Aging with spinal cord injury: A narrative review of consequences and challenges

Given the increase in life expectancy, aging with a pre-existing spinal cord injury (SCI) is becoming more common. This condition is challenging as compromised health status and functional independence can worsen. We aimed to provide an updated overview of the consequences of aging with SCI, highlighting the main challenges facing this population in a narrative review of the current literature we retrieved from the PubMed database from 2000 to 2022 on any aspect related to aging in persons with SCI. Here we address adverse circumstances that increase disability and hinder an active lifestyle, such as progressive physical deterioration, secondary health conditions, limitations in personal activity, changes in family and social support structures, aging of caregivers, and depletion of economic resources. Favorable changes are also observed, including psychosocial adjustments that improve quality of life. Additionally, various interventions are discussed to promote well-being, health, and social participation. Due to the relevance of this issue, people with SCI and all those who take care of them must have up-to-date information to carry out the necessary measures to promote healthy aging in a more inclusive social environment.

Functional improvement in individuals with chronic spinal cord injury treated with 4-aminopyridine: A systematic review

Study design

Systematic review.

Objective

To provide current evidence on the efficacy of 4-aminopyridine (4-AP) to bring about functional improvement in individuals with chronic traumatic spinal cord injury (SCI).

Methods

The Medline (PubMed), Web of Science and SCOPUS databases were systematically searched for relevant articles on the efficacy of 4-AP to treat SCI, from the dates such articles were first published until May 2022. Full-text versions of all the articles selected were examined independently by two reviewers. Methodological quality was rated using the Modified Jadad Scale, and risk of bias was assessed with the RoB-2 test. Data extracted included human models/types, PRISMA assessment protocols, and the results of each study. Descriptive syntheses are provided.

Results

In total, 28 articles were initially identified, 10 of which were included after screening. Most of the studies reviewed reported some degree of patient improvement in one or more of the following parameters: motor, sensitivity and sexual function, sphincter control, spasticity, ability to function independently, quality of life, central motor conduction, pain, and pulmonary function.

Conclusions

This review confirms the efficacy of 4-AP in improving several conditions resulting from SCI but further research on this topic is warranted. Additional randomized clinical trials with 4-AP involving larger sample sizes are needed, as are consistent outcome measures in order to obtain adequate data for analysis with a view to enhance treatment benefits.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=334835, PROSPERO CRD42022334835.

Evolution of Spinal Cord Transection of Rhesus Monkey Implanted with Polymer Synthesized by Plasma Evaluated by Diffusion Tensor Imaging

In spinal cord injury (SCI) there is damage to the nervous tissue, due to the initial damage and pathophysiological processes that are triggered subsequently. There is no effective therapeutic strategy for motor functional recovery derived from the injury. Several studies have demonstrated neurons growth in cell cultures on polymers synthesized by plasma derived from pyrrole, and the increased recovery of motor function in rats by implanting the polymer in acute states of the SCI in contusion and transection models. In the process of transferring these advances towards humans it is recommended to test in mayor species, such as nonhuman primates, prioritizing the use of non-invasive techniques to evaluate the injury progression with the applied treatments. This work shows the ability of diffusion tensor imaging (DTI) to evaluate the evolution of the SCI in nonhuman primates through the fraction of anisotropy (FA) analysis and the diffusion tensor tractography (DTT) calculus. The injury progression was analysed up to 3 months after the injury day by FA and DTT. The FA recovery and the DTT re-stabilization were observed in the experimental implanted subject with the polymer, in contrast with the non-implanted subject. The parameters derived from DTI are concordant with the histology and the motor functional behaviour.

Semi-quantitative evaluation of brain gliomas in adults: A focus on neuropathological characteristics

Introduction

Gliomas are neoplasms with high recurrence and mortality. Due to the difficulty to apply the World Health Organization (2016) classification, developing countries continue to use histological evaluation to diagnose and classify these neoplasms.

Objective

To develop a semi-quantitative scale to numerically grade gliomas by its morphological characteristics.

Method

A cohort of patients with gliomas was assessed and followed for 36 months. Tumor tissue sections were analyzed and graded, including aspects such as cell line, cellularity, nuclear pleomorphism, mitosis, endothelial hyperplasia, hypoxic changes, apoptotic bodies, necrosis, hemorrhage and proliferation index.

Results

58 cases were analyzed. Low-grade gliomas median score was 12 points (9 and 13.5 for percentiles 25 and 75, respectively), whereas for high-grade gliomas it was 17 points (16 and 20.5 for percentiles 25 and 75, respectively) (p < 0.0001). Thirty-six-month survival of patients with low (13/17) and high grade gliomas (6/41) was also significantly different (p < 0.0001).

Conclusions

The semi-quantitative morphological scale allows an objective evaluation of gliomas, with an adequate correlation between the score, tumor grade and survival time.

Zika Virus infection and Guillain-Barré syndrome in Northeastern Mexico: A case-control study

BACKGROUND

Beginning August 2017, we conducted a prospective case-control investigation in Monterrey, Mexico to assess the association between Zika virus (ZIKV) and Guillain-Barré syndrome (GBS).

METHODS

For each of 50 GBS case-patients, we enrolled 2-3 afebrile controls (141 controls in total) matched by sex, age group, and presentation to same hospital within 7 days.

RESULTS

PCR results for ZIKV in blood and/or urine were available on all subjects; serum ZIKV IgM antibody for 52% of case-patients and 80% of controls. Subjects were asked about antecedent illness in the two months prior to neurological onset (for case-patients) or interview (for controls). Laboratory evidence of ZIKV infection alone (PCR+ or IgM+) was not significantly different between case-patients and controls (OR: 1.26, 95% CI: 0.45-3.54) but antecedent symptomatic ZIKV infection [a typical ZIKV symptom (rash, joint pain, or conjunctivitis) plus laboratory evidence of ZIKV infection] was higher among case-patients (OR: 12.45, 95% CI: 1.45-106.64). GBS case-patients with laboratory evidence of ZIKV infection were significantly more likely to have had typical ZIKV symptoms than controls with laboratory evidence of ZIKV infection (OR: 17.5, 95% CI: 3.2-96.6). This association remained significant even when only GBS case-patients who were afebrile for 5 days before onset were included in the analysis, (OR 9.57 (95% CI: 1.07 to 85.35).

