Traumatic Spinal Cord Injury: Long-Term Motor, Sensory, and Urinary Outcomes

Inner and outer penetrating spinal cord injuries lead to distinct overground walking in mice

Spinal cord injury (SCI) is a devastating mechanical trauma. Although locomotion of model animals that mimic contusion SCI was actively examined, locomotion after penetrating SCI caused by sharp objects was not extensively studied. Severity of walking difficulty after partial transection of the spinal cord including penetrating SCI likely depends on the regions affected. Therefore, we compared beam walking and overground walking between mice after penetrating SCI at inner spinal cord region and mice with the injury at the outer region. Mice with the both penetrating SCIs did not display changes in beam walking. When appearance and movements of hindlimbs during overground walking was rated using Basso Mouse Scale for locomotion (BMS), however, mice with inner penetrating SCI showed low score shortly after the SCI. However, the score became high at later time points, as seen in contusion SCI mice. By contrast, BMS score did not decrease shortly after the outer penetrating SCI. However, the score became low 3 weeks after the SCI. As quantitative values during overground walking, movement duration in an open field were shorter at 1 day after the two penetrating SCIs. However, slower moving speed and fewer number of movement at 1 day were specific to mice with inner and outer penetrating SCIs, respectively. Moreover, BMS score was correlated with walking distance in open field only in mice with inner penetrating SCI. Thus, inner and outer penetrating SCI cause difficulty in overground walking with different severity and progress.

Clinical Characteristics and Outcomes of Patients with Traumatic Spinal Cord Injury at a Tertiary Care Center in the Philippines

OBJECTIVES

Traumatic spinal cord injury (TSCI) is a devastating condition that may result to lifelong complications that affect patient outcome and quality of life. Because of the increasing incidence of TSCI, it is important to comprehend the extent of this condition in terms of demographics, mechanism, and degree of disability to raise awareness and develop strategies in approaching care for these patients. There is a lack of information regarding data on TSCI in Southeast Asia, especially in the Philippines. This study aims to describe the clinical characteristics and outcomes of patients with TSCI in a tertiary care hospital in the Philippines.

METHODS

This is a retrospective descriptive cohort study in individuals aged 18 years older who were admitted for TSCI in a Philippine tertiary care hospital between 2022 and 2023. Of 118 admitted patients, 100 patients were included in the study. The data were obtained from the review of patients' medical records. Demographics of TSCI, mechanism, presenting clinical characteristics, American Spinal Injury Association Impairment Scale (AIS) grade, radiographic findings, outcomes, and complications were analyzed.

RESULTS

A total of 100 patients with TSCI were included in the study. The mean age of the patients was 43.4 ± 15.8 in years, with male patients being predominant, at 92%. The most common mechanism of injury was motor vehicular crash, at 68%, followed by fall, at 22%. Most patients, 38%, were graded AIS C, on admission. The most common level of injury was cervical, at 70%. The usual complications recorded were sacral ulcer 28%, and hospital-acquired pneumonia, 20%.

CONCLUSIONS

TSCI is common in young adult male patients with motor vehicular crash as the mechanism of injury. Most patients in the study had incomplete spinal cord injury (AIS C), with the cervical region as the most common level. The recorded mean length of hospital stay was 1-2 weeks. The most common co-occurring extra spinal injury was traumatic brain injury. At discharge, most developed sacral ulcer and hospital-acquired pneumonia, with stable neurologic status. A multicenter prospective data collection with a larger population and inclusion of more variables are necessary to formulate a regression model and establish the factors that improve the outcomes of TSCI.

Impact of spinal injury on mortality in patients with major trauma: A propensity-matched cohort study

