Three-dimensional piezoelectric fibrous scaffolds selectively promote mesenchymal stem cell differentiation

The discovery of electric fields in biological tissues has led to efforts in developing technologies utilizing electrical stimulation for therapeutic applications. Native tissues, such as cartilage and bone, exhibit piezoelectric behavior, wherein electrical activity can be generated due to mechanical deformation. Yet, the use of piezoelectric materials have largely been unexplored as a potential strategy in tissue engineering, wherein a piezoelectric biomaterial acts as a scaffold to promote cell behavior and the formation of large tissues. Here we show, for the first time, that piezoelectric materials can be fabricated into flexible, three-dimensional fibrous scaffolds and can be used to stimulate human mesenchymal stem cell differentiation and corresponding extracellular matrix/tissue formation in physiological loading conditions. Piezoelectric scaffolds that exhibit low voltage output, or streaming potential, promoted chondrogenic differentiation and piezoelectric scaffolds with a high voltage output promoted osteogenic differentiation. Electromechanical stimulus promoted greater differentiation than mechanical loading alone. Results demonstrate the additive effect of electromechanical stimulus on stem cell differentiation, which is an important design consideration for tissue engineering scaffolds. Piezoelectric, smart materials are attractive as scaffolds for regenerative medicine strategies due to their inherent electrical properties without the need for external power sources for electrical stimulation.

Higher autoantibody levels and recognition of a linear NH2-terminal epitope in the autoantigen GAD65, distinguish stiff-man syndrome from insulin-dependent diabetes mellitus

The smaller form of the GABA-synthesizing enzyme glutamic acid decarboxylase (GAD65) is a major autoantigen in two human diseases that affect its principal sites of expression. Thus, destruction of pancreatic beta cells, which results in insulin-dependent diabetes mellitus (IDDM), and impairment of GABA-ergic synaptic transmission in Stiff-Man syndrome (SMS) are both characterized by circulating autoantibodies to GAD65. Anti-GAD65 autoantibodies in IDDM are predominantly directed to conformational epitopes. Here we report the characterization of humoral autoimmune responses to GAD65 in 35 SMS patients, of whom 13 (37%) also had IDDM. All SMS patients immunoprecipitated native GAD65 and the main titers were orders of magnitude higher than in IDDM patients. Furthermore, in contrast to the situation in IDDM, autoantibodies in 35 of 35 (100%) of SMS patients recognized denatured GAD65 on Western blots. Two major patterns of epitope specificity were identified on Western blots. The first pattern, detected in 25 of 35 SMS patients (71%), of whom 11 had IDDM (44%), was predominantly reactive with a linear NH2-terminal epitope residing in the first eight amino acids of GAD65. Nine of nine individuals who were HLA-haplotyped in this group carried an IDDM susceptibility haplotype and HLA-DR3, DQw2 was particularly abundant. The second pattern, detected in 10 of 35 patients (29%) of whom two had IDDM (20%), included reactivity with the NH2-terminal epitope plus strong reactivity with one or more additional epitope(s) residing COOH-terminal to amino acid 101. The second epitope pattern may represent epitope spreading in the GAD65 molecule, but may also include some cases of epitope recognition associated with IDDM resistant HLA-haplotypes. The principal NH2-terminal linear epitope in GAD65 distinguishes the reactivity of SMS and IDDM autoantibodies and may be a determinant of pathogenicity for GABA-ergic neurons. The greater magnitude and distinct specificity of the humoral response to GAD65 in SMS may reflect a biased involvement of the T helper cell type 2 (Th2) subset of CD4+ T cells and antibody responses, whereas IDDM is likely mediated by the Th1 subset of CD4+ T cells and cytotoxic T cell responses.

The effect of employment on quality of life and community integration after traumatic brain injury

OBJECTIVES

To investigate the effect of employment on perceived quality of life (QOL), social integration, and home and leisure activities for individuals with traumatic brain injuries (TBIs).

DESIGN

A number of demographic and injury-related variables (age at injury, time since injury, severity of injury, education, gender, preinjury household income, and marital status) were analyzed for their association first with employment and then with the QOL, social integration, and home and leisure activities. Any of these variables showing significant associations were then included along with level of employment in three final multivariate analyses of variance (MANOVAs), again predicting QOL, social integration, and home and leisure activities.

SETTING

Urban, suburban, and rural New York state.

PARTICIPANTS

337 adults with TBI who resided in New York state and were between the ages of 18 and 65 years.

MAIN OUTCOME MEASURES

The Craig Handicap Assessment Capacity Technique, the Bigelow Quality of Life Questionnaire, the Flanagan Scale of Needs (adapted), and a global QOL measure.

