Label efficiency

Figure 3. Effects of molecular weight on labelling efficiency. Three heparins were independently labelled at increasing degrees of substitution. Molecular weight ranges of 3,000 (open square), 4,000-6,000 (solid circle), and 12,000-15,000 (open diamond).

Photoreactive aryl azide linked retinoic acid derivative (termed ADAM-3,55, Fig. 18) labeled efficiently the recombinant E-subunit and the covalent attachment was identified within residues 492 - 510 and 589 - 594, which correspond to similar sequences found in the human retinoic receptor [148]. 

It is important to note that even in the presence of sufficient proton density and in the case of differential isotope labeling, efficient spin-diffusion may complicate the interpretation of the NOE data and result in structures or relative orientations that are erroneous. A similar problem does not occur when using residual dipolar couplings. 

Recently, this method was adapted to label two commercially available liposomal formulations doxorubicin encapsulated in polyethylene glycol (PEG)-coated liposomes (Caelyx /Doxil ) (14) and daunorubicin encapsulated in small distearoyl-phosphatidyl-choline/cholesterol liposomes (Daunoxome ) (15). Although no DTPA was encapsulated in these liposomes, the labeling efficiency was typically between 70% and 80% and the radiolabeled preparations were stable in vivo during the time course of the experiment (four hours). Most likely, the lipophilic In-oxine avidly associates with the lipid bilayer and encapsulation of DTPA might not be necessary when the experimental observation period does not exceed four to six hours. 

The DTPA-PE conjugates were also investigated for labeling liposomes with Tc (34,35). DTPA-PE liposomes were found to be less useful for Tc labeling than for In labeling because it was difficult to maintain precise control of the amount of stannous chloride needed to reduce the Tc to achieve a high labeling efficiency. Also, in vivo stability of the Tc-lipo-somes was lower due to the dissociation of Tc nonspecifically bound to the liposome surface. 

This method is relatively inexpensive and easy to apply, although there is no commercially available kit. However, recently succinimidyl-HYNIC became commercially available (Solulink, Inc., San Diego, California, U.S.). Liposomes are labeled rapidly and with a labeling efficiency generally higher... 

Tilcock C, Ahkong QF, Fisher D. Tc-labeling of lipid vesicles containing the lipophilic chelator PE-DTTA effect of tin-to-chelate ratio chelate content surface polymer on labeling efficiency biodistribution behavior. Nucl Med Biol 1994 21 89. 

Designing an array is not a trivial task. In addition to the probes of interest, an array should include appropriate numbers of positive and negative control elements, such as housekeeping genes and controls that can be used to monitor the efficiency of important steps within the process. For example, you may wish to spike in internal standards that track recovery or labeling efficiency among different samples. It is also important to consider how you will print. How many replicates do you want Should these replicates be... 

Total mRNAs from confrol and induced cells were labeled using reverse franscripfase wifh fhe incorporation of fluorescene-dCTP (control, green label) or Cy5-dCTP (induced, red label). The two populations were hybridized to separate arrays. However, the labels were also swapped to verify fhaf any differences in labeling efficiency did not affect the result. 

Fragmented, biotinylated RNA prepared in this manner was hybridized to the array and the signal developed using streptavidin-R-phycoerytherin. A confocal laser scanner was used for detection. The researchers estimated that they could detect two transcripts per cell based upon labeling efficiency and an estimated 4% mRNA content in total bacterial RNA. Thus, chip detection of labeled transcripts was found to be more sensitive than detection by Northern blot. Specific genes (e.g., basal levels of cinA) undetectable on Northern blots were quantifiable on the microarray. In addition, it was... 

The intensity of the color as judged by the eye is normally a good indicator of labeling efficiency. Alternatively, the labeling efficiency may be checked by scanning with a densitometer. 

Some evidence indicates increased labeling efficiency of certain diluted antibodies (e.g., antiamylase antibodies and anti-MHC class II antibodies) when they are exposed to microwave heating prior to their application (Chicoine and Webster, 1998). However, such... 

It is known that antibody labeling efficiency over tightly packed antigens is reduced because of steric hindrance. 

Chicoine, L., and Webster, P. 1998. Effect of microwave irradiation on antibody labeling efficiency when applied to ultrathin cryosections through fixed biological material. Microsc. Res. Tech. 42 24-32. 

Robinson, J. M., Takizawa, T., and Vandre, D. D. (2000) Enhanced labeling efficiency using ultrasmall immunogold probes immunocytochemistry. J. Histochem. Cytochem. 48,487 192. 

---