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Articles by Laura Chalmers in JoVE

 JoVE Bioengineering

Electric Field-controlled Directed Migration of Neural Progenitor Cells in 2D and 3D Environments


JoVE 3453 2/16/2012

1School of Dentistry, Cardiff Institute of Tissue Engineering & Repair, Cardiff University, 2Shandong Qianfoshan Hospital, Shandong University School of Medicine, 3Dermatology and Ophthalmology Research, Institute for Regenerative Cures, University of California at Davis

This protocol demonstrates methods used to establish 2D and 3D environments in custom-designed electrotactic chambers, which can track cells in vivo/ex vivo using time-lapse recording at the single cell level, in order to investigate galvanotaxis/electrotaxis and other cellular responses to direct current (DC) electric fields (EFs).

Other articles by Laura Chalmers on PubMed

Type 2 Diabetes in Children: Oxymoron or Medical Metamorphosis?

The full public health effects of the new epidemic of obesity and diabetes in children and adolescents may not be known for many years but are certain to be substantial. Diagnosed diabetes, which is present in only 4.2% of the US population, along with its consequences, already represents approximately 19% of the total personal healthcare expenditures in this country. Between 1997 and 2002, the estimated direct medical cost of diabetes increased from 44 billion dollars to 92 billion dollars, a staggering increase of 8 billion dollars a year. In 2002, diabetes annual costs per capita rose by more than 30% to 13,243 dollars per person, compared with the average annual health care costs for persons without diabetes of 2560.92 dollars. An estimate from the CDC indicates that approximately one-third of children born in 2000 will develop diabetes at some time in their life, and nearly one-half of all Hispanic children born in 2000 will develop diabetes. As type 2 diabetes is being diagnosed at an earlier age, more young people can expect to live many more years with diabetes and its complications, adding even further to this already enormous health burden. An appropriate starting place is recognition of the magnitude of the problem by physicians, politicians, public health policy makers, and other healthcare workers. An aggressive approach to management of diabetes must begin well before the appearance of cardiovascular, eye, renal, and other complications of diabetes appear, and even before obesity leads to diabetes. Currently, physicians and other healthcare workers are poorly reimbursed for management of obesity, for diabetes education, and for ongoing telephone contact with diabetic patients and families, essential for optimal diabetes management. National policies and priorities must be readjusted to emphasize prevention, rather than crisis management, if we are to avoid a catastrophic public health crisis within the next several decades.

The Role of Obesity and Its Bioclinical Correlates in the Progression of Chronic Kidney Disease

In spite of a progressive fall in the incidence of traditional risk factors of cardiovascular morbidity (cigarette smoking, high blood pressure, and hyperlipidemia), there is an upward trend in the prevalence of obesity and chronic kidney disease (CKD). Furthermore, there is a strong correlation between body mass indices and the relative risk of progression of CKD. The close biophysiological interaction between obesity and CKD is evident by a similar occurrence of comorbidities including insulin resistance, hyperlipidermia, endothelial dysfunction, and sleep disorders. Truncal obesity is a primary component of metabolic syndrome; unlike peripheral fat, the visceral adipocytes are more resistant to insulin. In addition, lipolysis results in a release of free fatty acid and TG, whereas hypertriglycedemia is potentiated by uremic activation of fatty acid synthase. Hypertriglycedemia and low HDL cholesterol increase the relative risk of progression of CKD. Furthermore, endothelial inflammation and premature atherosclerosis are promoted by hyperhomocysteinemia and oxidation of LDL, both of which are commonly observed in CKD and obesity. Predominance of oxidative stress in both obesity and azotemia stimulate synthesis of angiotensin II, which in turn increases TGF-B and plasminogen activator inhibitor-1, thereby propagating glomerular fibrosis. Furthermore, local synthesis of angiotensinogen by adipocytes, leptin activation of sympathetic nervous system, and hyperinsulinemia contribute to the development of hypertension in obesity and CKD. In addition, increased renal tubular expression of Na-K-ATPase and a blunted response to natiuretic hormones in obesity promote salt and water retention. Glomerular hyperfiltration from systemic volume load and hypertension results in mesangial cellular proliferation and progressive renal fibrosis. In addition, maternal nutritional deprivation increases the incidence of obesity, hypertension, and diabetes in adulthood. Reduced fetal protein synthesis contributes to oxidative glomerular injury and impairment of renal morphogenesis. Thus, kidneys are poorly equipped to handle physiologic stress that may result from the rapid body growth and programmed metabolic dysfunction later in life. Finally, in order to minimize morbidity of obesity-related kidney disease, preventive strategy must include optimal maternal health care, promotion of healthy nutrition and routine physical exercise, and early detection of CKD.

Prolongation of Growth by Treatment of 11-hydroxylase Deficiency with Depot-leuprolide, Growth Hormone, and Hydrocortisone

A 4-10/12 year-old boy presented with tall stature and advanced secondary sexual characteristics. His bone age was 13 years giving him a height prediction of 147 cm. An initial 11-deoxycortisol level of 13,770 ng/dl and associated hypertension suggested the diagnosis of 11-hydroxylase deficiency, which was confirmed by dexamethasone suppression and genotyping. Treatment strategy was based on the premise that known hypothalamic priming resulting in early pubertal development could be averted by delaying puberty with leuprolide; also that effects of hydrocortisone and leuprolide on attenuating growth could be counteracted by growth hormone. The combined treatment resulted in a final height at age 12 years which was 25.4 cm greater than predicted, and bone density above average. We conclude that delaying puberty until an appropriate age, offsetting growth suppression, and improving bone mineralization can be effectively achieved using glucocorticoids, leuprolide and growth hormone in patients with 11-hydroxylase deficiency.

