Aug
12
Mon
2013
Invited Talk: Osteoarthritis: diagnosis, treatment and challenges @ Acharya Hall
Aug 12 @ 11:42 am – 12:07 pm

hideakiHideaki Nagase, Ph.D.
Kennedy Institute of Rheumatology-Centre for Degenerative Diseases, University of Oxford, UK


Osteoarthritis: diagnosis, treatment and challenges

Hideaki Nagase1, Ngee Han Lim1, George Bou-Gharios1, Ernst Meinjohanns2  and Morten Meldal3

  1. Kennedy Institute of Rheumatology, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, London, W6 8LH  UK
  2. Carlsberg Laboratory, Copenhagen, Denmark,
  3. Nano-Science Center, Department of Chemistry, University of Copenhagen, Denmark

Osteoarthritis (OA) is the most prevalent age-related degenerative joint disease. With the expanding ageing population, it imposes a major socio-economic burden on society.  A key feature of OA is a gradual loss of articular cartilage and deformation of bone, resulting in the impairment of joint function. Currently, there is no effective disease-modifying treatment except joint replacement surgery. There are many possible causes of cartilage loss (e.g. mechanical load, injury, reactive oxygen species, aging, etc.) and etiological factors (obesity, genetics), but the degradation of cartilage is primarily caused by elevated levels of active metalloproteinases.  It is therefore attractive to consider proteinase inhibitors as potential therapeutics. However, there are several hurdles to overcome, namely early diagnosis and continuous monitoring of the efficacy of inhibitor therapeutics. We are therefore aiming at developing non-invasive probes to detect cartilage degrading metalloproteinase activities.

We have designed in vivo imaging probes to detect MMP-13 (collagenase 3) activity that participates in OA by degrade cartilage collagen II and MMP-12 (macrophage elastase) activity involved in inflammatory arthritis. These activity-based probes consist of a peptide that is selectively cleaved by the target proteinase, a near-infrared fluorophore and a quencher. The probe’s signal multiplies upon proteolysis.  They were first used to follow the respective enzyme activity in vivo in the mouse model of collagen-induced arthritis and we found MMP-12 activity probe (MMP12AP) activation peaked at 5 days after onset of the disease, whereas MMP13AP activation was observed at 10-15 days. The in vivo activation of these probes was inhibited by specific low molecule inhibitors.  We proceeded to test both probes in the mouse model of OA induced by the surgical destabilization of medial meniscus of the knee joints.  In this model, degradation of knee cartilage is first detected histologically 6 weeks after surgery with significant erosion detectable at 8 weeks. Little activation of MMP12AP was detected, which was expected, as macrophage migration is not obvious in OA. MMP13AP, on the other hand, was significantly activated in the operated knee at 6 weeks compared with the non-operated contralateral knee, but there were no significant differences between the operated and sham-operated knees.  At 8 weeks, however, the signals in the operated knees were significantly higher than both the contralateral and sham-operated controls. Activation of aggrecanases and MMP-13 are observed before structural changes of cartilage. We are therefore currently improving the MMP-13 probe for earlier detection by attaching it to polymers that are retained in  cartilage.

 

Invited Talk: Functional MR Imaging of the brain: An Overview
Aug 12 @ 11:51 am – 12:17 pm

claudiaClaudia AM Wheeler-Kingshott, Ph.D.
University Reader in Magnetic Resonance Physics, Department of Neuroinflammation, UCL Institute of Neurology, London, UK


Abstract

Detecting neuronal activity in vivo non-invasively is possible with a number of techniques. Amongst these, in 1990 functional magnetic resonance imaging (fMRI) was proposed as a technique that has a great ability to spatially map brain activity by exploiting the blood oxygenation level dependent (BOLD) contrast mechanism [1, 2]. In fact, neuronal activation triggers a demand for oxygen and induces a localised increase in blood flow and blood volume, which actually exceeds the metabolic needs. This in turns causes an increase of oxyhaemoglobin in the venous compartment, which is a transient phenomenon and is accompanied by a transient change (decrease) in the concentration of deoxyhaemoglobin. Due to its paramagnetic properties, the amount of deoxyhaemoglobin present in the venous blood affects the local magnetic field seen by the spins (protons) and determines the local properties of the MR signal. A decrease in deoxyhaemoglobin during neuronal activity, therefore, induces local variations of this magnetic field that increases the average transverse relaxation time of tissue, measured via the T2* parameter [3]. This means that there is an increase of the MR signal (of the order of a few %, typically <5%) linked to metabolic changes happening during brain function. Activation can be inferred at different brain locations by performing tasks while acquiring the MR signal and comparing periods of rest to periods of activity.

The macroscopic changes of the BOLD signal are well characterised, while the reason for the increased blood supply, exceeding demands, needs further thoughts. Here we will discuss two approaches for explaining the BOLD phenomenon, one that links it to adenosine triphosphate production [4] and enzyme saturation, the other that relates it to the very slow diffusion of oxygen through the blood-brain-barrier with a consequent compensatory high demand of oxygen [5]. Some evidence of restricted oxygen diffusion has been shown by means of hypercapnia [6], although it is not excluded that both mechanisms may be present.

Overall, the BOLD signal changes theory and its physiological basis will be presented and discussed.