CONCLUSIONS

During ZIKV epidemics, this study indicates that increases in GBS will occur primarily among those with antecedent symptomatic ZIKV.

Single vs. Combined Therapeutic Approaches in Rats With Chronic Spinal Cord Injury

The regenerative capability of the central nervous system is limited after traumatic spinal cord injury (SCI) due to intrinsic and extrinsic factors that inhibit spinal cord regeneration, resulting in deficient functional recovery. It has been shown that strategies, such as pre-degenerated peripheral nerve (PPN) grafts or the use of bone marrow stromal cells (BMSCs) or exogenous molecules, such as chondroitinase ABC (ChABC) promote axonal growth and remyelination, resulting in an improvement in locomotor function. These treatments have been primarily assessed in acute injury models. The aim of the present study is to evaluate the ability of several single and combined treatments in order to modify the course of chronic complete SCI in rats. A complete cord transection was performed at the T9 level. One month later, animals were divided into five groups: original injury only (control group), and original injury plus spinal cord re-transection to create a gap to accommodate BMSCs, PPN, PPN + BMSCs, and PPN + BMSCs + ChABC. In comparison with control and single-treatment groups (PPN and BMSCs), combined treatment groups (PPN + BMSCs and PPN + BMSCs + ChABC) showed significative axonal regrowth, as revealed by an increase in GAP-43 and MAP-1B expression in axonal fibers, which correlated with an improvement in locomotor function. In conclusion, the combined therapies tested here improve locomotor function by enhancing axonal regeneration in rats with chronic SCI. Further studies are warranted to refine this promising line of research for clinical purposes.

Evaluación semicuantitativa de gliomas cerebrales en adultos: un enfoque de las características neuropatológicas

Introduction

Gliomas are neoplasms with high recurrence and mortality. Due to the difficulty to apply the World Health Organization (2016) classification, developing countries continue to use histological evaluation to diagnose and classify these neoplasms.

Objective

To develop a semi-quantitative scale to numerically grade gliomas morphological characteristics.

Method

A cohort of patients with gliomas was assessed and followed for 36 months. Tumor tissue sections were analyzed and graded, including aspects such as cell line, cellularity, nuclear pleomorphism, mitosis, endothelial hyperplasia, hypoxic changes, apoptotic bodies, necrosis, hemorrhage and proliferation index.

Results

58 cases were analyzed. Low-grade gliomas median score was 12 points (9 and 13.5 for percentiles 25 and 75, respectively), whereas for high-grade gliomas it was 17 points (16 and 20.5 for percentiles 25 and 75, respectively) (p < 0.0001). Thirty-six-month survival of patients with low (13/17) and high grade gliomas (6/41) was also significantly different (p < 0.0001).

Conclusions

The semi-quantitative morphological scale allows an objective evaluation of gliomas, with an adequate correlation between the score, tumor grade and survival time.

Effects of 4-aminopyridine on attention and executive functions of patients with multiple sclerosis: Randomized, double-blind, placebo-controlled clinical trial. Preliminary report

BACKGROUND

A high percentage of patients with multiple sclerosis present cognitive alterations. Because 4-aminopyridine improves nerve conduction and efficient synaptic connection could improve cognitive dysfunction.

OBJECTIVE

To evaluate the efficacy on cognitive performance and safety of 4-aminopyridine administered to patients with relapsing-remitting multiple sclerosis.

METHODS

A randomized, double-blind, placebo controlled clinical trial was conducted in patients with relapsing-remitting multiple sclerosis diagnosis according to the McDonald criteria. At the beginning and at the end of the treatment different tests were used to assess cognitive performance. Subsequently, patients were randomized 1:1 to receive treatment or placebo. A bootstrap-t test was proposed to test the effectiveness of cognitive performance, considering a p-value < 0.05 as statistically significant.

RESULTS

Twenty-four patients were recruited of which 21 completed the trial, 11 with 4-aminopyridine and 10 with placebo treatment. No significant differences between groups in the initial assessments were observed. In terms of efficacy, the experimental group achieved significantly higher scores in attention span, verbal fluency, planning and graphics and constructive motion.

CONCLUSIONS

4-aminopyridine proved to be an effective treatment on cognitive aspects in patients with relapsing-remitting multiple sclerosis. Drug doses were shown to be safe with mild to moderate adverse events (ClinicalTrials.gov number, NCT02280096).

[Oxidative stress in the elderly with diabetes mellitus or hypertension]

BACKGROUND

Mexico City has the highest aging rate in the country, as well as a high prevalence of diabetes mellitus (DM) and hypertension (HT). It is known that each one of these conditions increase oxidative stress (OS) independently.

METHODS

With this study we described changes in OS of 18 patients without DM or HT (controls), 12 with DM, 23 with HT, and 18 with DM and HT, all of them members of the COSFAMM (Cohorte de Obesidad, Sarcopenia y Fragilidad en Adultos Mayores de México). OS was measured by the quantification of reactive oxygen species (ROS), by the oxidation of diclorofluorosceine, and by determination of lipid peroxidation by product malondialdehyde (MDA).

RESULTS

HT patients showed increased ROS levels, as did men with HT compared with the respective DM and HT groups. Also, women of control group showed higher levels of ROS compared with men.

CONCLUSIONS

Generally, HT turned out to be the most influential factor for the increase of oxidative stress in the elderly while DM has no effect whatsoever.

