An improved method for generating human spinal cord neural stem cells.

Neural stem cells have exhibited efficacy in pre-clinical models of spinal cord injury (SCI) and are on a translational path to human testing. We recently reported that neural stem cells must be driven to a spinal cord fate to optimize host axonal regeneration into sites of implantation in the injured spinal cord, where they subsequently form neural relays across the lesion that support significant functional improvement. We also reported methods of deriving and culturing human spinal cord neural stem cells derived from embryonic stem cells that can be sustained over serial high passage numbers in vitro, providing a potentially optimized cell source for human clinical trials. We now report further optimization of methods for deriving and sustaining cultures of human spinal cord neural stem cell lines that result in improved karyotypic stability while retaining anatomical efficacy in vivo. This development improves prospects for safe human translation.

African Americans have lower TBS than whites among densitometry patients at a Chicago academic center.

Trabecular bone score, an indirect measure of bone structure, may differ between ethnicities. We found that African Americans had lower trabecular bone score than do whites referred for densitometry, even when controlling for age and abdominal soft tissue thickness. PURPOSE: Trabecular bone score (TBS), an indirect measure of bone structure, has been shown to predict fractures in predominantly white populations. Analysis of NHANES data revealed lower TBS in African Americans than in whites. However, it is not clear if this is true in patients referred for densitometry (where fracture risk stratification is most pertinent) or if ethnic differences in TBS may be related to differences in abdominal soft tissue (tissue thickness), which was not controlled for in the NHANES study. METHODS: We retrospectively analyzed all BMD scans obtained at a university hospital in Chicago between 2011 and 2016. RESULTS: There were 3187 women (51 % African American) and 675 men (32 % African American). African American women were older (69.6 ± 10.4 vs. 64.8 ± 1.3) and heavier (BMI 28.3 ± 4.7 vs. 25.4 ± 4.5) than whites were, while men were of similar age and BMI. African American women had higher T-scores at all sites (the lowest of T-scores, termed LowT, -1.5 ± 1.2 vs. -1.9 ± 1.0, p < 0.001) but lower TBS than white women even when adjusting for age and tissue thickness (1.231 ± 0.130 versus 1.251 ± 0.130, p < 0.001). While LowT was higher in African American men (-1.1 ± 1.2 vs. -1.5 ± 1.4, p < 0.001), TBS was lower than in white men even after adjusting for age and tissue thickness (1.232 ± 0.144 vs. 1.275 ± 0.144, p < 0.001). CONCLUSIONS: African Americans had lower TBS than whites did, even with adjustment for age and tissue thickness. Ethnic differences in TBS should be considered when assessing fracture risk in clinical practice.

Prevalence of vertebral fractures on chest radiographs of elderly African American and Caucasian women.

The prevalence of vertebral fractures on routine chest radiographs of elderly Caucasian women was only 1.3 times higher than in African American (AA) women, a difference considerably smaller than reported in population studies. AAs with medical problems may have higher risk of vertebral fractures than previously suspected. INTRODUCTION: Earlier studies noted a 1.9- to 3.7-fold higher prevalence of vertebral fractures in Caucasian (CA) compared to African American (AA) women. These studies, however, may have suffered from selection bias. We reported that among women referred for bone density testing, the prevalence of vertebral fractures in AA was the same as in CA women. Suspecting that the latter might have been due to a referral bias, we examined the racial difference in the prevalence of vertebra fractures on chest radiographs of patients seeking general medical care, not selected for osteoporosis. METHODS: Consecutive chest radiographs (N = 1,200) of women over age 60 were evaluated using Genant's semi-quantitative method. Patients' race and the presence of diseases or medications associated with increased fracture risk were ascertained from the electronic medical records. RESULTS: Among 1,011 women (76% AA) with usable radiographs, 11% had moderate or severe vertebral fractures. The prevalence of vertebral fractures was 10.3% in 773 AA and 13% in 238 CA women (p = 0.248 for difference between races). The lack of difference persisted after controlling for age, smoking, use of glucocorticoids, or presence of cancer, rheumatoid arthritis, organ transplantation, and end-stage renal disease. Among all subjects, CA women were more likely to be diagnosed and treated for osteoporosis (p <0.001). CONCLUSION: Among subjects seeking medical care, the difference in the prevalence of vertebral fractures between AA and CA women is smaller than previously suspected. Greater attention to the detection of vertebral fractures and the management of osteoporosis is warranted in AA women with medical problems.

Using clinical risk factors and bone mineral density to determine who among patients undergoing bone densitometry should have vertebral fracture assessment.