Activating Autoantibodies to the Beta-1 Adrenergic and M2 Muscarinic Receptors Facilitate Atrial Fibrillation in Patients with Graves' Hyperthyroidism

We studied activating autoantibodies to beta-1 adrenergic receptors (AAbeta1AR) and activating autoantibodies to M2 muscarinic receptors (AAM2R) in the genesis of atrial fibrillation (AF) in Graves' hyperthyroidism.

An Evidence-Based Model of Multidisciplinary Care for Patients and Families Affected by Classical Congenital Adrenal Hyperplasia Due to 21-Hydroxylase Deficiency

In 2002 a consensus statement pertaining to the management of classical congenital adrenal hyperplasia due to 21-hydroxylase deficiency was jointly produced by the Lawson Wilkins Pediatric Endocrine Society and the European Society of Pediatric Endocrinology. One of the recommendations of this consensus was that centers should maintain multidisciplinary teams for providing care and support to these patients and their families. However, the specifics for how this should be accomplished were not addressed in the original consensus statement. Here we interpret and translate the 2002 consensus statement recommendations into medical, surgical and mental health protocols. Additionally, we provide preliminary evidence that such protocols result in improved care and support for patients and families.

Paradoxical Increase in Arterial Compliance in Obese Pubertal Children

We determined whether arterial compliance measured by pulse wave analysis is impaired in obese pubertal children compared to normal weight controls, and assessed whether arterial compliance is associated with ambulatory activity. Body fat percentage was significantly different between the normal (n = 33) and obese (n = 34) participants (P < .001). Large (P = .012) and small (P < .001) arterial compliance were lower in the normal-weight group. After adjusting for height, systolic and diastolic blood pressure, race, sex, and Tanner stage, large arterial compliance was no longer different between groups (P = .066), whereas small arterial compliance remained higher in the obese group (P < .001). Obese pubertal children have paradoxically increased small arterial compliance compared to that of normal weight children, even after adjusting for height, blood pressure, race, sex, and Tanner stage. Thus, obesity in adolescence is not associated with impairments in small arterial compliance.

Normal Sex Differences in Prenatal Growth and Abnormal Prenatal Growth Retardation Associated with 46,XY Disorders of Sex Development Are Absent in Newborns with Congenital Adrenal Hyperplasia Due to 21-hydroxylase Deficiency

Congenital adrenal hyperplasia due to 21-hydroxylase deficiency is the most common presentation of a disorder of sex development (DSD) in genetic females. A report of prenatal growth retardation in cases of 46,XY DSD, coupled with observations of below-optimal final height in both males and females with congenital adrenal hyperplasia due to 21-hydroxylase deficiency, prompted us to investigate prenatal growth in the latter group. Additionally, because girls with congenital adrenal hyperplasia are exposed to increased levels of androgens in the absence of a male sex-chromosome complement, the presence or absence of typical sex differences in growth of newborns would support or refute a hormonal explanation for these differences.

Electrical Signaling in Control of Ocular Cell Behaviors

Epithelia of the cornea, lens and retina contain a vast array of ion channels and pumps. Together they produce a polarized flow of ions in and out of cells, as well as across the epithelia. These naturally occurring ion fluxes are essential to the hydration and metabolism of the ocular tissues, especially for the avascular cornea and lens. The directional transport of ions generates electric fields and currents in those tissues. Applied electric fields affect migration, division and proliferation of ocular cells which are important in homeostasis and healing of the ocular tissues. Abnormalities in any of those aspects may underlie many ocular diseases, for example chronic corneal ulcers, posterior capsule opacity after cataract surgery, and retinopathies. Electric field-inducing cellular responses, termed electrical signaling here, therefore may be an unexpected yet powerful mechanism in regulating ocular cell behavior. Both endogenous electric fields and applied electric fields could be exploited to regulate ocular cells. We aim to briefly describe the physiology of the naturally occurring electrical activities in the corneal, lens, and retinal epithelia, to provide experimental evidence of the effects of electric fields on ocular cell behaviors, and to suggest possible clinical implications.

A Model of Delivering Multi-disciplinary Care to People with 46 XY DSD

In 2006, a consensus statement was jointly produced by the Lawson Wilkins Pediatric Endocrine Society (LWPES) and the European Society of Paediatric Endocrinology (ESPE) concerning the management of disorders of sex development (DSD) [1]. A recommendation provided by this consensus was that evaluation and long-term care for people affected by DSD should be performed at medical centers with multi-disciplinary teams experienced in such conditions. Here we provide our team's interpretation of the 2006 consensus statement recommendations and its translation into a clinical protocol for individuals affected by 46 XY DSD with either female, or ambiguous, genitalia at birth. Options for medical and surgical management, transitioning of care, and the use of mental health services and peer support groups are discussed. Finally, we provide preliminary data to support the application of our model for delivering multi-disciplinary care and support to patients and their families.

Insulin Edema in a Patient with Cystic Fibrosis-related Diabetes

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