Major trauma is defined as a significant injury or injury that has the potential to be life-threatening and is quantitatively identified as an injury severity score (ISS) >15. Spinal injuries are common in patients with major trauma; however, because spinal injury is not independently included in the ISS calculation, the impact of spinal injury on mortality in patients with major trauma has not been fully elucidated. The purpose of this study is to identify the association between spinal injury and mortality in patients with major trauma. From January 1, 2016, to December 31, 2020, retrospective analysis was conducted on 2893 major trauma adult patients admitted to a level 1 trauma center. There were 781 patients in the spinal injury group and 2112 patients in the group without spinal injury. After matching the 2 groups 1:1, we compared injury mechanism, mortality, cause of death, intensive care unit length of stay (ICU LOS), and duration of ventilator use between spinal injury group and matched cohorts. Falls and traffic accidents were the most common injury mechanisms in the spinal injury group and the matched cohort, respectively. The mortality was significantly lower in the spinal injury group compared with the matched cohort (4.0% vs 7.9%, P = .001), and the ICU LOS was longer than the matched cohort (8.8 ± 17.4 days vs 7.2 ± 11.7 days, P = .028). In the spinal injury group, multiple organ failure (MOF) was the most common cause of death (41.9%), while that in the matched cohort was central nervous system (CNS) damage (61.3%). In patients with major trauma, spinal injury may act as a shock absorber for internal organs, which is thought to lower the mortality rate.

A simple scoring of beam walking performance after spinal cord injury in mice

Precise evaluation of motor functions using simple and reproducible tests for mouse models of spinal cord injury (SCI) are required. Overground walking of SCI mice has been tested by Basso Mouse Scale for locomotion (BMS). In contrast, only a few works quantify walking performances of SCI mice on narrow beams, a different task. Here, we established a novel scoring system using a single beam walking apparatus for SCI mice. The scoring system uses binary judgments of values such as retention, moving forward and reaching the goal on a beam for rating. In addition, high score was given to SCI mouse when the mouse efficiently used hindlimbs for locomotion on the beam. A high rate of concordance of the score derived from positions of hindlimbs between two observers was obtained. Mice displayed the lowest total score on the beam immediately after the SCI, then the score gradually increased like time course of BMS score. Furthermore, the total scores reflected gradation of severity of SCI in 2 strains of mice. The beam walking score proved to be strongly correlated with that of BMS score, indicating that performances between overground walking and beam walking are partly correlated in SCI mice. Collectively, the novel scoring system offers an opportunity to easily evaluate motor performances of mice with SCI.

Factors for Predicting Instant Neurological Recovery of Patients with Motor Complete Traumatic Spinal Cord Injury

The objective of this study was to analyze the factors affecting the instant recovery of neurological function in patients with motor complete traumatic spinal cord injury (TSCI) treated in hospital. Methods: A retrospective analysis of 1053 patients with TSCI classified according to the American Spinal Cord Injury Association (ASIA) as grades A and B at 59 tertiary hospitals from 1 January 2018 to 31 December 2018 was performed. All patients were classified into motor complete injury (ASIA A or B) and motor incomplete injury (ASIA C or D) groups, according to the ASIA upon discharge. The injury level, fracture segment, fracture type, ASIA score at admission and discharge, treatment protocol, and complications were recorded. Univariate and multivariate analyses were performed to evaluate the relationship between various factors and the recovery of neurological function. Results: The results of multiple logistic regression analysis revealed that the ASIA score on admission (p < 0.001, odds ratio (OR) = 5.722, 95% confidence interval (CI): 4.147−7.895), fracture or dislocation (p = 0.001, OR = 0.523, 95% CI: 0.357−0.767), treatment protocol (p < 0.001; OR = 2.664, 95% CI: 1.689−4.203), and inpatient rehabilitation (p < 0.001, OR = 2.089, 95% CI: 1.501−2.909) were independently associated with the recovery of neurological function. Conclusion: The recovery of neurological function is dependent on the ASIA score on admission, fracture or dislocation, treatment protocol, and inpatient rehabilitation.

Indicators of Quality of Care in Individuals With Traumatic Spinal Cord Injury: A Scoping Review

STUDY DESIGN

Scoping review.

OBJECTIVES

To identify a practical and reproducible approach to organize Quality of Care Indicators (QoCI) in individuals with traumatic spinal cord injury (TSCI).

METHODS

A comprehensive literature review was conducted in the Cochrane Central Register of Controlled Trials (CENTRAL) (Date: May 2018), MEDLINE (1946 to May 2018), and EMBASE (1974 to May 2018). Two independent reviewers screened 6092 records and included 262 full texts, among which 60 studies were included for qualitative analysis. We included studies, with no language restriction, containing at least 1 quality of care indicator for individuals with traumatic spinal cord injury. Each potential indicator was evaluated in an online, focused group discussion to define its categorization (healthcare system structure, medical process, and individuals with Traumatic Spinal Cord Injury related outcomes), definition, survey options, and scale.