RESULTS

Employment showed a strong and consistent relationship with perceived QOL, social integration within the community, and home and leisure activities. Part-time employment may have been superior to full-time employment for individuals with TBI: part-time workers had fewer unmet needs, were more socially integrated, and were more engaged in home activities than full-time workers. Loss of consciousness, as a measure of severity, was unexpectedly predictive of diminished sense of QOL for individuals with less severe injuries.

CONCLUSIONS

Being employed contributes to one"s sense of well-being, social integration, and pursuit of leisure and home activities. Select advantages of working part-time for individuals with TBI were identified.

Sleep, Sleep Disorders, and Mild Traumatic Brain Injury. What We Know and What We Need to Know: Findings from a National Working Group

Disturbed sleep is one of the most common complaints following traumatic brain injury (TBI) and worsens morbidity and long-term sequelae. Further, sleep and TBI share neurophysiologic underpinnings with direct relevance to recovery from TBI. As such, disturbed sleep and clinical sleep disorders represent modifiable treatment targets to improve outcomes in TBI. This paper presents key findings from a national working group on sleep and TBI, with a specific focus on the testing and development of sleep-related therapeutic interventions for mild TBI (mTBI). First, mTBI and sleep physiology are briefly reviewed. Next, essential empirical and clinical questions and knowledge gaps are addressed. Finally, actionable recommendations are offered to guide active and efficient collaboration between academic, industry, and governmental stakeholders.

Structural changes in PVDF fibers due to electrospinning and its effect on biological function

Polyvinylidine fluoride (PVDF) is being investigated as a potential scaffold for bone tissue engineering because of its proven biocompatibility and piezoelectric property, wherein it can generate electrical activity when mechanically deformed. In this study, PVDF scaffolds were prepared by electrospinning using different voltages (12-30 kV), evaluated for the presence of the piezoelectric β-crystal phase and its effect on biological function. Electrospun PVDF was compared with unprocessed/raw PVDF, films and melt-spun fibers for the presence of the piezoelectric β-phase using differential scanning calorimetry, Fourier transform infrared spectroscopy and x-ray diffraction. The osteogenic differentiation of human mesenchymal stem cells (MSCs) was evaluated on scaffolds electrospun at 12 and 25 kV (PVDF-12 kV and PVDF-25 kV, respectively) and compared to tissue culture polystyrene (TCP). Electrospinning PVDF resulted in the formation of the piezoelectric β-phase with the highest β-phase fraction of 72% for electrospun PVDF at 25 kV. MSCs cultured on both the scaffolds were well attached as indicated by a spread morphology. Cells on PVDF-25 kV scaffolds had the greatest alkaline phosphatase activity and early mineralization by day 10 as compared to TCP and PVDF-12 kV. The results demonstrate the potential for the use of PVDF scaffolds for bone tissue engineering applications.

Characterization and in vitro cytocompatibility of piezoelectric electrospun scaffolds

Previous studies have shown that electrical charges influence cell behavior (e.g. enhancement of nerve regeneration, cell adhesion, cell morphology). Thus, piezoelectric scaffolds might be useful for various tissue engineering applications. Fibrous scaffolds were successfully fabricated from permanent piezoelectric poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) by the electrospinning technique. Scanning electron microscopy and capillary flow analyses verified that the fiber mats had an average fiber diameter of 970 +/- 480 nm and a mean pore diameter of 1.7 microm, respectively. Thermally stimulated depolarization current spectroscopy measurements confirmed the piezoelectric property of the PVDF-TrFE fibrous scaffolds by the generation of a spontaneous current with the increase in temperature in the absence of an electric field, which was not detected in the unprocessed PVDF-TrFE powder. Differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction and Fourier transform infrared spectroscopy results showed that the electrospinning process increased the crystallinity and presence of the polar, beta-phase crystal compared with the unprocessed powder. Confocal fluorescence microscopy and a cell proliferation assay demonstrated spreading and increased cell numbers (human skin fibroblasts) over time on PVDF-TrFE scaffolds, which was comparable with tissue culture polystyrene. The relative quantity of gene expression for focal adhesion proteins (measured by real-time RT-PCR) increased in the following order: paxillin < vinculin < focal adhesion kinase < talin. However, no differences could be seen among the TCPS surface and the fibrous scaffolds. Future studies will focus on possible applications of these cytocompatible PVDF-TrFE scaffolds in the field of regenerative medicine.