Creation of an intramedullary cavity by hemorrhagic necrosis removal 24 h after spinal cord contusion in rats for eventual intralesional implantation of restorative materials

Intramedullary hemorrhagic necrosis occurs early after spinal cord injury at the site of injury and adjacent segments. It is considered harmful because of its potential to aggravate secondary injury, and to interfere with axonal regeneration; it might also lead to an unfavorable environment for intralesional implants. Removal of hemorrhagic necrosis has been attempted before with variable results. The invasive nature of these procedures carries the risk of exacerbating damage to the injured cord. The overall objective for this study was to test several strategies for non-damaging removal of hemorrhagic necrosis and characterize the resulting cavity looking for a space for future intralesional therapeutic implants in rats with acute cord injury. Rats were subjected to graded cord contusion, and hemorrhagic necrosis was removed after 24h. Three grades of myelotomy (extensive, medium sized, and small) were tested. Using the small surgical approach to debridement, early and late effects of the intervention were determined by histology and by analytical and behavioral analysis. Appearance and capacity of the resulting cavity were characterized. Satisfactory removal of hemorrhagic necrosis was achieved with all three surgical approaches to debridement. However, bleeding in spared cord tissue was excessive after medium sized and extensive myelotomies but similar to control injured rats after small cord surgery. Small surgical approach to debridement produced no swelling nor acute inflammation changes, nor did it affect long-term spontaneous locomotor recovery, but resulted in modest improvement of myelination in rats subjected to both moderate and severe injuries. Cavity created after intervention was filled with 10 to 15 μL of hydrogel. In conclusion, by small surgical approach to debridement, removal of hemorrhagic necrosis was achieved after acute cord contusion thereby creating intramedullary spaces without further damaging the injured spinal cord. Resulting cavities appear suitable for future intralesional placement of pro-reparative cells or other regenerative biomaterials in a clinically relevant model of spinal cord injury.

Human papillomavirus genotypes among females in Mexico: a study from the Mexican institute for social security

BACKGROUND

The aetiological relationship between human papillomavirus (HPV) infection and cervical cancer (CC) is widely accepted. Our goal was to determine the prevalence of HPV types in Mexican women attending at the Mexican Institute for Social Security from different areas of Mexico.

MATERIALS AND METHODS

DNAs from 2,956 cervical samples were subjected to HPV genotyping: 1,020 samples with normal cytology, 931 with low-grade squamous intraepithelial lesions (LGSIL), 481 with high grade HGSIL and 524 CC.

RESULTS

Overall HPV prevalence was 67.1%. A total of 40 HPV types were found; HPV16 was detected in 39.4% of the HPV-positive samples followed by HPV18 at 7.5%, HPV31 at 7.1%, HPV59 at 4.9%, and HPV58 at 3.2%. HPV16 presented the highest prevalence both in women with altered or normal cytology and HPV 18 presented a minor prevalence as reported worldwide. The prevalence ratio (PR) was calculated for the HPV types. The analysis of PR showed that HPV16 presents the highest association with CC, HPV 31, -33, -45, -52 and -58 also demonstrating a high association.

CONCLUSIONS

The most prevalent HPV types in cervical cancer samples were -16, -18, -31, but it is important to note that we obtained a minor prevalence of HPV18 as reported worldwide, and that HPV58 and -52 also were genotypes with an important prevalence in CC samples. Determination of HPV genotypes is very important in order to evaluate the impact of vaccine introduction and future cervical cancer prevention strategies.

Genetic polymorphisms associated with antiepileptic metabolism

Several factors, including pharmacogenetics, contribute to inter-individual variability in drug response. Many antiepileptic drugs (AEDs) are metabolized by a variety of enzymatic reactions, and the cytochrome P450 (CYP) family has attracted considerable attention. Some of the CYPs exist as genetic (allelic) variants, which may also affect the plasma concentrations or drug exposure. Regarding the metabolism of AEDs, the polymorphic CYP2C9 and CYP2C19 are of particular interest. There have been recent advances in discovering factors such as these, especially those underlying the risk of medication toxicity. This review summarizes the evidence about whether such polymorphisms affect the clinical action of AEDs to facilitate future studies on the pharmacogenetics of epilepsy. We performed Key Words searches in the public databases PubMed, Medscape, and Rxlisty, Pharm GKB for genetic polymorphisms and the NCBI website for the nomenclature of alleles of CYP450, finding that CYP2D6, CYP2C9, CYP3A4, and CYP2D19 were involved in the metabolism of most antiepileptic drugs, given the allele frequency in the population and the associated variability in the clinical response.

Value of EQ-5D in Mexican city older population with and without dementia (SADEM study)

BACKGROUND

The EuroQoL-5D (EQ-5D) is a brief, multi-attribute, preference-based health status measurement. The objective of this study was to assess the validity and reliability of EQ-5D in older adults with and without dementia in Mexico City.

METHODS

The Study on Aging and Dementia in Mexico (SADEM) was a survey of 3101, Mexican adults (60 + years old). An in-home face-to-face interview was administered. EQ-5D using ranking to rate states on a 100-point visual analogue scale; Daily Living Activities (ADL), Instrumental Activities of Daily Living (IADL), Mini Mental State Examination (MMSE), Short Form of the quality of life survey (SF-36), and Charlson comorbility index were used for comparison. The validity and reliability of EQ-5D were tested. We identified states of health for direct valuation; state 11111 ("no problems") had to be included because it was essential to the reseating (onto a 0-1 scale) of the visual analogue scale data. We included all plausible combinations of levels across each of the five EQ-5D dimensions and evaluated any significant interaction effects and factorial designs, based on balanced complete blocks.

RESULTS

The EQ-5D was applied to 3101 older people, of whom 109 (3.4%) had dementia. The general reliability of EQ-5D for cases was 0.80 and for controls 0.76, for each dimension. We had a total of 103 combinations for controls and 45 for cases. The percentage for the state of health "no problems" (11111) for controls was 30.4%, and had the highest percentage of cases (8.8%).

CONCLUSION

The resulting valuations form the basis for clinical use and facilitate the interpretation and evaluation of health care.

