Circulating leptin concentrations can be used as a surrogate marker of fat mass in acute spinal cord injury patients

Whole-body vibration may not affect bone mineral density and bone turnover in persons with chronic spinal cord injury: A preliminary study

CONTEXT

Spinal-cord injury (SCI) induces bone loss and dramatically increases the risk of fracture.

OBJECTIVES

Determine the effects of whole-body vibration (WBV) on areal bone mineral density (aBMD), whole body composition and bone biological parameters in individuals with chronic-state SCI.

DESIGN

Randomized study.

SETTING

Centre Neurologique PROPARA.

PARTICIPANTS

Fourteen subjects were randomly assigned to a WBV or a control group.

INTERVENTIONS

WBV (20-45 min, 30-45 Hz, 0.5 g) was performed in verticalized persons twice weekly for 6 months.

OUTCOME MEASURES

aBMD was measured by DXA at baseline and 6 months and bone biological parameters at baseline, 1, 3 and 6 months.

RESULTS

No significant aBMD change was found in either the WBV or control group after 6 months of follow-up. Similarly, periostin, sclerostin and bone turnover markers remained relatively stable throughout follow-up and no difference in variation was observed within-group and between groups. Except for whole-body fat mass, which showed a significant decrease in the WBV group compared to controls, no difference in changes was observed, whatever the localization for fat and lean body mass.

CONCLUSIONS

During the chronic phase, aBMD and bone remodeling reach a new steady state. However, the DXA technique and the bone markers, including sclerostin and periostin, both of which reflect bone cell activity influenced by mechanical strain, showed that the bone tissue of individuals with SCI was insensitive to 6 months of WBV training at the study dose. Nevertheless, results of this preliminary study that was underpowered need to be confirmed and other modalities of WBV may be more effective in improving aBMD of this population.

TRIALS REGISTRATION

N°IDRCB:2011-A00224-37.

Endocrinological and inflammatory markers in individuals with spinal cord injury: A systematic review and meta-analysis

Spinal cord injury (SCI) can lead to dramatic physiological changes which can be a factor in developing secondary health conditions and might be reflected in biomarker changes in this elevated risk group. We focused specifically on the endocrine and inflammation profile differences between SCI and able-bodied individuals (ABI). Our aim was to determine the differences in inflammatory markers and endocrine profiles between SCI and ABI. We systematically searched 4 electronic databases for relevant studies. Human observational (cross-sectional, cohort, case-control) studies that compared biomarkers of interest between SCI and ABI population were included. Weighted mean difference between SCI and ABI was calculated using random-effects models. Heterogeneity was computed using I² statistic and chi-squared test. Study quality was evaluated through the Newcastle-Ottawa Scale. The search strategy yielded a total of 2,603 studies from which 256 articles were selected for full-text assessment. Sixty-two studies were included in the meta-analysis. SCI individuals had higher levels of pro-inflammatory C-reactive protein and IL-6 than ABI. Creatinine and 25-hydroxyvitamin D₃ levels were lower in SCI than ABI. Total testosterone levels and IGF-1 were also found to be lower, while cortisol and leptin levels were higher in SCI when compared to ABI. Accordingly, meta-regression, subgroup analysis, and leave-one-out analysis were performed, however, they were only able to partially explain the high levels of heterogeneity. Individuals with SCI show higher levels of inflammatory markers and present significant endocrinological changes when compared to ABI. Moreover, higher incidence of obesity, diabetes, osteoporosis, and hypogonadism in SCI individuals, together with decreased creatinine levels reflect some of the readily measurable aspects of the phenotype changes in the SCI group. These findings need to be considered in anticipating medically related complications and personalizing SCI medical care.

