Is there a doctor in the house?

[Lance]

Hi Arneb,

I have an academic question about allergies. Is that a subject within your expertise?

[Arneb]

Not my favourite subject, I admit. But that is only to my shame, as I am a lung specialist and should, by rights, be an expert on allergy as well. Let's say I'm serviceably educated at this. I suggest you just fire off your question(s) and if I go , I'll pass.

[Lance]

Okay, here goes:

Cyndi has many allergies. Among them are things that come from the water: fish, crustaceans and mollusks. The closest these 3 groups of things are related taxonomically is that they are all within the kingdom Animalia but in different Phyla. I will refer to these collectively as Group "A".

In group "B" we have tomatillos, potatoes, tomatoes, eggplant, chili peppers and bell peppers. These are closely taxonomically related in the family of Solanaceae.

So how can you be allergic to just one of many closely related items in group B (tomatillos) but also allergic to everything from the completely unrelated Phyla of group A? I should probably also mention that she is _not_ allergic to iodine.

[Arneb]

Tough. I have an idea or two but I need to have a look.

[Lance]

I guess it is possible there is some protein common to everything that lives in water (fresh and salt). I wish there was an easy way (outside of Japan) to see if she's allergic to Cetaceans which are more closely related to land mammals than fish.

[Arneb]

It's an interersting topic.

You have probably heard of cross-allergies. Cross-allergies may reflect evolutionary closeness of the causeative agent - for example, the common allergen in the crustaceans/mollusks/fish cross-allergy is tropomyosin, a conserved muscle protein common to all groups -, but then again, they may not. Antibodies do not recognize amino acid similarities, like a sequence analyzing software would, they recognize spatial similarities. A simple and untrue, but not too untrue analogy for this is the key-and-lock analogy. The smallest possible structure that can serve as a sensitizing agent (the smallest possible "key", if you like) is called an epitope. It is possible for two cross-sensitizing epitopes to be made up of comletely different amino acids, even , IIRC of completely different chemical substances, as long as the spatial and charge conformations are similar enough.

The common allergen in the fish/Crustacean/mollusc across-allergies also confers the risk for cockroach and house dust mite allergies.

In the case of the tomatilla, well. It is always possible not to have a cross-allergy, and all the better for Cindy.

I think the crucial bit of thinking here is that antibodies aren't machines that recognize evolutionary relations (expressed as DNA/protein sequence similarities; although they may happen to do just that), they are machines that recognize spatial structures.

[tubeswell]

Your grasp of this topic is highly impressive Arneb. The spatial - mechanistic analogy is interesting re: antibodies as machines

[Lance]

I hadn't heard of cross-allergies before actually. What a fascinating topic.

So like in two sets of wrenches, one metric and the other SAE (inch); though completely unrelated sets, some fit each other's nuts and bolts.

Thank you for helping me understand this. My curiosity was purely academic, but I feel better now.

[Enzo]

And as much as we want to find patterns in everything, it is also possible she simply has more than one allergy. In the sense like I enjoy Italian food, but I also enjoy sushi, even lacking a common element between them.

[Lance]

And as much as we want to find patterns in everything, it is also possible she simply has more than one allergy. In the sense like I enjoy Italian food, but I also enjoy sushi, even lacking a common element between them.

Yeah, that's true. I was just trying to understand it a little better.

In some people that are allergic to just fish, they are often only allergic to a specific species or family and if you can identify it that person can safely eat other fish. So with that on one side of sea food allergies and then Cyndi's condition on the other, I wanted to make sense of how both conditions can be true.

And thankfully, Arneb made it so.

[Arneb]

So like in two sets of wrenches, one metric and the other SAE (inch); though completely unrelated sets, some fit each other's nuts and bolts.

Yep, good analogy. The extent to which one antibody "fits" with a different, possibly unrelated, antigen is called cross-reactivity, and one observes everything from a near total fit to just barely above no fit at all. If the antibody is one that sets off an allergic reaction, there is your cross-allergy.

Thank you for helping me understand this. My curiosity was purely academic, but I feel better now.

Now that's good to know - Anytime, boss.

[Мастер]

So like in two sets of wrenches, one metric and the other SAE (inch); though completely unrelated sets, some fit each other's nuts and bolts.

