Magnetic resonance imaging-guided delivery of adeno-associated virus type 2 to the primate brain for the treatment of lysosomal storage disorders.

Gene replacement therapy for the neurological deficits caused by lysosomal storage disorders, such as in Niemann-Pick disease type A, will require widespread expression of efficacious levels of acid sphingomyelinase (ASM) in the infant human brain. At present there is no treatment available for this devastating pediatric condition. This is partly because of inherent constraints associated with the efficient delivery of therapeutic agents into the CNS of higher order models. In this study we used an adeno-associated virus type 2 (AAV2) vector encoding human acid sphingomyelinase tagged with a viral hemagglutinin epitope (AAV2-hASM-HA) to transduce highly interconnected CNS regions such as the brainstem and thalamus. On the basis of our data showing global cortical expression of a secreted reporter after thalamic delivery in nonhuman primates (NHPs), we set out to investigate whether such widespread expression could be enhanced after brainstem infusion. To maximize delivery of the therapeutic transgene throughout the CNS, we combined a single brainstem infusion with bilateral thalamic infusions in naive NHPs. We found that enzymatic augmentation in brainstem, thalamic, cortical, as well subcortical areas provided convincing evidence that much of the large NHP brain can be transduced with as few as three injection sites.

MR imaging of adult supratentorial astrocytomas: an attempt of semi-automatic grading.

Using multiple regression analysis, six MR parameters were correlated with three histological grades among 43 proven adult supratentorial astrocytic gliomas to ascertain important MR parameters and their optimal contributions. Analysis revealed that two parameters, border definition and tumor hemorrhage, were unreliable. Using the remaining four parameters an equation was derived: Tumor grade = 0.32 (ring enhancement) +0.29 (degree of contrast enhancement) +0.13 (heterogeneity) +0.12 (edema) +0.41. Ring enhancement was the most reliable predictor of tumor grade, followed by degree of contrast enhancement. The maximum accuracies of the "semi-automatic" approach using this equation for predicting low-grade astrocytomas, anaplastic astrocytomas, and glioblastoma multiforme were 91%, 83%, and 88%, respectively. Although "semi-automatic" grading provided relatively high accuracy, possible sampling errors and some atypical cases reduced such accuracy.

Epidural abscess in the cervical spine.

A ten-year retrospective review of 23 cases of documented spinal epidural abscess in the cervical spine was undertaken to define the clinical features and establish current diagnostic and therapeutic criteria. Diagnosis was made by magnetic resonance imaging or myelography. Risk factors included intravenous drug abuse, diabetes mellitus, previous trauma, and a positive serologic test for the human immunodeficiency virus. A bacterial agent was isolated in 21 cases (91%). Neurologic deficits were present in 20 of the cases (87%) at the time of diagnosis. Erythrocyte sedimentation rate was elevated in all patients in whom it was measured. All patients were treated with appropriate antibiotics, usually for 6 to 8 weeks. Twenty-one patients underwent operative procedures using percutaneous aspiration (1 patient), the anterior approach (14 patients) or the posterior approach (4 patients), or a combination of the two approaches (2 patients). Four of ten patients who initially had less than antigravity strength were eventually ambulatory and continent; in each case, operative decompression was performed within 36 hours of initial consultation. Three patients who had no initial neurologic deficits remained intact.

Diffusion-weighted magnetic resonance imaging: rapid and quantitative detection of focal brain ischemia.

We examined serial changes of diffusion- (DWI) and T2-weighted (T2WI) magnetic resonance images 30 minutes to 3 hours after intraluminal suture occlusion of the middle cerebral artery (MCA) in eight rats and after sham occlusion in four. We correlated the abnormal areas on DWI and T2WI with postmortem areas of infarction determined by 2,3,5-triphenyltetrazolium chloride (TTC), 24 hours after the operation. The 30-minute DWI in each MCA-occluded rat demonstrated increased signal intensity in the ipsilateral MCA territory, while T2WI showed no changes. At 3 hours, the ipsilateral DWI signal intensity increased further and the area of abnormality slightly increased. In some animals, the 3-hour T2WI disclosed an area of hyperintensity significantly smaller than that seen on the 30-minute DWI. TTC staining demonstrated an extensive MCA infarction in all rats with permanent MCA occlusion, confirmed by hematoxylin and eosin staining. The percent infarcted area of coronal brain sections, as determined by TTC staining, correlated significantly with areas on similar DWI sections at both 30 minutes and 3 hours. Sham-occluded control animals did not display any changes on DWI, T2WI, or TTC staining. The present study suggests that DWI is a very sensitive modality for detecting early ischemic brain injury, being highly correlated with post-mortem area of infarction, and may be useful to assess pharmacologic intervention.

New insights and technologies in brain grafting.