Spatial and temporal morphological changes in the subarachnoid space after graded spinal cord contusion in the rat

Spontaneous repair or treatment-induced recovery after spinal cord injury (SCI) is very limited and might be related to extramedullary alterations that have only briefly been documented. Here we report on the morphological changes of the spinal subarachnoid space (SAS) in a clinically relevant model of SCI. Anesthetized rats were subjected either to mild or severe spinal cord contusion at T9. Spine blocks from the site of injury and adjacent segments were harvested at acute (1 h and 1 day [d]), subacute (3 and 7 d), and chronic (1 and 3 months) stages post-injury. Histopathology and morphometry at each decalcified vertebral level were assessed. At acute and subacute stages, reduction of SAS lumen was observed after both mild and severe injuries. Acutely, after severe injuries, SAS occlusion was associated mainly with cord swelling and subarachnoid hematomas; a trend for dural sac constriction was observed for mild injuries. At 7 d, cord swelling diminished in both instances, but dural sac constriction increased for severe injuries. At early stages, in the epicenter and vicinity, histopathology revealed compression of neurovascular elements within the SAS, which was more intense in severe than in mild injuries. In the chronic stage, SAS lumen increased notably, mostly from cord atrophy, despite dural sac constriction. Myelograms complemented observations made on SAS lumen permeability. Post-traumatic arachnoiditis occurred mainly in animals with severe injury. In conclusion, early extramedullary SAS changes described here might be expected to produce alterations in cerebrospinal fluid (CSF) dynamics and cord blood perfusion, thereby contributing to the pathophysiology of SCI and becoming novel targets for treatment.

Neuroprotection of completely lacerated spinal cord of adult rats by homotopic and heterotopic transplantation

To evaluate the neuroprotective effect of transplants placed in the lesion zone after a complete spinal cord (SC) laceration, two independent series of experiments were carried out. In the first, allogeneic or xenogeneic fetal SC was transplanted into the gaps of the damaged lower thoracic SC of adult rats. In the transplanted rats the incidence of life-threatening complications was reduced, and the survival rate was increased compared with the control group (lesion, without implant). Histological examination showed less damage to the neighboring SC parenchyma in the transplanted rats. The measurement of this neuroprotective effect was made in a second series of experiments. Using the same model of SC injury, allogeneic fetal SC, autologous peripheral nerve and/or adipose tissue were implanted. Rats with implants of Gelfoam and damaged rats without implants were the controls. The implanted rats of all groups, including the Gelfoam group, showed a better survival rate than the nonimplanted rats. Significantly less damage to the neighboring SC parenchyma was measured in implanted rats with any of the live tissues tested compared with non-implanted rats, although no significant differences were observed between the Gelfoam group and the nonimplanted rats. Histological evidence of tissue implant survival was observed in all corresponding groups. It is concluded that the transplanted tissues tested here have a neuroprotective effect, possibly by acting as a buffer to neurotoxic substance(s) released by the stumps, and/or by exerting trophic effect(s) on the host.

Autoreactivity against myelin basic protein in patients with chronic paraplegia

INTRODUCTION

Previous studies have shown the existence of either cellular or humoral MBP-reactive elements up to 5 years after spinal cord injury (SCI), but not the presence of both after 10 years.

MATERIALS AND METHODS

Twelve SCI patients, with more than 10 years of evolution, and 18 healthy blood donors were studied. Lymphocyte proliferation (colorimetric-BrdU ELISA assay) and antibody titers against MBP (ELISA Human IgG MBP-specific assay) were assessed.

RESULTS

SCI patients presented a significant T-cell proliferation against MBP (lymphocyte proliferation index: 3.7 ± 1.5, mean ± SD) compared to control individuals (0.7 ± 0.3; P < 0.001). Humoral response analysis yielded a significant difference (P < 0.0001) between the antibody titers of controls and SCI patients. A significant correlation between cellular and humoral responses was observed. Finally, patients with an ASIA B presented the highest immune responses.

CONCLUSION

This work demonstrates, for the first time, the existence of both cellular and humoral responses against MBP in the chronic stages (>10 years) of injury.

New approach for graded compression spinal cord injuries in Rhesus macaque: method feasibility and preliminary observations

BACKGROUND

Current models of spinal cord injury (SCI) have been ineffective for translational research. Primate blunt SCI, which more closely resembles human injury, could be a promising model to fill this gap.

METHODS

Graded compression SCI was produced by inflating at T9 an epidural balloon as a function of spinal canal dimensions in a non-uniform group of monkeys.

RESULTS

Sham injury and cord compression by canal invasion of 50-75% produced minimal morpho-functional alterations, if at all. Canal invasion of 90-100% resulted in proportional functional deficits. Unexpectedly, these animals showed spontaneous gradual recovery over a 12-week period achieving quadruped walking, although with persistent absence of foot grasping reflex. Histopathology revealed predominance of central cord damage that correlated with functional status.

CONCLUSIONS

Our preliminary results suggest that this model could potentially be a useful addition to translational work, but requires further validation by including animals with permanent injuries and expansion of replicates.

High doses of 4-aminopyridine improve functionality in chronic complete spinal cord injury patients with MRI evidence of cord continuity

BACKGROUND AND AIMS

Many patients with complete spinal cord injury (SCI) exhibit demyelinated and poorly myelinated nerve fibers traversing the lesion site. Conventional doses of 4-aminopyridine (4-AP, 30 mg/day) have shown to provide no or minor functional improvement in these patients. We undertook this study to test the functional effect of high doses of 4-AP on patients with chronic complete SCI with cord continuity at the site of injury demonstrated by magnetic resonance imaging.

METHODS

Fourteen patients were included in a double-blind, randomized, placebo-controlled trial followed by an open label long-term follow-up. Initially, patients received 4-AP or placebo orally, with 4-AP being increased gradually (5 mg/week) to reach 30 mg/day. For long-term treatment, 4-AP was increased 10 mg periodically according to negative electroencephalogram and blood test abnormalities and minor adverse reactions. Pre-treatment, 12 and 24 weeks of the controlled trial, and 6 and 12 months of open trial evaluations, or with the highest doses reached were obtained.

RESULTS

Three of 12 patients were able to walk with the assistance of orthopedic devices, 1/12 became incomplete (AIS B), 7/12 improved their somatosensory evoked potentials, 5/12 had sensation and control of bladder and anal sphincters, and 4/9 male patients had psychogenic erection.

CONCLUSIONS

Positive changes were seen mainly in patients with cyst (4/5) or atrophy (3/5) of the injury site. Two patients withdrew from the study: one had seizures and one had intolerant adverse reactions. We conclude that high doses of 4-AP in the studied population produced several functional benefits not observed using lower doses.

