Rhodri James Walters PhD

 

Professional Qualifications:

PhD. Biophysics, Babraham Institute, University of Cambridge.

BSc. Jt. Hons., Physiology and Biochemistry. University of Wales.

 

Key Skills and Experience:

 

Publishing

  • Commissioning/Editor: Cellscience Journal, Icqurimage magazine.
  • Author: Over thirty original scientific papers and reviews, The HiPaCC diet

 

Academic

  • Research: Molecular biology, electrophysiology, and cell biology of GABA receptors, Ca2+ channels, hormone secretion, epithelial transport, synaptic transmission and psychopharmacology, elected member of the New York Academy of Sciences 1998.
  • Teaching: Lecturer in Molecular Pharmacology, post-graduate course advisor.
  • Reviewer: Hormone & Metabolic Research, Cellscience, American Journal of Physiology, British Journal of Pharmacology.  

 

Management (Technical & Marketing)

  • Research group leader: supervision of six research students to International publication level. Wrote reports, grants, proposals & papers, supervised six students, ran logistics, and edited and reviewed papers & grants.
  • Vice-President: then President, St. Edmund’s College (events, dinners, meetings).
  • Conference organiser: Mind Aid New York City 2000. 
  • E-commerce: Conceived, initiated and directed highest ranked medical directory & Reviews Journal on the Internet, Cellscience.com (30-50,000 visitors per month).
  • Web design: CSS, HTML, JS, ASP.  Award winning web designer.
  • Internet Marketing: Search Engine Optimisation, Direct Marketing.  Created Cellscience directory & Journal, top of search engines within 1 year.  HiPaCC diet to market in 2 months.

Professional Societies

Biophysical Society (1995-     )

Society for Neuroscience (1996-    )

Elected Member of the New York Academy of Sciences (April 1998 -    )

 

Employment History

Institution

Title

Research

Dates

Cellscience Ltd, HiPaCC Ltd

Managing Director

Medical Information Directory & on-line Journal; Webmaster

2002-present

Department of Endocrinology, University of Dusseldorf, Germany

Group Leader

Growth factor regulation of the expression of catecholaminergic enzymes and GABAA receptors in PC12 cells.

2001-2002

Department of Pharmacology, Mount Sinai School of Medicine, New York, U.S.A.

Fellow

Role of a2A and a2C norepinephrine receptors in voltage-independent and dependent inhibition of N-type Ca2+ channels.

2000-2001

Department of Pharmacology, University of South Florida, College of Medicine, U.S.A..

Fellow

Molecular structure-function relationship governing kinetics and pharmacology of GABAA and GABAC receptors.

1999-2000

Department of Physiology and Pharmacology at the Catholic University of Louvain, Brussels.

Associate

Regulation and properties of L- and G-type calcium channels in the pancreatic b-cell.

1997-1998

University of Durham, Laboratory of Psychopharmacology, Durham, DH1 4EP

Electro-physiologist

Regulation of pacemaker neurons  in the Ventral Tegmental Area

1997

Department of Ophthalmology and Visual Sciences, Kennedy Center, Albert Einstein College of Medicine, Bronx, New York, 10461, U.S.A..

Associate

Regulation of synaptic transmission in the retina by protein kinases A, GRK and CaMKII

1994-1996

Development and Signalling, BBSRC Babraham Institute, Cambridge, CB2 4AT, U.K..

Assistant

Role of the phosphatidylinositol 3,4,5 trisphosphate (PIP3) signalling pathway in U937 cells.

1993-1994

 

Teaching Experience

Course design: Molecular Pharmacology, University of South Florida

Teaching: Cyclic Nucleotide Signalling, 2 hours, examination question section.

Student Training: Manou Brandt (medical student, Düsseldorf) PCR, cell culture, cloning, scientific methodology (160 hours); Janette Seres (Ph.D. student , Düsseldorf) PCR, cell culture, scientific methodology (100 hours); Carmen Riggio (technician, Düsseldorf), cell culture, fluorescence microscopy and staining (150 hours); Jean-Francois Rolland (Ph.D. student, Brussels) patch-clamp, (50 hours); Delphine Beaujean (post-doctoral student, Düsseldorf) cell culture, immunocytochemistry, immunofluorescence (80 hours).

