico foi determinado analiticamente, enquanto que a função de dose radial e a função de anisotropia foram determinadas para distâncias de até      5 cm do centro da fonte utilizando simulação Monte Carlo com o pacote PENLEOPE.  Uma fonte de 192Ir de alta taxa de dose (Varian, modelo GammaMed Plus) foi modelada e posicionada no centro de um objeto simulador cúbico de 30 cm de lado e preenchido com água. Foi realizada a paralelização do pacote PENELOPE para a realização das simulações, utilizando 8 processadores, onde o número de partículas primárias em cada processador permaneceu constante em 109, a energia de corte para fótons e elétrons foi de 100 keV e os parâmetros de condensação de histórias (C1 e C2) foram de 0,3, otimizando o tempo de simulação e não adicionando incertezas sistemáticas aos resultados. Perfis de dose relativa obtidos utilizando simulação Monte Carlo foram comparados com o sistema de planejamento BrachyVision em três diferentes planos axiais em relação à fonte: plano central; 0,4 cm acima da fonte, na direção do topo do encapsulamento; e 0,4 cm abaixo da fonte, na direção do cabo. Quando comparados entre si, ambos os conjuntos de dados possuem o mesmo comportamento, com diferenças máximas de 2%, indicando que o pacote PENELOPE apresenta-se como ferramenta promissora em cálculos dosimétricos de fontes de braquiterapia de alta taxa de dose.

Lung disease severity in idiopathic pulmonary fibrosis is more strongly associated with impedance measures of bolus reflux than pH parameters of acid reflux alone

BACKGROUND

Gastroesophageal reflux (GER) has been associated with idiopathic pulmonary fibrosis (IPF). Pathogenesis may be related to chronic micro-aspiration. We aimed to assess objective measures of GER on multichannel intraluminal impedance and pH study (MII-pH) and their relationship with pulmonary function testing (PFT) results, and to compare the performance of pH/acid reflux parameters vs corresponding MII/bolus parameters in predicting pulmonary dysfunction in IPF.

METHODS

This was a retrospective cohort study of IPF patients undergoing prelung transplant evaluation with MII-pH off acid suppression, and having received PFT within 3 months. Patients with prior fundoplication were excluded. Severe pulmonary dysfunction was defined using diffusion capacity of the lung for carbon monoxide (DLCO) ≤40%. Six pH/acid reflux parameters with corresponding MII/bolus reflux measures were specified a priori. Multivariate analyses were applied using forward stepwise logistic regression. Predictive value of each parameter for severe pulmonary dysfunction was calculated by area-under-the-receiver-operating-characteristic-curve or c-statistic.

KEY RESULTS

Forty-five subjects (67% M, age 59, 15 mild-moderate vs 30 severe) met criteria for inclusion. Patient demographics and clinical characteristics were similar between pulmonary dysfunction groups. Abnormal total reflux episodes and prolonged bolus clearance time were significantly associated with pulmonary dysfunction severity on univariate and multivariate analyses. No pH parameters were significant. The c-statistic of each pH parameter was lower than its MII counterpart in predicting pulmonary dysfunction.

CONCLUSIONS & INFERENCES

MII/bolus reflux, but not pH/acid reflux, was associated with pulmonary dysfunction in prelung transplant patients with IPF. MII-pH may be more valuable than pH testing alone in characterizing GER in IPF.

Intensity modulated radiotherapy (IMRT) for patients of the Brazilian unified health system (SUS): an analysis of 508 treatments two years after the technique implementation

The Bosniak classification for renal cysts was developed in the late 1980s in an attempt to standardize the description and management of complex cystic renal lesions. Alterations were made to such a classification in the 1990s and, the last one, in 2005. Currently, five categories of cystic renal lesions are defined - namely, I, II, II-F, III and IV –, according to their degree of complexity and likelihood of malignancy. Despite being initially described for computed tomography, this classification has been also utilized with some advantages also for magnetic resonance imaging. The present article reviews the different phases of this classification, its diagnostic efficacy and the most controversial features of its use.