Nutritional Health Considerations for Persons with Spinal Cord Injury

Chronic spinal cord injury (SCI) often results in morbidity and mortality due to all-cause cardiovascular disease (CVD) and comorbid endocrine disorders. Several component risk factors for CVD, described as the cardiometabolic syndrome (CMS), are prevalent in SCI, with the individual risks of obesity and insulin resistance known to advance the disease prognosis to a greater extent than other established risks. Notably, adiposity and insulin resistance are attributed in large part to a commonly observed maladaptive dietary/nutritional profile. Although there are no evidence-based nutritional guidelines to address the CMS risk in SCI, contemporary treatment strategies advocate more comprehensive lifestyle management that includes sustained nutritional guidance as a necessary component for overall health management. This monograph describes factors in SCI that contribute to CMS risks, the current nutritional profile and its contribution to CMS risks, and effective treatment strategies including the adaptability of the Diabetes Prevention Program (DPP) to SCI. Establishing appropriate nutritional guidelines and recommendations will play an important role in addressing the CMS risks in SCI and preserving optimal long-term health.

Associations between lean mass and leptin in men with chronic spinal cord injury: Results from the FRASCI-muscle study

Leptin is an adipo-myokine that regulates appetite and energy expenditure by a neuroendocrine feedback loop. Leptin levels are positively correlated with BMI in the spinal cord injury population and leptin levels are greater in individuals with spinal cord injury compared to uninjured controls. Leptin is produced in multiple tissues, including fat, bone, and skeletal muscle and is a putative biomarker of sedentary behavior in older adults. We assessed body composition leptin, adiponectin, and IL-6 levels in 205 men with chronic spinal cord injury. We found no association between age, injury duration, injury level, injury completeness, or walking status and leptin. There was a significant positive association between lean mass and leptin in men with SCI that was independent of fat. Adjusting for body composition, leptin levels were positively associated with IL-6 and negatively associated with adiponectin levels. When considering men with SCI and sarcopenic obesity, only fat mass remained positively associated with leptin. We found no association between IL-6, adiponectin, or lean mass and leptin in the sarcopenic obesity group. Our findings suggest that lean mass is an under recognized, but substantial, source of circulating leptin. Furthermore, SCI-related sarcopenic obesity may result in dysregulated adipo-myokine metabolism with local and systemic physiologic effects.

The effect of the dietary protein restriction and re-feeding on the content of leptin, IGF-I and urea nitrogen in the blood plasma and growth performance in pigs

The aim of the present study was to examine the effect of the dietary protein restriction on the plasma concentrations of leptin, insulin-like growth factor (IGF-I), blood urea nitrogen (BUN) and growth performance in growing pigs. A total of 12 gilts were divided into experimental (ET) and control (CT) treatments. After the 14-day dietary restriction period during which the ET fed a low-protein diet (LPD, 5% of crude protein) and the CT fed a standard diet (SD, 16% of crude protein) the second 14-day re-feeding period followed, in which LPD was replaced by a SD that was fed by the both treatments. During the dietary protein restriction reduced (P < 0.05) N intake, average daily gain (ADG), concentration of BUN and tendency (P = 0.084) to the lower IGF-I in ET compared with CT were observed. Feed to gain ratio was greater (P < 0.05) in ET. During the subsequent re-feeding period, there was a tendency to the greater daily feed intake (P = 0.068) and N intake (P = 0.070), greater (P < 0.05) ADG, BUN and plasma leptin but no IGF-I in ET. These observations suggest that dietary protein restriction promotes body growth in pigs, which is associated with increase in blood leptin and BUN level in ET during the re-feeding, indicating that the increased ADG can be due to increased fat deposition but not of protein synthesis.

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.

Increased expression of ApoA1 after neuronal injury may be beneficial for healing

ApoA1 is a player in reverse cholesterol transport that initiates multiple cellular pathways on binding to its receptor ABCA1. Its relation to neuronal injury is however unclear. We found ApoA1 to be increasingly abundant at a later time point in the secondary phase of traumatic spinal cord injury. In a cellular injury model of neuroblastoma, ApoA1 showed an initial diminished expression after infliction of injury, which sharply increased thereafter. Subsequently, ApoA1 was shown to alter wound healing dynamics in neuroblastoma injury model. It was observed that an initial lag in scratch wound closure was followed by rapid healing in the ApoA1 treatment group. Activation of ERK pathway and Actin polymerisation by ApoA1 corroborated its role in healing after neuronal injury. We propose that ApoA1 is increasingly expressed and secreted as a delayed response to neuronal injury, and this is a self-protecting mechanism of the injured system.

