Delayed diagnosis of an epidural haematoma with a working epidural in situ.
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Aged, 80 and over↗
Biomedical subjects
J Dinsmore
Publications and source records attributed to J Dinsmore.
The use of hypothermia as a method of neuroprotection during neurosurgical procedures and after traumatic brain injury: a survey of clinical practice in Great Britain and Ireland.
Hypothermia has been employed as a method of neuroprotection for many decades. The evidence base for its use is limited, and the balance between benefit and risk is unclear. We felt that in light of this confusion it would be interesting to canvas the opinion of the members of The Neuroanaesthesia Society of Great Britain and Ireland. A questionnaire was sent to all 274 members enquiring into their use of hypothermia during a variety of different neurosurgical procedures and in the management of the head-injured patient. A 75% response rate was achieved. The results showed that over half (58%) of those who replied attempted to cool the patient during cerebral aneurysm surgery. Forty-one per cent of respondents attempt to induce hypothermia in the head-injured patient. However, for other neurosurgical procedures most felt that the disadvantages of cooling the patient outweigh the advantages. The use of hypothermia remains a contentious issue, and as yet there is no clear answer as to whether it should be employed as a method of neuroprotection.
Adult↗
Anaesthesia for awake craniotomy--evolution of a technique that facilitates awake neurological testing.
BACKGROUND: There is an increasing trend towards performing craniotomy awake. The challenge for the anaesthetist is to provide adequate analgesia and sedation, haemodynamic stability, and a safe airway, with an awake, cooperative patient for neurological testing. METHODS: The records of all patients who had awake craniotomy at our institution were reviewed. Patients were divided into three groups according to anaesthetic technique. Patients in Group 1 were sedated throughout the procedure. Patients in Groups 2 and 3 had an asleep-awake-asleep technique. Those in Group 2 were anaesthetized with a propofol infusion and fentanyl, and breathed spontaneously through a laryngeal mask airway (LMA). Patients in Group 3 had total i.v. anaesthesia with propofol and remifentanil, and ventilation was controlled using an LMA. We noted the incidence of complications in each group. RESULTS: There were 99 procedures carried out between 1989 and 2002. Group 3 had the fewest complications. No patients in Group 3 developed hypercapnia (E'(CO(2)) >6 kPa), compared with all of the patients in Group 2. Patients in Group 1 had no E'(CO(2)) monitoring, but 7% developed airway obstruction. No patients in Group 3 required additional analgesia for pain, compared with 70% of patients in Group 2. CONCLUSIONS: We have developed a technique for craniotomy, which facilitates awake neurological testing, is safe, and has good patient satisfaction.
Adolescent↗
Effect of diclofenac on cerebral blood flow velocity in patients with supratentorial tumours.
BACKGROUND: The aim of this investigation was to determine the effects of diclofenac on cerebral blood flow. Middle cerebral artery blood flow velocity was measured in nine patients with supratentorial tumours. METHODS: Using a transcranial Doppler ultrasound, we measured the baseline mean and systolic cerebral blood flow velocity. Measurements were repeated following administration of diclofenac 75 mg i.v. RESULTS: There was no significant change in cerebral blood flow velocity. All other physiological variables remained constant. CONCLUSION: Diclofenac does not cause a significant change in cerebral blood flow velocity in patients with supratentorial tumours.
Adult↗
Transplantation of embryonic porcine mesencephalic tissue in patients with PD.
OBJECTIVE: To assess the safety and the effect on standardized clinical rating measures of transplanted embryonic porcine ventral mesencephalic (VM) tissue in advanced PD. METHODS: Twelve patients with idiopathic PD underwent unilateral implantation of embryonic porcine VM tissue; six received cyclosporine immunosuppression and six received tissue treated with a monoclonal antibody directed against major histocompatibility complex class I. Patients were followed for 12 months and assessed by clinical examination, MRI, and 18F-levodopa PET. Porcine endogenous retrovirus testing was conducted by PCR-based method on peripheral blood mononuclear cells. RESULTS: Cell implantation occurred without serious adverse events in all patients. Cultures were negative for bacterial and unknown viral contamination. No porcine endogenous retrovirus DNA sequences were found. MRI demonstrated cannula tracts within the putamen and caudate, with minimal or no edema and no mass effect at the transplant sites. In the medication-off state, total Unified Parkinson's Disease Rating Scale scores improved 19% (p = 0.01). Three patients improved over 30%. There were two patients with improved gait. 18F-levodopa PET failed to show changes on the transplanted side. CONCLUSIONS: Unilateral transplantation of porcine embryonic VM cells into PD patients was well tolerated with no evidence of transmission of porcine endogenous retrovirus. Changes in standardized clinical PD rating measures were variable, similar to the results of the first trials of unilateral human embryonic allografts that transplanted small amounts of tissue.
