Integrated photoacoustic,ultrasound and fluorescence platform for diagnostic medical imaging-proof of concept study with a tissue mimicking phantom

The structural and molecular heterogeneities of biological tissues demand the interrogation of the samples with multiple energy sources and provide visualization capabilities at varying spatial resolution and depth scales for obtaining complementary diagnostic information. A novel multi-modal imaging approach that uses optical and acoustic energies to perform photoacoustic, ultrasound and fluorescence imaging at multiple resolution scales from the tissue surface and depth is proposed in this paper. The system comprises of two distinct forms of hardware level integration so as to have an integrated imaging system under a single instrumentation set-up. The experimental studies show that the system is capable of mapping high resolution fluorescence signatures from the surface, optical absorption and acoustic heterogeneities along the depth (>2cm) of the tissue at multi-scale resolution (<1µm to <0.5mm).OCIS codes: (110.5120) Photoacoustic imaging, (110.7170) Ultrasound, (170.2520) Fluorescence microscopy, (170.3880) Medical and biological imaging, (170.0110) Imaging systems, (170.3890) Medical optics instrumentation     

Analysis on the nature of thermally induced deformation in human dentine by electronic speckle pattern interferometry (ESPI)

Objective: To examine the in-plane and out-of-plane response of human dentine to thermal loads in real time.

Methods: An Electronic Speckle Pattern Interferometry (ESPI) system sensitive to both the in-plane and out-of-plane displacements was configured and used in conjunction with an advanced fringe processing technique. Specimens were prepared from freshly extracted lower central incisor teeth and were separately mounted on a thermal block to apply thermal loads from room temperature (25°C) to 60°C. The real time speckle patterns were acquired using a digital camera. These digital fringe patterns were subjected to further image processing to enhance the quality of fringes. The resultant images were later analyzed to study the out-of-plane and in-plane displacement gradients in the facio-lingual plane of the dentine.

Results: The out-of-plane deformations were observed in the plane perpendicular to the long axis of the tooth, while the in-plane deformations occurred in the plane parallel to the long axis of the tooth.

Conclusion: The ESPI analysis revealed whole-field and distinct thermal response in human dentine in-plane and out-of-plane. The cervical dentine experienced distinct and conspicuous displacement to the temperature changes.     

Klotho Deficiency Disrupts Hematopoietic Stem Cell Development and Erythropoiesis