The Obesity-Breast Cancer Conundrum: An Analysis of the Issues

Breast cancer develops over a timeframe of 2-3 decades prior to clinical detection. Given this prolonged latency, it is somewhat unexpected from a biological perspective that obesity has no effect or reduces the risk for breast cancer in premenopausal women yet increases the risk for breast cancer in postmenopausal women. This conundrum is particularly striking in light of the generally negative effects of obesity on breast cancer outcomes, including larger tumor size at diagnosis and poorer prognosis in both pre- and postmenopausal women. This review and analysis identifies factors that may contribute to this apparent conundrum, issues that merit further investigation, and characteristics of preclinical models for breast cancer and obesity that should be considered if animal models are used to deconstruct the conundrum.

Omega-3 fatty acids' effect on leptin and adiponectin concentrations in patients with spinal cord injury: A double-blinded randomized clinical trial

CONTEXT

Omega-3 fatty acids have been recently proposed to induce neural improvement in patients with spinal cord injury (SCI) while affecting some hormones including leptin and adiponectin.

OBJECTIVES

We tried to evaluate the effect of omega-3 fatty acids on circulatory concentrations of leptin and adiponectin among these patients.

DESIGN

This study is a double-blinded randomized clinical trial with intervention duration of 14 months.

SETTING

A tertiary rehabilitation center.

PARTICIPANTS

Total of 104 patients with SCI who did not meet our exclusion criteria entered the study. Those with history of diabetes, cancer, endocrinology disease, acute infection, and use of special medications were excluded. Patients were divided randomly into the treatment and control group by using permuted balanced block randomization.

INTERVENTION

The treatment group received two MorDHA® capsules per day (each capsule contain 465 mg of docosahexaenoic acid (DHA) and 63 mg of eicosapentaenoic acid (EPA)) for 14 months while the control group received placebo capsules with similar color, shape, and taste.

MAIN OUTCOMES MEASURES

Leptin and adiponectin concentrations in plasma were measured at the beginning of trial and then after 6 and 14 months.

RESULTS

Fourteen months of treatment with DHA and EPA did not influence concentrations of leptin but adiponectin level was significantly decreased (P: 0.03). Weight was positively correlated with leptin level at stage 0 of trial (P: 0.008, r=0.41) while this association was attenuated through stages of trial after intervention.

CONCLUSION

Our data show that omega-3 fatty acids may not affect plasma concentrations of leptin but adiponectin level is decreased in patients with SCI. Moreover, this intervention influences the linear relationship between weight and leptin after 14 months administration of DHA and EPA.

Relationship between leptin and adiponectin concentrations in plasma and femoral and spinal bone mineral density in spinal cord-injured individuals

BACKGROUND CONTEXT

Previously, the associations between leptin and adiponectin levels with bone mineral density (BMD) have been reported in different populations, and occasionally, controversial results have been demonstrated. Until now, these relationships in spinal cord-injured individuals have not yet been described.

PURPOSE

We tried to investigate the correlation between leptin and adiponectin concentrations in plasma and BMD in Iranian patients with spinal cord injury (SCI).

STUDY DESIGN/SETTING

Cross-sectional investigation.

PATIENT SAMPLE

Referred patients with SCI who did not meet our exclusion criteria such as pregnancy, lactation, amputation, history of diabetes, cancer, endocrinology disease, and use of special medications entered the study.

OUTCOME MEASURES

Bone mineral density of femoral neck, trochanter, intertrochanteric zone, total hip, and lumbar vertebrae assessed by dual-energy X-ray absorptiometry and serum leptin and adiponectin levels measured by blood sample analysis using immunoassay techniques.

METHODS

Patient demographic characteristics were measured during face-to-face visits. Injury level and Spinal cord Injury Association (ASIA) score were assessed by clinical examination and were confirmed by imaging aids. Measured levels of leptin and adiponectin and dual-energy X-ray absorptiometry results were analyzed with partial correlation analysis method after adjustment for weight, body mass index (BMI), and age.

