A Surgeon General “of size”: Liability or asset?

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Read all about it on the Examiner!

And to Smithies and co., happy Mountain Day! For those of you not familiar with the Smith holiday, here’s what the college website has to say:

Mountain Day is a surprise break from classes. The president chooses a beautiful fall day and announces the holiday by ringing the college bells. A picnic lunch can be provided by the college to be carried to the students’ various outdoor activities on campus or to nearby parks.

Classes and academic appointments scheduled before 7 p.m. are canceled. Evening classes, films, lectures and other events will be held as planned.

The first Mountain Day was held in 1877.

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Apologies…

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… as I use this here blog for wholly selfish (but educational!) purposes.

You see, I am someone for whom learning science often amounts to writing out mechanisms/processes over and over and over again. In psychopharmacology two years ago, a friend and I would regularly mark up whole chalkboards as we attempted to remember what this neurotransmitter did as opposed to that neurotransmitter.

So now, in this “post,” I plan to reason out for myself the PIP2-Calcium signaling mechanism, which I’ve been having trouble remembering. Feel free to zone out/not read any further because, quite frankly, I’m writing now for my own understanding, not others’ entertainment.

Why put it in Grub First, then? Because it’s my blog, dammit! No, really– publishing something necessitates I read it over several times and understand it myself. Really put in the effort, if you will.

If for some odd reason you feel like learning about how this particular hormone signaling process works, then by all means, read on!

PIP2-Calcium signaling

PIP2-Calcium, or PIP2-C, is a second messenger system not unlike that of cyclic adenosine monophosphate (cAMP). Because the hormones that make use of this activation mechanism (which are all amino acid-based, notably oxytocin, epinephrine, anti-diuretic hormone and gonadotropin-releasing hormone) are water-soluble and thus unable to diffuse across the lipid bilayer of a cell membrane, their target receptors exist on the surface of cell membranes. This is in contrast to the class of steroid hormones, which are lipid-soluble and can thus easily diffuse across the lipid bilayer.

In the cAMP second messenger system, the hormone (the “first messenger”) binds to its extracellular receptor, changing the shape of the receptor and thereby exposing a binding site for a G protein, which I like to refer as a “Guide” protein. As the G protein binds to the receptor in question, it exchanges a guanosine diphosphate (GDP) for a guanosine triphosphate (GTP) molecule, thereby allowing the G protein to move along the inner membrane and activating an enzyme known as adenylate cyclase. Adenylate cyclase will further generate cyclic adenosine monophosphate (again, cAMP), which will in turn activate enyzmes known as protein kinases to add phosphate groups to proteins at will, causing cellular changes.

The PIP2-C system is more confusing to me. In PIP2-C signaling, the hormone (oxytocin, let’s say) binds to a extracellular target receptor, activating a G protein via the same GDP/GTP swap as discussed above. The G protein in this case activates an enzyme known as phospholipase C, which might best be thought of as the equivalent of the adenylate cyclase of the cAMP system. Phospholipase C breaks down the membrane phospholipid PIP2 to yield inositol triphosphate (IP3) and diaglycerol (DAG), both of which are considered to be 2nd messengers much like cAMP. DAG in this case will activate protein kinase enzymes, while IP3 will head over to the endoplasmic reticulum, where it will bind to an IP3-specific receptor, which also happens to be a calcium ion channel. Once bound to its receptor, IP3 causes the channel to release calcium from the endoplasmic reticulum.

So there it is. It makes more sense to me, now that I’ve written it out. Yay for catering to your own learning style!

As published in today’s Sophian…

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… minus the fekakte editing. Hope you like it!

Exercise sheds its heavy, punitive connotations

Exercise. It’s a dirty word, invoking punishing routines at the gym, sweat rags and Spandex-clad aerobics instructors urging patrons to “step it up, people!”

That needn’t be the case, according to University of Colorado at Boulder Professor of Integrative Physiology Monika Fleshner, who is also affiliated with the university’s Center for Neuroscience.