RESULTS

A total of 87 indicators were identified from 60 studies screened using our eligibility criteria. We defined each indicator. Out of 87 indicators, 37 appraised the healthcare system structure, 30 evaluated medical processes, and 20 included individuals with TSCI related outcomes. The healthcare system structure included the impact of the cost of hospitalization and rehabilitation, as well as staff and patient perception of treatment. The medical processes included targeting physical activities for improvement of health-related outcomes and complications. Changes in motor score, functional independence, and readmission rates were reported as individuals with TSCI-related outcomes indicators.

CONCLUSION

Indicators of quality of care in the management of individuals with TSCI are important for health policy strategists to standardize healthcare assessment, for clinicians to improve care, and for data collection efforts including registries.

Meta-analysis of the Effectiveness of Steroid Pulse Therapy in Treating Patients with Spinal Cord Injury

Background:

High-dose steroid injection therapy is effective in reducing anti-inflammation and edema and is often used to treat patients with acute spinal cord injury. To evaluate the effectiveness of steroid pulse therapy and identify the factors that affect its effectiveness in patients with acute traumatic spinal cord injury.

Methods:

A comprehensive literature search of the databases Pubmed, Medline, the Cochrane Central Register of Controlled Trials, Embase, and CINAHL was performed on July 31, 2019, with no language and time limits. For analysis, studies conducted within the last 10 years were included to reflect on the recent trend.

Results:

A total of 3 randomized controlled trials and 5 observational studies with 2418 patients were included in this meta-analysis. High-dose steroid injection therapy was found to have a high effect on patients with acute spinal cord injury. The following factors had a strong influence on the effectiveness of high-dose steroid treatment in patients with acute spinal cord injuries: injury, onset ASIA, onset neurological assessment scales, time to start treatment after injury, age, BMI, and gender.

Conclusion:

It is necessary to accurately assess the scope of spinal injury in the early stages and actively provide nursing interventions to identify and mediate factors affecting the treatment effect.

Early Predictors of Neurological Outcomes After Traumatic Spinal Cord Injury: A Systematic Review and Proposal of a Conceptual Framework

BACKGROUND

Neurological outcomes after traumatic spinal cord injury are variable and depend on patient-, trauma-, and treatment-related factors as well as on spinal cord injury characteristics, imaging, and biomarkers.

OBJECTIVE

The aims of the study were to identify and classify the early predictors of neurological outcomes after traumatic spinal cord injury.

DATA SOURCES

The Medline, PubMed, Embase, and the Cochrane Central Database were searched using medical subject headings. The search was extended to the reference lists of identified studies.

STUDY ELIGIBILITY CRITERIA

The study eligibility criteria were assessment of neurological outcomes as primary or secondary outcome, predictors collected during the acute phase after traumatic spinal cord injury, and multivariate design.

PARTICIPANTS

The participants were adult patients with traumatic spinal cord injury followed at least 3 mos after injury.

STUDY APPRAISAL AND SYNTHESIS METHODS

The quality of studies was assessed by two independent reviewers using the Study Quality Assessment Tools for Observational Cohort and Cross-sectional Studies. The studies' narrative synthesis relied on a classification of the predictors according to quantity, quality, and consistency of the evidence. Results were summarized in a conceptual framework.

RESULTS

Forty-nine articles were included. The initial severity of traumatic spinal cord injury (American Spinal Injury Association Impairment Scale, motor score, and neurological level of injury) was the strongest predictor of neurological outcomes: patients with more severe injury at admission presented poor neurological outcomes. Intramedullary magnetic resonance imaging signal abnormalities were also associated with neurological outcomes, as the presence of intramedullary hemorrhage was a factor of poor prognosis. Other largely studied predictors, such as age and surgical timing, showed some inconsistency in results depending on cutoffs. Younger age and early surgery were generally associated with good outcomes. Although widely studied, other factors, such as vertebral and associated injuries, failed to show association with outcomes. Cerebrospinal fluid inflammatory biomarkers, as emerging factors, were significantly associated with outcomes.

CONCLUSIONS

This study provides a comprehensive review of predictors of neurological outcomes after traumatic spinal cord injury. It also highlights the heterogeneity of outcomes used by studies to assess neurological recovery. The proposed conceptual framework classifies predictors and illustrates their relationships with outcomes.