RESULTS

Total of 104 patients (19 females and 85 males) entered this investigation. Higher leptin concentration was significantly associated with higher BMD in femoral neck (p=.006, r=0.73), femoral intertrochanteric zone (p=.001, r=0.83), and hip (p=.001, r=0.81) only in female patients, whereas no such association was detected in male participants after adjusting for BMI and age. Leptin and adiponectin levels were not associated with lumbar spine BMD in both genders. Neither injury level nor ASIA score and plegia type (paraplegia or tetraplegia) influenced on leptin and adiponectin concentrations.

CONCLUSIONS

We found no association between leptin concentration and BMD in male individuals, whereas a positive correlation between leptin and BMD of femoral neck, intertrochanter, and hip was observed in female patients that shows a sexual polymorphism in this relationship. However, by considering the low number of female participants, these results should be interpreted cautiously. Lumbar spine BMD was associated with neither leptin nor adiponectin level in both genders.

Excess weight gain accelerates 1-methyl-1-nitrosourea-induced mammary carcinogenesis in a rat model of premenopausal breast cancer

In contrast to the null effects generally reported, high-risk premenopausal women (Gail score ≥1.66) enrolled in the Breast Cancer Prevention P-1 Trial were recently reported to be at increased risk for breast cancer when overweight (HR = 1.59) or obese (HR = 1.70). To investigate this clinical observation in a preclinical setting, ovary-intact female rats were intraperitoneally injected with 50 mg/kg 1-methyl-1-nitrosourea at 21 days of age to simulate premenopausal women with increased risk. Two commercially available strains of Sprague-Dawley rat (Taconic Farms) were used, which are dietary resistant (DR) or dietary susceptible (DS) to excess weight gain when fed a purified diet containing 32% kcal from fat, similar to levels consumed by the typical American woman. DS rats were approximately 15.5% heavier than DR rats at study termination and plasma leptin indicated a marked difference in adiposity. DS rats had higher incidence (26% increase), multiplicity (2.5-fold increase), and burden (5.4-fold increase) of mammary carcinomas with a concomitant reduction in cancer latency (16% earlier detection) compared with DR rats (P < 0.001 for all analyses), and displayed a higher proportion of hormone receptor negative tumors compared with DR rats [OR = 1.78; 95% confidence interval (CI), 0.83-3.81]. Circulating levels of several breast cancer-risk factors, including leptin, adiponectin:leptin ratio, insulin, insulin-like growth factor (IGF)-1, IGF-1:IGF-1 binding protein-3 ratio, and calculated insulin resistance (HOMA-IR) were negatively impacted in DS rats (P < 0.05 for all analyses). These findings support further investigation of the effects of excess weight in high-risk premenopausal women and demonstrate a useful preclinical model for rapid evaluation of mechanistic hypotheses.

Adiponectin is a candidate biomarker of lower extremity bone density in men with chronic spinal cord injury

Adipose tissue is a major regulator of bone metabolism and in the general population obesity is associated with greater bone mineral density (BMD). However, bone-fat interactions are multifactorial, and may involve pathways that influence both bone formation and resorption with competing effects on the skeleton. One such pathway involves adipocyte production of adipokines that regulate bone metabolism. In this study we determined the association between BMD, walking status, and circulating adipokines (adiponectin and leptin) in 149 men with chronic spinal cord injury (SCI). Although adipokine levels did not vary significantly based on walking status, there was a significant inverse association between adiponectin and BMD in wheelchair users independent of body composition. We found no association between adiponectin and BMD in the walkers and no association between leptin and BMD in either group. These findings suggest that for subjects with chronic SCI, walking may mitigate the effect of adiponectin mediated bone loss. For wheelchair users, adipose-derived adiponectin may contribute to SCI-induced osteoporosis because the osteoprotective benefits of obesity appear to require mechanical loading during ambulation.