 

Education, Qualifications and Activities

Institution

Dates

Subjects

Grade

Activities

University of Cambridge, BBSRC Babraham Institute & St. Edmund's College

1990-3

Ion channel regulation in small intestinal crypts

Ph.D.

CR Vice-President St.Edmund’s College, Rugby 1st XV, Rowing 1st VIII, Table Tennis 1st III

University of Wales College Cardiff,

1987-90

Part I: Physiology, Biochemistry, Chemistry

Part II: Physiology & Biochemistry Joint Honours.

II (i)

Physiology department Student Representative;

Company Director, Park Security

University of Leicester Medical School

1986-7

Biochemistry, Physiology, Anatomy

N/A

Career change

‘A’ levels

‘O’ levels

1986

1984

A, B2, C

6 ‘A’s, 3 ‘B’s

 

National X-Country Championships

 

Lectures & Seminars:

BBSRC Babraham Institute, Cambridge, 10th October 1991. Studies of conductances present in isolated mammalian crypts.

Department of Physiology, University of Wales College Cardiff, Park Place, Cardiff, U.K. 18th April 1993. Regulation of secretion and cell volume in small intestinal crypts.

St. Edmund's College, Mt.Pleasant, University of Cambridge. 14th October 1993. AIDS, cystic fibrosis and cancer; their impact on man, medicine and society.

IBIFKA, Julich, Germany. 18th October 1993. Regulation of exocrine secretion in the small intestinal crypt.

Regulation of the L-AP4 receptor pathway by protein kinases in the retinal On-bipolar cell at the:
Department of Physiology, University College London, 18th June 1996
Max-Planck Institut fur Hirnforschung, Frankfurt, Germany, 24th June 1996
Hirnforschung, University of Zurich, Switzerland, 28th June 1996

Modulation of synaptic transmission by protein kinases in a bipolar interneuron
Department of Physiology, University of South Florida College of Medicine. 
November 15th 1999

Characterization of two novel glucose-activated Ca2+-channels in the pancreatic beta-cell
Department of Pharmacology, University of South Florida College of Medicine.
November 17th 1999
Department of Endocrinology,
Heinrich-Heine University of Dusseldorf, August 15th, 2001
Department of Pharmacology,
University of Oxford, November 27th, 2001

Mind Aid Conference, Haft Auditorium, Fashion Institute of Technology, May 30th 2000 "A brief history of schizophrenia"

 

Publications:

Peer-reviewed original papers

            (i) Published

Walters, R.J., Sepulveda, F.V. A basolateral K+ conductance modulated by carbachol dominates the membrane potential of small intestinal crypts. Pflugers Arch. 1991 Nov; 419(5):537-9.

O'Brien, J.A., Walters, R.J., Sepulveda, F.V.  Regulatory volume decrease in small intestinal crypts is inhibited by K+ and Cl- channel blockers. Biochim Biophys Acta. 1991 Dec 9; 1070(2):501-4.

Walters, R.J., O'Brien, J.A., Valverde, M.A., Sepulveda, F.V. Membrane conductance and cell volume changes evoked by vasoactive intestinal polypeptide and carbachol in small intestinal crypts. Pflugers Arch. 1992 Sep; 421(6):598-605.

O'Brien, J.A., Walters, R.J., Valverde, M.A., Sepulveda, F.V. Regulatory volume increase after hypertonicity- or vasoactive-intestinal-peptide-induced cell-volume decrease in small-intestinal crypts is dependent on Na+-K+-2Cl- cotransport. Pflugers Arch. 1993 Apr; 423(1-2): 67-73.

Stephens, L., Cooke, F.T., Walters, R., Jackson, T., Volinia, S., Gout, I., Waterfield, M.D., Hawkins, P.T. Characterization of a phosphatidylinositol-specific phosphoinositide 3-kinase from mammalian cells. Curr. Biol. 1994, 4 (3):203-14.

P.T.Hawkins, A.Eguinoa, R-G.Qiu, D.Stokoe, F.T.Cooke, R.Walters, S.Wennstrom, L.Claesson-Welsh, T.Evans, M.Symons, L.Stephens. PDGF stimulates an increase in GTP-Rac via activation of phosphoinositide-3-kinase. Curr. Biol. 1995, 5 393-403.

Walters, R.J., Hawkins, P., Cooke, F.T., Eguinoa, A., Stephens, L.R. Insulin and ATP stimulate actin polymerization in U937 cells by a wortmannin-sensitive mechanism. FEBS Lett.1996 Aug.19; 392(1):66-70.

