Study of the Link Between Neuronal Death, Glial Response, and MAPK Pathway in Old Parkinsonian Mice

Background: Parkinson’s disease (PD) is described as an age-related neurodegenerative disorder. However, the vast majority of research is carried out using experimental models of young animals lacking the implications of the decline processes associated with aging. It has been suggested that several molecular pathways are involved in the perpetuation of the degeneration and the neuroinflammation in PD. Among others, mitogen-activated protein kinases (MAPKs) have been highly implicated in the development of PD, and regulating components of their activity are indicated as promising therapeutic targets.

Methods: To further define how MAPKs expression is related to the glial response and neuronal cell death, Parkinsonism was induced under an acute regimen in old mice. Moreover, the sacrifice was carried out at different time points (4, 8, 24, and 48 h) after 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine hydrochloride (MPTP) injections to describe the early dynamic changes over time produced by the intoxication.

Results: The results revealed that neuronal death increases as glial response increases in the nigrostriatal pathway. It was observed that both processes increase from 4 h in the ventral mesencephalon (VM), and neuronal death becomes significant at 48 h. In the striatum, they were significantly increased from 48 h after the MPTP administration compared with that in the control mice. Moreover, the p-ERK levels decrease, while phospho-p38 expression increases specifically in the striatum at 48 h after MPTP intoxication.

Conclusions: The importance of these data lies in the possibility of elucidating the underlying mechanisms of neurodegenerative processes under aging conditions to provide knowledge for the search of solutions that slow down the progression of PD.

Combined 1-Deoxynojirimycin and Ibuprofen Treatment Decreases Microglial Activation, Phagocytosis and Dopaminergic Degeneration in MPTP-Treated Mice

Inflammation is a predominant aspect of neurodegenerative diseases and experimental studies performed in animal models of Parkinson's disease (PD) suggesting that a sustained neuroinflammation exacerbates the nigrostriatal degeneration pathway. The central role of microglia in neuroinflammation has been studied as a target for potential neuroprotective drugs for PD, for example nonsteroidal anti-inflammatory drugs (NSAIDs) and matrix metalloproteinases (MMP) inhibitors that regulates microglial activation and migration. The aim of this study was to investigate the neuroprotective response of the iminosugar 1-deoxynojirimycin (1-DNJ) and compare its effect with a combined treatment with ibuprofen. MPTP-treated mice were orally dosed with ibuprofen and/or 1-DNJ 1. Open-field test was used to evaluate behavioral changes. Immunohistochemistry for dopaminergic neurons marker (TH⁺) and microglia markers (Iba-1⁺; CD68⁺) were used to investigate neuronal integrity and microglial activation in the substantia nigra pars compacta (SNpc). The pro-inflammatory cytokines TNF-α and IL-6 were analysed by qPCR. Treatments with either 1-DNJ or Ibuprofen alone did not reduce the damage induced by MPTP intoxication. However, combined treatment with 1-DNJ and ibuprofen prevents loss of mesencephalic dopaminergic neurons, decreases the number of CD68⁺/ Iba-1⁺ cells, the microglia/neurons interactions, and the pro-inflammatory cytokines, and improves behavioral changes when compared with MPTP-treated animals. In conclusion, these data demonstrate that the combined treatment with a MMPs inhibitor (1-DNJ) plus an anti-inflammatory drug (ibuprofen) has neuroprotective effects open for future therapeutic interventions. Graphical Abstract MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) is a protoxicant that, after crossing the Blood Brain Barrier, is metabolized by astrocytic MAO-B to MPDP+, a pyridinium intermediate, which undergoes further two-electron oxidation to yield the toxic metabolite MPP+ (methyl-phenyltetrahydropyridinium) that is then selectively transported into nigral neurons via the mesencephalic dopamine transporter. In this study, we demonstrated that MPTP induced death of dopaminergic neurons, microgliosis, increase of gliapses, motor impairment and neuroinflammation in mice, which were inhibited by combined 1-deoxynojirimycin and ibuprofen treatment.

Retinal aging in the diurnal Chilean rodent (Octodon degus): histological, ultrastructural and neurochemical alterations of the vertical information processing pathway