Simultaneous observation of collagen and elastin in normal and pathological tissues: analysis of Sirius-red-stained sections by fluorescence microscopy

In order to observe collagen and elastic fibers simultaneously, sections of human aorta, skin, lung, liver, and bladder were stained by Sirius red and analyzed by fluorescence microscopy. In all cases, the fibers of collagen presented the characteristic fluorescent red-orange color that results from the interaction of this extracellular protein with the dye, whereas elastic fibers showed strong green fluorescence (intrinsic fluorescence). This method efficiently detects collagen and elastic fibers when these two structures are present and could have valuable applications in processes that involves both fibers.

Extramedullary hemangioblastoma of the conus medullaris

BACKGROUND

We report the case of an extramedullary pathologically proven hemangioblastoma of the conus medullaris. As spinal dural arteriovenous fistulas most commonly present with a conus medullaris syndrome, our presentation of the MRI, myelographic, and angiographic findings of this unique lesion may be useful in differentiating these two entities.

CLINICAL MATERIAL

We report the case of a 57 year old woman with a two year history of progressive low back and right lower extremity pain and weakness. Spinal MRI and myelography demonstrated serpiginous vasculature on the dorsum of the spinal cord consistent with either a vascular tumor or malformation. Selective spinal angiography was thus undertaken by the neuroendovascular team which revealed a tumor nodule consistent with vascular tumor. T12-L1 laminectomy was performed and a 6 mm vascularized tumor was found in the intradural extramedullary compartment adjacent to the conus medullaris. The tumor was completely removed and pathological analysis was consistent with hemangioblastoma.

CONCLUSION

This report documents a unique location for extramedullary spinal hemangioblastomas. Although both MRI and myelography are helpful in studying these lesions, angiography remains the gold standard in differentiating between vascular tumor and malformation. We suggest that the angiography be performed by a neurointerventional team to facilitate embolization, should this be warranted.

Effect of phenylalanine and p-chlorophenylalanine on Na+, K+-ATPase activity in the synaptic plasma membrane from the cerebral cortex of rats

Na+, K+-ATPase activity was measured in synaptic plasma membrane from cerebral cortex of Wistar rats subjected to experimental phenylketonuria, i.e., chemical hyperphenylalaninemia induced by subcutaneous administration of 5.2 micromol phenylalanine / g body weight (twice a day) plus 0.9 micromol p-chlorophenylalanine / g body weight (once a day). The treatment was performed from the 6th to the 14th postpartum day and rats were killed 12 h after the last injection. Synaptic plasma membrane from cerebral cortex was prepared by a discontinuous density sucrose gradient for Na+, K+-ATPase activity determination. The results showed that the enzyme activity was decreased by 30% in animals subjected to experimental phenylketonuria when compared to control. The in vitro effects of the drugs on Na+, K+-ATPase activity were also investigated. Phenylalanine and p-chlorophenylalanine inhibited the enzyme activity and this inhibition was reversed by alanine. In addition, competition between phenylalanine and p-chlorophenylalanine for binding to the enzyme was observed, suggesting a common binding site for these substances. Our results suggest that reduction of Na+, K+-ATPase activity may be one of the mechanisms related to the brain dysfunction observed in human PKU.

Alanine prevents the decrease of Na+,K+-ATPase activity in experimental phenylketonuria

Our objective was to investigate the effect of alanine administration on Na+,K+-ATPase activity in cerebral cortex of rats subjected to chemically-induced phenylketonuria. Wistar rats were treated from the 6th to the 28th day of life with subcutaneous injections of either 2.6 micromol alanine or 5.2 micromol phenylalanine plus 2.6 micromol alpha-methylphenylalanine per g body weight or phenylalanine plus alpha-methylphenylalanine plus alanine in the same doses or equivalent volumes of 0.15 M saline. The animals were killed on the 29th or 60th day of life. Synaptic plasma membrane from cerebral cortex was prepared for Na+,K+-ATPase activity determination. The results showed that alanine injection prevents the decrease of Na+,K+-ATPase activity in animals subjected to experimental phenylketonuria. Therefore, in case the same effects are achieved with ingested alanine, it is possible that alanine supplementation may be an important dietary adjuvant for phenylketonuric patients.