Walters, R.J., Kramer, R.H., Nawy, S. Regulation of cGMP-dependent current in On bipolar cells by calcium/calmodulin-dependent kinase. Visual Neurosci. 1998 Mar-Apr; 15(2):257-61.

Walters, R.J., Hadley, S.H., Morris, K.D., Amin, J. Benzodiazepines act on GABAA receptors via two distinct and separable mechanisms. Nature Neurosci. 2000  December 3 (12):1274-81.

 

Walters, R.J.,  Rosenbaum, C., Willenberg H.S., Scherbaum, W.A., Bornstein S.R. Insulin, Nerve Growth Factor and PACAP modulate the expression of GABAA subunits in PC12 Cells. Neuroscience (www.neuroscience.com) 2002-1
 

(ii) In preparation

Walters, R.J., Pollock, V. Amin, J. Slowed kinetics of r1 receptors upon substitution at S439 correlate positively with both side chain volume and hydrophobicity.

 

Walters, R.J., Pattnaik, B., Pollock, V. Amin, J.  Cloning and characterisation of a novel r1 receptor variant r1-in from the retina.

 

Reviews

            (i) Published

R.J.Walters. A fourth strategy to contain the threat of HIV and AIDS? New York Times Science Article February 1996.

R.J.Walters. Seeing a change against the light: how neural circuits are adapted in the retina. New York Times Science Article, June 1996.

R.J.Walters. Excitation and Adrenaline: GABA - the bipolar neurotransmitter.  Cellscience Reviews, Vol.1 No.1 pp4-11 2004

R.J.Walters. Cystic Fibrosis: search for the NorthWest Passage. Cellscience Reviews Vol.1 No.2 pp13-23 2004

 

Books

Barber, M., Collier, J., Walters, R.J.  The HiPaCC Diet.  HiPaCC Press 2006.

 

Conference Papers

 

(i) Unpublished

R.J.Walters, F.V.Sepulveda. Ca2+ and voltage-dependence of K+ channels in the crypt basolateral membrane. Biophys.J., , W115, Baltimore 1996.

F.V.Sepulveda, R.J.Walters. The stage of enterocyte differentiation determines resting potential and agonist responses. Exp. Biol.'96, Washington D.C.  3104, FASEB J, 1996.

R.J.Walters, S.Nawy. Modulation of the retinal On-bipolar cell mGluR6 cascade by phosphorylation. Soc. for Neurosci , 435.2, San Diego 1995.

M.L.Chandler, I.H.Pang, R.Doshi, E.M.Wexler, R.J.Walters, S.Nawy, L.DeSantis, M.A.Kapin. In vitro and in vivo protective effects of eliprodil in the retina. Investigative Ophthalmology and Visual Science 1997, 38, No.4, Pt1, p.725.

Nawy, S., R.J.Walters. Modulation by PKA of the responses to L-AP4 in retinal bipolar cells. Soc. for Neurosci. , 498.12, New Orleans,1997.

Amin, J., Pollock, V., Walters, R.J. A novel r1 GABA receptor channel with slowed kinetics.  ARVO, Ft.Lauderdale, FL, May, 2000 

Walters, R.J. Synergistic activation of G- and L-type Ca2+ channels by D-glucose and membrane depolarization in pancreatic beta-cells. Soc.for Neurosci. (platform), New Orleans, 2000.

Brandt, M.V., Walters, R.J., Willenberg, H.S, Scherbaum, W.A., Bornstein, S.R. Nerve Growth Factor Increases Expression of Tyrosine Hydroxylase in Serum-Starved PC12 Pheochromocytoma Cells. Endocrine Soc. Abst., San Francisco, 2002.

Walters, R.J., Rosenbaum, C, Willenberg, H.S., Ehrhart-Bornstein, M, Muller, H-W, Siebler, M., Scherbaum, W.A., Bornstein, S.R. Insulin Induces Increased Expression and Focal Clustering of GABA-A Receptors in PC12 Cells. Endocrine Soc. Abst. (platform), San Francisco, 2002.

 


Research History

Undergraduate final year projects:

(1) Localization and characterization of a serine-O-sulfatase activity in bovine liver.
(2) Effects of caffeine upon glutamate and 5-HT release from hippocampal synaptosomes.
(3) Dissertation: Physiological roles of the endothelins.