Effects of repetitive magnetic stimulation on motor function and GAP43 and 5-HT expression in rats with spinal cord injury

Objectives

Spinal cord injury (SCI) is a disabling central nervous system disorder. This study aimed to explore the effects of repetitive trans-spinal magnetic stimulation (rTSMS) of different spinal cord segments on movement function and growth-associated protein-43 (GAP43) and 5-hydroxytryptamine (5-HT) expression in rats after acute SCI and to preliminarily discuss the optimal rTSMS treatment site to provide a theoretical foundation and experimental evidence for clinical application of rTSMS in SCI.

Methods

A rat T10 laminectomy SCI model produced by transient application of an aneurysm clip was used in the study. The rats were divided into group A (sham surgery), group B (acute SCI without stimulation), group C (T6 segment stimulation), group D (T10 segment stimulation), and group E (L2 segment stimulation).

Results

In vivo magnetic stimulation protected motor function, alleviated myelin sheath damage, decreased NgR and Nogo-A expression levels, increased GAP43 and 5-HT expression levels, and inhibited terminal deoxynucleotidyl transferase dUTP nick end labeling-positive cells and apoptosis-related protein expression in rats at 8 weeks after the surgery.

Conclusions

This study suggests that rTSMS can promote GAP43 and 5-HT expression and axonal regeneration in the spinal cord, which is beneficial to motor function recovery after acute SCI.

Traumatic atlanto-axial rotatory subluxation and dens fracture with subaxial SCIWORA of Brown-Sequard syndrome: A case report

RATIONALE

A case of traumatic atlanto-axial rotatory subluxation (AARS), dens fracture, rupture of transverse atlantal ligament (TAL), and subaxial spinal cord injury without radiographic abnormality (SCIWORA) of Brown-Sequard syndrome has never been reported in a child.

PATIENT CONCERNS

A 7-year-old boy presented to hospital with torticollis, neck pain, and limited neck rotation after a seat-belt injury sustained during a car accident. Neurologic examination revealed right-side motor weakness and left-side sensory abnormality, known as Brown-Sequard syndrome.

DIAGNOSIS

Radiologic examinations revealed type II AARS (Fielding and Hawkins classification), increased atlanto-dental interval (ADI) of 4.5 mm due to a type 1B TAL rupture (Dickman classification), a displaced transverse dens fracture along with an ossiculum terminale, and an intramedullary hemorrhage on the right side of the spinal cord at C3-4.

INTERVENTIONS

The patient immediately received methylprednisolone, and his motor weakness and sensory abnormality gradually improved. At the same time, the patient underwent initial halter traction for 2 weeks, but he failed to achieve successful reduction and required manual reduction under general anesthesia.

OUTCOMES

At the 7-month follow-up visit, radiologic examinations showed a corrected type II AARS that was well maintained and normalization of the ADI to 2 mm. The reduced transverse dens fracture was well maintained but still not united. All clinical symptoms were significantly improved, except the remaining motor weakness of the right upper extremity.

LESSONS

To the best of our knowledge, this is the first report of traumatic AARS, dens fracture, TAL rupture, and subaxial SCIWORA of Brown-Sequard syndrome in a child. Appropriate diagnosis and careful treatment strategy are required for successful management of complex cervical injuries in a child.

Identification of potential oxidative stress biomarkers for spinal cord injury in erythrocytes using mass spectrometry

Oxidative stress is a hallmark of secondary injury associated with spinal cord injury. Identifying stable and specific oxidative biomarkers is of important significance for studying spinal cord injury-associated secondary injury. Mature erythrocytes do not contain nuclei and mitochondria and cannot be transcribed and translated. Therefore, mature erythrocytes are highly sensitive to oxidative stress and may become a valuable biomarker. In the present study, we revealed the proteome dynamics of protein expression in erythrocytes of beagle dogs in the acute and subacute phases of spinal cord injury using mass spectrometry-based approaches. We found 26 proteins that were differentially expressed in the acute (0-3 days) and subacute (7-21 days) phases of spinal cord injury. Bioinformatics analysis revealed that these differentially expressed proteins were involved in glutathione metabolism, lipid metabolism, and pentose phosphate and other oxidative stress pathways. Western blot assays validated the differential expression of glutathione synthetase, transaldolase, and myeloperoxidase. This result was consistent with mass spectrometry results, suggesting that erythrocytes can be used as a novel sample source of biological markers of oxidative stress in spinal cord injury. Glutathione synthetase, transaldolase, and myeloperoxidase sourced from erythrocytes are potential biomarkers of oxidative stress after spinal cord injury. This study was approved by the Experimental Animal Centre of Ningxia Medical University, China (approval No. 2017-073) on February 13, 2017.