Fleshner, who gave a lecture at Smith Monday titled “The Stress Buffering Effects of Exercise: Immune Consequences & Sympathetic Nervous System Mechanisms,” has made it her life’s work to study the effects of physical fitness on stress and depression.

Using animal models, Fleshner and her lab have established time and time again the protective capacity of physical activity against mental distress.

In the lab, rats exposed to a stressor will exhibit what is known as a “depressive response,” commonly refusing food and sex and choosing to lie dormant in their cages instead. If given a running wheel, however, the same rats will choose to run throughout their waking hours and will no longer show signs of behavioral depression, even when exposed to simulated stressors.

Fleshner has also noted that forcing rats to run (i.e. forcing the animals to run on her, rather than their own, schedule) does not confer the same decrease in depressive symptoms. Rather, the forced exercise-condition rats exhibit the same aversion to food and sex seen in their “depressed” counterparts.

Fleshner extrapolates from such findings, arguing that human beings must develop ways to make exercise a “natural” part of our lives, rather than yet another item to check off each day. Furthermore, Fleshner believes that exercise “makes evolutionary sense,” as humans evolved to live in environments in which physical activity was the norm.

Smith students, faculty and staff also struggle to make exercise normative and enjoyable, rather than something that they “should” do. Director of Athletics Lynn Oberbillig exercises to “feel better, [for] weight control… [to] feel strong” and to help her injured back heal. Oberbilling greatly enjoys her regular workouts, which alternately comprise pilates, strength training and walking. She also golfs on a regular basis. For Oberbillig, “working out” is enjoyable only if it requires mental, as well as physical, dedication.

Jessica Wignall ’13, who is pre-med, quantifies exercise as “anything that makes me sweat. Running, spinning, lifting weights, etc.” Wignall also enjoys her workouts, and considers her primary motivation for maintaining a regular fitness routine to be stress reduction, a true necessity as she navigates a challenging and unyielding course load.

Anna Burke ’12 put it in more dire terms. “If I don’t exercise, I am absolutely miserable. Ideally, when I have time, I go for about a half-hour run and do some ab exercises,” but said that she sometimes only has time for a 20-minute run. Burke runs outside if the weather allows, and occasionally alternates her running with a swim. Time, she said, sometimes “gets in the way.”

Burke enjoys being active “most days. On a really good day, I’ll do it [exercise] because I enjoy it, but otherwise I know that if I do it, I’ll be happier and have more energy.” Burke also mentioned that her attitude towards exercise has evolved over the years, and has come to be as of late more of an “enjoyment thing.”

The question then becomes of course how to inspire Smith students to adopt regular fitness routines that renew and reinvigorate, rather than eliciting that forced feeling that is all too common.

Oberbillig has some ideas. While she would “love it” if every student visited the gym regularly, Oberbillig places a premium on providing a variety of physical activities for students to choose from, and hopes that “each person can find something to do, whether it is working out alone, taking a class with others, attending Get Fit [Smith, the college-sponsored not-for-credit fitness classes], learning a new skill or sport, [or] climbing a wall.”

Said Oberbillig, “exercising is a lifetime commitment to good health and a strong heart. If students develop a good pattern, then they are more likely to continue as adults. Even if you stop exercising for a period of time, you will come back to it eventually, and that is what we hope students learn.”

Indeed, Fleshner maintains that one need not “be an athlete to get a lot of the mental health benefits” of exercise.

Move thyself, it seems, and good health will follow.

Billy Rubin

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Do you know why your urine is yellow? Thanks to some guy named Billy Rubin.

That is, the heme groups of the red blood cells’ hemoglobin are degraded upon cell death/old age to a substance called bilirubin. Bilirubin is yellow in color, and an excess buildup thereof is an indicator of diseases like jaundice. In addition, Billy-Boy lends color to your mellow yellow.

