In vivo proton MRS of normal pancreas metabolites during breath-holding and free-breathing.

AIM: To characterize normal pancreas metabolites using in vivo proton magnetic resonance spectroscopy ((1)H MRS) at 3T under conditions of breath-holding and free-breathing. MATERIALS AND METHODS: The pancreases of 32 healthy volunteers were examined using (1)H MRS during breath-holding and free-breathing acquisitions in a single-voxel point-resolved selective spectroscopy sequence (PRESS) technique using a 3T MRI system. Resonances were compared between paired spectra of the two breathing modes. Furthermore, correlations between lipid (Lip) content and age, body-mass index (BMI), as well as choline (Cho) peak visibility of the normal pancreas were analysed during breath-holding. RESULTS: Twenty-nine pairs of spectra were successfully obtained showing three major resonances, Lip, Cho, cholesterol and the unsaturated parts of the olefinic region of fatty acids (Chol+Unsat). Breath-hold spectra were generally better, with higher signal-to-noise ratios (SNR; Z=-2.646, p=0.008) and Cho peak visible status (Z=-2.449, p=0.014). Correlations were significant between spectra acquired by the two breathing modes, especially for Lip height, Lip area, and the area of other peaks at 1.9-4.1ppm. However, the Lip resonance was significantly different between the spectra of the two breathing modes (p<0.05). In the breath-holding spectra, there were significant positive correlations between Lip peak height, area, and age (r=0.491 and 0.521, p=0.007 and 0.004), but not between Lip peak area and BMI. There was no statistical difference in Cho resonances between males and females. The Lip peak height and area were significantly higher in the Cho peak invisible group than in the Cho peak visible group (t=2.661 and 2.353, p=0.030 and 0.043). CONCLUSION: In vivo(1)H MRS of the normal pancreas at 3T is technically feasible and can characterize several metabolites. (1)H MRS during breath-holding acquisition is superior to that during free-breathing acquisition.

Study of the morphology of the olfactory organ of African ostrich chick.

The anatomy and histology of the olfactory organ of African ostrich chick were carefully observed by gross anatomy observation, paraffin sectioning and haematoxylin-eosin (HE) staining. The results showed that there were no keratotic nose lids at the entrance of the external naris, and that the nasal cavity was separated into two imperforate compartments by the nasal septum. The posterior conchae were connected with the middle conchae without cohering to nasal walls, and appeared to be part of a palinal elongation of the middle conchae. Olfactory cells were distributed in the mucosal epithelium of middle and posterior conchae. Nasal glands were shaped like irregular rectangles, and their connective tissue extended to the parenchyma, which was divided into many glandular lobules. The layers of the olfactory bulb were indistinct, the globular structure was inconspicuous and the granular cells were scattered relatively in the lamina granularis externa.

Identification of functionally important residues of human thrombopoietin.

Thrombopoietin (TPO) is a megakaryocyte growth and differentiation factor. It consists of a characteristic two domain structure. The amino-terminal domain of TPO has a sequence homology with erythropoietin and is required for the binding and activation of its receptor c-Mpl. To determine the functionally important regions interacting with its receptor, a series of site-directed mutants of TPO were constructed based on a three-dimensional model of the amino-terminal domain. Two strategies of mutagenesis were employed: 1) nonnative N-linked glycosylation scan of 12 residues predicted to be on the surface, and 2) alanine replacement scan of mostly charged 44 amino acid residues. Each TPO mutein was transiently expressed in COS7 cells, and the specific bioactivity of the TPO protein secreted into the culture medium was measured using a recombinant BaF3 cell line expressing human c-Mpl. Four alanine substitutions at Arg10, Pro42, Glu50, and Lys138 nearly or completely abolished the activity, whereas the mutation at Arg14 slightly decreased the activity, suggesting that these residues are functionally important in interacting with its receptor. These residues mapped to helix A, loop AB, and helix D. Sequence comparison between human TPO and other mammalian TPO showed that the identified residues are completely conserved among the species. However, unlike the recent report on the mutational analysis of TPO, alanine substitutions at Lys52, Lys59, Arg136, and Arg140 did not affect the TPO activity significantly in our system. The identified receptor binding regions of TPO are analogous to those of human growth hormone and erythropoietin. Based on the similarity of these three cytokines, we propose that Lys138 of helix D and Pro42 and Glu50 of loop AB may constitute one binding region, whereas Arg10 and Lys14 of helix A may constitute the other binding region to dimerize the receptors.