Protocatechuic aldehyde mitigates hydrogen peroxide-triggered PC12 cell damage by down-regulating MEG3

Background: Protocatechuic aldehyde (PA) extracts from S. miltiorrhiza, which anti-oxidative and anti-inflammatory functions have been certified in diverse diseases. Nonetheless, the influence of PA in spinal cord injury (SCI) is still hazy. The research probed the function of PA in hydrogen peroxide (H₂O₂)-damaged PC12 cells.Methods: The disparate dosages of H₂O₂ (0-400 µM) or PA (0-2 µM) were applied for stimulating PC12 cells, and subsequently cell viability, apoptosis, apoptosis- and autophagy-correlative factors were evaluated. After pc-MEG3 transfection, functions of MEG3 overexpression in H₂O₂ and/or PA-managed PC12 cells were reassessed. Western blot was conducted to determine Wnt/β-catenin and PTEN/PI3K/AKT pathways.Results: H₂O₂ stimulation clearly triggered PC12 cell damage via prohibiting cell viability and accelerating apoptosis and autophagy. But, PA management mitigated H₂O₂-triggered PC12 cells damage. Down-regulated MEG3 triggered by PA was presented in H₂O₂-managed cells. What's more, overexpressed MEG3 dramatically overturned the influences of PA in H₂O₂-damaged PC12 cells. Beyond that, PA activated Wnt/β-catenin and PTEN/PI3K/AKT via repression of MEG3 in H₂O₂-managed PC12 cells.Conclusions: The results disclosed the protective impacts of PA on PC12 cells to resist H₂O₂-provoked damage. MEG3, Wnt/β-catenin and PTEN/PI3K/AKT pathways joined in adjusting the activity of PA in H₂O₂-damaged PC12 cells.

Value of aggressive surgical and intensive care unit in elderly patients with traumatic spinal cord injury

OBJECTIVEThe elderly are a growing subpopulation within traumatic spinal cord injury (SCI) patients. Studies have reported high morbidity and mortality rates in elderly patients who undergo surgery for SCI. In this study, the authors compare the perioperative outcomes of surgically managed elderly SCI patients with those of a younger cohort and those reported in the literature.METHODSData on a consecutive series of adult traumatic SCI patients surgically managed at a single institution in the period from 2007 to 2017 were retrospectively reviewed. The cohort was divided into two groups based on age: younger than 70 years and 70 years or older. Assessed outcomes included complications, in-hospital mortality, intensive care unit (ICU) stay, hospital length of stay (LOS), disposition, and neurological status.RESULTSA total of 106 patients were included in the study: 83 young and 23 elderly. The two groups were similar in terms of imaging features (cord hemorrhage and fracture), operative technique, and American Spinal Injury Association Impairment Scale (AIS) grade. The elderly had a significantly higher proportion of cervical SCIs (95.7% vs 71.1%, p = 0.047). There were no significant differences between the young and the elderly in terms of the ICU stay (13.1 vs 13.3 days, respectively, p = 0.948) and hospital LOS (23.3 vs 21.7 days, p = 0.793). Elderly patients experienced significantly higher complication (73.9% vs 43.4%, p = 0.010) and mortality (13.0% vs 1.2%, p = 0.008) rates; in other words, the elderly patients had 1.7 times and 10.8 times the rate of complications and mortality, respectively, than the younger patients. No elderly patients were discharged home (0.0% vs 18.1%, p = 0.029). Discharge AIS grade and AIS grade change were similar between the groups.CONCLUSIONSElderly patients had higher complication and mortality rates than those in younger patients and were less likely to be discharged home. However, it does seem that mortality rates have improved compared to those in prior historical reports.