Aged↗
Long-term survival of fetal porcine lateral ganglionic eminence cells in the hippocampus of rats.
Embryonic porcine brain tissue from the lateral ganglionic eminence was transplanted into the adult rat hippocampus to determine whether fetal striatal cells could survive, differentiate, and integrate in a heterotopic site. The hippocampus, a common site of epileptic seizure activity, was chosen to determine if fetal striatal cells could supply inhibitory GABAergic neurons that may serve to block seizures. Cells were either implanted with a single deposit using a standard metal cannula or by five smaller disseminated deposits with a glass micropipette. At 20-24 weeks, animals immunosuppressed with cyclosporin showed long-term survival of porcine cells in the adult hippocampus. Analysis by immunohistochemistry and in situ hybridization showed that the grafts contained glial and neuronal cell types, including GABAergic neurons within graft core and networks of porcine neuronal fibers extending from the graft into the host parenchyma. In addition, a marker of porcine presynaptic terminals, synaptobrevin, was abundant within the grafts and was found associated with hippocampal structures and cell layers suggesting functional integration of grafted cells within the host. The survival of xenografts in the hippocampus and potential integration of inhibitory components provides evidence that these grafts may serve as an internal negative feedback mechanism to quench epileptiform activity.
Animals↗
Regulated expression of the homeobox gene, rPtx2, in the developing rat.
Using degenerate primers designed to amplify genes containing homeodomains, we have used reverse transcription and polymerase chain reaction to amplify and clone a rat homeobox gene. Based on the nucleotide and predicted amino acid sequences, the rat cDNA clone contains a high degree of sequence similarity to murine genes which are members of the paired-like class of homeobox genes (Ptx2, Otlx2, solurshin and Ptx1). Considering the high degree of sequence similarity and similar restricted expression patterns, we have named the cloned rat gene rPtx2 (rat Ptx2 homolog). Northern analysis revealed two rPtx2 transcripts expressed in the developing rat brain. Yet, only a single gene was detected by Southern blot hybridization, suggesting that multiple messages are the result of alternative transcriptional initiation, splicing or processing of a common message. The expression pattern of rPtx2 was further delineated by in situ hybridization to rat embryos. Within the brain, tissue specific expression was observed in the differentiating neural cells of the posterior hypothalamus, tegmentum, and rhombomere r1. Expression was also observed in the developing pituitary, maxilla, mandible, tongue and umbilical cord. To further study the control of Ptx2 gene expression, we used an in vitro model for neural differentiation by treating mouse embryonic stem cells with retinoic acid. Within 24 h and prior to detection of a neural phenotype in the culture, murine Ptx transcripts were induced and remained elevated for at least 6 days. This suggests that retinoic acid may be an important inductive signal which regulates the developmental and tissue-specific expression of Ptx2.
Aging↗
Embryonic stem cells as a model for studying regulation of cellular differentiation.
Mouse embryonic stem (ES) cells can be differentiated in vitro into near homogeneous populations of both neurons and skeletal muscle as well as other cell types. We previously showed that treatment of pluripotent ES cells with retinoic acid (RA) induced differentiation into highly enriched populations of gamma-aminobutyric acid (GABA) expressing neurons. The reasons for generation of only GABA neurons as opposed to other neuronal cell types were not known. We have extended our previous work and now show that with RA induction of ES cells we not only obtain GABA neurons, but also dopaminergic neurons. Critical for the production of dopaminergic neurons after RA induction was the post-induction plating conditions used. No dopaminergic neurons were detected if cells were plated in serum-free media optimized for neuronal survival. However, significant numbers of dopamine neurons could be detected when cells were plated in media containing fetal calf serum. These observations support the conclusion that RA acts as a general neural inducing agent and that conditions post-induction either selectively support survival of a particular class of neuronal cells or that the conditions post-induction actually further instruct cells to differentiate into different types of neurons.
