I cannot seem to find the best way to express this, both in terms of grammar and "correct sounding" feel to English/American readers (which I am not).

So, this is the scenario: the serum concentration of two peptides, peptide A and peptide B, is measured in a group of patients. The level of these peptides can be either high or low. Patients are tested for both at time zero and after 6 months. Our interest is on a subgroup of patients who have low levels of peptide A, and not peptide B, at six months. Thus, per our definition, this subgroup of patients includes:

  • those that have a low peptide A (and not peptide B) level at six months, AND
  • had either low peptide A/normal peptide B OR low peptide A/low peptide B at time zero

How would you refer to this group if you wanted to include in one sentence both the persistence of low levels and the fact that this only affects peptide A? I’d like for it to sound natural.

Additional examples for clarity's sake: Normal range for pep A is 10-20, anything below 10 is considered low pep A, anything more than 20 is considered high pep A. Same goes for pep B, identical normal range, identical cut-offs for low and high.

|         | time zero | time zero |  |  |  | at 6 months | at 6 months |
| patient | pep A     | pep B     |  |  |  | pep A       | pep B       |
| 1       | 6         | 11        |  |  |  | 4           | 15          |
| 2       | 6         | 2         |  |  |  | 4           | 4           |
| 3       | 6         | 2         |  |  |  | 4           | 16          |
| 4       | 3         | 11        |  |  |  | 6           | 14          |

Patients 1, 3 and 4 would be included in my group. Patient 2 would not be included because despite having low pep A both at time zero and at 6 months, pep B is also low both at time 0 and at 6 months. Note that patient 4 is included in my group despite having an increase in pep A levels: this is because despite the increase he still has low levels (below the normal range).

Would I use persistently decreased or should I use persistently low?

In the latter case, would the following expressions work:

Persistent low levels of peptide A-only;

Persistent A-only hypopeptidemia

(Peptide A is a fictional name, the real name would be similar to hypoalbuminemia and could be styled similarly).

  • 1
    I don’t understand what you mean by isolated. How are these two peptides isolated, and from what? If you say, “Persistently isolated low…”, then you’re saying it’s the isolation which is persistent, and I don’t think that’s what you’re trying to say – but I don’t really understand what it is you’re trying to say. – Janus Bahs Jacquet Sep 8 '19 at 22:02
  • Please reword your question so that it's not so impenetrable. – Hot Licks Sep 8 '19 at 22:21
  • I edited trying to address your questions. Thank you! – user3526613 Sep 8 '19 at 22:30
  • I mean you've got a wall of words there, with no paragraphs. – Hot Licks Sep 8 '19 at 22:40
  • Ok, hope it's more readable now. – user3526613 Sep 8 '19 at 23:01

I would phrase this as follows:

Patients who, at 6 months, showed persistently low values of peptide A (and normal peptide B) ...

You can further qualify this:

... after initially presenting with low peptide A (and low or normal peptide B) at time zero.

The parenthetical statements are optional if you feel it adds clarity to your statement. But, it also adds complexity.

It all sounds like a mouthful, but being a reader of these types of papers myself, I can say I'd understand your meaning.

Persistently works as an adverb to describe the adjective low which describes the value itself.

Persistent-low values is not preferable because the double adjective is not really a good descriptor for the value. It implies that it's persistent and low at the same time. It may be, but, you're not saying the value itself is persistent, but rather the lowness of the value.

In plainer terms: the value is still low (under 10), it's not still 3 and low. It could be 5 now, which is persistently below the cut off, but not the same that it was originally .....

Above values can be substituted with any appropriate phrase: plasma concentration, levels, etc.

  • Thank you, I think this would work perfectly in the manuscript. As for the title or tables etc. I would like to use something along the lines of "persistent hypopeptidemia A", would this work? I have the temptation to add isolated, and thus "persistent isolated hypopeptidemia A" (see other replies), but I get it would generate confusion, am I right? – user3526613 Oct 15 '19 at 14:50
  • @user3526613 Isolated doesn't really work there. You'd only say it if it were an isolated incident or you isolated it in the lab. Persistent hypopeptidemia A is good. If this answer works for you, consider upvoting and accepting it. – David M Oct 15 '19 at 14:52
  • 1
    Yes thank you David. I upvoted it but I guess I have not sufficient credit or something similar. – user3526613 Oct 15 '19 at 18:34

From the clarification of the question, the problem is to describe a group of patients typified by those satisfy columns 1, 3, and 4 in the first table below

     Start          6 months
    A     B         A     B
   low  normal     low  normal
   low  low        low  normal

but which excludes others such as those in the second table:

     Start          6 months
    A     B         A     B
   low  normal     low  high
   normal  low     low  normal
   low  low        low  high
   low  low        low  low
   low  low        normal  normal

This can be described as:

The group in which the level of peptide A remained low for 6 months and the level of peptide B was normal after 6 months.

and in writing this up in a report it would seem necessary to state it precisely in this or a very similar form.

The question is what to do if you have to refer repeatedly to such a group. A construct like “persistent low levels of peptide A-only” is clumsy, ugly and imprecise as it does not include the second condition regarding peptide B. I cannot imagine a phrase that embodies both conditions and would therefore second the suggestion made by @terdon to define them with code names — Group A, Group I, Hypo-A, or whatever.

