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Deafness is the most frequent sensory impairment in humans, with significant social and psychological implications. Early-onset hearing loss can have major adverse effects on the development of a child’s speech and language with important potential long-term consequences for cognitive development (Davis and Hind, 1999).These problems may be exacerbated in developing countries where poor nutrition and/or limited access to educational and medical facilities, coupled with increased reliance on verbal communication skills, can result in social isolation and reduced occupational opportunities (Kumar, 1997; Elahi et al., 1998).

Type II diabetes mellitus (DM) is characterized by amyloid deposition within the pancreatic islets of Langerhans [1, 2]. The major constituent of islet amyloid is a small protein designated islet amyloid polypeptide (IAPP), or amylin, which is synthesized by beta cells [3, 4]. The precise function of IAPP is unknown but it may act as a glucoregulatory hormone [5, 6] and may, possibly, play a pathogenetic role in Type II DM. This hypothesis in turn raises the question of the potential role of islet amyloid formation in the pathogenesis of Type II DM.

The identification of mRNA in tissue sections by in situ hybridization (ISH) has become a standard technique for studying gene expression in individual cells which has been applied to the study of many disorders including amyloidosis [1]. cRNA is the probe of choice for ISH due to its combination of high specificity, specific activity, hybrid stability and detection sensitivity [2,3]. Conventional transcription systems for generating cRNA utilize cloning vectors which contain bacteriophage RNA polymerase promoters [4]. The inherent disadvantage of such systems is the use of cloning techniques to amplify the desired DNA sequence prior to its transcription. We have developed a procedure for synthesizing cRNA probes in vitro which utilizes the polymerase chain reaction (PCR) as the method of DNA amplification rather than DNA cloning. This simple technique allowed the rapid and efficient synthesis of cRNA probes for murine SAA, SAP and basement membrane heparan sulfate proteoglycan (HSPG) mRNAs.

Serum amyloid A (SAA) is a family of acute phase proteins whose hepatic synthesis increases 500-1000 fold during inflammation [1]. Murine SAA consists of two markedly homologous apolipoproteins, SAA1 and SAA2, which circulate as components of HDL particles [2-4]. A third less homologous member of the murine SAA gene family, SAA3, is also induced by a variety of inflammatory stimuli [4-6] but a corresponding SAA3 protein has not been identified.