Low-grade systemic inflammation and leptin levels were improved by arm cranking exercise in adults with chronic spinal cord injury

OBJECTIVE

To ascertain the effect of arm cranking exercise on improving plasma levels of inflammatory cytokines and adipokines in untrained adults with chronic spinal cord injury (SCI).

DESIGN

Longitudinal study.

SETTING

Community-based supervised intervention.

PARTICIPANTS

Men (N=17) with complete SCI at or below T5 volunteered for this study. Participants were randomly allocated to the intervention (n=9) or control group (n=8) using a concealed method.

INTERVENTION

A 12-week arm cranking exercise program of 3 sessions per week consisted of warm-up (10-15min), arm crank (20-30min; increasing 2min and 30s every 3wk) at a moderate work intensity of 50% to 65% of heart rate reserve (starting at 50% and increasing 5% every 3wk), and cool-down (5-10min).

MAIN OUTCOME MEASURES

Plasma levels of leptin, adiponectin, plasminogen activator inhibitor-1, tumor necrosis factor-alpha, and interleukin-6 were determined. Furthermore, physical fitness (maximum oxygen consumption [V˙O2max]) and body composition (anthropometric index, waist circumference, and body mass index) were also assessed.

RESULTS

Plasma levels of leptin, tumor necrosis factor-alpha, and interleukin-6 were significantly decreased after the completion of the training program. Similarly, the anthropometric index and waist circumference were diminished too. A moderate correlation was found between leptin and the anthropometric index. Finally, V˙O2max was significantly increased, suggesting an improvement of physical fitness in the intervention group. No changes were found in the control group.

CONCLUSIONS

Arm cranking exercise improved low-grade systemic inflammation by decreasing plasma levels of inflammatory cytokines. Furthermore, it also reduced plasma leptin levels. Long-term, well-conducted studies are still required to determine whether these changes may improve clinical outcomes of adults with chronic SCI.

Neuroendocrine and cardiac metabolic dysfunction and NLRP3 inflammasome activation in adipose tissue and pancreas following chronic spinal cord injury in the mouse

CVD (cardiovascular disease) represents a leading cause of mortality in chronic SCI (spinal cord injury). Several component risk factors are observed in SCI; however, the underlying mechanisms that contribute to these risks have not been defined. Central and peripheral chronic inflammation is associated with metabolic dysfunction and CVD, including adipokine regulation of neuroendocrine and cardiac function and inflammatory processes initiated by the innate immune response. We use female C57 Bl/6 mice to examine neuroendocrine, cardiac, adipose and pancreatic signaling related to inflammation and metabolic dysfunction in response to experimentally induced chronic SCI. Using immuno-histochemical, -precipitation, and -blotting analysis, we show decreased POMC (proopiomelanocortin) and increased NPY (neuropeptide-Y) expression in the hypothalamic ARC (arcuate nucleus) and PVN (paraventricular nucleus), 1-month post-SCI. Long-form leptin receptor (Ob-Rb), JAK2 (Janus kinase)/STAT3 (signal transducer and activator of transcription 3)/p38 and RhoA/ROCK (Rho-associated kinase) signaling is significantly increased in the heart tissue post-SCI, and we observe the formation and activation of the NLRP3 (NOD-like receptor family, pyrin domain containing 3) inflammasome in VAT (visceral adipose tissue) and pancreas post-SCI. These data demonstrate neuroendocrine signaling peptide alterations, associated with central inflammation and metabolic dysfunction post-SCI, and provide evidence for the peripheral activation of signaling mechanisms involved in cardiac, VAT and pancreatic inflammation and metabolic dysfunction post-SCI. Further understanding of biological mechanisms contributing to SCI-related inflammatory processes and metabolic dysfunction associated with CVD pathology may help to direct therapeutic and rehabilitation countermeasures.

Changes of leptin concentration in plasma in patients with spinal cord injury: a meta-analysis

OBJECTIVE

The aim of this study was to investigate changes of leptin concentration in plasma in patients with spinal cord injury to come to a single concept by using a Meta-analysis.

SETTING

Systematic Review.

