Changes in thyroid hormones, thyroid stimulating hormone and cortisol in acute spinal cord injury

A comprehensive look at the psychoneuroimmunoendocrinology of spinal cord injury and its progression: mechanisms and clinical opportunities

Spinal cord injury (SCI) is a devastating and disabling medical condition generally caused by a traumatic event (primary injury). This initial trauma is accompanied by a set of biological mechanisms directed to ameliorate neural damage but also exacerbate initial damage (secondary injury). The alterations that occur in the spinal cord have not only local but also systemic consequences and virtually all organs and tissues of the body incur important changes after SCI, explaining the progression and detrimental consequences related to this condition. Psychoneuroimmunoendocrinology (PNIE) is a growing area of research aiming to integrate and explore the interactions among the different systems that compose the human organism, considering the mind and the body as a whole. The initial traumatic event and the consequent neurological disruption trigger immune, endocrine, and multisystem dysfunction, which in turn affect the patient's psyche and well-being. In the present review, we will explore the most important local and systemic consequences of SCI from a PNIE perspective, defining the changes occurring in each system and how all these mechanisms are interconnected. Finally, potential clinical approaches derived from this knowledge will also be collectively presented with the aim to develop integrative therapies to maximize the clinical management of these patients.

To Be or Not to Be: Environmental Factors that Drive Myelin Formation during Development and after CNS Trauma

Oligodendrocytes are specialized glial cells that myelinate central nervous system (CNS) axons. Historically, it was believed that the primary role of myelin was to compactly ensheath axons, providing the insulation necessary for rapid signal conduction. However, mounting evidence demonstrates the dynamic importance of myelin and oligodendrocytes, including providing metabolic support to neurons and regulating axon protein distribution. As such, the development and maintenance of oligodendrocytes and myelin are integral to preserving CNS homeostasis and supporting proper functioning of widespread neural networks. Environmental signals are critical for proper oligodendrocyte lineage cell progression and their capacity to form functional compact myelin; these signals are markedly disturbed by injury to the CNS, which may compromise endogenous myelin repair capabilities. This review outlines some key environmental factors that drive myelin formation during development and compares that to the primary factors that define a CNS injury milieu. We aim to identify developmental factors disrupted after CNS trauma as well as pathogenic factors that negatively impact oligodendrocyte lineage cells, as these are potential therapeutic targets to promote myelin repair after injury or disease.

C-reactive protein as an available biomarker determining mental component of health-related quality of life among individuals with spinal cord injury

OBJECTIVES

C-reactive protein (CRP) has been shown to correlate with health-related quality of life (HRQL) in some chronic medical conditions. However, these associations have not yet described in spinal cord injury (SCI). In this study, we tried to identify biomarkers associated with HRQL in SCI.

DESIGN

Cross-sectional.

SETTING

Tertiary rehabilitation center.

PARTICIPANTS

Referred patients to Brain and Spinal Cord Injury Research Center between November 2010 and April 2013.

OUTCOME MEASURE

Blood samples were taken to measure circulatory CRP, leptin, adiponectin, ferritin, parathyroid hormone, calcitonin, thyroid hormones, fasting plasma glucose and lipid profile. All the analyses were performed with adjustment for injury-related confounders (level of injury, injury completeness and time since injury) and demographic characteristics. HRQL was measured with Short Form health survey (SF-36).

RESULTS

The initial inverse association between CRP and total score of SF-36 (P: 0.006, r = -0.28) was lost after adjustment for confounders. However, the negative correlation between CRP and Mental Component Summary (MCS) remained significant (P: 0.0005, r = -0.38). Leptin level was inversely correlated with Physical Component Summary (PCS) (P: 0.02, r = -0.30).

CONCLUSION

Although CRP and leptin levels were not related with total scores of SF-36 questionnaire, CRP can be more useful in determining mental component of HRQL whereas leptin can be a determinant of physical component. The combined consideration of these two biomarkers may help to predict HRQL in individuals with SCI.

Establishment of quantitative severity evaluation model for spinal cord injury by metabolomic fingerprinting