Klotho deficiency is a characteristic feature of chronic kidney disease in which anemia and cardiovascular complications are prevalent. Disruption of the Klotho gene in mice results in hypervitaminosis D and a syndrome resembling accelerated aging that includes osteopenia and vascular calcifications. Given that the bone microenvironment and its cellular components considerably influence hematopoiesis, in the present study, we addressed the in vivo role of klotho in blood cell formation and differentiation. Herein, we report that genetic ablation of Klotho in mice results in a significant increase in erythropoiesis and a decrease in the hematopoietic stem cell pool size in the bone marrow, leading to impaired hematopoietic stem cell homing in vivo. Our data also suggest that high vitamin D levels are only partially responsible for these hematopoietic changes in Klotho^−/− mice. Importantly, we found similar hematopoietic abnormalities in Klotho^−/− fetal liver cells, suggesting that the effects of klotho in hematopoietic stem cell development are independent of the bone microenvironment. Finally, injection of klotho protein results in hematopoietic changes opposite to the ones observed in Klotho^−/− mice. These observations unveil a novel role for the antiaging hormone klotho in the regulation of prenatal and postnatal hematopoiesis and provide new insights for the development of therapeutic strategies targeting klotho to treat hematopoietic disorders associated with aging.Hematopoiesis is a complex and tightly regulated process of blood cell formation that is hierarchically coordinated. During normal hematopoiesis, diverse blood cell types are produced by the bone marrow (BM) in a manner related to physiologic requirement. Certain conditions may trigger additional production of blood cells. When the oxygen content of body tissues is low, the kidneys produce and release erythropoietin (Epo), a hormone that stimulates the BM to produce more red blood cells (RBCs). Aging is associated with disruption of normal hematopoiesis, resulting in an increase in the prevalence of anemia, the emergence of hematopoietic malignancies, and the development of leukemias.^1,2 Deterioration of vital organ function, such as kidney and heart, is also associated with age-related changes, as seen in chronic kidney disease (CKD) and cardiovascular disease (CVD).The antiaging hormone klotho, predominantly expressed in the kidneys, is emerging as a multifunctional protein regulating vital cellular functions.^3–5 Klotho was serendipitously discovered by Kuro-o et al⁶ when they observed symptoms of accelerated aging associated with a mutation in a specific gene in mice. Klotho exists in a membrane-bound form expressed at high levels in the kidney and, to a lesser extent, in other tissues, whereas a soluble form of klotho is secreted into blood, urine, and cerebrospinal fluid after cleavage of the extracellular domain.^7–10 Earlier studies convincingly demonstrate that membrane-bound klotho (α-klotho) is indispensable for signaling of the phosphatonin fibroblast growth factor 23 and that secreted klotho functions as an endocrine hormone responsible for the multiple organ defects observed in Klotho^−/− mice.^11–14Maintaining mineral ion homeostasis is critical and involves a delicate and concerted action between bone- and kidney-derived endocrine factors that operate through a complex feedback mechanism(s). Patients with CKD often present with bone diseases, such as osteopenia, osteoporosis, or osteomalacia, as a result of significant derangement of mineral metabolism.^15,16 In patients with CKD, failure of appropriate fibroblast growth factor 23/Klotho signaling results in hyperphosphatemia and vascular calcifications.¹⁷ Klotho expression is decreased progressively with loss of renal function,¹⁸ whereas blood levels of fibroblast growth factor 23 are elevated and are associated with increased CVD and mortality in these patients and in patients undergoing dialysis.^19–22 Moreover, abnormal blood cell production leading to severe anemia is a common complication in CKD and CVD and is caused by insufficient renal production of Epo.^23,24Disruption of the Klotho gene in mice due to mutations or inactivation (Klotho^−/− mice) results in growth retardation and early demise, osteopenia, extensive vascular calcifications, and skin atrophy, coupled with phosphate retention and hypervitaminosis D.^6,13,25–27 Conversely, overexpression of Klotho has been shown to rescue the klotho-deficient phenotype and extend the life span in mice, suggesting that Klotho functions as an aging suppressor gene in mammals.^6,28 Loss of klotho is further known to cause endothelial dysfunction by promoting oxidative stress.²⁹ It has been well appreciated that aging and oxidative stress adversely affect hematopoiesis by altering the niche functions.^30,31 An earlier report has also highlighted that klotho deficiency in mice results in reduced B lymphopoiesis, suggesting changes in immune regulatory functions by klotho.³² In addition, klotho expression at the mRNA level has been found to be significantly decreased in resting human CD4⁺ lymphocytes proportionally to advancing age.³³Signals emanating from the BM microenvironment and extrinsic soluble factors associated with the bone and marrow milieu are known to modulate hematopoietic stem cell (HSC) proliferation and differentiation.^34,35 Identifying the contributing factors involved in the regulation of hematopoiesis is an area of active research. Several lines of evidence highlight the role of bone-forming cells, the osteoblasts, in the HSC niche; postnatal depletion of osteoblasts negatively regulates the HSC pool size in the BM, whereas an increase in osteoblast number is associated with an augmentation in HSC number.^36–39 In addition, a series of advances indicate the importance of the bone-resorbing osteoclasts in regulation of the HSC microenvironment. Osteoclasts actively participate in HSC mobilization from the BM to the circulation and also promote formation of the HSC niche by controlling the maturation of osteoblasts.^40–44 Not only do bone cells participate in the regulation of hematopoiesis but the mineral content of the niche may also have a key function in localization of adult hematopoiesis, as reported in studies showing involvement of the calcium-sensing receptor and vitamin D signaling in this process.^45,46 Therefore, alterations in bone modeling and remodeling processes and/or mineralization seem to have a prominent effect on the modulation or formation of the hematopoietic niche. However, the regulation of mineral ion balance and hematopoiesis still remains largely a naive area.Because the bone environment and its components and the process of aging are closely linked to the regulation of hematopoiesis, and klotho deficiency is associated with a marked defect in skeletal mineralization and premature aging-like features, we hypothesized that klotho is involved in the regulation of RBC production and differentiation. In the present study, we demonstrate that loss of klotho severely affects erythropoiesis and HSC number and function. More important, we show that klotho affects hematopoiesis independently of changes in the BM environment and that the absence of klotho results in aberrant hematopoiesis prenatally, providing evidence for a novel and direct role for klotho in hematopoietic development. Although the kidney is the adult hematopoietic organ in zebra fish equivalent to mammalian BM,^47–49 the present data demonstrate for the first time, to our knowledge, a link between the kidney-bone-hematopoiesis axes in the mammalian system and attest that klotho is a key factor in the process of hematopoiesis.     

