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There have been 7 items by cells (Search limited from 14-April 20)


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#136696 How does one select species/strain for toxicity testing?

Posted by cells on 30 June 2012 - 08:40 AM in Pharmacology and Pharmaceutics

Hi, this is just a general question for toxicologists but I was just wondering how one goes about selecting which species to perform testing on for any toxicity endpoints (developmental/reproductive effects, chronic toxicity, sensitization, etc.).

Why would someone select a mice over a rat (what are the big differences between the two)? And why pick a specific strain of mice (eg. CD-1 mice vs BALB/c mice).

Anyways, if anyone has any good discussion on this material that would be great.

Thanks.



#133547 anova using raw data - confused...

Posted by cells on 25 April 2012 - 09:18 PM in Bioinformatics and Biostatistics

Hi,

I am trying to perform statistics for my MTT assay but I am a bit confused as how to proceed. For simplicity sake I will present some example data.

Biological replicate 1 (done in triplicates):

Control: Absorbance: 500, 520, 510
Dose 1: Absorbance : 300, 290, 270
Dose 2: Absorbance: 200, 180, 160
Dose 3: Absorbance: 150, 130, 120


Biological replicate 2 (done in triplicates):

Control: Absorbance: 700, 720, 710
Dose 1: Absorbance : 400, 420, 430
Dose 2: Absorbance: 280, 260, 240
Dose 3: Absorbance: 210, 230, 220


Biological replicate 3 (done in triplicates):

Control: Absorbance: 400, 420, 410
Dose 1: Absorbance : 240, 230, 240
Dose 2: Absorbance: 160, 150, 155
Dose 3: Absorbance: 120, 110, 125



So if I was to take the means from each biological replicate and make the doses relative to the control, I would get almost the same % relativity between the doses. So for biological replicates 1, 2 and 3, the % relative to control for dose 1, dose 2 and dose 3 will be 60%, 40% and 30%, respectively, for all the 3 biological replicates even though there is significant variation between the absorbance of the biological replicates for the same sample (ex. control has absorbances of approx 500, 700 and 400 between the three biological replicates).

I am wondering how I would go about doing ANOVA on data such as this. Is it ok to perform anova on the percent data or should it be done on the raw absorbances?

Thanks



#126111 qPCR statistics (ANOVA) after normalization.

Posted by cells on 28 December 2011 - 10:27 PM in PCR, RT-PCR and Real-Time PCR

Hi,

I was wondering about performing statistical analysis of qPCR data after you have normalized all your data to your reference genes and you only have the fold changes (along with SEM) to work with. I was wondering if it's ok to use normalized data to do things like ANOVA. So the type of data I have is something like this:


---------------------------------------------------------------
| 24h | 48h | 72h |
---------------------------------------------------------------
DMSO | 1 +/- 0.2 | 1 +/- 0.15 | 1 +/- 0.12 |
---------------------------------------------------------------
100nM | 1.5 +/- 0.12 | 1.8 +/- 0.2 | 1.25 +/- 0.22 |
---------------------------------------------------------------
1uM | 2 +/- 0.21 | 2.5 +/- 0.25 | 1.78 +/- 0.23 |
---------------------------------------------------------------

Where x +/- y represents fold change +/- SEM...it's all relative to DMSO control so that ends up being 1 fold change. I was wondering if it's ok to do ANOVA analysis on this type of data or do you need to go back to your Ct values to perform ANOVA. Any help would be great as I'm kind of desperate. Thanks!



#117973 RNA isolation from frozen cells

Posted by cells on 22 August 2011 - 09:06 AM in PCR, RT-PCR and Real-Time PCR

Hi, I was wondering if there is any drawback to isolating RNA from cells frozen in -80 for a month. I had treated cells with a compound, collected the pellet, rinsed with PBS and stored the cells at -80...it's been a month and I would like to extract RNA for gene expression analysis from these cells. Will storing my cells for a month affect my RNA isolation and gene expression results? Just curious since I really don't want to retreat my cells with the compound.

Thanks.



#116321 Using a different media than recommended

Posted by cells on 29 July 2011 - 08:20 PM in Tissue and Cell Culture

Hi, I have quick question. I'm trying to grow RPWE-1 prostate epithelial cells (details here) and ATCC and every article seems to grow them in keratinocyte serum free media. I've recently started growing them in RPMI-1640 phenol red free media with charcoal stripped FBS added to it and they seem to be growing ok so far. I'm wondering if there is anything to worry about if they are growing fine in a different than recommended media - can different media potentially have an effect on expression of certain genes or receptors and potentially cause any stress to the cells? I'm not well experienced with cell biology so if anyone has any advice that will be really helpful.

Thanks.



#116320 Weird qPCR curves

Posted by cells on 29 July 2011 - 08:14 PM in PCR, RT-PCR and Real-Time PCR

Thanks for the responses...yea, I'm not going to worry about it too much:)



#116088 Weird qPCR curves

Posted by cells on 26 July 2011 - 05:13 PM in PCR, RT-PCR and Real-Time PCR

Hi, can anybody look at my qPCR curves attached. I'm wondering why it keeps going up instead of reaching a plateau..the melt curve looks fine and I haven't run the product on a gel but is it simply the case that I haven't run enough cycles yet for the plateau to be reached?

Thanks.

Attached Thumbnails

  • pcr curves.jpg




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