Long-term intracaval calcium infusion therapy in end-organ resistance to 1,25-dihydroxyvitamin D

Two boys aged six and four with the syndrome of hereditary resistance to 1,25-dihydroxyvitamin D3 with rickets alopecia and growth retardation are presented. After unsuccessful therapeutic trials with pharmacologic doses of vitamin D or its active metabolites, the patients were treated by long-term intracaval infusions of calcium through an implantable catheter. A total of 0.5 to 0.9 g of elemental calcium was infused daily for 18 months and the serum calcium concentration was maintained at 9 to 10 mg/dl. Bone pain subsided within one week of treatment. Serum phosphorus, immunoreactive parathyroid hormone, and 1,25-dihydroxyvitamin D concentrations and alkaline phosphatase activity were normalized within four to nine months. Radiographs of the knees and hands revealed progressive healing of rickets with complete resolution after one year of treatment. The patients gained 12 cm and 8 cm per year in height as compared with 3 cm and 2 cm, respectively, in the previous year. A transilial bone biopsy obtained from one patient prior to treatment revealed severe osteomalacia associated with osteitis fibrosa. A follow-up biopsy examined after 12 months of therapy showed almost complete healing of osteomalacia and normal mineralization. These observations indicate the following: (1) Long-term intracaval calcium infusions are an effective mode of therapy for these patients, and (2) When adequate serum calcium and phosphorus concentrations are maintained, healing of rickets and normal growth rate could be achieved even in the absence of a normal 1,25-dihydroxyvitamin D3 receptor-effector system.

Water, electrolyte, and endocrine homeostasis in infants with bronchiolitis

Twenty-two of 23 consecutive infants with bronchiolitis, 5.5 +/- 3.5 mo of age, showed a 1.9 +/- 1.4% increase in body weight, increased urinary osmolality of 737 +/- 193 mmol/L with low plasma osmolality of 275 +/- 4 mmol/L, and markedly elevated plasma antidiuretic hormone (ADH) levels of 114 +/- 225 pg/mL. Increased ADH, which usually suppresses plasma renin activity, was associated with increased plasma renin activity of 11-55 ng angiotensin 1/mL/h (normal for age less than 10 ng angiotensin 1/mL/h). Hyperaldosteronism was evident from the low fractional excretion of sodium of 0.27 +/- 0.2% and high fractional excretion of potassium of 21 +/- 15%. Serum sodium concentrations were normal. All of the pathologic findings returned to normal when the bronchiolitis subsided. A control group of 10 infants with nonrespiratory febrile illness did not show any of the above abnormalities. Thus, bronchiolitis of infancy is characterized by both increased ADH secretion and hyperreninemia with secondary hyperaldosteronism, which induce water retention but counterbalance each other with respect to serum sodium. Increased ADH secretion as well as increased plasma renin activity are not "inappropriate," but rather suggest a response to the perception of hypovolemia by intrathoracic receptors. We therefore conclude that the clinical management of bronchiolitis requires close monitoring of body wt and plasma osmolality-urinary osmolality relationship; serum sodium levels may be misleading.

Motor function in the normal aging population: treatment with levodopa

In normal elderly humans there is progressive motor dysfunction and loss of nigrostriatal neurons and brain dopamine similar to, although of a milder degree than, that seen in Parkinson's disease. Ten healthy elderly volunteers were given carbidopa/levodopa or placebo in a double-blind crossover study. We measured movement velocity, reaction time, tremor, visual evoked response (VER), and electroretinography (ERG). Significant changes were seen only in ERG. Motor functions and VER were unchanged. Although there appeared to be pharmacologic activity (ie, changes in ERG), levodopa, in adequate antiparkinson dosage, had no impact on the mild extrapyramidal impairment of normal elderly subjects.

The effect of parental traumatic brain injury on parenting and child behavior

OBJECTIVES

To examine (1) the parenting skills of individuals with traumatic brain injury (TBI) and their spouses, (2) the effects of parental TBI on children, and (3) the effects of parental TBI on levels of depression for all family members.

DESIGN

Independent two-tailed t tests and Pearson chi-square analyses were utilized to compare parents with TBI versus parents without TBI, spouses of parents with TBI versus spouses of parents without TBI, and children of parents with TBI versus children of parents without TBI.

SETTING

Urban, suburban, and rural New York State.

PARTICIPANTS

32 families participated in the study; in 16 families one parent had a TBI and in the remaining 16 families, no parent had a TBI. Eighteen children from families with parental TBI and 26 children from families without TBI were interviewed. On average, parents with TBI were 9 years post-onset of injury at the time of interview.

MAIN OUTCOME MEASURES

The parents' battery explored parents' perspectives of their own parenting skills (Parent Behavior Form, Parent Practices Questionnaire, Parenting Dimensions Inventory), their mood (Beck Depression Inventory), and the behaviors of their children (Children's Problem Checklist, Behavior Rating Profile). The child's battery tapped the children's perspective of their own behaviors (Behavior Rating Profile), their mood (Children's Depression Inventory), and the parental abilities of both parents (Parent Behavior Form, Parent Practices Questionnaire).