Thesis Dissertation: Ion channel regulation in small intestinal crypts.

(Department of Cell Biology, October 1991 - August 1993).

A low temperature method was developed to isolate populations of small intestinal crypts using biochemical assays for specific marker enzymes. The single-channel and perforated-patch modes of the patch-clamp technique were employed to characterize the role of the various ion channels present within the crypt in fluid and electrolyte secretion. Imaging techniques were devised to determine the nature and mechanism of crypt volume regulation in response to changes in external osmolarity and secretagogues.  Radioimmunoassays were performed to measure changes in crypt cGMP and cAMP levels in response to Atrial Natriuretic Peptide and Angiotensin II (AII).

Collaborations: The crypt isolation method was used to examine changes in expression of AII receptor protein and mRNA along the rat jejunal crypt-villus axis. Radioimmunoassay and membrane conductance measurements were performed to elucidate the signalling mechanisms of AII. A truncated form of the CFTR gene product was expressed in Hela cells using the vaccinia virus transfection system, and gene function was evaluated using the conventional whole-cell patch-clamp recording technique.

Pre-doctoral Research Assistant, Laboratory of Development and Signalling, BBSRC Babraham Institute, Cambridge, CB2 4AT, U.K. (August 1993 - December 24th 1993) and as a visiting scientist (July -September 1994). Collaboration with Dr. Len Stephens and Dr. Phillip Hawkins investigating the role of the phosphatidylinositol 3,4,5 trisphosphate (PIP3) signalling pathway in regulating actin polymerization in myeloid-derived U937 cells. Mutants of the p85 regulatory subunit of phosphatidylinositol 3-kinase were ligated into plasmid vectors under eukaryotic promoters using restriction endonucleases. An assay using a fluorescence activated cell-sorter, with FITC-conjugated phalloidin as the probe, was developed to evaluate the role of ATP and insulin in stimulating phosphoinositide-3-kinase (PI3K) and calcium-dependent mediated changes in F-actin polymerization in the U937 cell line.  The role of phosphatidylinositol-3-kinase (PI3K) in the regulation of phospholipase D in the U937 cell line was assayed by measurement of 3H-choline or 3H-phosphatidylpropanol release by ion exchange resins and thin layer chromatography respectively, and the regulation of mitosis by PI3K in these cells was studied by the FACScan quantification of DNA content.

Post-doctoral Research Associate, Department of Ophthalmology and Visual Sciences, Kennedy Ctr, Albert Einstein College of Medicine, Bronx, New York, 10461, USA. (1994-1996). The conventional whole-cell patch-clamp recording technique was used to record from flat-mounted retina to demonstrate that dendrites in retinal ganglion cells are anisopotential. The conventional whole-cell patch clamp technique was then employed to selectively dialyse the retinal On-bipolar cell to determine the role of protein phosphorylation in the regulation of the mGluR6 receptor cascade. Western blotting and whole-cell recordings were used to show that P10 cultured rat on-bipolar cells expressed the components of the L-APB-receptor cascade (see Wexler et al.,1998).  In addition the action of the NMDA-receptor antagonist eliprodil upon ganglion cells was tested using a fast piezo-driven perfusion system, and a viable cultured rat retinal slice system was developed in agarose.

Electrophysiologist at the University of Durham, Laboratory of Psychopharmacology, Durham, DH1 4EP (1997). Extracellular single-unit recordings were obtained from dopaminergic neurons from within the ventral tegmental A10 area of rat brain slices to study the effects of calcium channel antagonists upon the kinetics of these pacemaker neurons, which are implicated in drug dependence pathways.

Post-doctoral scientist at the Department of Physiology and Pharmacology at the Catholic University of Louvain, Brussels (October 3rd 1997- December 31st 1998). Current and voltage-clamp modes of the patch-clamp technique were used to record from primary cultures of pancreatic B-cells to investigate the behaviour and regulation of novel glucose-activated calcium channels, and also to study their direct modulation by sulphonylureas, D-glucose and ketogenic amino acids. The modulation of membrane potential by D-glucose was investigated under a range of conditions, and measurements of changes in free calcium in response to D-glucose and membrane depolarization were studied by ratiometric calcium fluorescence imaging.