Gentle suggestions from an old-timer

  1. Diagram or tabulate your problem to explain it. It may also help you explain it to yourself.
  2. Scientific language is difficult because precision is paramount and this often means using words that are not in everyday use. However when you can use a simple English word, do so. There is nothing clever about replacing plain English by long latinate words.
  3. Avoid strings of adjectival nouns (e.g. the ugly and clumsy suggestion of “persistent Peptide A-only-decrease”) by the simple expedient of a preposition. “Of” is not a four-letter word. You may have to use such combinations in the column headings of a table, but that doesn’t mean you need to use them in the text.
  4. If you think this will make the sentence too long, you probably need to divide it in two.
  5. Make your own decisions on style on the basis of reading clarity — don’t just blindly follow the majority.
  6. As a scientist use a precise term such as “concentration” or “amount”, rather than the aqueous “level”.
  • Looking at your table I think you've misread the OP's condition had either low peptide A/normal peptide B OR low peptide A/low peptide B at time zero. The OP doesn't talk of zero levels of peptide B but normal ... OR ... low peptide B at time zero. That is normal or low levels of peptide B at the start of the period. The subjects to be eliminated are, therefore, those in whom the level of peptide B was high at either end of the period regardless of the level of peptide A AND those in whom the level of peptide A was normal or high at either or both ends of the period. – BoldBen Oct 10 '19 at 2:34
  • @BoldBen — It’s possible, but I have provided the poster with the principles he can use to answer whatever his question was. If he needs to be told how to set out a table he need only ask. – David Oct 10 '19 at 19:50
  • Thank you David. Since you declare yourself a scientist, you know that a specific group of individuals that meet your study criteria often needs a short name, as ugly as it might be, rather than two sentences to define it. In this case it is not an easy expression to find, otherwise I would not have asked for help. As for the concentration rather then level, without any specification of the media (serum, urine, etc.), they both appear aqueous to me. I have no interest in appearing clever by using latinate words, "persistente" is commonly used in Italian, so it might just be a false friend. – user3526613 Oct 14 '19 at 16:49
  • @user3526613 use "group A" and "group B" and define the groups in the paper the first time you use them. Don't try to build a complicated, descriptive name. I agree with David 100% and I am also a biologist, as he is. Writing papers is hard enough, don't make it harder than it needs to be! Consider the classic example of "test group" and "control group". You just need to explain what conditions are met by the test group once, and then refer to them as "test group" in the rest of the paper. – terdon Oct 14 '19 at 17:54
  • With all due respect, this is a language platform and not a place where people ask for advice in scientific paper writing. Moreover, I don't see any conceptual complexity in the observation of a low value which stays low when rechecked. I respect your opinion, but the point here is to determine what's the most correct and understandable expression from a linguistic point of view. Moreover, "test group" and "control group" don't mean anything here as there is no intervention. – user3526613 Oct 14 '19 at 19:03

You're interested in the following sub-group at time zero who had the following criteria:

Low Peptide A/Normal Peptide B


Low Peptide A/Low Peptide B

IF, at the six month point that after measuring the peptide levels of these patients that your findings show that there has been a significant decrease in levels of Peptide A, in particular, and peptide A only and not peptide B, you can say as you mentioned in the comments:

persistent peptide A-only decrease

But to make this into a sentence:

There has been a persistent Peptide A-only-decrease from time zero and at the sixth month period.

Personally, I would avoid compounding words but the above style is normal in scientific journals and it would not be uncommon to see them have a similar style of writing. If you don't want to follow this format you can say:

There has been a persistent/constant/significant decrease in Peptide A levels from time zero to the sixth month period, compared to Peptide B.

From my share of writing experimental designs, the above sentence is proper structure for writing a hypothesis but instead it goes along the lines of "There will be a significant decrease/increase in Group A than Group B...", but in the conclusion/result section people are less picky with the wording.

Irrelevant, but I'm curious:

If your findings supported what you were interested in, low levels of peptide A in patients at the sixth month period did that support your hypothesis? What were your actual findings (other than Peptide A levels continued to decrease at already low-level at time zero and at the sixth month mark)?

However, from what I understand from your experiment, there may be a little bit of a selection bias or investigator bias with your target sample, judging from your sub-group.

  • 1
    Thank you so much for your in-depth answer. As for your final question, yes there is definitely a bias but it's somewhat desired: it is a retrospective study, we wanted to see if the persistent decrease in peptide a-only was associated with worse long term outcomes. Thank you again! – user3526613 Sep 9 '19 at 15:06
  • Would also "persistent low levels of pep A-only" be correct? I can't seem to find a rule for hyphenated only at the end of an expression. – user3526613 Sep 9 '19 at 15:46
  • The form of words you give does not, to me, describe the required situation. You talk about a "persistent decrease" in levels of peptide A while the original question talks about subjects in whom the level of peptide A started off low and remained low throughout the period of the investigation. That is not a "persistent decrease" since the levels remain, for the purposes of the investigation, the same. Also you do not exclude the logical possibility, of subjects in whom the level of peptide B was high at either end, of the period even though the level of peptide A was low. – BoldBen Oct 10 '19 at 2:11
  • @BoldBen how does “persistent decrease” not suit your tastes buds? The OP doesn’t seem to have any problem with it—it started low and remained low. When talking about a “persistent decrease” this is all about the scale, without some actual data I can’t comment precisely but my answer isn’t wrong, it depends on perception, think of a scale -5, 0 and +5. (...) – aesking Oct 12 '19 at 12:13
  • “It started off low and remained low”—from where, at which point? at -5 to +5 it may have been decreasing and hence the statement from start (0) to end (+5) that it started off low and remained low (note this is not STATIONARY; remain low shows some activity) is still true but it depends where you start and end points are. – aesking Oct 12 '19 at 12:13

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