References

  1. Ogawa, S., et al., Brain magnetic resonance imaging with contrast dependent on blood oxygenation. Proc Natl Acad Sci U S A, 1990. 87(24): p. 9868-72.
  2. Kwong, K.K., et al., Dynamic magnetic resonance imaging of human brain activity during primary sensory stimulation. Proc Natl Acad Sci U S A, 1992. 89(12): p. 5675-9.
  3. Bandettini PA, et al. Spin-echo and gradient-echo EPI of human brain activation using BOLD contrast: a comparative study at 1.5 T. NMR Biomed. 1994 Mar;7(1-2):12-20
  4.  Fox, P.T., et al., Nonoxidative glucose consumption during focal physiologic neural activity. Science, 1988. 241(4864): p. 462-4.
  5. Gjedde, A., et al. Reduction of functional capillary density in human brain after stroke. J Cereb Blood Flow Metab, 1990. 10(3): p. 317-26.
  6. Hoge, R.D., et al., Linear coupling between cerebral blood flow and oxygen consumption in activated human cortex. Proc Natl Acad Sci U S A, 1999. 96(16): p. 9403-8.

Invited Talk: Neuroprotective and neurodestructive effects of Ayurvedic drug constituents: Parkinson’s disease @ Amriteshwari Hall
Aug 12 @ 2:55 pm – 3:20 pm

mohanakumarK. P. Mohanakumar, Ph.D.
Chief Scientist, Cell Biology & Physiology Division, Indian Institute of Chemical Biology, Kolkata


Neuroprotective and neurodestructive effects of Ayurvedic drug constituents: Parkinson’s disease

The present study reports the good and the bad entities in an Indian traditional medicine used for treating Parkinson’s disease (PD). A prospective clinical trial on the effectiveness of Ayurvedic medication in a population of PD patients revealed significant benefits, which has been attributed to L-DOPA present in the herbs [1]. Later studies revealed better benefits with one of the herbs alone, compared to pure L-DOPA in a clinical trial conducted in UK [2], and in several studies conducted on animal models of PD in independent laboratories world over [3-5]. We have adapted strategies to segregate molecules from the herb, and then carefully removed L-DOPA contained therein, and tested each of these sub-fractions for anti-PD activity in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, rotenone and 6-hydroxydopamine -induced parkinsonian animal models, and transgenic mitochondrial cybrids. We report here two classes of molecules contained in the herb, one of which possessed severe pro-parkinsonian (phenolic amine derivatives) and the other having excellent anti-parkinsonian potential (substituted tetrahydroisoquinoline derivatives). The former has been shown to cause severe dopamine depletion in the striatum of rodents, when administered acutely or chronically. It also caused significant behavioral aberrations, leading to anxiety and depression [6]. The latter class of molecules administered in PD animal model [7], caused reversal of behavioral dysfunctions and significant attenuation of striatal dopamine loss. These effects were comparable or better than the effects of the anti-PD drugs, selegiline or L-DOPA. The mechanism of action of the molecule has been found to be novel, at the postsynaptic receptor signaling level, as well as cellular α-synuclein oligomerization and specifically at mitochondria. The molecule helped in maintaining mitochondrial ETC complex activity and stabilized cellular respiration, and mitochondrial fusion-fission machinery with specific effect on the dynamin related protein 1. Although there existed significant medical benefits that could be derived to patients due to the synergistic actions of several molecules present in a traditional preparation, accumulated data in our hands suggest complicated mechanisms of actions of Ayurvedic medication. Our results also provide great hope for extracting, synthesizing and optimizing the activity of anti-parkinsonian molecules present in traditional Ayurvedic herbs, and for designing novel drugs with novel mechanisms of action.

  1. N, Nagashayana, P Sankarankutty, MRV Nampoothiri, PK Mohan and KP Mohanakumar, J Neurol Sci. 176, 124-7, 2000.
  2. Katzenschlager R, Evans A, Manson A, Patsalos PN, Ratnaraj N, Watt H, Timmermann L, Van der Giessen R, Lees AJ. J Neurol Neurosurg Psychiatry.75, 1672-7, 2004.
  3. Manyam BV, Dhanasekaran M, Hare TA. Phytother Res. 18, 706-12, 2004.
  4. Kasture S, Pontis S, Pinna A, Schintu N, Spina L, Longoni R, Simola N, Ballero M, Morelli M. Neurotox Res. 15, 111-22, 2009.
  5. Lieu CA, Kunselman AR, Manyam BV, Venkiteswaran K, Subramanian T. Parkinsonism Relat Disord.16, 458-65, 2010.
  6. T Sengupta and KP Mohanakumar, Neurochem Int. 57, 637-46, 2010.
  7. T Sengupta, J Vinayagam, N Nagashayana, B Gowda, P Jaisankar and KP Mohanakumar, Neurochem Res 36, 177-86, 2011

MOhan (1) MOhan (2)

Aug
13
Tue
2013
Plenary Talk: Biosensor and Single Cell Manipulation using Nanopipettes @ Amriteshwari Hall
Aug 13 @ 10:06 am – 10:49 am

NaderNader Pourmand, Ph.D.
Director, UCSC Genome Technology Center,University of California, Santa Cruz


Biosensor and Single Cell Manipulation using Nanopipettes

Approaching sub-cellular biological problems from an engineering perspective begs for the incorporation of electronic readouts. With their high sensitivity and low invasiveness, nanotechnology-based tools hold great promise for biochemical sensing and single-cell manipulation. During my talk I will discuss the incorporation of electrical measurements into nanopipette technology and present results showing the rapid and reversible response of these subcellular sensors  to different analytes such as antigens, ions and carbohydrates. In addition, I will present the development of a single-cell manipulation platform that uses a nanopipette in a scanning ion-conductive microscopy technique. We use this newly developed technology to position the nanopipette with nanoscale precision, and to inject and/or aspirate a minute amount of material to and from individual cells or organelle without comprising cell viability. Furthermore, if time permits, I will show our strategy for a new, single-cell DNA/ RNA sequencing technology that will potentially use nanopipette technology to analyze the minute amount of aspirated cellular material.