Spinal cord injury (SCI) is a devastating event with a limited hope for recovery and represents an enormous public health issue. It is crucial to understand the disturbances in the metabolic network after SCI to identify injury mechanisms and opportunities for treatment intervention. Through plasma 1H-nuclear magnetic resonance (NMR) screening, we identified 15 metabolites that made up an "Eigen-metabolome" capable of distinguishing rats with severe SCI from healthy control rats. Forty enzymes regulated these 15 metabolites in the metabolic network. We also found that 16 metabolites regulated by 130 enzymes in the metabolic network impacted neurobehavioral recovery. Using the Eigen-metabolome, we established a linear discrimination model to cluster rats with severe and mild SCI and control rats into separate groups and identify the interactive relationships between metabolic biomarkers in the global metabolic network. We identified 10 clusters in the global metabolic network and defined them as distinct metabolic disturbance domains of SCI. Metabolic paths such as retinal, glycerophospholipid, arachidonic acid metabolism; NAD-NADPH conversion process, tyrosine metabolism, and cadaverine and putrescine metabolism were included. In summary, we presented a novel interdisciplinary method that integrates metabolomics and global metabolic network analysis to visualize metabolic network disturbances after SCI. Our study demonstrated the systems biological study paradigm that integration of 1H-NMR, metabolomics, and global metabolic network analysis is useful to visualize complex metabolic disturbances after severe SCI. Furthermore, our findings may provide a new quantitative injury severity evaluation model for clinical use.

Endobiogeny: a global approach to systems biology (part 1 of 2)

Endobiogeny is a global systems approach to human biology that may offer an advancement in clinical medicine based in scientific principles of rigor and experimentation and the humanistic principles of individualization of care and alleviation of suffering with minimization of harm. Endobiogeny is neither a movement away from modern science nor an uncritical embracing of pre-rational methods of inquiry but a synthesis of quantitative and qualitative relationships reflected in a systems-approach to life and based on new mathematical paradigms of pattern recognition.

The changing landscape of spinal cord injury

In the past quarter century, spinal cord injury medicine has welcomed the proliferation of new medications and technologies that improve the survival and quality of life for people with spinal cord injury, but also endured the failure of strategies we hoped would salvage the cord in the acute phase. Surgical decompression and spinal stabilization should be pursued whenever indicated and feasible; however, there is no compelling evidence that early decompression facilitates neurological improvement. Methylprednisolone, the subject of over two decades of trials, has proven to be of marginal benefit in improving functional outcome. Recent advances in the management of the respiratory, cardiovascular, autonomic, endocrine, skeletal and integumentary systems have not only changed morbidity and survival of spinal cord injury patients but also improved quality of life. Progress has been made in the early diagnosis and effective treatment of cardiac arrhythmias, neurogenic shock, autonomic dysreflexia and orthostatic hypotension. Aggressive respiratory care for high cervical level of injury patients should include an option for phrenic nerve pacing as it is a viable rehabilitative strategy for appropriately selected patients. Pressure ulcers remain a significant psychological, financial, and functional burden for many people with SCI and for healthcare providers. This area will continue to require further work on early prevention and education. Despite extensive scientific and clinical data on neurogenic osteoporosis, there is no consensus regarding the best pharmacotherapeutic agents, dosing regimens, or rehabilitative strategies for prevention and treatment of bone loss. This chapter will focus on the advances.

Mechanisms of osteoporosis in spinal cord injury

Osteoporosis is a known complication of spinal cord injury (SCI), but its mechanism remains unknown. The pathogenesis of osteoporosis after SCI is generally considered disuse. However, although unloading is an important factor in the pathogenesis of osteoporosis after SCI, neural lesion and hormonal changes also seem to be involved in this process. Innervation and neuropeptides play an important role in normal bone remodelling. SCI results in denervation of the sublesional bones and the neural lesion itself may play a pivotal role in the development of osteoporosis after SCI. Although upper limbs are normally loaded and innervated, bone loss also occurs in the upper extremities in patients with paraplegia, indicating that hormonal changes may be associated with osteoporosis after SCI. SCI-mediated hormonal changes may contribute to osteoporosis after SCI by different mechanisms: (1) increased renal elimination and reduced intestinal absorption of calcium leading to a negative calcium balance; (2) vitamin D deficiency plays a role in the pathogenesis of SCI-induced osteoporosis; (3) SCI antagonizes gonadal function and inhibits the osteoanabolic action of sex steroids; (4) hyperleptinaemia after SCI may contribute to the development of osteoporosis; (5) pituitary suppression of TSH may be another contributory factor to bone loss after SCI; and (6) bone loss after SCI may be caused directly, at least in part, by insulin resistance and IGFs. Thus, oversupply of osteoclasts relative to the requirement for bone resorption and/or undersupply of osteoblasts relative to the requirement for cavity repair results in bone loss after SCI. Mechanisms for the osteoporosis following SCI include a range of systems, and osteoporosis after SCI should not be simply considered as disuse osteoporosis. Unloading, neural lesion and hormonal changes after SCI result in severe bone loss. The aim of this review is to improve understanding with regard to the mechanisms of osteoporosis after SCI. The understanding of the pathogenesis of osteoporosis after SCI can help in the consideration of new treatment strategies. Because bone resorption after SCI is very high, intravenous bisphosphonates and denosumab should be considered for the treatment of osteoporosis after SCI.

