Hartmut Porst and Ira D. Sharlip
It seems paradoxical that among the physiologic functions of the human body, sexual function has generated the greatest popular awareness and curiosity, but the least scientific inquiry. Despite the considerable human behavior, both virtuous and evil, that has been motivated by human sexuality, restrictive social attitudes and taboos have severely inhibited scientific investigation of human sexual function. Working within a restrictive social environment, a few irrepressible investigators and observers of human behavior have changed the course of modern social science and philosophy through their interests in sexual medicine and sexual psychology. Sigmund Freud brought new concepts of the importance of sexuality to the forefront of Western creative thinking at the end of the 19 th century and beginning of the 20th century . As early as 1896, the aphrodisiac effects of yohimbine were reported by Leopold Spiegel, who extracted this substance from the bark of the West African yohimbe tree . Around that time reports on the successful treatment of "atonic impotence" by dorsal penile vein ligature procedures were also published in the literature [3,4]. Only a few years later in 1914, a patent for "a device for the artificial erection of the penis", the prototype of the vacuum devices, was awarded to Otto Lederer in Germany . Decades later, Alfred Kinsey's epidemiologic studies of human sexual behavior, published in 1948 and 1953, profoundly liberalized popular attitudes about sexuality in American society . In the 1960s, Masters and Johnson contributed groundbreaking studies of sexual anatomy and physiology as well as new concepts about sex therapy, further lessening societal barriers to open discussion of human sexuality [7,8]. At about the same time, research in sex steroid biochemistry led to the development of the birth control pill in the 1960s. The ability for women to control their own reproductive choices played a vital role in the rise of feminism in Western countries; and the rise of feminism was a crucial element in producing more liberal social attitudes about human sexuality and the resulting sexual revolution of the late 1960s and early 1970s.
Perhaps made possible by this sexual revolution, progress in male sexual medicine accelerated in the 1970s. Prior to this time, sexual dysfunction was considered to be an endocrine or a psychologic problem. The usual treatments were testosterone therapy for men with hypogonadism, and psychotherapy. In the early 1970s, Vaclav Michal, a vascular surgeon from Prague, began to investigate the role of penile revas-cularization techniques for the treatment of vasculo-genic erectile dysfunction [9,10]. Interest in Michal's surgical techniques led Adrian Zorgniotti in 1978 to organize the First International Conference on Corpus Cavernosum Revascularization in New York. This conference evolved into biennial conferences, which expanded to cover the entire field of sexual medicine. By 1984, these conferences became the meetings of the International Society for Impotence Research (ISIR). ISIR has since been renamed the International Society for Sexual Medicine (ISSM).
Also in the early 1970s, Small, Carrion, Scott and others in the United States created a dramatic change in treatment options for erectile dysfunction with the introduction of the modern era of penile prostheses [11,12]. This resulted in new access to treatment for erectile dysfunction for tens of thousands of men worldwide, and created a new wave of popular and medical interest in sexual medicine.
Subsequently, in 1981 the serendipitous discovery in Paris by Ronald Virag of the erectogenic action of intracavernous injection of papaverine produced major advances in both the treatment of erectile dysfunction and the understanding of erectile physiology . By the mid-1980s, intracavernous injection therapy with papaverine, the mixture of papaverine/pentolamine, and later with prostaglandin E1, became a common and effective treatment for erectile dysfunction [14-17].
A particularly important development in sexual medicine occurred in 1992 when the National Institutes of Health in the United States called for a consensus development conference on impotence. The conference recommended using the term erectile dysfunction rather than impotence, and defined erectile dysfunction as the "consistent inability to attain or maintain a penile erection, or both, sufficient for adequate sexual relations." This effectively identified erectile dysfunction as a recognized disease state, thus helping to qualify it for governmental and private insurance medical benefits.
As scientists dedicated more and more effort in the 1990s to elucidating the molecular biology of sexual and erectile physiology, a major basic science breakthrough occurred in the mid-1990s with the discovery of the role of nitric oxide in smooth muscle relaxation of the corpus cavernosum. Only a few years later, the greatest clinical breakthrough event in the history of male sexual medicine occurred with the approval of sildenafil, the first effective oral therapy for erectile dysfunction, which was launched in March 1998 in the US . The social impact of sildenafil may have been even greater than its medical impact. While some 25 million men have benefited from sildenafil, and another five million or more have benefited from the newer phosphodi-esterase inhibitors, vardenafil and tadalafil; the commercialization of these drugs has brought the subject of sexual dysfunction into common parlance and social discussion for hundreds of millions of men and women throughout the world. The introduction of sildenafil may have been the most important event in medical history in destigmatizing sexual dysfunction and reducing taboos about discussing sexuality.
Proceeding into the beginning of the 21st century, new trends in sexual medicine promise to promote more popular interest and public discussion. A new and specific treatment for premature ejaculation, one of the most common forms of male sexual dysfunction, is in the final stages of clinical development and may be approved in 2007 . And an entirely new method of treating erectile dysfunction using the cutting-edge technique of gene therapy has just entered the initial stages of clinical development . Importantly, progress in both male and female sexual health has been aided by the World Health Organization (W.H.O.) which has designated the years 2004 to 2009 for worldwide public emphasis on sexual health using the campaign slogan, "Sexual Health: a new focus for W.H.O.". The recognition by W.H.O. of the importance of sexual health is another signal of the vital role that sexual medicine is likely to play in the future.
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