Renal cell carcinoma: a rare source of cauda equina metastasis. Case report

The authors present the case of a patient in whom intradural metastasis from renal cell carcinoma spread to the cauda equina. To the authors' knowledge, this is only the second report of its kind. This male patient had undergone nephrectomy for the treatment of renal cell carcinoma for 5 years and was diagnosed as having metastatic lung disease 1 year prior to admission. The patient presented with lower back pain that radiated to both legs, but he exhibited no sensorimotor deficits. The majority of cauda equina tumors are primary tumors, and metastases are very rare. The literature is reviewed with reference to current molecular genetic paradigms of metastatic renal cell carcinoma.

Intrathecal administration of recombinant human superoxide dismutase 1 in amyotrophic lateral sclerosis: a preliminary safety and pharmacokinetic study

We undertook a safety and pharmacokinetic study of intrathecal (i.t.) recombinant human superoxide dismutase (rhSOD1). We administered rhSOD1 as an acute bolus in three sheep and 16 human subjects with amyotrophic lateral sclerosis (ALS). Two sheep received chronic i.t. infusion of rhSOD1 (one at 17.7 mg per day, the second at 38.0 mg per day) for six months. Two of the 16 subjects had familial ALS and mutations in the gene for Cu/Zn SOD1. They both received i.t. infusion of rhSOD1 (5 to 10 mg per day) for 3 to 6 months. Intrathecal rhSOD1 administration was safe. Bolus i.t. administration of 0.25 mg rhSOD1 in sheep revealed a mean elimination half-life of 0.4 (SD +/- 0.06) hours, clearance of 12.2 +/- 3.2 ml per hour, and volume of distribution of 7.3 +/- 0.9 ml. After chronic i.t. infusion, the initial alpha-phase half-life was estimated as 1.2 hours and the extended beta-phase half-life was 15.0 hours. The mean clearance rate was 25.9 ml per hour and the steady-state volume of distribution was 920.6 ml. Bolus i.t. administration of 20 micrograms of rhSOD1 in ALS subjects revealed a mean elimination half-life of 2.2 +/- 0.8 hours, clearance of 1.2 +/- 0.6 ml per hour, and volume of distribution of 3.5 +/- 0.4 ml. With chronic i.t. infusion of 5 mg per day, cerebrospinal SOD1 levels increased approximately fortyfold. We detected no benefit of this treatment in the two patients with familial ALS.

Idiopathic spinal cord herniation: a treatable cause of the Brown-Sequard syndrome--case report

Symptomatic herniation of the spinal cord through the dura is an uncommon clinical problem. Since 1989, we have encountered three patients who each presented with an unexplained, longstanding Brown-Sequard syndrome and were found to have idiopathic herniation of the thoracic spinal cord. This report describes the clinical, radiographic, and surgical findings in these three patients and reviews the five previously reported patients with this syndrome. Idiopathic herniation of the spinal cord is a treatable cause of the Brown-Sequard syndrome that may be more common than is currently recognized and should be known to all surgeons managing spinal disorders.

Central neurocytomas of the cervical spinal cord. Report of two cases

Central neurocytoma is a neuronal neoplasm that occurs supratentorially in the lateral or third ventricles. The authors report the clinical, neuroradiological, and neuropathological features of two neurocytomas arising in the spinal cord of two men, aged 65 and 49 years. The patients presented with progressive neurological deficits referable to the cervical spinal cord. Magnetic resonance imaging revealed isodense intramedullary spinal cord tumors at the C3-4 level. Both tumors were initially misdiagnosed as gliomas. In Case 1 the correct diagnosis was made after electron microscopy revealed neuronal features. Immunostaining in Case 2 revealed that tumor cells were positive for synaptophysin and negative for glial fibrillary acidic protein, strongly indicating a neuronal tumor. It is suggested that this spinal cord neoplasm be included under the designation "central neurocytoma."

