Kaur P.,Research Division |
Potten C.S.,Epistem Ltd.
Experimental Dermatology | Year: 2011
Adult stem cells in rapidly renewing tissues have been classically defined as rare, relatively quiescent cells with the unique capacity to constantly self-renew and regenerate tissues during homeostasis. Although this view remains firmly embedded in the skin field, particularly in the area of hair follicle stem cell biology, it has been challenged by a number of notable publications in 2007. These papers leave an uncomfortable feeling with the reader if one believes that stem cells and transit amplifying cells are two polar opposites and 'never the twain shall meet.' Even if you do not subscribe to this extreme view, the implications appear to be far-reaching given that the majority of techniques devised for stem cell identification have used the fundamental tenet that the proliferating compartment is comprised of two distinct, mutually exclusive compartments, i.e. a minor proportion of long-lived quiescent stem cells with unlimited self-renewal and a large pool of rapidly cycling, short-lived transient amplifying cells with limited or no self-renewal capacity in normal steady-state conditions. However, these recent findings have resulted in papers that could be described as sensationalistic because they make little or no attempt to reconcile their observations with the large bulk of historical data with direct bearing on the interpretation of stem cell activity in normal steady-state conditions. Here, we offer some explanations that may help to integrate all of the data while presenting a case that both quiescent stem cells and cycling 'transit amplifying' cells contribute to epidermal replacement. © 2011 John Wiley & Sons A/S. Source
EPISTEM Ltd | Date: 2013-08-07
We describe a quantitative PCR (qPCR) instrument for combined qPCR and melt curve (dissociation and/or association curve) analysis. The instrument has at least one optical channel; a fluorescence excitation source; a fluorescence detector; an electronic analogue signal amplifier having an input coupled to an output of the fluorescence detector; and an analogue-to-digital converter (ADC) having analogue input coupled to an output of the analogue signal amplifier. The instrument further comprises a quantified automatic gain control (AGC) loop coupled between the signal output of the fluorescence detector and the analogue input of the ADC. The AGC loop is configured to apply a determined, numerical gain value to a fluorescence signal for the analogue input of the ADC. The instrument also includes a system to scale a digital output of the ADC responsive to the numerical gain value and to provide a digital fluorescence level signal from the scaled digital output.
Epistem Ltd | Date: 2012-11-16
An assembly and related methods are described for the preparation and processing of samples in molecular biology assays and nucleic acid amplification reactions. The assembly allows rapid and easy processing with reduced sample handling compared to known sample preparation apparatus and methods. The assembly comprises a reaction vessel, a sample matrix and a lid. The invention further provides an integrated punch to punch out discs of the sample matrix into the reaction vessel (without handling); thereby reducing the sample handling required to generate the final amplified nucleic acid product.
Epistem Ltd | Date: 2012-01-06
A method for analysing genetic mutations, and in particular single nucleotide polymorphisms (SNPs) and/or somatic mutations, is described, as well as methods for preferentially amplifying one allelic form compared with another form. The methods use an oligonucleotide probe which hybridises to a first allele with a lower melting temperature (Tm) than that with which it hybridises to a second allele, together with amplification primers which flank the oligonucleotide probe binding site and which bind to the sample with a higher Tm than that of the probe and the first allele. An amplification reaction may be carried out at a temperature such that the probe is preferentially hybridised to the second allele, thereby amplifying the first allele. The amplified sequences may be detected using the same probe as acted as the blocking probe during amplification.
Epistem Ltd | Date: 2012-09-25
An assay for mutations in JAK2 is described. The assay uses selective amplification of mutant alleles with a blocker probe which preferentially hybridises to wild type alleles. The same probe is then used to detect presence or absence of wild type sequences. It is not necessary to know the specific mutant sequence beforehand.