SUMMARY: Vertebral fracture assessment (VFA) is a new method for imaging thoracolumbar spine on bone densitometer. Among patients referred for bone densitometry, the selection of patients for VFA testing can be optimized using an index derived from clinical risk factors and bone density measurement. PURPOSE: VFA, a method for imaging thoracolumbar spine on bone densitometer, was developed because vertebral fractures, although common and predictive of future fractures, are often not clinically diagnosed. The study objective was to develop a strategy for selecting patients for VFA. METHODS: A convenience sample from a university hospital bone densitometry center included 892 subjects (795 women) referred for bone mineral density (BMD) testing. We used questionnaires to capture clinical risk factors and dual-energy X-ray absorptiometry to obtain BMD and VFA. RESULTS: Prevalence of vertebral fractures was 18% in women and 31% in men (p = 0.003 for gender difference). In women, age, height loss, glucocorticoid use, history of vertebral and other fractures, and BMD T-score were significantly and independently associated with vertebral fractures. A multivariate model which included above predictors had an area under the receiver operating curve of 0.85 with 95% confidence interval (CI) of 0.81 to 0.89. A risk factor index was derived from the above multivariate model. Using a level of 2 as a cut-off yielded 93% sensitivity (95% CI 87, 96) and 48% specificity (95% CI 69, 83). Assuming a 15% prevalence of vertebral fractures, this cut-off value had a 24% positive and 97% negative predictive value and required VFA scanning of three women at a cost of $60 (assuming a $20 cost/VFA scan) to detect one with vertebral fracture(s). CONCLUSIONS: Selecting patients for VFA can be optimized using an index derived from BMD measurement and easily obtained clinical risk factors.

Evaluation of vertebral fracture assessment by dual X-ray absorptiometry in a multicenter setting.

SUMMARY: The utility of vertebral fracture assessment (VFA) by DXA to detect prevalent vertebral fracture in a multicenter setting was investigated by comparison to conventional radiography. While limited by lower image quality, overall performance of VFA was good but had a tendency to miss mild prevalent fractures. INTRODUCTION: In osteoporosis clinical trials standardized spine radiographs are used to detect vertebral fractures as a study endpoint. Lateral spine imaging with dual X-ray absorptiometry (DXA) scanners, known as vertebral fracture assessment (VFA) by DXA, presents a potential alternative to conventional radiography with lower radiation dose and greater patient convenience. METHODS: We investigated in a multicenter setting the ability of VFA to detect fractures in comparison with conventional radiography. The study examined 203 postmenopausal women who had imaging of the spine by DXA and radiography. Three radiologists experienced in vertebral fracture assessment independently read the VFA scans and radiographs using the Genant semiquantitative method on two occasions. CONCLUSIONS: Analyzing the data from all readable vertebrae, the kappa statistic, sensitivity, and specificity ranged from 0.64-0.77, 0.65-0.84, and 0.97-0.98, respectively. Considering only moderate and severe fractures improved the kappa statistic (0.80-0.91) and sensitivity (0.70-0.86). While image quality of VFA is inferior to radiography, the detection of vertebral fractures using visual scoring is feasible. However, VFA underperformed due to unreadable vertebrae and reduced sensitivity for mild fractures. Nevertheless, VFA correctly identified most moderate and severe vertebral fractures. Despite this limitation, VFA by DXA provides an important tool for clinical research.

Radiographic texture analysis of densitometer-generated calcaneus images differentiates postmenopausal women with and without fractures.

INTRODUCTION: Bone fragility is determined by bone mass, measured as bone mineral density (BMD), and by trabecular structure, which cannot be easily measured using currently available noninvasive methods. In previous studies, radiographic texture analysis (RTA) performed on the radiographic images of the spine, proximal femur, and os calcis differentiated subjects with and without osteoporotic fractures. The present cross-sectional study was undertaken to determine whether such differentiation could also be made using high-resolution os calcis images obtained on a peripheral densitometer. METHODS: In 170 postmenopausal women (42 with and 128 without prevalent vertebral fractures) who had no secondary causes of osteoporosis and were not receiving treatment for osteoporosis, BMD of the lumbar spine, proximal femur, and os calcis was measured using dual energy x-ray absorptiometry. Vertebral fractures were diagnosed on densitometric spine images. RTA, including Fourier-based and fractal analyses, was performed on densitometric images of os calcis. RESULTS: BMD at all three sites and all texture features was significantly different in subjects with and without fractures, with the most significant differences observed for the femoral neck and total hip measurements and for the RTA feature Minkowski fractal (p<0.001). In univariate logistic regression analysis, Minkowski fractal predicted the presence of vertebral fractures as well as femoral neck BMD (p<0.001). In multivariate logistic regression analysis, both femoral neck BMD and Minkowski fractal yielded significant predictive effects (p=0.001), and when age was added to the model, the effect of RTA remained significant (p=0.002), suggesting that RTA reflects an aspect of bone fragility that is not captured by age or BMD. Finally, when RTA was compared in 42 fracture patients and 42 nonfracture patients matched for age and BMD, the RTA features were significantly different between the groups (p=0.003 to p=0.04), although BMD and age were not. CONCLUSION: This study suggests that RTA of densitometer-generated calcaneus images provides an estimate of bone fragility independent of and complementary to BMD measurement and age.

Disorders of antidiuretic hormone.