RESULTS

Although parents with TBI and their spouses were similar to their comparison group in many parenting skills, parents with TBI reported less goal setting, less encouragement of skill development, less emphasis on obedience to rules and orderliness, less promotion of work values, less nurturing, and lower levels of active involvement with their children. Spouses of individuals with TBI, compared to their counterparts, reported less feelings of warmth, love, and acceptance toward their children. Children from families in which a parent had a TBI perceived both parents as more lax in their discipline, with the parent without TBI perceived as less actively involved in parenting roles. No differences in the frequency of behavioral problems were found between children of parents with TBI and children of parents without TBI. Parents with TBI and their children experienced more symptoms of depression relative to their respective comparison groups.

CONCLUSION

Parental TBI has select consequences for all family members: individuals with TBI, their spouses, and their children. Prospective clinical evaluations of family members and proactive interventions to maximize family adjustment and minimize affective distress are indicated.

Infrainguinal revascularization in end-stage renal disease

Patients with end-stage renal disease are being maintained for longer periods with dialysis or renal transplantation. Although renal failure itself is associated with occlusive peripheral vascular disease, such patients often have additional comorbid risk factors. In this series, 88% of patients were diabetic, 93% were hypertensive, and 44% were smokers, all factors that exacerbate the severity of their vasculopathy. As a consequence, the vascular surgeon is increasingly being confronted with limb-threatening peripheral vascular disease in this population. We performed 34 infrainguinal bypasses in 27 patients during a 8-year period from 1986 to 1993. Fifty percent of these were bypasses to the infrapopliteal level. The 12- and 48-month graft patency was 64% and 38%, respectively, by life-table analysis. The limb salvage rate was 65% and 58% at 12 and 48 months. The perioperative mortality rate was 5.9% and the morbidity rate was 37%. Most of the limb loss (66%) occurred during the first 3 months after surgery as a result of acute graft occlusion or nonhealing of an ulcer or minor amputation site. We believe that this reflects an increasingly aggressive approach to limb salvage in patients with end-stage renal disease. Four limbs were lost despite a patent graft. Infrainguinal bypass is a viable management option for limb salvage in patients with end-stage renal disease. These procedures can be undertaken with acceptable perioperative mortality and with a 12-month limb salvage rate of 65%.

Sleep Patterns of Infants and Young Children in Israel

The sleep habits of 661 Israeli children between the ages of 4 months and 4 years were described by their mothers. Twenty-eight per cent reported that their children woke up at least once a week. In the group of regular wakers, the mean number of interrupted nights per week was 4.7, and the mean number of awakenings per night was 2.0. Significant age-related changes in sleep patterns were indicated. The results of this study suggest that sleep and settling patterns in different sociocultural groups are quite similar. These data indicate the existence of an inherent pattern in the maturation of sleep behaviour in the developing child.

The influence of age on fibromyalgia symptoms

OBJECTIVES

Studies of the influence of age on health and well-being in chronically ill patients have produced mixed findings. This study examined young (20-39), middle-aged (40-59), and older (60-85) individuals with fibromyalgia (FMS), a chronic pain condition. The purpose of this study was to determine whether there were differences among the age groups in symptomatology and to examine potential mediating psychosocial variables.

METHODS

Participants were 600 (95% female, mean age = 54, SD = 11) diagnosed FMS patients who were members of a health maintenance organization. Multivariate analyses of covariance were used to examine differences.

RESULTS

There were significant differences among the age groups in most of the variables: With increasing age symptom duration increased but FMS symptomatology decreased. No age differences were found among the psychosocial mediators. The results suggest that the effects of FMS decrease over time.

Joint mobility and motor development

The association of joint hypermobility and motor development was sequentially investigated in 715 infants from the ages of 8 to 14 months. Seven joints were evaluated for mobility, and each infant underwent a physical and neurological examination. Parents were given a Denver Developmental Parents' Questionnaire. All subjects with a general developmental delay, systemic illness or syndrome were excluded. The infants were classified as having normal or delayed motor development with normal or delayed joint mobility. They were re-examined six months later. Multivariate statistical techniques was used for categorical analysis, and three joints were found to be significantly associated with motor delay at the first examination--hip abduction, elbow hyperextension, and foot dorsiflexion. Of the 715 infants, 126 had joint hypermobility and of these 38 (30.2%) had motor delay. Sixty four of 589 (10.9%) with normal joints had delayed motor development. Six months later 23 out of 35 of the group with joint hypermobility and 42 out of 53 of the group with normal joints had normal motor function. Joint hypermobility is associated with an increased incidence of motor delay in infancy. Over the ensuing six months most of the subjects will catch up. These findings, indicating a favourable prognosis, have implications regarding clinical assessment and parental counselling.