The retina is sensitive to age-dependent degeneration. To find suitable animal models to understand and map this process has particular importance. The degu (Octodon degus) is a diurnal rodent with dichromatic color vision. Its retinal structure is similar to that in humans in many respects, therefore, it is well suited to study retinal aging. Histological, cell type-specific and ultrastructural alterations were examined in 6-, 12- and 36-months old degus. The characteristic layers of the retina were present at all ages, but slightly loosened tissue structure could be observed in 36-month-old animals both at light and electron microscopic levels. Elevated Glial fibrillary acidic protein (GFAP) expression was observed in Müller glial cells in aging retinas. The number of rod bipolar cells and the ganglion cells was reduced in the aging specimens, while that of cone bipolar cells remained unchanged. Other age-related differences were detected at ultrastructural level: alteration of the retinal pigment epithelium and degenerated photoreceptor cells were evident. Ribbon synapses were sparse and often differed in morphology from those in the young animals. These results support our hypothesis that (i) the rod pathway seems to be more sensitive than the cone pathway to age-related cell loss; (ii) structural changes in the basement membrane of pigment epithelial cells can be one of the early signs of degenerative processes; (iii) the loss of synaptic proteins especially from those of the ribbon synapses are characteristic; and (iv) the degu retina may be a suitable model for studying retinal aging.

Neurotrophic bone marrow cellular nests prevent spinal motoneuron degeneration in amyotrophic lateral sclerosis patients: a pilot safety study

The objective of this article is to assess the safety of intraspinal infusion of autologous bone marrow mononuclear cells (BMNCs) and, ultimately, to look for histopathological signs of cellular neurotrophism in amyotrophic lateral sclerosis (ALS) patients. We conducted an open single arm phase I trial. After 6 months observation, autologous BMNCs were infused into the posterior spinal cord funiculus. Safety was the primary endpoint and was defined as the absence of serious transplant-related adverse events. In addition, forced vital capacity (FVC), ALS-functional rating scale (ALS-FRS), Medical Research Council scale for assessment of muscle power (MRC), and Norris scales were assessed 6 and 3 months prior to the transplant and quarterly afterward for 1 year. Pathological studies were performed in case of death. Eleven patients were included. We did not observe any severe transplant-related adverse event, but there were 43 nonsevere events. Twenty-two (51%) resolved in ≤2 weeks and only four were still present at the end of follow-up. All were common terminology criteria for adverse events grade ≤2. No acceleration in the rate of decline of FVC, ALS-FRS, Norris, or MRC scales was observed. Four patients died on days 359, 378, 808, and 1,058 post-transplant for reasons unrelated to the procedure. Spinal cord pathological analysis showed a greater number of motoneurons in the treated segments compared with the untreated segments (4.2 ± 0.8 motoneurons per section [mns per sect] and 0.9 ± 0.3 mns per sect, respectively). In the treated segments, motoneurons were surrounded by CD90+ cells and did not show degenerative ubiquitin deposits. This clinical trial confirms not only the safety of intraspinal infusion of autologous BMNC in ALS patients but also provides evidence strongly suggesting their neurotrophic activity.

[Bone marrow stem cell transplantation in amyotrophic lateral sclerosis: technical aspects and preliminary results from a clinical trial]

Patients with amyotrophic lateral sclerosis (ALS) experience progressive and irreversible paralysis as a result of the continued loss of motor neurons, which leads to death in less than five years. To date, there is no treatment that can change the progression of this disease. Bone marrow stem cells have shown neural regenerative and neural repairing properties. Specifically, our group showed in a murine model of the disease that these cells, when injected in the spinal cord, can rescue motor neurons through the secretion of GDNF. Based on these results, we designed a phase I/II clinical trial for the purpose of demonstrating the viability of the intraspinal injection of autologous bone marrow mononuclear cells in patients with bulbar onset ALS, with an evolution between 6 and 36 months, with a forced vital capacity (FVC) 50% and T90 29%. This article describes the technique for extracting 60 mL of bone marrow used for the intervention, processing it by density gradient, and the neurosurgical technique used for implanting it. After 6 months of follow-up, the few adverse events reported in the first seven patients included seem to show that the procedure is safe and viable. Most of these patients, including two with a rapid deterioration, have stabilized the progression of their FVC and the neurologic scales measured. The data obtained so for seem to justify the design of new trials more oriented toward the efficacy of the procedure.

Cervical spinal cord infarction after posterior fossa surgery: a case-based update

BACKGROUND

Several positions are currently utilized for operating patients with posterior fossa lesions. Each individual position has its own risks and benefits, and none has demonstrated its superiority. A dreaded, and probably underreported, complication of these procedures is cervical cord infarction with quadriplegia.

DISCUSSION

We reviewed eight previous reported instances of this devastating complication aimed at ascertaining its pathogenesis to suggest preventive strategies. Several hypotheses have been put forward to explain the occurrence of this complication. Some factors involved in the production of cervical cord infarction include patient's position (seated or prone), hyperflexion of the neck, excessive spinal cord traction, canal stenosis, and systemic arterial hypotension. We hypothesize that spinal cord infarction in our patient might have resulted from compromised blood supply to the midcervical cord caused by tumor infiltration of the cervical leptomeninges in addition to a brief episode of arterial hypotension during venous air embolism.

