We have used a thermo-responsive polymer, poly-N-isopropyl acrylamide (PNI-PAAm), as a substratum for the culture of human dermal fibroblasts by conjugating it with collagen. The cells attached well, spread, and grew on the substratum, indicating that the polymer has no toxicity towards the cells. PNIPAAm is insoluble in water over the lower critical solution temperature (LCST; about 32 degrees C) and reversibly solubilized below the LCST. Taking advantage of this conversion, monolayered fibroblasts cultured on the substratum containing the PNIPAAm over the LCST, were completely detachable from the substratum by simply lowering the temperature below the LCST, without the use of conventional detaching agents such as trypsin and EDTA. The detached cell sheet gradually aggregated and finally formed a multicellular spheroid. This polymer may provide a convenient and potentially useful technology for cell culture.

Hyperestrogenemic states, including pregnancy, cause an increase in serum T4-binding globulin (TBG) concentrations and an increase in the proportion of TBG molecules with greater anodal mobility on isoelectric focusing, indicating greater sialic acid content. The possible causal relationship between the degree of sialylation and accumulation of TBG in serum was explored by measuring the in vivo half-lives (t1/2) of TBGs with different isoelectric points. TBG in unfractionated serum and its major peaks, isolated by chromatofocusing and defined by their isoelectric points on isoelectric focusing were each injected iv into rats. The resulting TBG concentrations, measured by specific RIA in serum samples obtained at intervals after injection, were used for the calculation of the t1/2. TBG in serum from a pregnant woman had a significantly longer t1/2 of 17.2 +/- 1.2 h (mean +/- SD) compared to those of 13.3 +/- 1.5 and 12.9 +/- 0.9 h for TBG in serum from a man and a nonpregnant woman, respectively. TBG peaks II, III, IV, and V, with increasing anodal mobility, had progressively longer t1/2 values of 11, 13, 15, and 33 h, respectively. However, TBG peaks of the same mobility on IEF isolated from serum of pregnant or nonpregnant subjects had similar t1/2 values. Neither the TBG concentration nor estrogen had a direct effect on the rate of TBG clearance. Indeed, the t1/2 of TBG from a subject with inherited TBG excess was not different from that of TBG from a nonpregnant woman or a man. Chronic treatment of rats with estradiol did not alter the rate of clearance of injected human TBG. Finally, the more heavily sialylated anodal bands of purified but unfractionated serum TBG, analyzed by Western blots, survived longer in the circulation of a rat. These results indicate that the rate of in vivo metabolism of TBG is dependent on its sialic acid content. The increased proportion of TBG molecules with higher sialic acid content thus contributes to the increase in the serum TBG concentration in hyperestrogenemic states.

The authors propose an energy cycle based on a renewable fuel. Magnesium is chosen as an energy carrier and is combusted with water to retrieve energy using many power devices. MgO, the combustion residue, is reduced back to Mg by laser radiation generated from solar and other renewable energy sources. They have achieved an energy recovery efficiency of 42.5% for converting MgO to magnesium, using a laser. Combined with a demonstrated 38% efficiency for converting an artificial sunlight source (metal halide lamp) into laser output energy indicates that the proposed energy cycle is already in a feasible range for practical use.

To elucidate the molecular mechanism of familial central diabetes insipidus (FDI), we sequenced the arginine vasopressinneurophysin II (AVP-NPII) gene in 2 patients belonging to a pedigree that is consistent with an autosomal dominant mode of inheritance. 10 patients with idiopathic central diabetes insipidus (IDI) and 5 normals were also studied. The AVP-NPII gene, locating on chromosome 20, consists of three exons that encode putative signal peptide, AVP, NPII, and glycoprotein. Using polymerase chain reaction, fragments including the promoter region and all coding regions were amplified from genomic DNA and subjected to direct sequencing. Sequences of 10 patients with IDI were identical with those of normals, while in 2 patients with FDI, a single base substitution was detected in one of two alleles of the AVP-NPII gene, indicating they were heterozygotes for this mutation. It was a G --A transition at nucleotide position 1859 in the second exon, resulting in a substitution of Gly for Ser at amino acid position 57 in the NPII moiety. It was speculated that the mutated AVP-NPII precursor or the mutated NPII molecule, through their conformational changes, might be responsible for AVP deficiency. (J.

No abstract