Thalidomide fails to be therapeutic following contusive spinal cord injury in rats

Mechanical damage to the spinal cord (SC) generates self-destructive processes that contribute to post-traumatic neurodegeneration. Because thalidomide apparently counteracts these effects its use clinically has been proposed enthusiastically. Nonetheless, we tested its action as a neuroprotectant in a clinically relevant model of SC injury in rats. We administered thalidomide intraperitoneally to rats subjected to thoracic SC contusion as single or repeated doses within the first 24 h after injury. Edema, neutrophil infiltration, and cord tissue preservation/destruction were assessed in the SC 24 h after injury and motor function for 7 weeks. Rats treated with thalidomide showed significant increase in SC water compared with naive rats, but not vehicle-treated rats; their neutrophil infiltration and amount of spared/destroyed cord tissue was not different from vehicle-treated rats; and in no case was motor performance improved after thalidomide. In conclusion, thalidomide failed here to be therapeutic, discouraging its use clinically for SC trauma.

L-arginine reverses alterations in drug disposition induced by spinal cord injury by increasing hepatic blood flow

High hepatic extraction drugs--such as phenacetin, methylprednisolone, and cyclosporine--exhibit an increased bioavailability after acute spinal cord injury (SCI) due to an impaired clearance. For these drugs, metabolic clearance depends on hepatic blood flow. Thus, it is possible that pharmacokinetic alterations can be reversed by increasing liver perfusion. Therefore, we evaluated the effect of L-arginine, a nitric oxide precursor, on the pharmacokinetics of a prototype drug with high hepatic extraction, and on hepatic microvascular blood flow (MVBF) after acute SCI. Pharmacokinetics of i.v. phenacetin was studied in rats 24 h after a severe T-5 spinal cord contusion; animals being pretreated with L-arginine 100 mg/kg i.v. or vehicle. MVBF was assessed under similar experimental conditions using laser Doppler flowmetry. SCI significantly altered phenacetin pharmacokinetics. Clearance was significantly reduced, resulting in a prolonged half-life and an increase in bioavailability, while volume of distribution was decreased. Pharmacokinetic alterations were reversed when injured rats were pretreated with L -arginine. It was also observed that L-arginine significantly increased hepatic MVBF in injured rats, notwithstanding it exhibited a limited effect on sham-injured animals. Our data hence suggest that L-arginine is able to reverse SCI-induced alterations in phenacetin pharmacokinetics due to an impaired hepatic MVBF, likely by increased nitric oxide synthesis leading to vasodilation. Further studies are warranted to examine the potential usefulness of nitric oxide supplementation in a clinical setting.

Gastric emptying effect by 4-aminopyridine in patients with chronic spinal cord injury

BACKGROUND

4-Aminopyridine (4-AP) given to patients with chronic spinal cord injury (SCI) has shown beneficial effects in some somatic and autonomic functions, although patients often develop dyspeptic symptoms. 4-AP is a potassium-channel blocker capable of altering gastro-pyloric functions as demonstrated experimentally. Our objective was to examine the influence of 4-AP treatment on gastric emptying in patients with chronic SCI.

METHODS

Gastric emptying was measured by the acetaminophen absorption test in 18 patients (9 with cervical and 9 with thoracic injury), and 9 healthy volunteers. Patients received increasing oral doses, 5 mg day(-1) of oral 4-AP (5-30 mg day(-1)), for 12 weeks. Patients were studied before and at the end of the last week of 4-AP treatment, whereas healthy volunteers (without 4-AP treatment) were studied only once. Whole blood samples of 2.5 mL were drawn at 0 (before 1 g of oral acetaminophen) and at 15, 30, 45, 60, 75, 90, 105 and 120 min postdose. Acetaminophen concentration in plasma was determined by high-pressure liquid chromatography.

RESULTS

Treatment with 4-AP significantly delayed stomach emptying in patients with chronic SCI, considering the significant decreasing of acetaminophen absorption (t paired test, p <0.05). This effect did not correlate either to the level or ASIA score of the injury (linear regression correlation analysis, r(2) = 0.003 and 0.015, respectively). No significant differences were observed by comparing data of patients before 4-AP treatment with healthy volunteers.

CONCLUSIONS

4-AP intake in patients with chronic spinal cord injury significantly slowed gastric emptying regardless of level and ASIA score of the injury.

Expression of neurotrimin in the normal and injured adult human spinal cord

STUDY DESIGN

Neurotrimin (Ntm) is a member of the family of neural cell adhesion molecules. Its expression pattern suggests that Ntm promotes axonal fasciculation, guides nerve fibers to specific targets and stabilizes synapses as it accumulates coincident with synaptogenesis. Strong labeling of Ntm was observed in motor and sensory areas of the postnatal rat cortex. It is not known whether Ntm is present in adult human spinal cord (SC). In the present study, a monoclonal antibody specific for Ntm (1B1), is applied to the first study of the expression of Ntm in normal and injured adult human SC.

OBJECTIVE

(1) To investigate the expression pattern of Ntm in adult normal human SC, and (2) to observe the changes of Ntm expression after SC injury and compare the differences between normal and injured adult human SC.

METHODS

Human SC tissue was obtained from necropsies of patients with (n=5) and without (n=4) SC injury. The 1B1 Ntm monoclonal antibody was used for immunohistochemical staining on paraffin embedded sections with an ABC kit.

RESULTS

(1) In total, 12 slides were analyzed for each group from both cervical and thoracic levels. Motor neurons and Clarke's neurons and glial-like cells were mild to moderately positive in all uninjured SC specimens. (2) In injured SC, no staining was observed in the injury epicenter between two and three levels proximally and distally, but was detected five levels away. (3) In patients older than 67 years of age, Ntm-positive inclusions were present in the white matter of the SC with or without injury. (4) Some meningeal cells were strongly Ntm-positive, especially in the uninjured human SC.

CONCLUSION

Ntm is expressed by motor and Clarke's neurons and glial cells in uninjured human SC. The downregulation of Ntm in the injured SC suggests that its expression is regulated by afferent input.

