Increased Expression of Aquaporin 9 in Trophoblast From Gestational Diabetic Patients

Gestational diabetes mellitus is the most frequent pathophysiological alteration in pregnancy, increasing the incidence of complications in both mother and fetus. The macrosomia that occurs in these fetuses may be related with some changes in nutrient transport mechanism in placenta. The presence of aquaporin 9, an aquaglyceroporin, has previously been demonstrated in placenta. We raised the question whether aquaporin 9 expression may be upregulated in placenta from gestational diabetes, thus providing a faster transport of glycerol and water through placenta. We studied 21 placentas (13 controls and 8 gestational diabetes) from cesarean delivery at term. The expression of aquaporin 9 was analyzed by quantitative PCR, immunoblot, and immunohistochemistry. The median values from quantitative PCR were compared by nonparametric tests for independent samples (Mann-Whitney U-test). We have found that trophoblast from gestational diabetes express higher amount of aquaporin 9, which was found statistically significant (p<0.05). The increase in aquaporin 9 expression was confirmed by immunoblot, and localization in the syncytiotrophoblast was checked by immunohistochemistry. The increase in aquaporin 9 expression in placenta from gestational diabetes may contribute to the higher transport rate in this pathology of pregnancy.

[Cutaneous malignant peripheral nerve sheath tumor in neurofibromatosis type 1]

Patients with neurofibromatosis have an increased risk of developing malignant tumors in comparison to the general population. We describe a woman who developed a malignant peripheral nerve sheath tumor in a pre-existing neurofibroma.

Cortical reorganization in patients with high frequency cochlear hearing loss

Animal research has shown that tonotopic representation in the auditory cortex is not statically fixed in the adult organism but can be altered after deafferentation. The present study examines the plasticity of the human auditory cortex in patients with high frequency cochlear hearing loss by means of magnetoencephalographic measurements. The data show that the cortical map can reorganize such that cortical neurons deprived of their usual most sensitive afferent input now respond to tone frequencies adjacent to the frequency range of the partial hearing loss. The results suggest that deafferentation due to cochlear damage in adults may lead to functional reorganization of auditory cortical structures.

Distribution patterns of HP1, a heterochromatin-associated nonhistone chromosomal protein of Drosophila

We have previously reported the identification of a nonhistone chromosomal protein (nhcp-19; now called HP1) preferentially associated with the heterochromatin of Drosophila melanogaster. A detailed study of the HP1 distribution pattern on polytene chromosomes by immunofluorescent staining, using monoclonal antibody C1A9, has been carried out. The results indicate that this protein is found within the centric beta-heterochromatin, in cytological regions 31, 41 and 80, and throughout polytene chromosome 4. Staining of telomeres is frequently observed, those of chromosome arms 2R and 3R and the X chromosome being the most conspicuous. Analysis of a fourth chromosome insertional translocation T(3;4)f/In(3L)P confirms an autonomous interaction with chromosome 4 material. Similarly, the beta-heterochromatin distal to light on chromosome arm 2L, moved to position 97D2 on chromosome arm 3R in the rearrangement ltx13, is prominently stained using the C1A9 antibody. Staining of intact salivary glands indicates that this rearranged segment of beta-heterochromatin is not associated with the polytene chromocenter, but provides an independent structural reference point. HP1 is not observed in the nuclei of the early syncytial embryo, but becomes concentrated in the nuclei at the syncytial blastoderm stage (ca. nuclear division cycle 10). This suggests that heterochromatin formation occurs at approximately the same stage at which nuclei first become transcriptionally competent. Thus, the C1A9 antibody may serve as a useful marker for both structural and functional studies of the Drosophila nucleus.

Multiple forms and cellular localization of Drosophila DNA topoisomerase II

Purified type II topoisomerase from Drosophila melanogaster embryos was reported earlier to contain a major polypeptide of 166,000 daltons and several smaller peptides between 132,000 and 145,000 daltons (Shelton, E. R., Osheroff, N. and Brutlag, D. L. (1983) J. Biol. Chem. 258, 9530-9535). Using purified topoisomerase II we have raised antibodies against the 132,000-166,000-dalton cluster of polypeptides. In this paper we demonstrate that at least three of these polypeptides are also present in embryos immediately upon lysis. Using antigen-affinity purified antibody from the cluster of purified topoisomerase II antigens, we have also discovered several smaller polypeptides in the molecular size range of 30,000-40,000 daltons in embryo extracts. These observations suggest the presence of multiple forms of DNA topoisomerases in the cell. In addition, we demonstrate that purified Drosophila topoisomerase II antibody recognizes yeast topoisomerase II antigens expressed by lambda gt 11-yeast topoisomerase II recombinants (Goto, T. and Wang, J. C. (1984) Cell 36, 1073-1080) establishing a structural homology between yeast and Drosophila enzymes. Antibody preparations were also used to localize the distribution of topoisomerase II in polytene nuclei. In contrast with the distribution of topoisomerase I which is located primarily at puffs, the Drosophila topoisomerase II is distributed generally along the chromosomes paralleling the distribution of DNA itself.