Animals↗
Blastula-stage stem cells can differentiate into dopaminergic and serotonergic neurons after transplantation.
In order to assess the potential of embryonic stem cells to undergo neuronal differentiation in vivo, totipotent stem cells from mouse blastocysts (D3 and E14TG2a; previously expanded in the presence of leukemia inhibitory factor) were transplanted, with or without retinoic acid pretreatment, into adult mouse brain, adult lesioned rat brain, and into the mouse kidney capsule. Intracerebral grafts survived in 61% of cyclosporine immunosuppressed rats and 100% of mouse hosts, exhibited variable size and morphology, and both intracerebral and kidney capsule grafts developed large numbers of cells exhibiting neuronal morphology and immunoreactivity for neurofilament, neuron-specific enolase, tyrosine hydroxylase (TH), 5-hydroxytryptamine (5-HT), and cells immunoreactive for glial fibrillary acidic protein. Though graft size and histology were variable, typical grafts of 5-10 mm3 contained 10-20,000 TH+ neurons, whereas dopamine-beta-hydroxylase+ cells were rare. Most grafts also included nonneuronal regions. In intracerebral grafts, large numbers of astrocytes immunoreactive for glial fibrillary acidic protein were present. Both TH+ and 5-HT+ axons from intracerebral grafts grew into regions of the dopamine-lesioned host striatum. TH+ axons grew preferentially into striatal gray matter, while 5-HT+ axons showed no white/gray matter preference. These findings demonstrate that transplantation to the brain or kidney capsule can induce a significant fraction of totipotent embryonic stem cells to become putative dopaminergic or serotonergic neurons and that when transplanted to the brain these neurons are capable of innervating the adult host striatum.
Animals↗
The effect of increasing degrees of spinal flexion on cerebrospinal fluid pressure.
The effects of increasing degrees of flexion on cerebrospinal fluid pressure were investigated in 12 neurosurgical patients requiring lumbar subarachnoid drains. Cerebrospinal fluid pressure and central venous pressure were measured in three positions: fully flexed ('chin on chest'), flexed at ninety degrees and straight. There was a significant increase in cerebrospinal fluid pressure on moving from the fully flexed to the flexed position (p < 0.0001), but not from the flexed to the straight position. These results were mirrored by smaller changes in central venous pressure. In patients without intracranial pathology these increases in cerebrospinal fluid pressure are probably unimportant. However, intracranial pathology may result in low cerebral perfusion pressures and any increase in cerebrospinal fluid pressure in this group may be harmful. The fully flexed position should be avoided when inserting lumbar drains in at risk patients.
Central Venous Pressure↗
Histological evidence of fetal pig neural cell survival after transplantation into a patient with Parkinson's disease.
The movement disorder in Parkinson's disease results from the selective degeneration of a small group of dopaminergic neurons in the substantia nigra pars compacta region of the brain. A number of exploratory studies using human fetal tissue allografts have suggested that transplantation of dopaminergic neurons may become an effective treatment for patients with Parkinson's disease and the difficulty in obtaining human fetal tissue has generated interest in finding corresponding non-human donor cells. Here we report a post-mortem histological analysis of fetal pig neural cells that were placed unilaterally into the caudate-putamen brain region of a patient suffering from Parkinson's disease. Long-term (over seven months) graft survival was found and the presence of pig dopaminergic neurons and other pig neural and glial cells is documented. Pig neurons extended axons from the graft sites into the host brain. Furthermore, other graft derived cells were observed several millimeters from the implantation sites. Markers for human microglia and T-cells showed only low reactivity in direct proximity to the grafts. This is the first documentation of neural xenograft survival in the human brain and of appropriate growth of non-human dopaminergic neurons for a potential therapeutic response in Parkinson's disease.