Thanks, Billy. Without you, life would be a lot less colorful.

Calorie counts in college dining halls?

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Below is a fabulous Letter-to-the-Editor from fellow Smithie and student blogger Jackie, published this past Thursday in the Sophian, our student newspaper.

Jackie’s letter addresses Smith’s recent decision to post nutrition information (calories, grams of fat, protein, etc.) on the dining menus available online.

To the Editor:

As a senior at Smith, I’ve seen many unfortunate changes take place within our campus and community, many as a result of recent budget cuts. Despite this, I adore Smith College, and it pains me when the administration or offices on campus make choices that are out of touch with the needs and desires of the students. Dining Services’ recent decision to provide nutritional information alongside the online menus strikes me as a choice that, while surely well-intentioned, reflects an ignorance of the type of student body we have.

I’ve struggled with an eating disorder for nine years, and though recovered now, know many other Smithies who also deal with eating disorders and disordered eating. Although I have no hard facts, my personal estimate is that at least 20% of our campus has had some struggles with this, if not more. It is nearly epidemic.

While attempting to fight a mental illness and maintain a real concept of what healthy eating looks like, easy access to calorie counts can be devastating and a real setback. I have no doubt that many of the students dealing with EDs on campus can estimate the calories in their food with startling accuracy, but I see no legitimate reason to provide us with the cold hard facts to further enable eating disorders. Even for students who may be trying to lose weight for legitimate health reasons, given Smith’s style of dining services, it’s hard to make healthy choices if you realize the mac n’ cheese has a bazillion calories, but there’s no other real option presented except the salad bar, which does not a dinner make.

I fully support Dining Services in publishing allergy information, ingredient lists, sodium, and the like, and even macronutrients like carbohydrates and protein. Providing this information gives individuals with health conditions the ability to eat with confidence that they won’t be adversely affected by their food, and that’s great. But to put the fat grams and calorie counts for foods I’ve eaten, blissfully ignorant of their caloric values over the past three years, seems to be a decision out of touch with the needs of Smith’s unique student body. Women already fight an uphill battle in trying to treat their bodies with love and respect, and Smith shouldn’t make this any harder than it has to be.

Sincerely,
J.S.

First off, I applaud Jackie for making her voice heard. Like she says, Smith has made quite a few decisions in recent years (phasing out college chaplains, for example) that have angered the student body. Yes, cuts must be made to maintain a viable college budget, but many such cost-saving measures seem to have gone too far. Similarly, with Dining Services’ decision to publish the nutritional and caloric break-down of our beloved vegan Caesar salad, chocolate chip brownies and cheddar-broccoli bake, we students have once again a chance to make our opposition heard.

I agree wholeheartedly with Jackie on this issue. Smith College is home to 2,500-some young women who regularly push themselves for excellence in the classroom, on the soccer field and in all aspects of their lives. As a result of our collective tendency towards perfectionism, it is unsurprising that many Smithies have struggled or struggle with disordered eating and eating disorders. As Jackie points out, providing such students with yet another reminder of the ways in which food (that which is meant to nourish and sustain) can ohmygod! make you fat! is unnecessary and in fact harmful.

Because I am often at UMass for Anatomy & Physiology and Biochem., I eat most lunches in the university dining halls. Beyond providing far greater variety (and soft-serve!), UMass also adorns its many eating options with nutrition tags. Brown rice, I read today, contains 107 calories per serving, and 1.4 grams of fiber. Couscous, on the other hand, contains only 100 calories per serving, but less fiber. Interesting for a future nutritionist, yes, but dangerous information in the hands of someone who has struggled with disordered eating.

I understand as Jackie does that such nutrition tags can help students avoid allergic reactions, and influence a student to pick a protein-rich item over one that has comparatively little protein, but, especially on a campus where so many of us attach undue meaning and importance to food, publishing such information can be quite damaging.