Spontaneous and induced aberrant sprouting at the site of injury is irrelevant to motor function outcome in rats with spinal cord injury

In the absence of effective regeneration following spinal cord (SC) injury, sprouting from undamaged axons has been regarded as an underlying factor for functional improvement after incomplete SC injury. The influence of spontaneous and induced axonal sprouting at the injury site on motor function was tested using rats subjected to moderate SC contusion at T9 level, using megadoses of methylprednisolone (MP) and intralesion implantation of cells from sciatic nerve (PNI). Groups using MP and PNI combined, implant vehicle, and injury with no treatment were also included. Amount of sprouting at the injury sites was significantly different depending on treatment. It was abundant in PNI-treated rats, moderate in rats treated with vehicle or nontreated, and limited in rats given MP with or without PNI (chi2, p=0.0084). This sprouting showed an aberrant course and was located in proliferating tissue at the site of injury, characterized by the presence of ependymal cells, macrophages, and myelinating and nonmyelinating Schwann cells. Functional scores and amount of spared white matter were not significantly different among groups. Correlation of the amount of sprouting vs. functional outcome or vs. amount of spared tissue was not significant, while correlation of functional outcome vs. amount of spared tissue was significant (p<0.0001). In conclusion, PNI increase aberrant sprouting at the injury site, while MP limits such sprouting, in either case without impact on motor function outcome. Missing guiding channels for sprouting axons could explain the absence of any functional improvement.

Effects of cyclosporin-A on immune response, tissue protection and motor function of rats subjected to spinal cord injury

The aim of this work was to test the effect of cyclosporin-A (CsA) on some immunological, morphological and functional aspects developed after spinal cord injury. The specific cellular immune response against spinal cord constituents, the amount of spared tissue and myelination at the site of injury, and the motor function outcome were assessed in a first series of experiments. Rats were subjected to spinal cord compression and treated with cyclosporin-A before lesion and during the entire study. A specific lymphocyte response against spinal cord antigens was found in untreated spinal cord injured rats but not in cyclosporine-A treated injured rats. A significantly better myelination index was also found in injured cyclosporin-A-treated rats, as compared to untreated animals. The amount of spared spinal cord tissue at the epicenter was not significantly different comparing CsA-treated with vehicle-treated rats. Looking for a potential therapeutic use of CsA, in a second series of experiments, rats were subjected to spinal cord contusion and treated with cyclosporin-A from 1 to 72 h after lesion. Motor recovery and red nuclei neurons survival, were evaluated, and found to be significantly better in spinal cord injured rats treated with cyclosporin-A than in injured-untreated rats. This work confirms the existence of an autoimmune cellular reaction after injury that can be inhibited by cyclosporin-A treatment. Furthermore, cyclosporin-A promotes neuroprotection by diminishing both demyelination and neuronal cell death, resulting in a better motor outcome after spinal cord injury.

Efficacy and safety of 4-aminopyridine in patients with long-term spinal cord injury: a randomized, double-blind, placebo-controlled trial

OBJECTIVES

To study the efficacy and safety of 4-aminopyridine (4-AP), and to document sensorimotor changes after discontinuation of the drug in patients with long-term spinal cord injury.

DESIGN

Randomized, double-blind, placebo-controlled trial.

SETTING

Clinical research unit.

PATIENTS

Twenty-seven patients with long-term spinal cord injury.

INTERVENTION

Patients were randomized to receive either oral 4-AP 5 mg/day, which was increased by 5 mg/week to a maximum dosage of 30 mg/day, or placebo for 12 weeks. They switched to the opposite treatment for the next 12 weeks.

MEASUREMENTS AND MAIN RESULTS

Twenty-five patients finished the study. The results from the first 12 weeks were used to test efficacy. Positive gains in motor function, sensation, and independence occurred more frequently in patients receiving 4-AP (69%) than those receiving placebo (46%). Significant functional improvement was also noted in those treated with 4-AP (chi2, p=0.042). When each evaluation scale was considered separately, significant improvement was seen only in motor function (4-AP 92% vs placebo 46%, Fisher exact test, p=0.03). Persistent effects of the drug were assessed at week 24 in the group that initially received 4-AP. A persistent, significant 4-AP effect was observed in evaluations of sensation and independence (67% and 83% of patients, respectively; Wilcoxon signed rank test, p=0.032 and 0.042, respectively). Fourteen (56%) patients had 26 adverse reactions. One moderate adverse reaction--posterior tibial artery vasospasm--and 25 mild adverse reactions, such as dry mouth, dizziness, nausea, gastritis, oral and peripheral paresthesia, resolved adequately. Six (24%) patients experienced transitory alterations of enzyme levels (alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and creatine kinase) and thrombocytopenia.

CONCLUSION

Patients who received 4-AP showed significant improvement in motor function, and a persistent effect on sensation and independent function occurred. The drug is safe; however, after starting 4-AP therapy, patients must be carefully monitored for the possible occurrence of peripheral vasospasm.

Labeling Schwann cells with CFSE-an in vitro and in vivo study

Schwann cell (SC) transplantation is a promising strategy for axonal regeneration in the nervous system. Identifying the grafted SCs is an important aspect of this approach. The current study sought to establish a simple, reliable, fluorescent labeling method for SCs with a lipophilic molecule, 5-(and-6)-carboxyfluorescein diacetate succinimidyl ester (CFSE). Human SCs were incubated with varying concentrations of CFSE for different time periods. Based on the viability of labeled SCs and its plating efficiency, 1 min incubation with 5 microM CFSE at 37 degrees C was selected as the optimal labeling condition. Flow cytometric analysis and fluorescence microscopy demonstrated that the fluorescence of labeled SCs would fade over 4 weeks. Immunostaining for the phenotypic expression of SC markers, including S100, GFAP, P75, and MHC-I/II at 1 and 4 weeks after incubation with CFSE showed no difference between labeled and non-labeled SCs. Mixed cultures of labeled human SCs and rat SCs for 48 h were performed in triplicate and demonstrated that no leakage of dye from labeled SCs in cell culture occurred across species. A total of 14 injections of 2x10(5) labeled SCs were performed within the spinal cord at T8 and/or L1 level in 9 nude rats. The animals were euthanized at 1 (6 injections) and 4 weeks (8 injections). Grafted labeled SCs survived for at least 4 weeks, and could be easily recognized in the nude rat spinal cord without leakage of dye to surrounding cells. The SCs migrated in white and gray matter 3-6 mm away from the injection and in the central canal for up to 12 mm. These results suggest that CFSE can be used as a fluorescent tracer of human SCs for both in vitro and in vivo studies, for a period of at least 4 weeks.