Aged↗
Fetal pig neural cells as a restorative therapy for neurodegenerative disease.
With proper immunosuppression, interspecies transplantation of porcine as well as other species of neural cells survive, mature, and integrate into the host in a manner which reconstructs much of the appropriate neural circuitry. These transplants have been shown to alleviate many of the symptoms of various disorders of the central nervous system. In this study, we addressed immunological and maturation issues with regards to intracerebral transplantation of fetal porcine neural cells. First, we compared fetal neural xenograft survival in athymic nude rats versus rats immunosuppressed with cyclosporin A and found that there is little discernible difference between porcine grafts in the 2 recipients. We also found that ectopic transplantation of cells isolated from the porcine striatal primordium can survive and develop into grafts composed of both neuronal and glial phenotypes within the rat hippocampus. This fact raises the possibility that cells of a particular neurotransmitter type (e.g., GABAergic cells) developing from the striatal precursor cells can be transplanted outside the striatum of the adult brain and have physiological effects.
Animals↗
Xenotransplantation of porcine fetal ventral mesencephalon in a rat model of Parkinson's disease: functional recovery and graft morphology.
Neurotransplantation of human fetal dopamine (DA) neurons is currently being investigated as a therapeutic modality for Parkinson's disease (PD). However, the practical limitations of human fetal transplantation indicate a need for alternative methodologies. Using the 6-hydroxydopamine rat model of PD, we transplanted dopaminergic neurons derived from Embryonic Day 27 porcine fetuses into the denervated striatum of cyclosporine-A (CyA)-treated or non-CyA-treated rats. Functional recovery was assessed by amphetamine-induced rotation, and graft survival and morphology were analyzed using neuronal and glial immunostaining as well as in situ hybridization with a porcine repeat element DNA probe. A significant, sustained reduction in amphetamine-induced rotational asymmetry was present in the CyA-treated rats whereas the non-CyA-treated rats showed a transient behavioral recovery. The degree of rotational recovery was highly correlated to the number of surviving transplanted porcine dopaminergic neurons. TH+ neuronal survival and graft volume were significantly greater in the CyA-treated group as compared to the non-CyA group. By donor-specific neuronal and glial immunostaining as well as donor-specific DNA labeling, we demonstrate that porcine fetal neuroblasts are able to survive in the adult brain of immunosuppressed rats, mediate functional recovery, and extensively reinnervate the host striatum. These findings suggest that porcine DA neurons may be a suitable alternative to the use of human fetal tissue in neurotransplantation for PD.
Animals↗
A novel mode of immunoprotection of neural xenotransplants: masking of donor major histocompatibility complex class I enhances transplant survival in the central nervous system.
To determine the role of major histocompatibility complex (MHC) class I in immunological rejection of neural xenotransplants, F(ab')2 fragments of a monoclonal antibody to porcine MHC class I were used to mask this complex on porcine fetal striatal cells transplanted into rat striata previously lesioned with quinolinic acid. Presence of MHC class I on the surface of porcine striatal cells was confirmed by fluorescence-activated cell sorting prior to F(ab')2 treatment. At three to four months post-transplantation, survival of F(ab')2-treated xenografts was assessed by means of donor-specific immunostaining and compared to that of untreated xenografts in non-immunosuppressed rats and in rats immunosuppressed with cyclosporine A. In this study, masking of donor MHC class I by F(ab')2 treatment resulted in enhanced xenografts survival compared to the non-immunosuppressed controls (graft survival rates, 52% and 7%, respectively; P < 0.005) at survival times up to four months. While xenograft survival in F(ab')2-treated animals was not significantly different from that in cyclosporine-treated rats (74% graft survival), mean graft volume in F(ab')2-treated animals was smaller than that in cyclosporine-treated animals (1.07 +/- 0.30 mm3 versus 3.14 +/- 0.51 mm3; P < 0.005). The cytoarchitectonic organization of the xenografts was similar in F(ab')2- and cyclosporine-treated animals, and grafts in both groups exhibited long distance target-directed axonal outgrowth. The pattern of immunoreactivity to porcine MHC class I in the xenografts corresponded to the regional distribution of donor glia. In xenografts undergoing rejection, infiltration with host inflammatory cells was restricted to necrotic graft remnants and spared the nearby host structures. We conclude that MHC class-I-restricted immune mechanisms play an important role in neural xenograft rejection and that masking of this complex on donor cells may provide a useful strategy for immunoprotection of neural xenografts.