[Atriofascicular connection with slow conduction and longitudinal dissociation. Electrophysiologic evidence and clinical implications]

We report on a patient with paroxysmal left bundle branch block-like tachycardia with electrophysiologic findings suggestive of nodoventricular pathway (ventricular pre-excitation dependent on slowing of AV conduction, and accessory pathway with exclusive anterograde conduction). There was no pre-excitation during sinus rhythm but it was brought on by intravenous verapamil. Atrioventricular node conduction curves showed no signs of duality. Diagnosis of an atriofascicular pathway with decremental properties was based on the following findings: 1) absence of AV dissociation during reciprocating tachycardia; 2) absence of fusion beats or narrowing QRS complexes during tachycardia; 3) advancement of right ventricular activation with late atrial extrastimuli delivered during antidromic tachycardia at a time of low right atrium refractoriness; 4) observation that earliest ventricular endocardial electrogram during tachycardia (activation mapping) was simultaneous with the right bundle potential; 5) surgical ablation of the accessory pathway by endocardial incision at the right anterior aspect of the tricuspid ring, far away from the AV node region. Evidences showing anterograde longitudinal dissociation of the accessory pathway included cycle length alternation during tachycardia and duality of accessory pathway conduction times and refractory periods. We hypothesize that reentry occurring in such AV node-like structure could give to a pre-excited tachycardia with AV dissociation mimicking antidromic tachycardia associated with nodoventricular pathway.

Infections in neurologic surgery. Host defenses

Normal host defense mechanisms are effective in preventing central nervous system (CNS) infection. Opsonins and compliment levels are normally low in the CNS, however. The relationship of these factors to CNS infection, specifically surgical wound infection and shunt infection, is discussed.

Sprouting of corneal sensory fibers in rats treated at birth with capsaicin

Normal structure and function of corneal epithelium is known to be related to proper innervation. To investigate possible trophic actions of sensory neurons on corneal epithelium, corneal innervation and various physical parameters were studied in normal rats and in rats treated as neonates with intraperitoneal injections of capsaicin. Corneal lesions were noted in treated rats which varied from multiple punctate areas of corneal opacity to deep stromal opacity with ulceration and neovascularization. These lesions waxed and waned throughout the animal's life. In addition, mechanical threshold of the corneal reflex was higher in capsaicin-treated rats. The tear rate in response to a provocative test was diminished in treated rats, presumably due to reduced afferent trigeminal input to the brain stem; blinking rates were more frequent in these animals. Using fluorescent retrograde tracing techniques, the number of cells innervating the cornea in capsaicin-treated rats was found to be significantly less compared with control animals. Innervation in the cornea (examined using a gold chloride technique) demonstrated a decrease in the number of corneal large axons in treated rats with neurite sprouting of these axons yielding a higher density of nerve fibers compared with controls. Thus, sprouting of residual sensory neurons occurs in response to the partial corneal denervation produced by capsaicin, and this sprouting does not functionally compensate to prevent the development of chronic keratitis.

Biologically inert synthetic dural substitutes. Appraisal of a medical-grade aliphatic polyurethane and a polysiloxane-carbonate block copolymer

Two types of artificial membranes, a medical-grade aliphatic polyurethane and a polysiloxane-carbonate block copolymer, were tested as substitutes for dura in 24 and 12 rabbits, respectively. The films were placed either epidurally, subdurally, or as dural grafts in equal subgroups of animals. The postoperative course was uneventful with no manifestations of convulsive disorder or cerebrospinal fluid leak. The animals were sacrificed 3, 6, or 9 months after implantation of the artificial membranes. Both types of artificial membranes were easily removed from the underlying nervous and the other surrounding tissues. The histological examination failed to reveal adhesions, neomembrane formations, or any type of foreign body reactions to the polyurethane film. The implantation of the polysiloxane-carbonate film caused no reaction when it was applied epidurally. As a dural graft, the polysiloxane-carbonate copolymer induced the formation of a thin neomembrane of one to two layers of fibroblasts which formed a watertight seal of the dural defect. A similar thin neomembrane was found to encase this artificial membrane in the group of animals in which it was implanted subdurally. There was no foreign body reaction to the polysiloxane-carbonate film. The authors conclude that these materials hold promise as dural substitutes or in the prevention of spinal dural scarring, and should be evaluated clinically.

Changes in corneal innervation during postnatal development in normal rats and in rats treated at birth with capsaicin

This study was undertaken to learn more about the keratitis that follows the neonatal administration of capsaicin to rats. In the first part of the study the density and pattern of corneal innervation were followed throughout postnatal development in litters of control rats and in rats that received capsaicin as neonates. In rats treated with capsaicin, the density of corneal innervation was lower than that of control rats until 28 days of age. Thereafter nerve fiber sprouting was observed within the corneas of capsaicin-treated rats. By 56 days of age the capsaicin-treated rats had a denser corneal innervation than did control rats. In the second part of the study the incidence and severity of the corneal trophic changes induced by capsaicin were studied in litters of rats treated with chronic tarsorrhaphy and in litters raised in the dark. Neither of these manipulations altered the incidence or severity of keratitis. These observations demonstrate that sprouting of the remaining corneal axons is related temporally to the previously observed decrease in keratitis. Furthermore the more severe keratitis observed in early postnatal life does not appear to be related to physical injury of the cornea.