METHODS

Searching relevant articles was performed in Ovid data base, Medline (PubMed) EMBASE, Google Scholar, Cochrane and Scopus up to February 2013. Five articles were selected using two independent reviewers. Analysis were performed using SPSS version 18 and Comparative Meta-analysis software version 2.0.

RESULTS

The combined analysis with confidence interval of 95% using comprehensive meta-analysis showed significant higher leptin levels in patients with spinal cord injury in comparison with able bodies (P<0.0001). The effect of spinal lesion level on plasma leptin concentration was also statistically significant (P<0.0001). Body mass index was positively related to plasma leptin concentration in both groups (P<0.0001).

CONCLUSION

This Meta analysis approves increased level of leptin in spinal cord injured patients which can be due to fat distribution changes and sympathetic dysfunction in these patients. Our results also showed that patients with higher spinal lesion level have higher plasma leptin concentration.

Bone remodeling and calcium homeostasis in patients with spinal cord injury: a review

Patients with spinal cord injury exhibit early and acute bone loss with the major functional consequence being a high incidence of pathological fractures. The bone status of these patients is generally investigated by dual-energy x-ray absorptiometry, but this technique does not reveal the pathophysiological mechanism underlying the bone loss. Bone cell activity can be indirectly evaluated by noninvasive techniques, including measurement of specific biochemical markers of bone formation (such as osteocalcin or bone-alkaline phosphatase) and resorption (such as procollagen type I N- or C-terminal propeptide). The bone loss in spinal cord injury is clearly due to an uncoupling of bone remodeling in favor of bone resorption, which starts just after the injury and peaks at about 1 to 4 months. Beyond 6 months, bone resorption activity decreases progressively but remains elevated for many years after injury. Conversely, bone formation is less affected. Antiresorptive treatment induces an early and acute reduction in bone resorption markers. Level of injury and health-related complications do not seem to be implicated in the intensity of bone resorption. During the acute phase, the hypercalcemic status is associated with the suppression of parathyroid hormone and vitamin D metabolites. The high sensitivity of these markers after treatment suggests that they can be used for monitoring treatment efficacy and patient compliance. The concomitant use of bone markers and dual-energy x-ray absorptiometry may improve the physician's ability to detect patients at risk of severe bone loss and subsequent fractures.

Weight gain following spinal cord injury: a pilot study

STUDY DESIGN

Retrospective chart review.

OBJECTIVE

To define the temporal course of weight gain in persons with new spinal cord injury (SCI), and to identify predictors of weight gain in this population.

SETTING

A United States Department of Veterans Affairs (VA) SCI Unit.

METHODS

A retrospective chart review in a VA SCI Unit was conducted. Participants (n = 85) included all persons with new SCI completing initial rehabilitation at the center between 1998 and 2006. Outcome measures were mean change in body mass index (BMI) between rehabilitation admission and final follow-up, time of greatest BMI change, and distribution of participants by BMI classification. These measures were also examined relative to SCI level, American Spinal Injury Association Impairment Scale (AIS) grade, primary mode of mobility, and age at rehabilitation admission.

RESULTS

Mean BMI increased by 2.3 kg/m2 between rehabilitation admission (mean 45 days post-injury) and final follow-up (mean 5 years post-injury). The distribution of participants shifted from lower BMI classifications at rehabilitation admission to higher BMI classifications at final follow-up. For participants transitioning from normal to overweight or obese, the greatest increase occurred during the first year after acute rehabilitation. Neurological level, impairment category, primary mode of mobility, and age at rehabilitation admission did not significantly predict BMI change. BMI at rehabilitation admission correlated significantly with BMI at final follow-up (P < 0.0005).

CONCLUSIONS

These findings confirm a significant increase in BMI after new SCI and suggest that persons with new SCI are at greatest weight gain risk during the first year following acute rehabilitation.

Serum leptin levels following acute experimental spinal cord injury

BACKGROUND/OBJECTIVE

Spinal cord injury influences many hormones that are known to be involved in the modulation of neurotrophic, neurogenic, and neuroprotective events. Recent studies showed that leptin could be neuroprotective, enhancing neuronal survival in vitro and in vivo. The objective of this study was to evaluate the pattern of the serum leptin levels in rats during acute traumatic SCI.

