MC3T3 infiltration and proliferation in bovine trabecular scaffold regulated by dynamic flow bioreactor and augmented by low-intensity pulsed ultrasound.

BACKGROUND: Low-intensity pulsed ultrasound (LIPUS) has been used in both basic research and clinical settings for its therapeutic potential in promoting tissue healing. Clinical data has shown that LIPUS can accelerate fresh fracture healing. However, the treatment for aging osteoporosis and non-union is still unclear. In addition, the mechanism of ultrasound promoted bone healing has remained unknown. OBJECTIVE: It is proposed that noninvasive ultrasound treatment can enhance local fluid flow within the tissue to initiate remodeling and regeneration. The goal of this study was to evaluate the effects of dynamic ultrasound in promoting cellular mechanotransduction within bioengineered organic scaffolds to trigger osteogenesis and mineralization. METHODS: The experiment was designed in two-fold: to evaluate the role of LIPUS on osteoblastic-like (MC3T3) cell proliferation and mineralization in response to acoustic waves, using biomechanical rate-dependent signals in a bioreactor; and, to evaluate the new scaffold experimentation techniques, in order to generate a potential implantable biomaterial for orthopedic tissue regeneration and repair. RESULTS: LIPUS treatment on MC3T3 cells yielded enhanced cellular mineralization (**p < 0.001) in 3-D scaffolding, but reduced the total cell numbers (*p < 0.05), using Alizarin Red staining and cell counting analyses, respectively, in comparison to the control. CONCLUSION: This study suggests that LIPUS, if applied at proper frequency and duty cycle, can promote cell mineralization within the 3-D organic scaffold under in vitro setting. The translational component of this experiment seeks to draw a parallel to the potential pre-treatment of scaffolds for implantation before orthopedic surgery, which could prove to greatly benefit the patient in accelerating fracture healing and tissue regeneration. THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE: LIPUS stimulation was critical in contributing to the mechanical signaling transductions that activated bone enhancement parameters in MC3T3 cells regulated by bioreactor, and thus has potential to change how we pretreat scaffolds for orthopedic surgery and noninvasively accelerate healing in the future, e.g., in an extreme condition such as long-term space mission.

Acute Encephalitis in an Adult with Diffuse Large B-Cell Lymphoma with Secondary Involvement of the Central Nervous System: Infectious or Non-Infectious Etiology?

Both infectious and non-infectious etiologies of acute encephalitis have been described, as well as their specific presentations, diagnostic tests, and therapies. Classic findings of acute encephalitis include altered mental status, fever, and new lesions on neuroimaging or electroencephalogram (EEG). We report an interesting case of a 61-year-old male with a history of diffuse large B-cell lymphoma with secondary involvement of the central nervous system (SCNS-DLBCL). He presented with acute encephalitis: altered mental status, fever, leukocytosis, neuropsychiatric symptoms, multiple unchanged brain lesions on computed tomography scan of the head, and EEG showed mild to moderate diffuse slowing with low-moderate polymorphic delta and theta activity. With such a wide range of symptoms, the differential diagnosis included paraneoplastic and autoimmune encephalitis. Infectious and autoimmune/paraneoplastic encephalitis in patients with SCNS-DLBCL are not well documented in the literature, hence diagnosis and therapy becomes challenging. This case report describes the patient's unique presentation of acute encephalitis.

Obsessive-Compulsive Disorder in a 19-Year-Old Female Adolescent With Turner Syndrome.

Obsessive-compulsive disorder (OCD) in patients with Turner syndrome (TS) is an uncommon neuropsychiatric presentation that has not been well characterized in the scientific literature. Though no clear psychiatric component is syndromic to TS, the clinical manifestations of certain neuropsychiatric disorders, including mood, anxiety and eating disorders, have all been well documented in patients with TS. However, the presence of OCD in these patients has not been previously described. This report details a 19-year-old TS patient who presented with OCD since the age of 13, comorbid with several other psychiatric pathologies, including bipolar I disorder, anorexia nervosa and attention deficit hyperactivity disorder (ADHD). It will also discuss those comorbidities in relation to the patient's genetic syndrome and mention the contribution it makes to her multiple disabilities diagnosis as well as her patient-specific therapy. Patients with TS often present to treating physicians for overwhelming somatic complaints, likely resulting in poor recognition of psychiatric disorders. Thus, OCD may be significantly under-diagnosed in patients with TS and should be explored by clinicians treating this vulnerable population.

Regulation of bone remodeling by vasopressin explains the bone loss in hyponatremia.

Although hyponatremia is known to be associated with osteoporosis and a high fracture risk, the mechanism through which bone loss ensues has remained unclear. As hyponatremic patients have elevated circulating arginine-vasopressin (AVP) levels, we examined whether AVP can affect the skeleton directly as yet another component of the pituitary-bone axis. Here, we report that the two Avp receptors, Avpr1α and Avpr2, coupled to Erk activation, are expressed in osteoblasts and osteoclasts. AVP injected into wild-type mice enhanced and reduced, respectively, the formation of bone-resorbing osteoclasts and bone-forming osteoblasts. Conversely, the exposure of osteoblast precursors to Avpr1α or Avpr2 antagonists, namely SR49059 or ADAM, increased osteoblastogenesis, as did the genetic deletion of Avpr1α. In contrast, osteoclast formation and bone resorption were both reduced in Avpr1α(-/-) cultures. This process increased bone formation and reduced resorption resulted in a profound enhancement of bone mass in Avpr1α(-/-) mice and in wild-type mice injected with SR49059. Collectively, the data not only establish a primary role for Avp signaling in bone mass regulation, but also call for further studies on the skeletal actions of Avpr inhibitors used commonly in hyponatremic patients.