Significant progress has been made in the field of brain grafting over the last 15 years. Neurosurgeons have been involved directly in the preclinical and clinical efforts in this fascinating and promising field, along with their neuroscience colleagues. Through a better understanding of the complex mechanisms involved in response to transplants in the brain, new technologies and experimental strategies are being developed to improve the safety and efficacy of these procedures. The time is right for carrying out appropriate preclinical studies in rodents and nonhuman primates to answer one of the most basic questions: Is a tissue graft necessary for behavior improvement in degenerative diseases such as PD, HD, or AD? With available tools and technology and an open mind to new ideas, brain grafting has a tremendous potential in the neurosurgeon's armamentarium, both today and in the future.

NGF-like trophic support from peripheral nerve for grafted rhesus adrenal chromaffin cells.

Autopsy results on patients and corresponding studies in nonhuman primates have revealed that autografts of adrenal medulla into the striatum, used as a treatment for Parkinson's disease, do not survive well. Because adrenal chromaffin cell viability may be limited by the low levels of available nerve growth factor (NGF) in the striatum, the present study was conducted to determine if transected peripheral nerve segments could provide sufficient levels of NGF to enhance chromaffin cell survival in vitro and in vivo. Aged female rhesus monkeys, rendered hemiparkinsonian by the drug MPTP (n-methyl-4-phenyl-1,2,3,6 tetrahydropyridine), received autografts into the striatum using a stereotactic approach, of either sural nerve or adrenal medulla, or cografts of adrenal medulla and sural nerve (three animals in each group). Cell cultures were established from tissue not used in the grafts. Adrenal chromaffin cells either cocultured with sural nerve segments or exposed to exogenous NGF differentiated into a neuronal phenotype. Chromaffin cell survival, when cografted with sural nerve into the striatum, was enhanced four- to eightfold from between 8000 and 18,000 surviving cells in grafts of adrenal tissue only up to 67,000 surviving chromaffin cells in cografts. In grafts of adrenal tissue only, the implant site consisted of an inflammatory focus. Surviving chromaffin cells, which could be identified by both chromogranin A and tyrosine hydroxylase staining, retained their endocrine phenotype. Cografted chromaffin cells exhibited multipolar neuritic processes and numerous chromaffin granules, and were also immunoreactive for tyrosine hydroxylase and chromogranin A. Blood vessels within the graft were fenestrated, indicating that the blood-brain barrier was not intact. Additionally, cografted chromaffin cells were observed in a postsynaptic relationship with axon terminals from an undetermined but presumably a host origin.

Response of the monkey cholinergic septohippocampal system to fornix transection: a histochemical and cytochemical analysis.

Transection of the fimbria-fornix pathway is a paradigm that has been richly exploited in rats to assess the structural and functional correlates of cognitive behavior, neural grafting, and growth factor administration. Principally, the degeneration of cholinergic neurons within the septal/diagonal band region has received detailed attention following this manipulation. In contrast, no studies have examined the response of the cholinergic septal/diagonal neurons following axotomy in nonhuman primates. This study examined the neuronal and glial responses within the septal region to selective fornix transection (without cingulate gyrus ablation) in four Cebus apella monkeys. One month following unilateral transection of the fornix by means of an open microsurgical approach, a comprehensive loss of acetylcholinesterase [AChE]-containing fibers was observed throughout the hippocampal formation and dentate gyrus ipsilateral to the lesion. Decreases in AChE fiber densities were also observed within the entorhinal cortex ipsilateral to the lesion. No such changes in AChE-fiber density were consistently observed within the subicular region. The decrease in hippocampal AChE-positive fibers was paralleled by a 49.5% reduction in cholinergic medial septal neurons as revealed by Nissl stains and immunohistochemical staining for the receptor for nerve growth factor, a marker of cholinergic basal forebrain neurons in primates. In contrast, no significant changes in the number of neurons within the vertical limb of the diagonal band were noted. Following the transection, a relatively intense reactive gliosis was observed within the dorsal half of the septal region ipsilateral to the transection and within the overlying transected corpus callosum. These data provide the foundation in nonhuman primates on which novel therapeutic factors can be evaluated in paradigms relevant to the study of Alzheimer's disease.

Adrenal chromaffin cells as transplants in animal models of Parkinson's disease.

The field of neural transplantation has moved rapidly forward in the last decade. Initially, fetal cells were used as implants to investigate their potential to ameliorate deficits in animal models of Parkinson's disease. However, because of the moral and legal problems associated with the use of fetal tissues in humans, alternative sources of donor tissue were sought which possessed the structural and functional characteristics needed to improve motor function in Parkinsonian patients. To date, one of the most promising tissues being investigated is the adrenal medulla, whose chromaffin cells possess an inherent plasticity of form and function. Transplanted chromaffin cells currently are being studied by a variety of approaches, including electron microscopy, in mouse, rat, and primate models of Parkinson's disease. An overview of the role of the chromaffin cell in this exciting and clinically important arena is briefly reviewed, with an emphasis on the fine structure of implanted chromaffin cells.

Adrenal medullary autografts into the basal ganglia of Cebus monkeys: injury-induced regeneration.