METHODS

Forty male Sprague-Dawley rats were divided randomly into 4 groups. In the control group, neither laminectomy nor SCI was performed; only laminectomy was performed without SCI in the sham group. In the cervical and thoracic spinal trauma groups, laminectomies were performed following the same trauma procedure. Blood samples were drawn 2, 6, 12, and 24 hours after the procedures and assayed immediately.

RESULTS

In the first 2 hours, levels of leptin were similar in control and sham-operated groups and higher in neurotrauma groups (P < 0.05). At the sixth hour, leptin levels increased in the sham-operated group, decreased in the neurotrauma groups (P < 0.05), and did not change in the control group (P > 0.05). At the 12th hour, the levels of leptin increased in all groups (P > 0.05). At the 24th hour, they decreased in the control, sham-operated, and cervical groups (P < 0.05); levels did not change in the thoracic group (P > 0.05). The decrease was higher in the control group than in the other groups (P < 0.05).

CONCLUSIONS

Activation of endogenous leptin secretion started immediately after the SCI. The level of neurologic lesion (either cervical or thoracic regions) affected the levels of serum leptin differently, but with the exception of the first 12-hour period, this difference did not reach a statistically significant level.

Determinants of lung volumes in chronic spinal cord injury

OBJECTIVE

To characterize determinants of lung volumes in chronic spinal cord injury (SCI).

DESIGN

Cross-sectional.

SETTING

VA Boston Healthcare System.

PARTICIPANTS

White men (N=330) with chronic SCI.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Questionnaire responses and measurements of lung volumes.

RESULTS

Adjusted for SCI severity and stature, greater body mass index (BMI) was associated (all P<.05) with lower total lung capacity (TLC) (-38.7 mL x kg(-1) x m(-2)), functional residual capacity (FRC) (-73.9 mL x kg(-1) x m(-2)), residual volume (RV) (-40.4 mL x kg(-1) x m(-2)), and expiratory reserve volume (ERV) (-32.2 mL x kg(-1) x m(-2)). The effect of BMI on RV was most pronounced in quadriplegia (-72 mL x kg(-1) x m(-2)). Lifetime smoking was associated with a greater FRC (5.3 mL/pack-year) and RV (3.1 mL/pack-years). The effects of lifetime smoking were also greatest in quadriplegia (11 mL/pack-year for FRC; 7.8 mL/pack-year for RV). Time since injury, independent of age, was associated with a decrease in TLC, FRC, ERV, and RV (P<.05). Age was not a predictor of TLC once time since injury was considered.

CONCLUSIONS

Determinants of FRC, TLC, ERV, and RV in chronic SCI include factors related and unrelated to SCI. The mechanisms remain to be determined but likely involve the elastic properties and muscle function of the respiratory system and perhaps the effects of systemic inflammation related to adiposity. Addressing modifiable factors such as obesity, muscle stiffness, and smoking may improve respiratory morbidity and mortality in SCI by improving pulmonary function.

Serum leptin, abdominal obesity and the metabolic syndrome in individuals with chronic spinal cord injury

STUDY DESIGN

Cross-sectional comparison.

OBJECTIVE

The mortality rate is higher in individuals with spinal cord injury (SCI), and one major cause is cardiovascular disease (CVD). In the general population, the metabolic syndrome (MetS) is associated with an increased risk of CVD, and abdominal obesity is a major feature. Adipokines, secreted by adipose tissue, contribute to obesity-linked metabolic diseases. The aim of this study is to evaluate the prevalence of MetS, the components of this syndrome, especially body composition, and the relations between adipokines and body composition, in SCI individuals.

SETTING

Kanagawa Rehabilitation Hospital, Kanagawa, Japan.