Constitutive and inducible nitric oxide synthase activities after spinal cord contusion in rats

Nitric oxide (NO) plays a role in the secondary damage after spinal cord (SC) injury. NO is produced by the activity of two classes of enzymes: calcium-dependent constitutive nitric oxide synthase (NOS) and calcium-independent inducible NOS. To determine the time course of both NOS activities after SC injury, 50 Wistar rats were submitted to severe SC contusion. NOS activities were assayed at the site of SC injury at several times after lesion. Results showed a significant increase of 138 and 96% in the constitutive NOS activity at 4 and 8 h after the lesion, respectively, as compared to sham-operated rats. iNOS activity was increased 72 h after lesion by 103% (P<0.05). In conclusion, both isoforms of NOS increase their activity at different time periods after SC injury.

Medical treatment for neurocysticercosis characterized by giant subarachnoid cysts

BACKGROUND

Infection with the larval form of the pork tapeworm, Taenia solium, can lead to the development of cysts in the brain. Surgical removal of cysts has been the accepted treatment for neurocysticercosis characterized by giant cysts when there is associated intracranial hypertension.

METHODS

We describe 33 patients whom we treated medically for malignant forms of neurocysticercosis. All patients had evidence of intracranial hypertension and subarachnoid cysts at least 50 mm in diameter. All patients received 15 mg of albendazole per kilogram of body weight per day for four weeks. Ten patients were also treated with 100 mg of praziquantel per kilogram per day for four weeks. Seventeen patients received a second course of albendazole, three received a third course, and one received a fourth course. During the first cycle of treatment, all patients also received dexamethasone. Five patients had previously undergone neurosurgery for giant cysts.

RESULTS

After a median of 59 months of follow-up (range, 7 to 102), the condition of all 33 patients had improved, and the cysts had disappeared or become calcified. Of the 22 patients with a history of seizures, only 11 continued to receive antiseizure medications. The median quality-of-life score on the Karnofsky scale improved from 40 to 100. Fifteen patients received a ventriculoperitoneal shunt because of hydrocephalus. Four patients had persistent sequelae (bilateral partial optic atrophy, stroke, or diplopia) of the cysts.

CONCLUSIONS

Intensive medical treatment can be effective in patients with neurocysticercosis characterized by giant cysts. Neurosurgery may be required only when there is an imminent risk of death.

[Carotid-basilar artery communication in gerbils (Meriones unguiculatus)]

INTRODUCTION

Since 1966 when Levine and Payan observed that the Mongolian gerbil (Meriones unguiculatus) was unusually susceptible to cerebral infarction following occlusion of one or both common carotid arteries, the model has been used for the experimental study of cerebral ischemia.

OBJECTIVE

To assess the presence of anterior-posterior arterial communication in the Mongolian gerbil (Meriones unguiculatus).

MATERIAL AND METHODS

26 animals were used and divided in the following groups: 1. Bilateral carotid ligation (n = 10); 2. Unilateral left carotid ligation (n = 5); 3. Unilateral carotid right carotid ligation (n = 5); and 4. Control group without carotid ligation (n = 6).

RESULTS

Postmortem intra-aortic dye injection demonstrated communication between anterior and posterior cerebral arteries in 30% of gerbils that previously were subjected to bilateral common carotid artery occlusion. A number of vessels, between 8.95-11.35 microns in diameter, were linking the basilar artery with the posterior cerebral artery. In the remaining animals, the absence of communication was confirmed.

CONCLUSION

Communicating carotid-basilar in lower number of cases and anastomosis the smallest diameter to give the gerbil advantage on others species as model of experimental regional ischemia.

Lipid peroxidation inhibition in spinal cord injury: cyclosporin-A vs methylprednisolone

To compare the effectiveness of cyclosporin-A (CsA) with methylprednisolone (MP) or a combination of both upon inhibition of lipid peroxidation (LP) after spinal cord (SC) injury, rats were treated with either CsA, MP, CSA+MP or vehicle starting 1 h after SC contusion at T9 level. LP was assessed 24h after injury by the lipid fluorescent product formation method. The survival rate was also evaluated in other series of rats by the Kaplan-Meier curves. Lipid peroxidation was similarly inhibited in rats treated with CsA, MP, or CSA+MP (p>0.05). Animals receiving MP (alone or combined with CsA) showed the poorest surviving rate. LP was inhibited by CsA to the same extent as by MP but without the lethal effect of the latter.

Search for an IgG response against neural antigens in experimental spinal cord injury

In order to determine if a specific response is induced after spinal cord injury, we performed a kinetic search for IgG antibodies against various spinal cord antigenic preparations in a rat contusion model. Even though spinal cord injured animals showed two reactive bands, these could be originated by the reaction of natural antibodies, since they were also observed before lesion. Thus, these antibodies would not be of relevance in the pathogenic events of spinal cord injury in this rat model. Our findings do not demonstrate the existence of a specific IgG response against spinal cord constituents after injury.

Cyclosporin-A inhibits lipid peroxidation after spinal cord injury in rats

Besides its immunosuppressive/anti-inflammatory activity, cyclosporin-A (CsA) may protect damaged tissues from lipid peroxidation (LP) by free radicals. To determine the effect of CsA on LP spinal cord (SC) injury, Wistar rats were treated with either vehicle or CsA (2.5 mg/kg per 12 h i.p.) 1, 2, 6 or 12 h after SC trauma by T8-T9 spinal cord contusion, analyzing LP 24 h after injury at the lesion site by the lipid fluorescent products formation method. CsA significantly diminished LP to levels below control values after contusion (P < 0.05). The greater inhibition was observed when CsA was given during the first 6 h after injury, furthermore, animals showed a significant clinical improvement. Results show that CsA may be beneficial to injured tissue by inhibiting the levels of LP.