Questions arising from recent clinical neural transplantation trials in Parkinson's disease have under-scored the necessity for a thorough experimental evaluation of the structural and functional consequences of this procedure. The present study investigated the neuroanatomical host reaction to intrastriatal implants in normal and 1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine (MPTP)-treated nonhuman primates. Nine monkeys (Cebus apella) received intrastriatal implants using either a stereotactic approach with a silver tissue carrier or an open microsurgical procedure. Seven of these animals received intrastriatal adrenal medullary autografts, while two received control implants consisting of the tissue carrier alone. One month following transplantation, the hosts' brains were evaluated via immunohistochemical and routine histologic methods. In both MPTP-treated and normal monkeys, enhanced ipsilateral expression of tyrosine hydroxylase-like immunoreactive (TH-IR) fibers in the caudate nucleus was observed, despite minimal survival of adrenal chromaffin cells in the implants. The intensity of this response was greatest adjacent to the implant site, but a clearly increased degree of ipsilateral striatal fiber staining also could be seen several millimeters from the graft. TH-IR fibers also were more dense and of thicker caliber throughout the nigrostriatal and mesolimbic pathways ipsilateral to the implant. Control stereotactic implants, consisting of a silver tissue carrier alone, produced a similar enhancement of immunoreactive fibers, suggesting an induction of TH-IR fibers by the parenchymal injury produced during surgical implantation. There are two major hypotheses proposed to explain why adrenal medullary grafts may promote functional recovery in human parkinsonism: (1) replacement of lost striatal neurotransmitter (dopamine) by the viable grafted tissue, or (2) induction of recovery of remaining host dopaminergic systems by the implantation procedure. Our current data appear to support the latter.

Adrenal medullary autografts into the basal ganglia of Cebus monkeys: graft viability and fine structure.

Based largely upon studies done in rats, a number of medical centers are now performing autografts of adrenal medullary tissue in consenting patients with Parkinson's disease. However, a systematic experimental evaluation of adrenal medullary autografts in nonhuman primates is necessary. This study provides a detailed analysis of the implant site at the fine structural level 30 days post-transplantation in the Cebus monkey. Five normal and two 1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine (MPTP)-treated Cebus monkeys received adrenal medullary autografts using an open microsurgical approach (n = 3) or via stereotactic placement with a tissue carrier (n = 4). Analysis of preimplant samples of the adrenal medulla confirmed that viable chromaffin cells were implanted into the basal ganglia. However, 30 days later, the implant site resembled a chronic inflammatory focus, with grafted chromaffin cells identified ultrastructurally in only two of the seven transplanted monkeys. The grafted cells showed overt signs of cellular degeneration and were surrounded by phagocytic macrophages. All of the implant sites, regardless of the surgical approach, were filled with macrophages, cells of hematogenous origin, and fibrous astrocytes. The vasculature of the implant site was of the nonfenestrated type, characteristic of the host striatum. Despite the poor survival of implanted chromaffin cells, robust sprouting of tyrosine hydroxylase-like immunoreactive fibers was evident in the striatum adjacent to the implant site (see accompanying manuscript, M.S. Fiandaca, J. H. Kordower, J.T. Hansen, S.-S. Jiao, and D.M. Gash, 1988, Exp. Neurol. 102: 76-91), suggesting that implantation may have precipitated a host response that was beneficial to the transplanted animal. Additional studies that provide a better understanding of the cellular elements residing in the implant site and their potential for trophic influence seem warranted.

Tyrosine hydroxylase-immunoreactive somata within the primate subfornical organ: species specificity.

The present study describes a collection of tyrosine hydroxylase-immunoreactive (TH-ir) somata within the subfornical organ (SFO) of the Cebus monkey. In contrast, no cell bodies, and only sparse TH-ir fibers, were observed within the SFO in rats. In the monkey, these TH-ir neurons were observed throughout the rostrocaudal extent of the SFO, preferentially located at its lateral and dorsal aspects. These neurons were bipolar and multipolar with long, beaded, varicose fibers emanating from the cell soma. Cebus monkeys displayed dopamine beta hydroxylase and phenylethanolamine-N-methyltransferase- immunoreactive neurons within established noradrenergic and adrenergic nuclei respectively, but not within the SFO, suggesting that the neurons which are immunoreactive for TH in this region contain dopamine.

Carcinoid tumor in a presacral teratoma associated with an anterior sacral meningocele: case report and review of the literature.

We report a case of a presacral teratoma containing a malignant carcinoid component associated with an anterior sacral meningocele that presented in a 35-year-old woman. The clinical, radiographic, and pathological features of these rare tumors, of presacral meningoceles, and of the hereditary presacral teratoma syndrome are discussed.

Recurrent intramedullary enterogenous cyst of the cervical spinal cord.

Intramedullary enterogenous cysts of the cervical spinal cord are rare. We report a case of symptomatic recurrence of this type of cyst 8 years following its original surgical treatment.

Unilateral septic cavernous sinus thrombosis. A case report with digital orbital venographic documentation.

In its early stages, septic cavernous sinus thrombosis may be difficult to differentiate from orbital cellulitis. We describe a case in which digital subtraction orbital venography proved to be a superior technique for clarifying this clinical dilemma, and we stress the clinical importance of making this differentiation.