METHODS

Forty-four male SCI individuals (57+/-13 years and 28 paraplegia) and age-matched able-bodied controls were studied. Body composition was assessed by dual-energy X-ray absorptiometry (DXA) and anthropometry (waist circumference). The visceral fat area (VFA) was measured by computed tomography (CT). Plasma adipokine levels, including that of leptin, adiponectin and plasminogen activator inhibitor-1 (PAI-1), were measured.

RESULTS

Overall, 43% of SCI individuals met the criteria for MetS. Total and regional fat mass (FM), as well as VFA, were higher, whereas total and regional lean mass, except for arm, were lower than able-bodied controls. In the SCI, leptin and PAI-1 levels were positively associated and adiponectin levels were negatively associated with waist circumference, VFA and trunk FM. In multiple regression models, only leptin level was independently associated with waist circumference, VFA and trunk FM.

CONCLUSION

SCI individuals were predisposed to excessive abdominal obesity, and higher leptin levels were strongly associated with higher prevalence of abdominal obesity in this population.

Bone loss in spinal cord-injured patients: from physiopathology to therapy

STUDY DESIGN

Review article on bone metabolism and therapeutic approach on bone loss in patients with spinal cord injury (SCI).

OBJECTIVE

The first part aims to describe the process of bone demineralization and its effects on bone mass in patients with SCI. The second part describes and discusses the therapeutic approaches to limiting the alteration in bone metabolism related to neurological lesions.

SETTING

Propara Rehabilitation Center, Montpellier, France.

RESULTS

During the first 24 months postinjury, demineralization occurs exclusively in the sublesional areas and predominantly in weight-bearing skeletal sites such as the distal femur and proximal tibia, both of which are trabecular-rich sites. Reduced bone mass, in association with a modified bone matrix property and composition, is very likely at the origin of pathological fractures after minor trauma to which these patients are frequently exposed. Since these fractures may be asymptomatic yet may lead to complications, preventing and managing 'neurological osteoporosis' remains a considerable challenge. Two main approaches are considered: the first consists in applying a mechanical stimulus to the bone tissue by standing, orthotically aided walking or functional electrical stimulation (FES). The second uses medications, particularly antiresorptive drugs such as calcitonin or diphosphonates.

CONCLUSION

To develop well-adapted treatments, a more precise understanding of bone loss etiology is needed. The current rehabilitation programs are based on the idea that the bone physiological changes observed in patients with SCI are due to immobility, but results indicate that alterations inherent to neurological damage may play an even greater role in inducing osteoporosis.

The role of androgens or growth factors in the bone resorption process in recent spinal cord injured patients: a cross-sectional study

STUDY DESIGN

This cross-sectional study compared the androgen and growth factor profiles and the bone turnover of patients with spinal cord injury (SCI) versus able-bodied controls (AB).

OBJECTIVE

Determine whether androgens, GH, or either IGF-I or IGFBP-3, are implicated in bone turnover alteration in patients with recent SCI.

SETTING

Propara Center, Montpellier, France.

METHODS

In all, 16 men (31.3 years) with complete SCI, seven paraplegics and nine tetraplegics, who had sustained injury an average of 3 months earlier, and 12 AB who served as controls (27.5 years) participated. Androgens, growth hormone and its mediators were investigated. The bone resorption process was evaluated by urinary and plasma type I collagen C-telopeptide (CTXu, CTXp), while bone formation was evaluated by osteocalcin (OC) and bone alkaline phosphatase.

RESULTS

Total testosterone (TT) and the free androgen index (FAI) were significantly lower in the SCI patients, whereas FSH was significantly higher (P<0.05). These hormonal variations were not related to the level of neurological lesion. There was no significant difference in GH, IGF-I, or IGFBP-3 levels. CTXu and CTXp indicated high bone resorption activity in the SCI patients (P<0.05). Regarding bone formation markers, only OC was affected by neurological lesion (P<0.05). Basal hormone levels did not correlate with markers of bone turnover.

CONCLUSION

The high bone resorption process observed in SCI patients did not seem directly related to testicular endocrine abnormalities or an altered growth factor profile. Nevertheless, the reduced TT and FAI levels could be aggravating factors in the development of acute bone loss.