Transitory expression of NADPH diaphorase (NOS) in axonal swellings after spinal cord injury

To investigate the sites of nitric oxide synthase (NOS) expression after a spinal cord (SC) injury, NADPH-d diaphorase histochemistry was performed in the SC of adult rats sacrificed at different times from 1 h to 90 days after both SC contusion or transection. NOS could first be seen 12 h after injury in axonal swellings (AS) (club shaped structures at the tip of damage axons, associated with tissue destruction). NOS expression reached a maximum 3 days after injury, and gradually disappeared after 7 days. Finally, AS collapsed leaving behind microcysts. NOS expression and the consequent production of nitric oxide could be involved in the pathophysiology of the secondary damage, and/or could reflect a failed attempt for axonal regeneration.

Spontaneous long-term remyelination after traumatic spinal cord injury in rats

The capability of the central nervous system to remyelinate axons after a lesion has been well documented, even though it had been described as an abortive and incomplete process. At present there are no long-term morphometric studies to assess the spinal cord (S.C.) remyelinative capability. With the purpose to understand this phenomenon better, the S.C. of seven lesionless rats and the S.C. of 21 rats subjected to a severe weight-drop contusion injury were evaluated at 1, 2, 4, 6, and 12 months after injury. The axonal diameter and the myelination index (MI = axolemmal perimeter divided by myelinated fiber perimeter) were registered in the outer rim of the cord at T9 SC level using a transmission electron microscope and a digitizing computer system. The average myelinated fiber loss was 95.1%. One month after the SC, 64% of the surviving fibers were demyelinated while 12 months later, only 30% of the fibers had no myelin sheath. The MI in the control group was 0.72 +/- 0.07 (X +/- S.D.). In the experimental groups, the greatest demyelination was observed two months after the lesion (MI = 0.90 +/- 0.03), while the greatest myelination was observed 12 months after the injury (MI = 0.83 +/- 0.02). There was a statistical difference (p < 0.02) in MI between 2 and 12 months which means that remyelination had taken place. Remyelination was mainly achieved because of Schwann cells. The proportion of small fibers (diameter = 0.5 micron or less) considered as axon collaterals, increased from 18.45% at 1 month to 27.66% a year after the contusion. Results suggest that remyelination is not an abortive phenomenon but in fact a slow process occurring parallel to other tissue plastic phenomena, such as the emission of axon collaterals.

Use of cyclosporin-A in experimental spinal cord injury: design of a dosing strategy to maintain therapeutic levels

Cyclosporin-A (CsA) is frequently used as an immunosuppressive agent in experimental transplantations. CsA has been used in nervous tissue transplants in spinal cord injury (SCI). However, optimal results have not been obtained. This is likely due to the fact that SCI alters CsA pharmacokinetics and hence fixed dose regimens are not adequate. In this study, several CsA dosing regimens were evaluated in Long-Evans female rats subjected to a severe low thoracic (T8) SCI by the contusion method. Serum CsA concentrations were measured to determine which dosing regimen allowed CsA levels to be maintained within the therapeutic window. It was found that administration of 2.5 mg/kg/12 h intraperitoneally during the first 2 days after SCI (acute phase) followed by 5 mg/kg/12 h orally thereafter (subacute and chronic phases) yields CsA circulating levels within the therapeutic window, i.e., 0.120-0.275 microgram/mL. This dosing regimen represents a suitable alternative to fixed dosing to achieve an optimal CsA-induced immunosuppression in experimental models of SCI.

Alteration of cyclosporin-A pharmacokinetics after experimental spinal cord injury

The pharmacokinetics of the immunosuppressive agent cyclosporin-A (CsA) were studied in rats submitted to spinal cord (SC) injury. A single CsA 10 mg/kg dose was given either intraperitoneally (i.p.) or orally to rats submitted to experimental SC injury at the T8 level. Twenty four hours after lesion (acute stage of SC injury) i.p. CsA bioavailability was increased, while t1/2 was prolonged. However, oral bioavailability was reduced. Seven weeks after lesion (chronic stage of SC injury) CsA bioavailability, by either route, was not significantly different from control values. Results indicate that parenteral CsA bioavailability is increased during the acute stage of SC lesion, probably due to an impaired elimination. Oral bioavailability, however, is decreased, since there is also an important reduction in gastrointestinal CsA absorption that overrides the effect of impaired elimination. Alterations in CsA pharmacokinetics appear to revert during the chronic stage of SC injury. Changes in CsA bioavailability, depending on the route of administration and on time, must be considered to design an adequate immunosuppressive treatment in SC injury.

Magnetic resonance imaging of the normal and chronically injured adult rat spinal cord in vivo

We assessed the capacity of MRI to show and characterise the spinal cord (SC) in vivo in normal and chronically injured adult rats. In the chronically injured animals the SC was studied by MRI and histological examination. MRI was performed at 1.5 T, using gradient-echo and spin-echo (SE) sequences, the latter with and without gadolinium-DTPA (Gd-DTPA). Several positions were tried for good alignment and to diminish interference by respiratory movements. Images of the SC were obtained in sagittal, coronal, and axial planes. Normal SC was observed as a continuous intensity in both sequences, although contrast resolution was better using SE; it was not possible to differentiate the grey and white matter. Low signal was seen in the damaged area in chronically injured rats, which corresponded to cysts, trabeculae, mononuclear infiltrate, and fibroglial wall on histological examination. Gd-DTPA failed to enhance the SC in normal or chronically injured rats. It did, however, cause enhancement of the lesion after acute SC injury.

Development of post-traumatic cysts in the spinal cord of rats-subjected to severe spinal cord contusion

To study the development of post-traumatic spinal cord (SC) cysts, and their fine anatomic characteristics, rats were subjected to severe SC contusion. Specimens were analyzed from day 1 to 1 year post-injury. Using conventional light, and transmission and scanning electron microscopy, three stages were typified, namely: necrosis, repair, and stability. The final cell composition and thickness of the cyst walls were not uniform. Astrocytes, fibroblasts, ependymal cells, and collagen fibers were the main constituents. Chronic inflammatory cells were also observed. The neuropathologic characterization of posttraumatic SC cysts could be useful in planning strategies for SC reconstruction at different times post-injury.