A modified gold chloride technique for optimal impregnation of nerves within corneal whole mounts and dura of the albino rat

Ranvier's method of staining tissue whole mounts with gold chloride to visualize nerve fibers was modified by lengthening the incubation time in gold chloride and reducing the time in acidulated water. These simple modifications of an old technique give consistent impregnation of nerve fibers with light background staining in whole mounts of cornea and dura.

A quantitative analysis of the retrograde axonal transport of 4 different fluorescent dyes in peripheral sensory and motor neurons and lack of anterograde transport in the corticospinal system

Many fluorescent dye compounds are transported by axons in retrograde and anterograde directions. In the present study the uptake and retrograde axonal transport of 4 chemically related fluorescent dyes was evaluated in the peripheral nervous system of adult mice. Anterograde transport was studied in the corticospinal tract of adult rats. In addition to confirming the previously reported intra-axonal transport of Rhodamine-B-isothiocyanate, we report the transport of Rhodamine-X-isothiocyanate. Sulforhodamine-101-acid chloride and Lissamine rhodamine-B-sulfonyl chloride. By using the fluorescence intensity of the labeled motor and sensory neurons as well as cell counts of fluorescently labeled motor neurons and percent of labeled dorsal root ganglia (DRG) cells, we were able to quantitate the amount of retrograde transport of a given fluorescent compound. The two dyes with isothiocyanate groups available for conjugation were transported in higher amounts compared to the dyes containing sulfonyl chloride groups. No anterograde transport in the corticospinal system was observed. We conclude that the 4 dyes described are useful for retrograde neuroanatomical tracing experiments. We describe methods for quantifying the amount of retrograde transport by peripheral motor and sensory neurons.

Treatment of symptomatic syringomyelia with a ventriculoperitoneal shunt: a case report with magnetic resonance scan correlation

This report describes a patient with communicating syringomyelia associated with enlarged cerebral ventricles who was managed by placing a ventriculoperitoneal shunt. His clinical improvement was rapid and dramatic. A comparison of preoperative and postoperative magnetic resonance scans documents shrinkage of the cervical syrinx.

Historical development of neural transplantation

The techniques of neural transplantation are almost 100 years old. As these techniques begin to be used to treat human neurological disorders, it is important to remember the contributions of the many investigators who have advanced this fascinating area of neurobiology.

Selective axonal transport of anthracycline antibiotics

The retrograde intraaxonal transport of several anthracycline antibiotics was assessed in the peripheral nervous system of adult mice. Despite certain chemical similarities, the intraaxonal transport of these molecules was variable and could be correlated with the structure of the aminosugar at the R-2 position. One particularly interesting compound, 4'-deoxydoxorubicin, was transported by dorsal root ganglia axons, but not by the axons of ventral horn neurons. These observations suggest that the sugar component of a molecule may be important for its intraaxonal transport in the peripheral nervous system.

Topography of choline acetyltransferase immunoreactive neurons and fibers in the rat spinal cord

The topography of choline acetyltransferase immunoreactivity was studied in the rat spinal cord with a monoclonal antibody. Cholinergic fibers were most prominent in lamina III of the dorsal horn and originated from cholinergic neurons within the spinal cord. Lamina X, which was rich in cholinergic neurons and fibers, provided cholinergic interconnections between the dorsal, intermediate and ventral gray. Within the ventral gray, choline acetyltransferase immunoreactive boutons were found on motor neurons. This study suggests that the cholinergic innervation of the spinal cord arises from neurons intrinsic to the spinal cord. The cholinergic neurons within the spinal cord may provide several, overlapping levels of regulation of spinal cord neurons.

