The expression of the catecholamine biosynthetic enzyme, tyrosine hydroxylase (TH), is confined to several different types of neuroendocrine cells. Using a transient assay system, we examined more than 10 kb of the human TH gene and 6.5 kb of 5' flanking sequences of the rat TH gene for DNA elements that confer cell-type specific expression. Surprisingly, these elements do not appear to be conserved in position or sequence across species. When plasmids containing DNA sequences - 749 bp from the transcription start site of the rat gene were introduced into PC12 cells, up to sixfold higher levels of expression were observed as compared to the same fragments introduced into HepG2 cells or LAN-1 cells. In contrast to the rat gene, analogous fragments of the human 5' promoter failed to confer cell-type specific expression. However, when plasmids containing a truncated thymidine kinase promoter and either orientation of a 760 by 3' human TH gene fragment were introduced into PC12 and LAN-1 cells, we observed a six- and 3.5-fold increase, respectively, over that observed for HepG2 cells. Subsequent deletion of this fragment led to significant activation of transcription in PC12 and HepG2 cell lines. These data indicate the presence of multiple elements contributing to the cell-type specific expression of tyrosine hydroxylase genes.

This report describes the organization of the rat tyrosine hydroxylase (TH) gene and compares its structure with the human phenylalanine hydroxylase gene. Both genes are single copy and contain 13 exons separated by 12 introns. Remarkably, the positions of 10 out of 12 intron/exon boundaries are identical for the two genes. These results support the idea that these hydroxylase genes are members of a gene family which has a common evolutionary origin. We predict that this ancestral gene would have encoded exons similar to those of TH prior to evolutionary drift to other members of this gene family.

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These studies demonstrate that soybean (Meff) roots and nodules possess an active system for fixing CO,. The Many investigators have suggested that one of the major effects of increased CO2 concentrations is to increase the rates of CO2 fixation in nodules (3,4,17,18,22,25) which is catalyzed primarily by PEP4 carboxylase forming the C4 acid, oxalacetate. Layzell et al. (18) proposed that the reassimilation of respired carbon in nodules of N2-fixing plants may actually increase the efficiency of these symbionts. Christeller and others (3, 18) have suggested that, in nodulated lupin, an asparagine-exporting plant, the primary function for the oxalacetate produced is to serve as the carbon skeleton for asparagine and aspartate biosynthesis.There are, however, many legumes which transport fixed nitrogen in the form of the ureides, allantoin and allantoic acid (21). Presumably, these plants would not require the same levels of synthesis of oxalacetate as plants which export asparagine. The purpose of the investigation here was to examine the extent and role of CO2 fixation in both roots and nodules of soybeans growing soleiy on symbiotically fixed N2, a condition which favors the export of ureides and not of asparagine. Measurements of CO2 Fixation and C2H2 Reduction. Plants to be used for experiments were gently uprooted and tapped to remove excess Perlite. A split one-or two-hole rubber stopper was positioned around the stem of each plant. The root system was placed into a 20-or 50-ml flask and Plasticine was molded around the stem to seal the flask. Gases were introduced or withdrawn through a serum stopper covering a sidearm of the smaller flasks or a glass tube inserted through the second hole in the rubber stopper of the larger flasks. "CO2 was liberated in a sealed vessel from [14C]NaHCO0 (Amersham, Arlington Heights, IL; 59.3 mCi/ mmol) after the addition of 100 ,ul of 1 N HCI.

CoSeal mark surgical sealant (CoSeal) was evaluated for inhibiting suture line bleeding using a canine iliac PTFE graft model. Both iliac arteries of 12 heparinized canines were grafted with PTFE. CoSeal was applied to the suture lines of one graft in each animal. The contra-lateral graft served as a control and bleeding was controlled with gauze and pressure (tamponade). The cross-clamps were removed 30 s following application of CoSeal. Times to hemostasis and volume of blood loss at each graft site were determined. Compared to tamponade control, CoSeal significantly reduced the time to hemostasis (average of 5 min vs. greater than 15 min, p< 0.05) and blood loss (19 g vs. 284 g, p < 0.05). Small amounts of CoSeal were visible grossly or histologically at day 7. Histology showed moderate to marked inflammation in CoSeal sites and moderate inflammation in control sites at day 7. At 30 and 60 days, no CoSeal was visible grossly or histologically. Histology showed moderate inflammation in both CoSeal treated sites and in control sites at day 30 and mild to moderate inflammation in both CoSeal and control sites at day 60. CoSeal significantly reduced the time to hemostasis and blood loss in comparison to tamponade.