Goljan RR path Errors.

[Teejay]

I just wanted to start this thread for those of us who are using Goljan RR for step one study.
On page 443, it says that prolactin enhances testosterone synthesis and spermatogenesis.
I thought this was the opposit since Prolactin inhibits GnRH which inturn decreases LH and FSH. BRS phys 3rd edition 262 also says Prolactin inhibits spermatogenesis.
Anyone has an answer for this discrepancy?

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[UditNarayan]

Looked at the errata and maybe corrected 1 thing in my RR path book. It looks like it everything has been corrected in my edition.
Got mine off ebay 2 weeks ago.

haha lucky!! I had to manually fix most of the errors

 

[albe]

Anyone notice how on page 126, it lists that Vitamin D is hydroxylated to 25-OH-D by the P450 system, but on 128, it says that induction of the P450 system by drugs (alcohol) will lead to metabolism of precursors of 25-OH-D? This seems to be contradictory.

It seems like he's saying the P450 system ACTIVATES/INCREASES as well as DECREASES Vitamin D. It seems like this as well if you listen to Day 2 Nutrition 1 between 29:50 and 31:00.

Would someone please clarify this concept for me?

 

[pseudoknot]

Anyone notice how on page 126, it lists that Vitamin D is hydroxylated to 25-OH-D by the P450 system, but on 128, it says that induction of the P450 system by drugs (alcohol) will lead to metabolism of precursors of 25-OH-D? This seems to be contradictory.

It seems like he's saying the P450 system ACTIVATES/INCREASES as well as DECREASES Vitamin D. It seems like this as well if you listen to Day 2 Nutrition 1 between 29:50 and 31:00.

Would someone please clarify this concept for me?

Wouldn't "metabolism of precursors of 25-OH-D" mean the creation of 25-OD-D? In other words, the precursors are metabolized into the active molecule?

 

[albe]

Wouldn't "metabolism of precursors of 25-OH-D" mean the creation of 25-OD-D? In other words, the precursors are metabolized into the active molecule?

I see what you're saying, but I don't think so. The reason I say that is because he specifically stated that this metabolism by P450 decreases 25-OH-D. I looked in his RR Biochemistry for the Vitamin D section to see if there's any more detail, and here it pretty much says the same thing: Vit D is converted to 25-OH-D by the P450 system (pg 63) and drugs like alcohol, phenytoin, and barbiturates that enhance the P450 system leads to Vit D deficiency (pg 64).

My best guess would be that there are different P450 enzymes where Enzyme A does the hydroxylation while Enzyme B does the inactivation, and that drugs like alcohol cause a rise in Enzyme B to such a level that it outcompetes Enzyme A for the substrate. Does anyone know if this is true?

 

[pseudoknot]

I see what you're saying, but I don't think so. The reason I say that is because he specifically stated that this metabolism by P450 decreases 25-OH-D. I looked in his RR Biochemistry for the Vitamin D section to see if there's any more detail, and here it pretty much says the same thing: Vit D is converted to 25-OH-D by the P450 system (pg 63) and drugs like alcohol, phenytoin, and barbiturates that enhance the P450 system leads to Vit D deficiency (pg 64).

My best guess would be that there are different P450 enzymes where Enzyme A does the hydroxylation while Enzyme B does the inactivation, and that drugs like alcohol cause a rise in Enzyme B to such a level that it outcompetes Enzyme A for the substrate. Does anyone know if this is true?

Yes, this appears to be the case. The enzyme that makes 1,25-OH D, 1-alpha-hydroxylase, is a cytochrome P450. There are other P450s that catabolize vitamin D and are induced by some drugs.

Since it took searching PubMed to get a definitive answer on this (there was nothing I could find on the issue in Robbins), I'd be shocked if it showed up on Step I. But then, I haven't taken it yet.

 

[Cirrus83]

Hey guys, am I the only one totally confused by what I'm supposed to be correcting on page 507 in the table? The official errata page says "Table 22-7: under Malignancy-induced hypercalcemia and serum phosphorus levels; subclassify into lytic and PTHr peptide where former (lytic) will be N for normal, and the latter (PTHr peptide) will be (down arrow); delete the (up arrow) sign."
But I have no idea what the arrows are supposed to be for, since there's 3 columns. Very confusing wording.

 

[future_dr_house]

Hey guys, am I the only one totally confused by what I'm supposed to be correcting on page 507 in the table? The official errata page says "Table 22-7: under Malignancy-induced hypercalcemia and serum phosphorus levels; subclassify into lytic and PTHr peptide where former (lytic) will be N for normal, and the latter (PTHr peptide) will be (down arrow); delete the (up arrow) sign."
But I have no idea what the arrows are supposed to be for, since there's 3 columns. Very confusing wording.

I think what it's saying is:

take malig induced hypercalc: incr, incr, decr
and split it into
Malig induced hyper calc

Lytic: incr, N (normal), decr​

PTHr peptide: incr, decr, decr​