Medical Examiner

Your Health This Month

Summer hazards and a potential sex gene. Plus, how much lobster is too much?

This month, Dr. Sydney Spiesel discusses summer hazards, a possible sex gene, treating women as ” prepregnant,” the reliability of pharma-sponsored drug studies, and eating lobster. Click here and here for his last two columns.

Summer hazards: What to watch out for.

Summer is close enough that kids still in school are gazing out the window while they tote up the remaining days, hours, minutes, and seconds. Pediatricians are drowning in pre-camp physical exams and, when they are not gazing out the window, getting ready for summer hazards. Here are some that are on my mind.

Poison ivy and its co-conspirators: I’ve been seeing a lot of rashes caused by poison ivy, which we can apparently look forward to more of. If I were in another part of the country—California, the Southeast, swamps of the Eastern Seaboard—I would see the same unpleasant effects of poison oak or poison sumac, two related plants.

All three of these plants—and a few others found around the world—commit their crimes in the same way. They produce an oil (urushiol) which attaches to proteins in the skin, forming an intensely allergenic product. The body’s immune mechanisms attacks cells altered by contact with urushiol as if they are foreign. The characteristic rash of poison ivy and its cousins are the result of inflammation caused by the attack.

Mostly, poison ivy is just annoying (very annoying!) because it is excruciatingly itchy. But sometimes it is dangerous. For example, serious facial swelling can compromise breathing, and genital swelling can be sufficiently severe as to prevent urinating. If some fool neighbor burns poison ivy, the inhaled smoke can cause deadly pulmonary edema.

As with most things, prevention is better than treatment.

Learn to recognize the plant. Remember that, as with all allergic diseases, if you don’t react the first time you are exposed, you don’t have license to roll around in the stuff. Remember that very quick washing with soap or with alcohol can remove the oil before it attaches to the skin that brushed against the plant. Remember also that your dog has been running through poison ivy patches and that walking in the woods has left a fine mist of oil—you wouldn’t believe how little it takes—on your jeans.

If, despite your best efforts at avoiding it, you get poison ivy anyway, treatments include wet compresses and hydroxyzine for itching, and local steroid creams and sometimes even oral steroids to treat the inflammation. Don’t worry about being contagious—the only way you can pass it on is by touching someone with hands that have urushiol on them.

Lip gloss in the sun: A few days ago I saw a teenager with very inflamed lips. The obvious culprit for an allergic reaction was lipstick, but she never wears it. She had, however, started wearing a new lip gloss, flavored with lime oil, and had also been enjoying the sun.

The oil of lime skin, like such diverse fruits and vegetables as figs, celery, and parsnips, dramatically increases sensitivity to sunlight, causing a condition called phytophotodermatitis. Another citrus product, oil of bergamot, commonly used to perfume Earl Gray tea, is also quite photosensitizing. Some antibiotics, including most drugs in the tetracycline family, do the same thing and sometimes turn what seems to be a trivial amount of sun exposure into a severe sunburn. Once a patient has been set up by a sun-sensitizing medication or fruit or vegetable, tanning rays actually cause the rash.

Sun: Which is yet another reason to save your skin by protecting it from the sun. I won’t go on about what you already know—avoid tanning rays and especially sunburns. But let me say something about sunscreens: It’s not enough to use them; they should be used well. Some tricks:

  • Don’t count on very high SPF products to provide super protection. I’ve found that some of these sunscreens can produce rashes or skin irritation even without sun exposure.
  • Instead, choose a brand that provides UVA protection in addition to the standard UVB protection. For many years it was thought that of the two kinds of ultraviolet light, only UVB caused serious sun damage, but it is now clear that both forms have significant effects.
  • Limit exposure time, make use of clothes, hats, and shade, and reapply the sunscreen often. The Australian motto seems to have helped lower the extremely high rates of skin cancer Down Under. It’s “slip, slop, slap”—slip on a shirt, slop on the sunscreen, and slap a hat on your head.

The genetics of desire.