Animals↗
Transplanted xenogeneic neural cells in neurodegenerative disease models exhibit remarkable axonal target specificity and distinct growth patterns of glial and axonal fibres.
Clinical trials are under way using fetal cells to repair damaged neuronal circuitry. However, little is known about how transplanted immature neurons can grow anatomically correct connections in the adult central nervous system (CNS). We transplanted embryonic porcine neural cells in vivo into adult rat brains with neuronal and axonal loss typical of Parkinson's or Huntington's disease. Using complementary species-specific cellular markers, we found donor axons and CD44+ astroglial fibres in host white matter tracts up to 8 mm from CNS transplant sites, although only donor axons were capable of reaching correct gray matter target regions. This work demonstrates that adult host brain can orient growth of transplanted neurons and that there are differences in transplant donor glial and axonal growth patterns in cellular repair of the mature CNS.
Animals↗
Cytoarchitectonic development, axon-glia relationships, and long distance axon growth of porcine striatal xenografts in rats.
Porcine fetal lateral ganglionic eminence cells were transplanted into the quinolinic-acid-lesioned corpus striatum of immunosuppressed adult rats. The resulting grafts were analyzed for graft development with respect to donor age, donor cell dosage, and survival time from 5 to 22 weeks postimplantation. Graft development is prolonged by a factor of 3-4 times in porcine xenografts as compared to rat allografts. As grafts matured, neuronal somata developed in clusters that expressed acetylcholinesterase (AChE), tyrosine hydroxylase, and dopamine- and cAMP-associated phosphoprotein. These clusters were interspersed with AChE-poor graft regions consisting of small densely packed cells that stained for glial fibrillary acidic protein and porcine cluster of differentiation factor 44 (a species-specific glial marker). Graft axons could be selectively stained for 70-kDa neurofilament and were preferentially associated with AChE-poor, glial-rich regions in younger grafts (8 weeks), but AChE-rich neuronal regions in older grafts (22 weeks). Both graft axons and graft glial fibers projected for long distances into the host internal capsule, external capsule, corpus callosum, and anterior commissure. Donor axons also innervated host target structures including the globus pallidus and substantia nigra. This demonstrates a prolonged development of striatal cells that is appropriate to the donor species and which produces long-distance target-specific axonal growth within the adult host brain.
Animals↗
Clathrin light chain B: gene structure and neuron-specific splicing.
The clathrin light chains are components of clathrin coated vesicles, structural constituents involved in endocytosis and membrane recycling. The clathrin light chain B (LCB) gene encodes two isoforms, termed LCB2 and LCB3, via an alternative RNA splicing mechanism. We have determined the structure of the rat clathrin light chain B gene. The gene consists of six exons that extend over 11.9 kb. The first four exons and the last exon are common to the LCB2 and LCB3 isoforms. The fifth exon, termed EN, is included in the mRNA in brain, giving rise to the brain specific form LCB2 but is excluded in other tissues, generating the LCB3 isoform. Primary rat neuronal cell cultures express predominantly the brain specific LCB2 isoform, whereas primary rat cultures of glia express only the LCB3 isoform, suggesting that expression of the brain-specific LCB2 form is limited to neurons. Further evidence for neuronal localization of the LCB2 form is provided using a teratocarcinoma cell line, P19, which can be induced by retinoic acid to express a neuronal phenotype, concomitant with the induction of the LCB2 form. In order to determine the sequences involved in alternative splice site selection, we constructed a minigene containing the alternative spliced exon EN and its flanking intron and exon sequences. This minigene reflects the splicing pattern of the endogenous gene upon transfection in HeLa cell and primary neuronal cell cultures, indicating that this region of the LCB gene contains all the necessary information for neuron-specific splicing.
Alternative Splicing↗
Communicate to avoid malpractice claims.
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Communication↗