Medpedia

From Dictionary.com a filter is defined as:

A porous device for removing impurities or solid particles from a liquid or gas passed through it
- an oil filter

the verb to filter is defined as:

Pass (a liquid, gas, light, or sound) through a device to remove unwanted material
- the patient is hooked up to a dialysis machine twice a week to filter out the cholesterol in the blood


Dr. Lazar Greenfield, recent president-elect of the American College of Surgeons and former editor-in-chief of Surgery News, is a world-reknowned vascular surgeon for which the Greenfield filter was named. This device was created as a component of a catheter management approach to massive pulmonary embolism, a life threatening condition in which a blood clot obstructs one or more of the pulmonary arteries. Dr. Greenfields' discovery was supported by industry which allowed further technical improvements and long-term patient followup studies. Dr. Greenfield has published many scientific articles about his work and research in various prestigious journals of surgery.

In Feburary 2011, Dr. Lazar Greenfield penned a Valentine's Day themed article "Gut Feelings" in Surgery News which erupted a firestorm of controversy. Touted as sexist, provocative and even perhaps homophobic, "Gut Feelings" demonstrated implied health messaging which encouraged unprotected sexual intercourse among young college age students to improve mental health. In reviewing the original article that Dr. Greenfield cited (Gallup et al 2002), the authors themselves noted specific limitations of their research. "It is important to acknowledge that these data are preliminary and correlational in nature, and as such are only suggestive. More definitive evidence for antidepressant effects of semen would require more direct manipulation of the presence of semen in the reproductive tract and, ideally, the measurement of seminal components in the recipient’s blood." The lack of substantive causative data offers little support to choose semen over chocolate.

In the short weeks which followed, the entire Februrary issue of Surgery News was removed from its publication website. However, the controversy surrounding Dr. Greenfield continued to bubble and has erupted into the popular press. Today in the Health section of the New York Times, Gardiner Harris wrote an article about how Dr. Greenfield's article was offensive to women. According to Harris, "The editorial outraged many women in the field, some of whom said that it reflected a macho culture in surgery that needed to change.

Dr. Barbara Bass, chairwoman of the department of surgery at Methodist Hospital in Houston and a former regent of the surgery group, the largest professional association for surgeons, said in a telephone interview Sunday that she was glad Dr. Greenfield had resigned, despite his long history of supporting women in the profession.

'Some things you can’t recover from if you’re in a leadership role,' Dr. Bass said.

She said the resignation demonstrated that the surgery association’s leadership 'does understand the continued challenges women face as they join and mature in the surgical profession.'

Others said the resignation would not end the controversy.

Dr. Colleen Brophy, a professor of surgery at Vanderbilt University, submitted a letter of resignation from the surgery association during the controversy and said Sunday that she had no intention of reversing herself now that Dr. Greenfield has resigned."

Despite his apologies, it is clear that Dr. Greenfield has struck a nerve with many within the medical and surgical communities. Although Greenfield may have had good intentions to be witty and entertaining with this article, his musings failed to account for diverse readership of surgeons and health providers in surgery - women, LGBT people and public health minded individuals who hold different views on gender, sex and sexuality.

So, I must agree with the boys at Retraction Watch--perhaps the inventor of the Greenfield filter did need a filter of his own.

Henry Ng, MD


A link to the NYTimes article can be found at: http://www.nytimes.com/2011/04/18/health/18surgeon.html?scp=1&sq=greenfield&st=cse


Dr. Greenfield's article is reproduced for your review below. It is available to read at retractionwatch.wordpress.com, a blog run by Ivan Oransky and Adam Marcus to follow the retractions of scientific articles from the literature. According to the website, they view "Tracking retractions as a window into the scientific process."

http://retractionwatch.wordpress.com/2011/04/06/forget-chocolate-on-valentines-day-try-semen-says-surgery-news-editor-retraction-resignation-follow/

Under the heading “Gut Feelings,” Greenfield wrote:

"One of the legends of St. Valentine says that he was a priest arrested by Roman Emperor Claudius II for secretly performing marriages. Claudius wanted to enlarge his army and believed that married men did not make good soldiers, rather like Halsted’s feelings about surgical residents. But Valentine’s Day is about love, and if you remember a romantic gut feeling when you met your significant other, it might have a physiological basis.

It has long been known that Drosophila raised on starch media are more likely to mate with other starch-raised flies, whereas those fed maltose have similar preferences. In a study published online in the November issue of the Proceedings of the National Academy of Sciences, investigators explored the mechanism for this preference by treating flies with antibiotics to sterilize the gut and saw the preferences disappear (Proc. Nad. Acad. Sci. U.S.A. 2010 Nov. 1).

In cultures of untreated flies, the bacterium L. plantarum was more common in those on starch, and sure enough, when L. plantarum was returned to the sterile groups, the mating preference returned. The best explanation for this is revealed in the significant differences in their sex pheromones. These experiments also support the hologenome theory of evolution wherein the unit of natural selection is the “holobiont,” or combination of organism and its microorganisms, that determines mating preferences.

Mating gets more interesting when you have an organism that can choose between sexual and asexual reproduction, like the rotifer. Biologists say that it’s more advantageous for a rotifer to remain asexual and pass 100% of its genetic information to the next generation. But if the environment changes, rotifers must adapt quickly in order to survive and reproduce with new gene combinations that have an advantage over existing genotypes. So in this new situation, the stressed rotifers, all of which are female, begin sending messages to each other to produce males for the switch to sexual reproduction (Nature 2010 Oct. 13). You can draw your own inference about males not being needed until there’s trouble in the environment.

As far as humans are concerned, you may think you know all about sexual signals, but you’d be surprised by new findings. It’s been known since the 1990s that heterosexual women living together synchronize their menstrual cycles because of pheromones, but when a study of lesbians showed that they do not synchronize, the researchers suspected that semen played a role. In fact, they found ingredients in semen that include mood enhancers like estrone, cortisol, prolactin, oxytocin, and serotonin; a sleep enhancer, melatonin; and of course, sperm, which makes up only 1%-5%. Delivering these compounds into the richly vascularized vagina also turns out to have major salutary effects for the recipient. Female college students having unprotected sex were significantly less depressed than were those whose partners used condoms (Arch. Sex. Behav. 2002;31:289-93). Their better moods were not just a feature of promiscuity, because women using condoms were just as depressed as those practicing total abstinence. The benefits of semen contact also were seen in fewer suicide attempts and better performance on cognition tests.

So there’s a deeper bond between men and women than St. Valentine would have suspected, and now we know there’s a better gift for that day than chocolates."