A sex gene? One of the most intriguing research reports I’ve read recently links a specific gene to human sexual desire. This preliminary research by a group of Israeli scientists, including I.Z. Ben-Zion and R.P. Ebstein, examined a human gene, DRD4, that controls one of the brain receptors for dopamine, a neurotransmitter (a chemical the nervous systems uses to relay electrical signals between nerve cells) that’s deeply involved in the brain’s reward-by-pleasure system. When the receptor this gene controls is manipulated in rats—through drugs that alter its sensitivity—sexual function is strongly affected. Also, many structural variations for this gene have been found and studied, and each variation seems to have significant and different effects on, or at least correlations with, other complex aspects of human behavior.

The research: Dr. Ben-Zion and colleagues sent an online questionnaire about sexual arousal, desire, and function to 148 men and women, anonymous to the researchers, whose DNA was available for study because they had participated in earlier genetic research. The results need to be replicated in many more subjects to be sure that the apparent correlations are real, but the findings are provocative and interesting nevertheless.

Findings: For starters, scores for sexual desire, arousal, and function were pretty well associated with each other. Now, that’s not surprising, no matter whether the basis is a genetic model or a purely psychological one—for example, it would be plausible for poor arousal for any reason to lead to poor function and from there to decreased desire. More interestingly, however, subjects who scored lower on the desire-arousal-function continuum were more likely to have one particular variant of DRD4, called D4.4. Subjects who scored higher were more likely to have other variants of this gene. This finding strongly implies that there is some genetic basis for differences in sexual desire. Earlier twin studies had pretty much established that genetic contribution. This new research suggests a biological site that might play an important role.

Not just sex: There’s more. The variants of DRD4 previously had been studied with great attention because they’re strongly associated with variation in other human behaviors. The D4.4 variant, for instance, has been shown to be associated with altruistic and prosocial behavior. Other variants associated with higher sexual desire-arousal-function scores were also more commonly found in subjects with a greater tendency toward aggressive, novelty-seeking, and maybe even anti-social behavior. These other variants were also to some degree associated with Attention Deficit Hyperactivity Disorder.

The joy of variety: Another interesting thing about the DRD4 variants is their existence. Most of the time, when a small variation in a gene appears, generally because of random mutation, it meets one of three fates. If the change has little effect on the function of the gene, it may well be preserved in the progeny of the ancestor in whom it first appeared, but it isn’t likely to be amplified in frequency (unless the original ancestor in whom the mutation appeared also had some other qualities likely to increase reproductive success). If the new gene variant doesn’t work as well as the original gene, it is likely to decrease reproductive success and so disappear with time. And if a new mutation does its job better than the original gene, it will likely replace the old form of the gene.

But the variants in DRD4 don’t fit any of these models. The variants associated with novelty-seeking behavior, increased sexual desire, and increased ADHD arose between 40,000 and 50,000 years ago and have been preserved in balance with an older variant associated with altruism, less adventure-seeking, less ADHD, and somewhat lower levels of sexual desire and arousal. It’s as if nature has preferentially selected for a mix of behavioral styles in humans, perhaps to best equip us to adapt flexibly to a broad range of environmental and cultural challenges.

Treating women as “prepregnant.”

The report: Last month, a report in a publication published by the Centers for Disease Control and Prevention made a pitch for improving pregnancy outcomes by treating all women as if they would one day be pregnant. The voluminous report by a work group of the CDC and Agency for Toxic Substances and Disease Registry contains about 20 pages of health recommendations intended for all women, whether they intend to become mothers or not, between menarche and menopause. Though much of the material is technically correct or at least plausible, the report rather set my teeth on edge by seeking to improve women’s health in the service of one goal: bettering their reproductive prospects. For example, the report urges that every “man, woman, and couple should be encouraged to have a reproductive life plan.” Visits to health care practitioners should include eight to 10 areas of “preconception” risk assessment and related counseling. 

The pros: Now don’t get me wrong. The authors of the report are right that women would do well to be sure to get enough folic acid even before conception. And though it’s sometimes hard to achieve, no one’s going to quarrel with urging women to stop smoking, cut down excessive weight, and diagnose and treat sexually transmitted diseases.