Disorders of thirst and vasopressin secretion present clinically in one of three ways: as hypotonic polyuria (DI), as hypodipsic hyponatremia, and as hyponatremia. In evaluating a patient with DI, the major challenge is to differentiate between primary polydipsia and neurogenic and nephrogenic DI. This is best accomplished through a series of steps that start with simple clinical observation, and progress, as necessary, to more complicated diagnostic procedures (Fig. 1). If the diagnosis is not clear from the clinical setting and the patient's history, the first step is to measure plasma osmolality and sodium under conditions of ad libitum fluid intake. If the results are clearly above the upper limit of normal range, primary polydipsia is excluded and the work-up can proceed directly to administration of vasopressin or DDAVP and/or a measurement of plasma vasopressin levels to differentiate between neurogenic and nephrogenic DI. If basal plasma osmolality and sodium fall within normal range, the standard dehydration test should be performed. If urine osmolality does not increase above that of plasma despite evident dehydration, primary polydipsia is excluded and the effect of vasopressin or DDAVP on urine osmolality should be examined to differentiate between neurogenic and nephrogenic DI. If administration of antidiuretic hormone increases urine osmolality by more than 50 per cent, the patient has severe neurogenic DI. If the increase in urine osmolality is less than 50 per cent, the patient has nephrogenic DI. In patients who do not concentrate urine above that of plasma in response to dehydration, the best approach is to measure plasma vasopressin, osmolality, and sodium after the latter have been increased above normal range by dehydration and/or infusion of hypertonic saline. When these results are plotted on a suitable nomogram (Fig. 2), neurogenic DI can be clearly diagnosed from the relative deficiency of vasopressin. In patients with normal vasopressin levels, primary polydipsia can be differentiated from nephrogenic DI by examining the relationship of urine osmolality to plasma vasopressin (Fig. 3), obtained during dehydration and/or graded vasopressin infusion. In evaluating a patient with sustained hypernatremia, it is only necessary to assess thirst, which can be done by a simple bedside observation. In a patient without obvious neurologic or cognitive impairment, absence of thirst in the face of plasma osmolality above 305 mosm/kg (plasma sodium above 150 mEq/L) is diagnostic for hypodipsic hypernatremia. In a patient who presents with hyponatremia, the main objective is to differentiate between hyper-, hypo-, and euvolemic (SIADH) types

Osmoregulation of thirst and vasopressin during normal menstrual cycle.

Changes in osmoregulation during normal menstrual cycle were examined in 15 healthy women. In 10 women, studied repetitively during two consecutive menstrual cycles, basal plasma osmolality, sodium, and urea decreased by 4 mosmol/kg, 2 meq/l, and 0.5 mM, respectively (all P less than 0.02) from the follicular to luteal phase. Plasma vasopressin, protein, hematocrit, mean arterial pressure, and body weight did not change. In five other women, diluting capacity and osmotic control of thirst and vasopressin release were assessed in follicular, ovulatory, and luteal phases. Responses of thirst and/or plasma vasopressin, urine osmolality, osmolal and free water clearance to water loading, and infusion of hypertonic saline were normal and similar in the three phases. However, the plasma osmolality at which plasma vasopressin and urine osmolality were maximally suppressed as well as calculated osmotic thresholds for thirst and vasopressin release were lower by 5 mosmol/kg in the luteal than in the follicular phase. This lowering of osmotic thresholds for thirst and vasopressin release, which occurs in the luteal phase, is qualitatively similar to that observed in pregnancy and should be taken into account when studying water balance and regulation of vasopressin secretion in healthy cycling women.

Antibodies to vasopressin in patients with diabetes insipidus. Implications for diagnosis and therapy.

STUDY OBJECTIVE: To determine whether antibodies to vasopressin play a role in the development of diabetes insipidus or interfere with diagnosis and treatment. DESIGN: Random plasma or serum samples for determining of antibodies to vasopressin were collected from patients and controls. SETTING: Referral university hospital with most patients studied in the clinical research center. PATIENTS: Twenty-nine healthy controls and 113 patients with polyuria (15 with primary polydipsia; 86 with neurogenic diabetes insipidus [60 studied before, 28 during, and 10 after antidiuretic hormone treatment]; and 12 with nephrogenic diabetes insipidus). INTERVENTIONS: Antibodies were detected by incubating samples with radiolabeled 125I-arginine vasopressin. The effect of antibodies on diagnosis was studied by examining the relation of plasma vasopressin to osmolality measured during dehydration or infusion of hypertonic saline and the relation of urine osmolality to plasma vasopressin measured during dehydration. MEASUREMENTS AND MAIN RESULTS: Antibodies to vasopressin were not detected in patients with primary polydipsia, nephrogenic diabetes insipidus, or neurogenic diabetes insipidus studied before therapy with antidiuretic hormone. Antibodies were detected in 6 of 28 patients studied during such treatments. All 6 patients reported decreased antidiuretic response to previously effective therapy with arginine or lysine vasopressin but had normal response to desmopressin or chlorpropamide. CONCLUSION: Diabetes insipidus does not result from spontaneously occurring antibodies to vasopressin. The antibodies occasionally develop during treatment with antidiuretic hormone and, when they do, almost always result in secondary resistance to its antidiuretic effect. Antibodies usually do not impair the response to other forms of therapy; they only rarely interfere with the diagnosis of diabetes insipidus, by falsely suggesting the presence of the partial nephrogenic form.