Genetic confirmation for a central role for TNFα in the direct action of thyroid stimulating hormone on the skeleton.

Clinical data showing correlations between low thyroid-stimulating hormone (TSH) levels and high bone turnover markers, low bone mineral density, and an increased risk of osteoporosis-related fractures are buttressed by mouse genetic and pharmacological studies identifying a direct action of TSH on the skeleton. Here we show that the skeletal actions of TSH deficiency are mediated, in part, through TNFα. Compound mouse mutants generated by genetically deleting the Tnfα gene on a Tshr(-/-) (homozygote) or Tshr(+/-) (heterozygote) background resulted in full rescue of the osteoporosis, low bone formation, and hyperresorption that accompany TSH deficiency. Studies using ex vivo bone marrow cell cultures showed that TSH inhibits and stimulates TNFα production from macrophages and osteoblasts, respectively. TNFα, in turn, stimulates osteoclastogenesis but also enhances the production in bone marrow of a variant TSHß. This locally produced TSH suppresses osteoclast formation in a negative feedback loop. We speculate that TNFα elevations due to low TSH signaling in human hyperthyroidism contribute to the bone loss that has traditionally been attributed solely to high thyroid hormone levels.

Vitamin C prevents hypogonadal bone loss.

Epidemiologic studies correlate low vitamin C intake with bone loss. The genetic deletion of enzymes involved in de novo vitamin C synthesis in mice, likewise, causes severe osteoporosis. However, very few studies have evaluated a protective role of this dietary supplement on the skeleton. Here, we show that the ingestion of vitamin C prevents the low-turnover bone loss following ovariectomy in mice. We show that this prevention in areal bone mineral density and micro-CT parameters results from the stimulation of bone formation, demonstrable in vivo by histomorphometry, bone marker measurements, and quantitative PCR. Notably, the reductions in the bone formation rate, plasma osteocalcin levels, and ex vivo osteoblast gene expression 8 weeks post-ovariectomy are all returned to levels of sham-operated controls. The study establishes vitamin C as a skeletal anabolic agent.

MMP-9/TIMP-1 imbalance induced in human dendritic cells by Porphyromonas gingivalis.

Matrix metalloproteinase-9 (MMP-9) cleaves collagen, allowing leukocytes to traffic toward the vasculature and the lymphatics. When MMP-9 is unregulated by tissue inhibitor of metalloproteinase-1 (TIMP-1), this can lead to tissue destruction. Dendritic cells (DCs) infiltrate the oral mucosa increasingly in chronic periodontitis, characterized by infection with several pathogens including Porphyromonas gingivalis. In this study, human monocyte-derived DCs were pulsed with different doses of lipopolysaccharide of P. gingivalis 381 and of Escherichia coli type strain 25922, as well as whole live isogenic fimbriae-deficient mutant strains of P. gingivalis 381. Levels of induction of MMP-9 and TIMP-1, as well as interleukin-10 (IL-10), which reportedly inhibits MMP-9 induction, were measured by several approaches. Our results reveal that lipopolysaccharide of P. gingivalis, compared with lipopolysaccharide from E. coli type strain 25922, is a relatively potent inducer of MMP-9, but a weak inducer of TIMP-1, contributing to a high MMP-9/TIMP-1 ratio.Whole live P. gingivalis strain 381, major fimbriae mutant DPG-3 and double mutant MFB were potent inducers of MMP-9, but minor fimbriae mutant MFI was not. MMP-9 induction was inversely proportional to IL-10 induction. These results suggest that lipopolysaccharide and the minor and the major fimbriae of P. gingivalis may play distinct roles in induction by DCs of MMP-9, a potent mediator of local tissue destruction and leukocyte trafficking.

Oxytocin deficiency impairs maternal skeletal remodeling.

We have reported that the posterior pituitary hormone, oxytocin (OT), known for its effects in inducing parturition, lactation and social bonding, is also a skeletal hormone. Here, we demonstrate that OT plays a key role in enabling maternal skeletal mobilization during pregnancy by enhancing the formation of bone resorbing osteoclasts. Osteoclast formation ex vivo is thus diminished in pregnant mothers with genetic OT-deficiency. OT(-/-) pups at day E20 also show a defect in trabecular bone. microCT measurements reveal normal bone volume, but increased trabecular numbers, suggesting that trabeculae in OT(-/-) pups are hypomineralized. We suggest that OT facilitates intergenerational transfer of calcium ions from a pregnant mother to the pups.

Thyroid-stimulating hormone, thyroid hormones, and bone loss.

It has become accepted by virtue of rich anecdotal experience and clinical research that thyrotoxicosis is associated with high-turnover osteoporosis. The bone loss, primarily due to accelerated resorption that is not compensated by a coupled increase in bone formation, has been attributed solely to elevated thyroid hormone levels. Evidence using mice lacking the thyroid hormone receptors alpha and beta establishes a role for thyroid hormones in regulating bone remodeling but does not exclude an independent action of thyroid-stimulating hormone (TSH), levels of which are low in hyperthyroid states, even when thyroid hormones are normal, as after thyroxine supplementation and in subclinical hyperthyroidism. We show that TSH directly suppresses bone remodeling and that TSH receptor null mice have profound bone loss, suggesting that reduced TSH signaling contributes to hyperthyroid osteoporosis. TSH and its receptor could become valuable drug targets in treating bone loss.