CASE REPORT

We treated an 8-year-old girl who developed quadriplegia after surgery for a fourth ventricular ependymoma. Postoperative magnetic resonance imaging demonstrated cervical cord infarction. Evoked potentials confirmed the diagnosis.

CONCLUSIONS

With this report, we want to draw the attention of neurosurgeons to the possibility of the occurrence of this dreadful complication during posterior fossa procedures. Retrospectively, the only measures that might have helped to avoid this complication in our patient would have been using the prone position and intraoperative monitoring of evoked potentials.

Partial conduction blocks in N-hexane neuropathy

Nerve conduction blocks, defined by a significant reduction in amplitude or area of the compound muscle action potential at proximal compared with distal sites of stimulation, have been described in glue-sniffers and in workers with industrial exposure at an early stage of n-hexane neuropathy. The frequency with which this focal conduction anomaly appears is described and discussed in the case of a very homogeneous group of 10 young workers diagnosed with n-hexane polyneuropathy. Partial conduction blocks occurred in only two workers and may have been related to the intensity and duration of toxic exposure.

[Acute respiratory insufficiency as onset form of Lambert-Eaton's syndrome associated with pulmonary small cell carcinoma]

The Lambert-Eaton myasthenic syndrome is a rare disorder of neuromuscular transmission, usually presenting as a paraneoplastic process associated with a small cell lung cancer. Recently, respiratory muscular impairment has been described in these patients. Acute respiratory failure as a presenting symptom has been reported in few cases. We present a case of acute ventilatory failure as the first manifestation of Lambert-Eaton myasthenic syndrome associated with small cell lung cancer and discuss the main features of this disease, including its treatment. The Lambert-Eaton myasthenic syndrome should be considered in cases of unexplained acute respiratory failure and clinical evidence of neoplasic disease. We thought that electromyographic studies could reveal the real involvement of respiratory muscles, including diaphragm, in this condition.

A comparison of electrophysiological tests for the early diagnosis of diabetic neuropathy

Clinical criteria and several electrophysiological parameters for detecting nerve damage were compared in 99 patients with diabetes mellitus type 1 and type 2. Abnormal results were found in sural/radial amplitude ratio (51%), minimal F-wave latency of the tibial nerve (36.4%), sensory conduction velocity of the sural nerve (29.8%), and sural sensory nerve action potential amplitude (29.3%) when pooling data from all patients and comparing them to age- and height-matched normal control subjects. Analysis of all the parameters revealed large differences between the diabetes mellitus type 1 and type 2 groups, suggesting that the type of diabetes must be taken into account when comparing the sensitivity of nerve conduction tests. In diabetes mellitus type 1, the sural/radial ratio had the clearest correlation with course of illness and was the first parameter to show a significant reduction. We conclude that the simple ratio between sural and radial amplitudes is a very sensitive parameter and abnormalities in this ratio provide the means for earliest detection of neuropathy in diabetes mellitus type 1.

[Early infantile epileptic encephalopathy and glycine encephalopathy]

INTRODUCTION

Early infantile epileptic encephalopathy (EIEE) with suppression burst activity in EEG (Ohtahara syndrome) is a rare type of epileptic encephalopathy in infancy and represents the earliest type of age-related symptomatic generalized epilepsy. The main etiologic factors associated to EIEE are cerebral dysgenesia and metabolopathies, principally nonketotic hyperglycinemia.

CLINICAL CASE

We report a neonate with EIEE secondary to glycine encephalopathy, diagnosed by increased of LCR/plasma glycine index.

[Variations in cerebral blood flow in various states of severe neonatal hypoxic-ischemic encephalopathy]

The clinical applications of Doppler sonography are numerous in pediatric practice. Of the all the measurements of arterial signals available, the one that has been most useful used and has proved to be of practical benefit is the Pourcelot resistance index (PI). The change in PI is more sensitive than the real-time image for documentation of the cerebral insult in full-term asphyxia. The PI is much lower and stays lower for several days in the more severely asphyxiated infants and is thus extremely useful for predicting outcome as well. But multiple factors affect the waveform and PI, and it is important to understand how physiological and pathological variables influence chances in the Doppler signal in order to better understand changes in newborn with neurological problems. We present the changes of cerebral blood flow by Doppler ultrasound in a newborn with severe perinatal asphyxia and hypoxic-ischemic encephalopathy, associated with other neurological problems; coma, seizures and hydrocephalus.

Retrograde migration of the abdominal catheter as a complication of ventriculoperitoneal shunts: the fishhook sign

Three cases of retrograde migration of the distal catheter of ventriculoperitoneal shunts into the subcutaneous fibrous tract of the thoracic wall are reported. To the authors' knowledge this is the first time that this complication of ventriculoperitoneal shunts has been described.