Stain available varieties

Figure 4.1 Some of the wide variety of stains available...

Mycobacteria of the Mycobacterium avium complex are implicated in disseminated bacterial infections in AIDS patients. RFLP studies followed by hybridization with radiolabeled probe specific for an insertion sequence in M. avium (IS 1311) have been useful for typing M. avium stains (R2). A variety of molecular techniques are available for the diagnosis of Chlamydia trachomatis infection. In addition to PCR, a method based on the ligase chain reaction has also been found to be sensitive to the detection of C. trachomatis infection in urine specimens collected from male and female subjects (VI). The differentiation between low-risk genotypes of human papilloma virus (HPV 6 or 11) from genotypes of high... 

A variety of methods are available to detect proteins separated by electrophoresis or to measure the concentration of total protein in a solution. These methods are normally based on the binding of a dye to one of the amino acids in protein, or a color reaction with an amino acid side chain. The most commonly used stains for protein detection on gels are Coomassie Brilliant Blue (98) and silver stain (99,100). These methods detect any protein residues, either in solution or on an electrophoresis gel. Their main requirement is sensitivity, not specificity. New, more sensitive dyes are being developed for the proteomic analysis of protein structure and sequence, for example Ruby Red (101). 

Topcoats arc usually applied over an undercoat (i.c., primer, stain, etc ). A topcoat must protect its undercoat from environmental damage and should provide the appearance characteristics desired for the particular application. Topcoats arc available in a variety of colors, textures, and glosses. One specialized topcoat is luapier, which is a solution of resin in organic solvents. Lacquers dry, but do not cure. Because of their high VOCs. the use of lacquers is declining. Enamel is a term used to describe a glossy, opaque topcoat. 

The reagents available for IHC, have increased in quality, but even more so in number of sources and variety of staining methods. This plentitude of reagents contributes to lack of standardization in significant ways, that in theory are manageable by good technique and use of proper controls, but in practice have led to requirements of such excellence in technical process, that many laboratories cannot find sufficient, or sufficiently skilled, staff to comply. 

Fibroblasts were selected because they are readily cultivated and radio-labeled and are available from skin explants of a variety of species. Autoradiograms of radiolabeled cellular proteins are more diverse and easily analyzable for molecular systematics than alternatives such as silver-stained serum or erythrocyte protein patterns. We have achieved nearly 100% success rates at minimal discomfort and risk to human subjects by establishing cultures from 3 mm punch biopsies from the upper buttock. Local lidocaine anesthesia is used. Samples are collected following informed consent and under an approved human research protocol. Other species are sampled by dart gun8 or while sedated. Skin samples can be collected from various body sites without compromising the 2D electrophoresis metric, which does not rely on quantitative differences in protein expression. To comply with the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), tissues collected from wild and captive exotic animals must be obtained under specific permits issued by the U.S. Fish and Wildlife Service. 

The pitfalls of interpretation of lymphatic channels in paraffin-embedded breast tissue are well known. Retraction artifacts, ducts with misplaced epithelium, and artifactual displacement of cells commonly complicate the interpretation of biopsy samples. A recently available antibody, D2-40, shows high sensitivity and specificity for normal lymphatic channels in a variety of tissues. 493 D2-40 stains the lymphatic endothelium crisply and intensely but does not stain the normal vascular endothelium (Fig. 19.30).It is highly sensitive and specific in identifying lymphatic space invasion. 

A variety of serologic and tissue-based assays including IHC, ISH, special stains, EM, and PCR are available. These should be selected individually on the basis of clinical situation and suspected organisms. 

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