Insulin-like growth factor-I treatment in primary growth hormone insensitivity: effect of recombinant human IGF-I (rhIGF-I) and rhIGF-I/rhIGF-binding protein-3 complex.

BACKGROUND/AIMS: Growth hormone insensitivity syndrome (GHIS) is a rare cause of growth retardation characterized by high serum GH levels, and low serum insulin-like growth factor I (IGF-I) levels associated with a genetic defect of the GH receptor (GHR) as well post-GHR signaling pathway. Based on clinical, as well as biochemical characteristics, GHIS can be genetically classified as classical/Laron's syndrome and nonclassical/atypical GHIS. Recombinant human IGF-I (rhIGF-I) treatment is effective in promoting growth in subjects who have GHIS. Further, pharmacological studies of a IGF-I compound containing a 1:1 molar complex of rhIGF-I and rhIGF-binding protein-3 (BP-3) demonstrated that the complex was effective in increasing levels of circulating total and free IGF-I and that the administration in patients with GHIS should be safe, well-tolerated and more effective than rhIGF-I on its own. PATIENT/METHODS: We describe the long-term effect of various IGF-I preparations (rhIGF; rhIGF-I/rhIGFBP-3) in a single subject treated for more than 14 years while focusing on height, height velocity as well as on additional auxological and laboratory data. RESULTS: This study confirms that rhIGF-I is effective in promoting growth in children with GHIS. However, on the combined rhIGF-I/rhIGFBP-3 treatment as well as off rhIGF-I therapy the height velocity decreased drastically (2 and 1.8 cm vs. overall 6.5 cm/year on rhIGF-I, respectively). On rhIGF-I treatment, serum IGF-I was found to be well within the normal range, whereas serum IGFBP-3 remained low. On the rhIGF-I/rhIGFBP-3 compound therapy, however, serum IGFBP-3 increased into the normal range, which was not the case for serum IGF-I. Importantly, the increase of the serum IGFBP-3 level excludes noncompliance. In addition, body mass index as well as dual-energy X-ray absorptiometry analysis underlined the positive effect of rhIGF-I treatment on body composition. CONCLUSIONS: The rhIGF-I/rhIGFBP-3 compound therapy seems to be not efficient in treating this individual patient with GHIS when compared with rhIGF-I alone.

EEG data compression techniques.

In this paper, electroencephalograph (EEG) and Holter EEG data compression techniques which allow perfect reconstruction of the recorded waveform from the compressed one are presented and discussed. Data compression permits one to achieve significant reduction in the space required to store signals and in transmission time. The Huffman coding technique in conjunction with derivative computation reaches high compression ratios (on average 49% on Holter and 58% on EEG signals) with low computational complexity. By exploiting this result a simple and fast encoder/decoder scheme capable of real-time performance on a PC was implemented. This simple technique is compared with other predictive transformations, vector quantization, discrete cosine transform (DCT), and repetition count compression methods. Finally, it is shown that the adoption of a collapsed Huffman tree for the encoding/decoding operations allows one to choose the maximum codeword length without significantly affecting the compression ratio. Therefore, low cost commercial microcontrollers and storage devices can be effectively used to store long Holter EEG's in a compressed format.

Telephone transmission of 20-channel digital electroencephalogram using lossless data compression.

BACKGROUND: The use of telecommunications for computer-assisted transmission of neurophysiological signals is a relatively new practice. With the development of digital technology, it is now possible to record electroencephalograms (EEGs) in digital form. Previous reports have demonstrated the possibility of real-time telephone transmission of a limited number of EEG channels. OBJECTIVES: To assess the effectiveness of specific data-compression software to improve the transmission of digital 20-channel EEG records over ordinary public telephone lines. METHODS: A prototype system was built to transmit digital EEG signals from one computer to another using two 14.4-kbps modems and proprietary lossless data-compression software. RESULTS: Forty compressed digital EEG records of 20 channels each were sent from different locations at variable distances using "plain old telephone service" (POTS). The mean compression ratio was 2.2 to 2.8:1 using a sampling frequency of 128 Hz and 2.8:1 at a sampling rate of 256 Hz. Transmission time was reduced proportionately. CONCLUSION: Although this study used a store-and-forward approach, the results suggest that it may be possible to transmit a large number of compressed EEG channels in real time using data compression.