!! I thought this can't be correct, so I checked.

If you go to an integer number of mm, the first correspondence is 0 mm == 0 in, the next one is 127 mm == 5 in. But multiples of 5/64 inches are within one percent of multiples of 2 mm. So I guess if your tolerances are 1%, there are some correspondences.

Going to half millimetres picks up some more correspondences at 1%, such as 19/64 inches, which is close to 7,5 mm.

[Lianachan]

Am I going to have to replace my trusty old imperial hammer, to use these new fangled metric nails?

[Arneb]

If you want to be part of the EU after independence, sure.

[Enzo]

In small hand tools, common metric wrenches tend to be in whole mm and half mm sizes, so 4mm, 5mm, 5.5mm, etc. Once past maybe 7mm they stick more to whole mm increments. At least in my world. SAE stuff can get down to 1/64ths of an inch increments.. The tool only has to work, it need not be precise. Oh NASA may disagree, but those of us in the real world can get by with close. So yes, 5/16" and 8mm are pretty close. If you grab from the wrong pile, a wrench can be oversize as long as it is not large enough for the shoulders on the nut to slip through the points. If you are snugging up a nut hand tight, close works. High torque may be another matter.

And while the tools are sized, the hardware is nominal, so some 5/16 nuts fit the wrench tighter than others.


We are still trying to determine why they put these "threads" on our nails.

[Мастер]

If you want to be part of the EU after independence, sure.

A little odd, given that he's in the EU now :)

[Arneb]

That, too. But as newly-independent country, they'd have to re-apply, and there would be a price...

I know at least one country of the EU that would have problems with Scottish membership, to the tune of "hoy, Escocia, manana, Cataluna". Then again, they might be unable to resist the temptation to piss of the English real good.

[Lianachan]

That, too. But as newly-independent country, they'd have to re-apply, and there would be a price...

I know at least one country of the EU that would have problems with Scottish membership, to the tune of "hoy, Escocia, manana, Cataluna". Then again, they might be unable to resist the temptation to piss of the English real good.

Contrary to what the BBC would have us believe, Spain wouldn't object (they've actually said that too, though it wasn't widely reported over here.....). Using one of your evil eurohammers is a small price that I'm willing to pay, anyway

[Мастер]

Contrary to what the BBC would have us believe, Spain wouldn't object (they've actually said that too, though it wasn't widely reported over here.....). Using one of your evil eurohammers is a small price that I'm willing to pay, anyway

So Arneb, maybe it would be helpful to mention the common Eurohammer sizes, for comparison to the imperial hammer sizes.

[MM_Dandy]

We are still trying to determine why they put these "threads" on our nails.

And they can't even have a standard thread size, either, can they?

[Enzo]

That is why hammers come by weight.

[Arneb]

Contrary to what the BBC would have us believe, Spain wouldn't object (they've actually said that too, though it wasn't widely reported over here.....). Using one of your evil eurohammers is a small price that I'm willing to pay, anyway

So Arneb, maybe it would be helpful to mention the common Eurohammer sizes, for comparison to the imperial hammer sizes.

In hammers with a square contact area, sizes are in mm^2, the sides of the contact surface having lengths of integer multiples of 1 mm. In hammers with a round contact area, both the diameter, circuference and area of the contact surface must be machined as integer multiples of one millimeter.

[Cyndi]

Before this gets too hijacked into 'Tool Time' talk (if it isn't already too late)...
I wanted to jump in and say Thank You to Arneb!! I have lived my entire life with severe allergy triggered bronchial asthma, which was discovered when I was only 18 months old. As a kid, it was far easier to remember and tell someone what I could eat, than what I could not eat, because I had just so many food allergies. You name it, I was probably allergic to it! Although many of the things that i was allergic to back then, are now in the, I can tolerate in small amounts occasionally category, there are still things that I react violently on in the scratch tests. My allergies and asthma have always been something I have tried to learn as much as I can about. Since the more i know, the safer I can be. As well as something that Lance and I frequently talk about. This as been a fascinating topic of discussion.
(up until the 'Tool Time' hijacking). ;)

[tubeswell]

So there's a Llama or two in Napierville huh?

[Cyndi]

There is indeed - the Head Llama and his mate. :)