Spontaneous functional full recovery from motor and sensory deficits in adult mice after mild spinal cord injury

The extent of spontaneous recovery in patients with a spinal cord injury (SCI) has not been thoroughly investigated. It is essentially not known whether SCI animals exhibit full recovery from both motor and sensory deficits as well. Here, we developed an appropriate condition to produce a mild SCI in mice. Mice given a mild contusion SCI showed transient low performances in the Basso Mouse Scale for locomotion (BMS), rotarod and beam walking tests after the SCI, which was followed by complete restoration in a short time. The SCI mice also showed functional full recovery from low sensitivity to light touch using dynamic touch test. Nevertheless, the fully-recovered SCI mice still exhibited significant loss of myelin in the spinal cord. These results suggest a high potential of adaptation of motor and sensory systems in mice and might provide insight into the prognoses of SCI patients.

Early (≤48 Hours) versus Late (>48 Hours) Surgery in Spinal Cord Injury: Treatment Outcomes and Risk Factors for Spinal Cord Injury

OBJECTIVES

Surgical management of spinal cord injury (SCI) is challenging. There is no standard guideline regarding the timing of surgery, although physicians have prioritized early surgery over the past decades. Although better outcomes have been observed from these studies, the definition of early surgery has been controversial, although mostly limited to 24-hours after injury. For some hospitals, this early surgery could be difficult to implement in practice. Hence, we re-evaluated the timing of early surgery as surgery within 48 hours and investigated the surgical outcomes of SCI depending on whether surgery was performed early (≤48 hours) or late (>48 hours). The primary outcomes were improvement in the American Spinal Injury Association Impairment Scale (AIS) grade in early and late surgery groups.

METHODS

This study was a retrospective cohort study in individuals aged 15-85 years, who underwent surgery for SCI between 2005 and 2016. The rate of AIS grade improvements was measured at 6 months after injury. Of the 86 enrolled patients, 31 (mean, 40.9 ± 12.64 hours) and 55 (mean, 168.25 ± 93.01 hours) patients were assigned to the early and late surgery groups, respectively.

RESULTS

AIS grade improvement was significantly greater in the early than in the late group (P = 0.039). In the early group, there was no significant difference in neurologic improvements among the AIS B, C, and D groups, but the AIS A group showed a significant improvement (P = 0.015). This finding was not observed in the late group (P = 0.060). AIS grade improvement was also significantly greater in the incomplete SCI group than in the complete SCI group, for all measurements (early, P = 0.007, late, P = 0.009). Other factors that significantly affected clinical outcomes were AIS grade on admission and the level of the injury.

Methotrexate remediates spinal cord injury in vivo and in vitro via suppression of endoplasmic reticulum stress-induced apoptosis

It has been suggested that endoplasmic reticulum stress (ERS) may induce apoptosis following spinal cord injury (SCI). Methotrexate (MTX) has been used as a long-term therapy regimen for rheumatoid arthritis. However, it is not clear whether MTX remediates SCI by inhibiting ERS. In the present study, to establish an in vitro ERS cell model, PC12 cells were pre-incubated with triglycerides (TG). MTT assays revealed that treatment with 1, 2.5, 5 and 10 µM TG decreased PC12 cell viability in a dose-dependent manner. Additionally, MTX treatment significantly reversed the TG-induced decrease in cell viability and increased apoptosis according to the flow cytometry assay (P<0.05). Notably, western blotting indicated that MTX significantly decreased levels of glucose-regulated protein (GRP)78, CCAAT-enhancer-binding protein homologous protein (CHOP) and caspase-12 expression (P<0.05), which were increased following treatment with TG. Furthermore, the in vivo role of MTX in a rat model of SCI was evaluated. The motor behavioral function of rats was improved following treatment with MTX according to Basso, Beattie and Bresnahan scoring (P<0.05). Terminal deoxynucleotidyl-transferase-mediated dUTP nick end staining indicated that there were no apoptotic cells present in sham rats. In the SCI model group, apoptotic cells were observed at day 7; however, the number of apoptotic cells was reduced following an additional 7 days of MTX administration. Furthermore, levels of ERS-associated proteins, including caspase-3, activating transcription factor 6, serine/threonine-protein kinase/endoribonuclease inositol-requiring enzyme 1 α, eukaryotic initiation factor 2 α and GRP78, were significantly increased following SCI; however, administration of MTX for 7 days significantly reversed this effect (P<0.05, P<0.01 and P<0.001). Therefore, MTX may improve SCI by suppressing ERS-induced apoptosis in vitro and in vivo.