Spinal cord injury causes more damage to bone mass, bone structure, biomechanical properties and bone metabolism than sciatic neurectomy in young rats

INTRODUCTION

Although both spinal cord injury (SCI) and sciatic neurectomy (NX) can cause osteopaenia in young rats, the effects of these two injuries on cortical and cancellous bone may differ. The objective of this study was to compare the effects of SCI and NX on bone weight, bone material property, bone mass, bone geometry, trabecular microarchitecture, mechanical strength and bone turnover in young rats.

MATERIALS AND METHODS

Thirty six-week-old male Sprague-Dawley rats were randomised into three groups (10 per group): SCI, bilateral sciatic NX and untreated control (CON). All rats were killed on day 21. Bone mineral density (BMD) was studied using dual-energy X-ray absorptiometry (DXA). At death, the right proximal tibial metaphysis and the fourth lumbar vertebra were examined for bone structural geometric analysis by micro-computed tomography (CT) and then processed for histomorphometry to assess bone cell activity. Serum N-terminal telopeptide of type I collagen (NTX) and osteocalcin (OC) levels were analysed by enzyme-linked immunosorbent assay (ELISA). Biomechanical strength properties of the femur and humerus were measured by three-point bending, and the third lumbar vertebra and the proximal end of tibia were tested by compression.

RESULTS

BMD in the sublesional areas of SCI rats was significantly lower than that of NX rats (proximal tibia, 0.176+/-0.018 g/cm(2) vs. 0.224+/-0.015 g/cm(2), P<0.001). Bone volume (BV/TV), trabecular number (Tb.N) and thickness (Tb.Th) in the tibial second spongiosa of SCI rats were significantly less than those in NX rats (BV/TV: 7.15+/-1.18% vs. 12.32+/-1.83%, P<0.001; Tb.N: 1.23+/-0.22 vs. 2.38+/-0.45, P<0.001; Tb.Th: 33.73+/-5.15 microm vs. 42.80+/-7.44 microm, P<0.01) and trabecular separation (Tb.Sp: 1,053.37+/-164.24 microm vs. 748.32+/-129.36 microm, P<0.01) was significantly greater than in NX rats. Furthermore, poorer trabecular connectivity was found in SCI rats than in NX rats (number of nodes, N.Nd/TV: 1.04+/-0.09 vs. 3.29+/-0.53; number of terminus, N.Tm/TV: 28.53+/-3.17 vs. 21.64+/-2.31, P<0.01). The bone formation rate of the tibial second spongiosa in SCI rats was significantly higher than in NX rats (2.06+/-0.13 vs. 1.53+/-0.09, P<0.001) and, also, the eroded surface in SCI rats was significantly higher than in NX rats (13.42+/-1.24 vs. 10.36+/-1.07, P<0.001). In addition, biomechanical tests showed that SCI rats had poorer biomechanical properties of the femur, proximal tibia and fourth lumbar vertebra than in NX rats. There were significantly higher levels of OC in SCI rats compared with NX rats (30.19+/-1.17 vs. 21.15+/-1.76, P<0.001). Also, serum NTX levels were significantly higher than in NX rats (51.60+/-2.61 vs. 33.85+/-1.93, P<0.001).

CONCLUSION

SCI caused more damage to bone mass, bone structure, biomechanical properties and bone metabolism than NX in young rats. This suggests that different mechanisms may underlie osteopaenia following SCI and NX.

Thyroid abnormalities in children infected with human immunodeficiency virus

OBJECTIVE

To study thyroid function in children infected with human immunodeficiency virus (HIV) and determine whether there are correlates of thyroid dysfunction with disease progression.

STUDY DESIGN

Total and free thyroxine, triiodothyronine, reverse triiodothyronine, thyrotropin, and thyroxine binding globulin (TBG) were measured in 167 children with HIV infection (age, 1 to 19 years; mean, 9.15 years).

SETTING

Pediatric Branch, National Cancer Institute.

RESULTS

Free thyroxine was at or below the lower limit of normal (normal, 1.0 to 1.9 ng/dl) in 18% of the children; thyrotropin and TBG levels were above the normal range in 31% and 30%, respectively. There was an inverse correlation between CD4+ cell count and thyrotropin, and between CD4+ cell count and TBG. No correlation was found between thyroid function and other disease symptoms or medications.

CONCLUSION

These findings indicate that thyroid abnormalities occur more frequently in children with HIV infection than was previously reported, have a different profile from the thyroid abnormalities associated with other chronic disease conditions, and correlate with disease progression.