If Sally Smithie reads that her favorite pasta dish contains 200 calories more than another entrée, she may decide to forgo the pasta. It is Sally’s right as owner of her body to choose what goes into said body, but what if Sally is a recovering anorexic? The dining halls then becomes a minefield for S.S. and similar students for whom eating is no second-nature affair.

I understand that Dining Services’ intentions are good, but I must, like Jackie, remind the administration that such a decision should not be undertaken without consideration of the myriad ways in which making calorie- and fat-counts part of the dining experience can endanger the health of the student body.

Obesity begins in the womb?

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Examiner article here.

Oh, and dear readers? I may in fact end up alternating Examiner and Grub posts every other week. That is, I may end up posting only once every other week instead of every week. Got to preserve the sanity (and some variation on good grades), you know.

To Hemoglobin, with love

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Oh, the things you can learn in school!

In Anatomy and Physiology this past week, we started our unit on the blood system. I’ve never spent any time in depth learning about blood, but I was pleasantly surprised to find that the subject was anything but boring.

In our discussion of red blood cells (RBC), the most abundant type of blood cells in the body, my professor of course spent a good deal of time talking about hemoglobin, the protein that enables RBC to serve as transport molecules for the oxygen our bodily tissues require. To illustrate the importance of hemoglobin, consider the fact that red blood cells are composed of 97% hemoglobin.

Each molecule of hemoglobin is made up of four globin protein chains. Each of a hemoglobin molecule’s four globin chains possesses a heme group, and each heme group in turn contains a charged iron atom. It is to this iron ion that oxygen binds.

When we humans breathe in, the oxygen that enters our lungs is loaded, molecule by molecule, onto these iron ion sites. Under ideal conditions, each hemoglobin molecule would be fully saturated with oxygen molecules; that is to say that the four iron ion sites of each hemoglobin molecule would be attached to four oxygen molecules.

As you may remember from high school biology, the energy currency of the body, ATP, is produced aerobically (in the presence of oxygen), by the cellular mitochondria, the energy “factories” of the body. Because red blood cells lack a nucleus and organelles, they have no such mitochondria and thus no way to aerobically produce ATP. This turns out to be advantageous, however, for the RBC. Because they have no need to use oxygen to make ATP, the RBC are able to conserve all of their oxygen and thus deliver a maximum number of oxygen molecules to the body cells.

Because it is to the iron sites in the hemoglobin that oxygen binds, you can imagine that iron is vital for the proper functioning of the body. Indeed, an iron deficiency is one of the most common forms of nutritional deficiencies, and has far-reaching implications beyond impairing oxygen transport.

Iron deficiencies can be caused by a variety of reasons, including chronic bleeding (e.g. as a result of a bleeding ulcer or excessive menstrual bleeding), acute blood loss (as caused by a car accident, for example), drugs that interfere with iron absorption and, most commonly, as a result of inadequate iron intake. Symptoms of iron deficiency include fatigue, paleness, weakness, brittle or grooved nails and irritability.

As someone who plans to pursue nutrition as a career path, it is of great interest to me to promote diets that contain adequate amounts of iron.

What, then, are good dietary sources of iron? Red meat, fish, poultry, lentils, beans and tofu are all good sources, as are dark leafy green vegetables and fortified breakfast cereals. Some iron can also be found in molasses.

As with most nutrients, iron from various dietary sources is absorbed and processed in different ways. Iron from meat (“heme iron source”) is more easily absorbed than the iron in grains and vegetables, for example. Because of this, vegetarians and vegans should take care to take in extra iron from their diets. Legumes and dark leafy greens are again good vegetarian and vegan sources of the nutrient, but spinach and Swiss chard unfortunately contain substances called oxalates that inhibit absorption of the very iron they contain. One solution to this is to consume vegetarian and vegan sources of iron with foods that contain Vitamin C, which enhances iron absorption.

Maybe Popeye should’ve taken his spinach with a tall glass of orange juice.

Happy Grubbin’!

Sarah

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