The caveats: But some of the advice in the report—avoid medications that can harm a fetus, adjust the dose of thyroid hormones during pregnancy—while well-known and widely applied during pregnancy, has little or no demonstrated benefit prior to conception. It’s a little hard to understand why the work group chose to include these items (except that practitioners ought to keep them in mind when talking to women on the cusp of pregnancy). 

Conclusion: All of the report’s recommendations relating to good care should be available to each of us, but for our own sakes, not because we are vessels bearing new life. Yet these writers sound as if they don’t care about women except via their baby-making role. The other problem with the report is that it’s blather. The 20 dense pages skirt any discussion of how these goals might be accomplished and—more to the point—who will pay for it.

Pharma-sponsored studies: How reliable are they?

The research: How useful and objective are drug studies sponsored by pharmaceutical manufacturers, as compared to studies not sponsored by industry? A fine recent study by a group of psychiatrists, mostly working in Munich and led by Dr. Stephan Heres, addresses these questions. This research group examined 42 reports in which two drugs in the same class used to treat mental illness were compared head-to-head for efficacy. 

The findings: Of these, 33 reports were industry sponsored, and of that group, 90 percent contained results favorable to the sponsored drug. Maybe in each of these cases the sponsor’s medication really was superior choice? To test that, Heres and his team focused on 21 reports in which the same two drugs were compared head-to-head in several different studies, some sponsored by the manufacturer of one product and some sponsored by the manufacturer of its rival. Remarkably (or not), the report almost always favored the product of its sponsor.

Conclusion: Heres’ group scrutinized these studies closely and were able to include in their paper an analysis of how the pharmaceutical manufacturers arranged their studies so they were technically correct, but nonetheless arrived at the desired—and presumably biased—conclusion. This makes a great case for industry-independent drug studies. Now if only we could find public funding for them.

Too much lobster: There is such a thing.

The warning: Not long ago, Canada’s FDA, Health Canada, put out a reminder that seemed, ah, a little startling. They urged that adult gluttons contemplating a meal of tomalley—the very green organ in the thorax of the lobster that functions as some combination of liver and pancreas—limit themselves to two lobsters’ worth of the slimy green goo. (Kids should eat no more than one lobster’s worth.)

The response: Many reporters covering the story were incredulous that anyone would want to eat a milligram of the stuff. Based on appearance, perhaps they have a point. (Though by the same standards, who would ever eat an artichoke?) I will concede that tomalley isn’t attractive, and I will not try to convert anyone as to its taste. But I was staggered by the report for a different reason: Are there really people who order three or four lobsters and eat the tomalley—enough to warrant a health advisory? How can I meet them?

Red tide: The medical issues are straightforward and, given my slightly off-kilter set of fascinations, to me rather interesting. “Red tide” is the great curse of the shellfishing industry—and one we are likely to encounter with increasing frequency as costal waters warm and fertilizers run off into the oceans. Red tide is a bloom of one of several species of microscopic swimming algae. These algae produce at least 18 related toxins that are taken up and concentrated by shellfish. When this happens, the shellfish (mostly clams and mussels) become poisonous. If eaten, they cause a condition called paralytic shellfish poisoning. PSP begins with the sensation of numbness or tingling of the lips and tongue (think cocktail party). It goes on to cause weakness and loss of muscle control (still cocktail party). But then it typically gets worse, causing paralysis, including paralysis of the breathing muscles, and death.

Conclusion: Even if lobsters swim in water heavily contaminated with red tide organisms, their meat is not affected and may be safely eaten. However, the tomalley may take up some of the PSP toxin, and that is the basis for Health Canada’s warning. The toxin is heat stable, so it isn’t destroyed by the heat of cooking, though to some degree it washes out of the tomalley during the cooking process. I haven’t been able to find any reported cases of PSP resulting from tomalley consumption, but you never know. I guess if an enthusiast wasn’t put off by the price of three or more lobsters, this could be a real problem.