EEG Microstate Correlates of Fluid Intelligence and Response to Cognitive Training

The neurobiological correlates of human fluid intelligence (Gf) remain elusive. Here, we demonstrate that spatiotemporal dynamics of EEG activity correlate with baseline measures of Gf and with its modulation by cognitive training. EEG dynamics were assessed in 74 healthy participants by examination of fast-changing, recurring, topographically-defined electric patterns termed “microstates”, which characterize the electrophysiological activity of distributed cortical networks. We find that the frequency of appearance of specific brain topographies, spatially associated with visual (microstate B) and executive control (microstate C) networks, respectively, is inversely related to Gf scores. Moreover, changes in Gf scores with cognitive training are inversely correlated with changes in microstate properties, indicating that the changes in brain network dynamics are behaviorally relevant. Finally, we find that cognitive training that increases Gf scores results in a posterior shift in the topography of microstate C. These results highlight the role of fast-changing brain electrical states in individual variability in Gf and in the response to cognitive training.     

Sebaceous adenomas in an MYH associated polyposis patient of Indian (Gujarati) origin

MYH associated polyposis is an autosomal recessive polyposis syndrome with a high risk of large bowel cancer, caused by mutations in the DNA repair gene MYH. Founder mutations have been described in different ethnic groups. Muir Torre Syndrome is the association of internal malignancies with sebaceous gland tumours; Lynch Syndrome/Hereditary Non Polyposis Cancer is the best known cause. There has been a previous report of sebaceous gland tumours in an Italian patient with MYH associated polyposis. We describe a man of Indian (Gujarati) descent who has MYH associated polyposis and multiple sebaceous adenomas of the skin.     

Red, green, and blue gray-value shift-based approach to whole-field imaging for tissue diagnostics

Identification of abnormal pathology in situ remains one of the challenges of medicine. The interpretation of tissue conditions relies mainly on optical assessment, which can be difficult due to inadequate visual differences or poor color delineation. We propose a methodology to identify regions of abnormal tissue in a targeted area based on red, green, blue (RGB) shift analysis employing a simple CCD color camera and light-emitting diode illumination in a whole-field-imaging scheme. The concept involves analysis of RGB components in an image with respect to a reference set of RGB values under different illumination wavelengths. The magnitude of the gray value shift is estimated by calculating the Euclidean distance between their normalized RGB coordinates. The shift values obtained using these concepts are thereafter used to construct pseudo-colored images with high contrast, enabling easy identification of abnormal areas in the tissue. Images processed from experiments conducted with excised Wistar rat colon sample (lightly doped with Alexafluor 488) and with simulated tumor (cancer cell pellet placed on colon) showed clear localization of tumor region. This proposed approach and methodology is expected to find potential applications for the in vivo diagnosis of disease.