Research Fellow at the Department of Pharmacology, University of South Florida, College of Medicine (1999-2000). Research focused upon the molecular structure-function relationship of GABA (g-aminobutyric acid) receptors, and in particular the amino acid residues which may be involved in mediating the differential sensitivity of GABAA and GABAC receptors to benzodiazepines and to other compounds with anaesthetic properties.  In addition a naturally occurring polymorphism that gives rise to a GABAC receptor with ultra-slow kinetics was studied, along with a spectrum of mutations created at this position.  mRNA generated by in vitro transcription from cDNAs of GABA receptor subunits a,b,g and r are injected into Xenopus Laevis oocytes and recorded by two electrode voltage-clamp after 2-3 days incubation.   Site-directed mutagenesis was used to create novel cDNA constructs, which were then used either as linearized templates to synthesize mRNA, or else for ligation into plasmid vectors under an ecdysone-driven eukaryotic promoter.  These cDNA constructs are then used to transfect mammalian cell lines for patch-clamp analysis using lipofectamine.  Our aim was to successfully derive the residue(s) responsible for conferring benzodiazepine sensitivity upon GABA receptors at the low affinity site, and also to determine the kinetic properties of GABAC receptors, as well as the specific involvement of the residues of the fourth transmembrane spanning domain in determining these differential kinetic rates of deactivation.

Research Fellow at the Department of Pharmacology, Mount Sinai School of Medicine (2000-2001). Whole-cell patch-clamp experiments using various agonists and antagonists were used to infer differences in the relative contributions of the a2A and a2C isoforms of the norepinephrine (NE) receptor to the voltage-independent and voltage-dependent forms of inhibition of the N-type Ca2+ channel by NE in chick dorsal root ganglion cells.  In addition, fluorescein-conjugated antisense S-oligos were derived against the known sequence of the chick a2C receptor, which was extended to the N-terminus by Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) using the 5’-Rapid Amplification of cDNA Ends (5’-RACE) technique with nested primers.

Group Leader, Department of Endocrinology, University of Dusseldorf, Germany (2001-2002).
Training, supervision, research direction and management of autonomous laboratory (with one technician and part-time medical student).  Also supervision and training of three other students and a post-doctoral student.  Personal projects: (1) Determination of the GABA subunits expressed in the adrenal and PC12 pheochromocytoma cell line and the regulation of their expression level using RT-PCR, TaqMan real-time quantitative PCR and immunocytochemistry.  (2) Polyadenylation of18S rRNA and its novel application in quantitative TaqMan PCR.  Supervised projects:  (i) Regulation of the appearance of punctate actin foci by insulin in PC12 cells; (ii) RACE cloning and regulation of tyrosine hydroxylase splice variant expression in the PC12 line.


Administrative and Community Contributions

Elected student Vice-President St.Edmund’s College, Cambridge (Combination Room, 1991), later became President. Responsibilities included chairing of "Combination Room" meetings to air student views and concerns; the organization of student dinners, sporting and social activities, and the representation of students on the Fellows' Council.

Served as principal co-ordinator of College team for Wintercomfort, a Cambridge winter night shelter for homeless people (1990-1993).  Wintercomfort for the Homeless liaison committee (1991-2). Duties included writing articles for newspapers, preparation of posters and meeting advertisements. Appointed secretary of Steering Committee of Cambridge Churches Homeless Network (1991-3). Co-founder of the Cambridge rent deposit and support scheme, finding accommodation for homeless people. <div class="MsoNormal" style="text-align:center">

Organized Current Research Discussion Group 1994 for Neuroscience Department, AECOM.

Organization of Mannarcc Mind Aid Conference, New York City, May, 2000.

 

 

 

Training and Development

Discipline

Technical Skills

Experience

Molecular Biology

Site-directed mutagenesis, cloning, RT-PCR, RACE, Real-time RT-PCR, in vitro transcription, eukaryotic expression systems, western blotting..

4 years

Electrophysiology

Conventional and perforated-patch whole-cell recording (current-clamp and voltage-clamp), Two electrode voltage-clamp, single-channel recording, extracellular single-unit slice recording.

9 years

Cell Biology

Radioimmunoassay, cell culture (primary and secondary), immunocytochemistry, fluorescence microscopy, fluorescence-activated cell sorting.

5 years

Web design

HTML, ASP, Javascript, CSS

5 years