Renal Research

Publication Analysis 1999-2010
by Kathleen Gransalke, Labtimes 02/2013


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Glomerular capillaries (purple) and podocytes (green) of the kidney – painting representation of a Scanning Electron Microscope image Image: Gabriele Perazza, University of Illinois

Studying the kidney and especially its pathology is a big topic in Europe, especially in Germany and, surprisingly, Italy. And it’s dominated by men.

When delving into kidney research, as we did with our current publication analysis, inevitably, one must first give in to one’s etymological cravings. Thus, we not only had to deal with the ‘kidney’, which is middle English with a history dating back to at least the 14th century, we also encountered the adjective ‘renal’, which stems from rēnēs, the Latin word for kidney, and the prefix ‘nephro-’, derived from nephros or νεφρός, which is the Ancient Greek expression of the very same organ.

Staying with history, in ancient times, people regarded the kidneys as more than just one of those ‘internal organs’; for them, they were ‘life centres’. In 2006, Eberhard Ritz, University Heidelberg and Andrzey Wiecek, Medical University of Silesia, Katowice, Poland wrote in the Christmas edition of the German medical journal Medizinische Wochenschrift, “In the bible, particularly in the old testament, more rarely in the new testament, one finds many passages mentioning the kidney – mostly together with the heart. The kidneys were a symbol for, and thought to be the seat of, the most intimate feelings, thoughts, intentions which only the Lord was thought able to assess.” Throughout the centuries, however, the kidneys lost their emotional link more and more to the brain and became what they are today, just one of those ‘internal organs’.

But the old Israelites got one thing right, there’s a strong connection between the kidneys and the heart. Through the hormonal renin-angiotensin (RA) system, the kidneys can indeed indirectly regulate blood pressure. The RA system also affected our publication analysis, in that we also included researchers studying hypertension. However, because high blood pressure is caused by many different factors including, for example, pregnancy, diet or genetic predisposition, we tried to focus our analysis on those researchers studying the kind of hypertension that is directly linked to the kidneys.

Obvious and not so obvious inclusions

We also excluded researchers studying the adrenal glands and their hormone secreting system. And, of course, researchers using kidney cell lines, like the easy-to-transfect human embryonic kidney cells, HEK, were left out of our publication analysis, too. The inclusion of a few other researchers was, however, not so obvious. Thus, studies on the oxygen-sensitive HIF proteins or hypoxia-inducible factors don’t, at first sight, sport a very straight-forward connection to the kidneys until you take a closer look. HIF-1 alpha, for example, is expressed by almost all cells in the kidney and, under normal oxygen conditions, is rapidly degraded by the von Hippel-Lindau (VHL) E3-ubiquitin ligase. The latter is a tumour suppressor, so if it fails to degrade its substrate, HIF accumulates leading to, amongst others, renal carcinomas.

During our chosen time frame, from 1999 to 2010, European renal researchers published almost 60,000 articles in our so-called “expert journals”, which we had to use for our country ranking, as Web of Science doesn’t allow us to extract renal research papers from multi-disciplinary journals. Most ‘expert’ articles, 30%, appeared in the Journal of Hypertension, followed by Nephrology Dialysis Transplantation (15%) and Hypertension (8%).

Italy maintains its 2006 good standing

Similarly to other second rounds of previous publication analyses, not much has changed at the top when adding up the citation numbers of the individual countries in Europe (see blue Table on p. 37). The first six spots are still occupied by Germany, Italy, England, France, The Netherlands and Spain – exactly the same as in 2006 when we did the first round of renal research ranking. The countries placed from 7 to 20, once again, only jumped or fell one or two spots. This time, there was no big winner or loser. Surprisingly, Italy could maintain its good standing from 2006, cosily positioning itself between Germany and England. Scoring especially well in the citations-per-article discipline were Ireland and Norway, with every article, on average, receiving more than 20 citations. The country performance also nicely mirrors our top heads’ institute affiliations. Thus, Germany fields eight kidney researchers, the UK five, Italy four, France three and Denmark, The Netherlands, Spain, Switzerland and Sweden two each. To find out how they did, just keep on reading. First, let’s compare Europe to the rest of the world.

When it comes to sheer publication output, Europe makes the USA, with ‘only’ 36,000 published renal expert articles, look small indeed. But the US compensates for this shortage with an almost equal number of citations, bringing their citations-per-article ratio to an impressive 16.2 (compared to 10 for European researchers). On a par with the US, in the citations-per-article area, are only Canada (even outcompeting their US neighbours by 0.1 citations) and Australia. A brief word about the hot topics in renal research. Obviously, it’s the human kidney and its pathology that fascinates the most highly-cited researchers. Thus, still high on the research agenda are the HIF proteins and their roles during kidney development and, most importantly, disease. Other research interests revolve around kidney transplantations, improving dialysis methods or the consequences of diabetes and other conditions on kidney function. Beside pathological aspects, a few researchers are more into basic research, deciphering the role of ion channels, water channels and basement membrane proteins in renal physiology.

Transplantation, dialysis, ion channels and HIF

Now back to our highly-cited scientists. As a little reminder, the top five in 2006 were Peter Ratcliffe, Giuseppe Remuzzi, Patrick Maxwell, Chris Pugh and Eberhard Ritz. Seven years on, Remuzzi has now stolen Ratcliffe’s Renal Research Ranking crown, demoting him to the runner-up position. Maxwell, in 2013, came in at spot 6, Pugh at 10 and Ritz at 8.

Giuseppe Remuzzi’s remarkable climb to the top of European renal research was highlighted in a 2010 article in The Lancet, wherein David Warnock, of the University of Alabama, praises him as “one of the most remarkable individuals in the field of kidney medicine, with contributions to a multitude of areas that span the spectrum from clinical science to basic research endeavours”. One of the topics closest to Remuzzi’s scientific heart is the early detection of renal dysfunction. This is not always easy as Remuzzi points out, “The heart beats, the lung breathes – the kidney does not make any noise and often people end up presenting with end-stage kidney disease having never realised anything was wrong.”

At the Groningen Institute for Chronic Kidney Disease, whose programme directors Dick de Zeeuw (9th) and Paul de Jong (28th) both made it into the top 30, scientists pursue a similar goal: the “development of strategies for the prevention of renal and related cardiovascular function loss and to resolve individual therapy resistance”. De Zeeuw, in particular, investigates the role of proteinuria and microalbuminuria in cardiac and renal disease, while de Jong is looking for better screening techniques for the early detection of kidney malfunction.

Claudio Ronco (14th) even has a catheter used for Continuous Flow Peritoneal Dialysis named after him – the Ronco catheter. Besides improving dialysis gadgets, he’s also interested in, for example, renal physiology in pregnancy and the treatment of acute renal failure.

Protect the kidney, protect the heart

Last but not least, Søren Nielsen (22nd) has devoted his research to aquaporins. In close collaboration with the discoverer of the water channels and Nobel Prize laureate Peter Agre from Johns Hopkins University, he studies function and regulation of these channels in the kidney and other organs. Directing the Water and Salt Research Centre at the University of Aarhus until 2011, Nielsen has a second research foothold in the study of sodium transporters and channels that are important for the regulation of the sodium balance in the kidney.

Even though they are not at the seat of one’s inner thoughts and feelings, the kidneys are not to be disregarded as sole urine producers, either. Ignoring our kidneys’ needs might, one day, come back to haunt us. Remuzzi advises, “By protecting the kidney, you can avoid cardiovascular disease, heart failure and coronary artery disease. It’s a simple message – protect the kidney, protect the heart.”


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