Trigeminal afferents to cerebral arteries and forehead are not divergent axon collaterals in cat

Horseradish peroxidase conjugated to wheat germ agglutinin (HRP-WGA), and bisbenzimide (a fluorescent dye) were used as retrograde axonal tracers to examine whether or not intracranial and extracranial trigeminal afferents represent divergent axon collaterals. HRP-WGA was applied to the proximal segment of the middle cerebral artery and bisbenzimide was injected into a branch of the ophthalmic nerve in 5 cats. Histologic examination of the ipsilateral trigeminal ganglion revealed HRP-labeled cell bodies located among clusters of cells exhibiting bisbenzimide fluorescence. Cells containing both labels were not observed. These results support the concept that divergent axon collaterals are probably not involved in the pathogenesis of referred pain during vascular headache.

Intraneuronal accumulation of myeloma proteins

We studied a patient with multiple myeloma who had immunologically identified myeloma light chain proteins within neurons projecting beyond the blood-brain barrier, but not within intrinsic neurons of the spinal cord, brain stem, and cerebral cortex. There was a possibility that these myeloma light chain proteins or their immunologically recognizable fragments were transported intra-axonally by human peripheral nerves. Myeloma light chain proteins were also identified within cerebellar Purkinje's neurons. This labeling may have been secondary to transport from cerebrospinal fluid.

Selective extraction of small and large molecules from the cerebrospinal fluid by Purkinje neurons

Cerebellar Purkinje neurons accumulated propidium iodide, granular blue, and horseradish peroxidase conjugated to wheat germ agglutinin but not unconjugated horseradish peroxidase, bisbenzimide, or Evans blue when these compounds were infused into the lateral cerebral ventricles of awake, unrestrained rats. Accumulation of propidium iodide by Purkinje neurons of the vermis was associated with a reproducible behavioral abnormality characterized by truncal tremor, ataxia, and nystagmus. Both the accumulation of propidium iodide in Purkinje cells and the behavioral abnormality were prevented by prior intracerebroventricular administration of ouabain or colchicine, drugs that block neuronal transport processes. The ability of cerebellar Purkinje neurons to extract small and large molecules from the cerebrospinal fluid has important implications for their physiology and pathology.

Uptake and transport of lectins from the cerebrospinal fluid by cells of the immature mouse brain

40 mice (C57BL/6J) 2, 3, 6, and 10 d old were injected intraventricularly with 2% wheat germ agglutinin (WGA) or soybean agglutinin (SBA). The transport of lectins from the ventricular cerebrospinal fluid (CSF) into brain parenchyma was studied by an unlabelled antibody technique ( BORGES and SIDMAN 1982). The granule product of the immunohistochemical reaction was found in the cytoplasm of ventricular ependymal cells, the choroid plexus and meninges in all age groups studied. Penetration of lectins into brain parenchyma was higher in younger animals and at more immature-cell-surrounded parts of lateral and the IVth ventricle. The stain product was dispersed throughout the neuropil excepting cell nuclei. Higher concentration of lectins appeared in nerve cell cytoplasm of some regions of the brain of younger animals (P2 to P3); in 10 d old mice granules of stain appeared in the cytoplasm of PURKINJE cells and pyramidal neurons of the hippocampus. A fiber-like staining, apparent especially in large commissures adjacent to brain ventricles (corpus callosum, fornix hippocampi) in all age groups, suggests that lectins are transported within axons, even at the earliest postnatal ages. Unlike WGA, densely stained glial cells appeared in parenchyma of SBA injected animals, especially of the younger age group (P3 to P6). The results of this study confirm earlier findings that macromolecules within the ventricular CSF can penetrate into brain parenchyma but suggest that the penetration is higher in less mature animals and at the ventricle regions surrounded by less differentiated parenchyma.(ABSTRACT TRUNCATED AT 250 WORDS)

Carotid body tumors managed with preoperative embolization. Report of two cases

Two patients with large vascular carotid body tumors underwent preoperative intravascular embolization of the major arterial feeders. The tumor vascularity was reduced markedly, and complete surgical extirpation was accomplished without difficulty. The literature on carotid body tumors is briefly reviewed. The role of preoperative embolization in the treatment of these difficult tumors is emphasized.

Do intracranial and extracranial trigeminal afferents represent divergent axon collaterals?

Trigeminal nerves provide the principal afferent pathways for the transmission of intracranial and extracranial head pain. This study, using two retrograde axonal tracers, demonstrated that first division afferents projecting to intracranial and extracranial targets are not commonly axon collaterals of the same neuron. Therefore, divergent axon collaterals probably are not responsible for the phenomenon of referred pain within the first trigeminal division.

Parasagittal organization of the olivocerebellar projection in the mouse

The inferior olivocerebellar projection of the normal inbred C57BL/6J mouse was visualized after anterograde transport of horseradish peroxidase conjugated to the lectin wheat germ agglutinin (HRP-WGA conjugate). Following injections of HRP-WGA conjugate which filled the entire inferior olivary nucleus on one side, olivocerebellar fibers were followed across the midline of the medulla and into the contralateral cerebellar cortex via the inferior cerebellar peduncle. The molecular layer was heavily but nonuniformly labeled in all cortical lobules. Labeled olivocerebellar fibers within the contralateral cerebellar molecular layer were grouped into distinct bands separated by regions of molecular layer containing no labeled fibers. The bands of olivocerebellar terminals in the molecular layer were in turn organized into distinct sets of bands oriented in parasagittal planes. The organizational basis for this banding pattern, previously recognized by other workers in other mammalian and avian species, remains unknown.

Axonal transport of lectins in the peripheral nervous system

The binding and axonal transport of six lectins were studied in the peripheral nervous system of adult mice by an immunocytochemical method. After injection into muscle and subcutaneous sites, lectins known to bind preferentially N-acetylglucosamine or mannose sugars were transported axonally to ventral horn and dorsal root ganglion neurons. Twelve to 96 hr postinjection, these lectins were bound at the injection site to neuromuscular junctions, muscle spindles, and cutaneous nerves. Lectins known to bind preferentially N-acetylgalactosamine or galactose sugars, by contrast, were transported only to dorsal root ganglion neurons. Except for Sophora japonica agglutinin, these lectins were bound at the injection site only to cutaneous nerves. These differences in axonal transport were seen also when the lectins were applied directly to the proximal end of a transected mixed nerve.

Cerebrospinal fluid shunts interfere with host defenses

Despite advances in neurosurgical therapeutics, cerebrospinal fluid shunt infections have continued to complicate the management of patients with shunted hydrocephalus. Although various factors have been proposed to explain the pathogenesis of these infections, they have remained poorly understood. This in vitro study determined the ability of human neutrophils and monocytes to adhere to two types of shunt catheters and to phagocytose bacteria. These white blood cells failed to adhere in normal numbers to the catheters and failed to ingest fully a bacterial inoculum on the catheters' surfaces. While in contact with the shunt apparatus, the neutrophils also exocytosed myeloperoxidase, a major component of the intracellular microbicidal system. These observations suggest that the shunt apparatus may diminish the effectiveness of the hosts' defenses at the site of implantation.

The anterior tarsal tunnel syndrome. Report of two cases

Two recently encountered patients with the anterior tarsal tunnel syndrome are presented. The various aspects of this probably under-recognized syndrome are discussed. Evidence is presented that this syndrome may be the result of abnormal stretch of the deep peroneal nerve.

Spinal cord regeneration: a review of the First International Symposium on Spinal Cord Reconstruction

The proceedings of the First International Symposium on Spinal Cord Reconstruction, held in Las Vegas, Nevada, on January 7 to 11, 1980, are reviewed and summarized. Major problems facing investigators of central nervous system regeneration are discussed.

Effect of magnesium on epileptic foci

Parenteral magnesium sulfate has been used to control acute convulsions of diverse etiologies and is currently a mainstay in controlling eclamptic convulsions. However, the site of this anticonvulsant action has remained controversial and not well studied in experimental epileptic models. Therefore we determined the effects of intravenously infused magnesium sulfate on the epileptic neural activity induced by topical application of penicillin G to motor cortex in anesthetized cats and dogs and in awake, undrugged primates. Magnesium sulfate was able to directly suppress neuronal burst firing and interictal EEG spike generation at serum levels below those producing paralysis. The degree of suppression corresponded to the serum magnesium concentration and was reversible. These results corroborate the clinical observations in patients that magnesium can produce an anticonvulsant effect apart from neuromuscular blockade and suggest it may have clinical applicability in treating a wider range of acute convulsions.