The effect of hypoxia on rat splanchnic prostanoid output

The effect of hypoxia on isolated perfused rat mesenteric basal venous prostanoid output was studied. Male rat splanchnic vasculature was removed without (SV) or with its end organ (SV + SI) and perfused with Krebs' buffer with a pO2 of 460 or 60 mm torr. Basal splanchnic venous effluent was assayed for 6-keto-PGF1 alpha, TxB2 and PGE by radioimmunoassay at 30, 60, 120 and 180 min of perfusion. Basal output of SV 6-keto-PGF1 alpha was five and ten fold higher than for PGE and TxB2 respectively and comprised 36% or greater of SV + SI 6-keto-PGF1 alpha output. SV PGE and TxB2 output comprised less than 19 and 12% respectively of SV + SI output. Hypoxia decreased SV + SI PG output, 6-keto-PGF1 alpha being most affected. Hypoxia did not alter SV 6-keto-PGF1 alpha output indicating the SI as the anatomic location most influenced by hypoxia. The relative amounts of distribution of PGE or TxB2 output were not altered by hypoxia. These data suggest that there are two distinct areas of splanchnic prostanoid output, the SV and the SI. Decreased 6-keto-PGF1 alpha output might alter splanchnic blood flow at two levels, the splanchnic vasculature, and/or within the bowel wall.     

Synergistic interaction of p185c-neu and the EGF receptor leads to transformation of rodent fibroblasts

The protein product of the rodent neu oncogene, p185neu, is a tyrosine kinase with structural similarity to the epidermal growth factor receptor (EGFR). Transfection and subsequent overexpression of the human p185c-erbB-2 protein transforms NIH 3T3 cells in vitro. However, NIH 3T3 cells are not transformed by overexpressed rodent p185c-neu. NIH 3T3 transfectants overexpressing EGF receptors are not transformed unless incompletely transformed. Several groups have recently demonstrated EGF-induced, EGFR-mediated phosphorylation of p185c-neu. During efforts to characterize the interaction of p185c-neu with EGFR further, we created cell lines that simultaneously overexpress both p185c-neu and EGFR and observed that these cells become transformed. These observations demonstrate that two distinct, overexpressed tyrosine kinases can act synergistically to transform NIH 3T3 cells, thus identifying a novel mechanism that can lead to transformation.     

Approximate matching of regular expressions

Given a sequenceA and regular expressionR, theapproximate regular expression matching problem is to find a sequence matchingR whose optimal alignment withA is the highest scoring of all such sequences. This paper develops an algorithm to solve the problem in timeO(MN), whereM andN are the lengths ofA andR. Thus, the time requirement is asymptotically no worse than for the simpler problem of aligning two fixed sequences. Our method is superior to an earlier algorithm by Wagner and Seiferas in several ways. First, it treats real-valued costs, in addition to integer costs, with no loss of asymptotic efficiency. Second, it requires onlyO(N) space to deliver just the score of the best alignment. Finally, its structure permits implementation techniques that make it extremely fast in practice. We extend the method to accommodate gap penalties, as required for typical applications in molecular biology, and further refine it to search for substrings ofA that strongly align with a sequence inR, as required for typical data base searches. We also show how to deliver an optimal alignment betweenA andR in onlyO(N+logM) space usingO(MN logM) time. Finally, anO(MN(M+N)+N ²logN) time algorithm is presented for alignment scoring schemes where the cost of a gap is an arbitrary increasing function of its length.     

Plant movements caused by differential growth--unity or diversity of mechanisms?

A very wide range of plant organ movements have been described and yet it is not clear how each of them is related to the others. This uncertainty has had two undesirable consequences. Firstly, some workers have accepted the idea of a vague unity in the area and have subsequently been misled by information obtained in one system and applied without adequate justification to a study of a quite different system. Secondly, some researchers have evoked a possible diversity to explain why a particular mechanistic explanation may continue to be valid even when the model fails to explain events of a very similar nature in a slightly different system. We argue that this confusion has resulted from a classification of organ movements which has been based on functional rather than on mechanistic considerations. Mechanistic unity is to be expected on evolutionary grounds. This unity, however, may apply only to certain elements of the stimulus-response chain, at certain levels of organization. It follows from this that in seeking this unity, comparisons should be made between equivalent elements of the stimulus-response chain at the same level of organization in different systems. Only when this is done will theories built around the concept of unity provoke meaningful discussion.     

Increased expression of the gene for the pro alpha 1(IV) chain of basement-membrane procollagen in cultured skin fibroblasts from two variants of osteogenesis imperfecta.

Fibroblasts from two lethal variants of osteogenesis imperfecta were shown to synthesize increased amounts of type IV procollagen. Previous studies established that one of these variants had a non-functional allele for the pro alpha 2 chain of type I procollagen, whereas the other pro alpha 2(I) allele contained a mutation leading to synthesis of shortened pro alpha 2(I) chains. In the two variants, the relative level of mRNA for pro alpha 1(IV) was 31 and 42% of the level of mRNA for pro alpha 1(I) chains. A value of less than 2% was found for a third lethal and four non-lethal variants of osteogenesis imperfecta. Immunofluorescent staining of fibroblasts from the two variants synthesizing increased amounts of type IV procollagen indicated that a homogeneous population of cells synthesized both type IV and type I procollagen. The results suggest that mutations in the type I procollagen genes that result in osteogenesis imperfecta can be associated with increased expression of the genes for type IV procollagen.     

Characterization of intracellular ice formation in Drosophila melanogaster embryos

Cryomicroscopy and differential scanning calorimetry (DSC) were used to characterize the incidence of intracellular ice formation (IIF) in 12- to 13-hr-old embryos of Drosophila melanogaster (Oregon-R strain P2) as influenced by the state of the eggcase (untreated, dechorionated, or permeabilized), the composition of the suspending medium (with and without cryoprotectants), and the cooling rate. Untreated eggs underwent IIF over a very narrow temperature range when cooled at 4 or 16 degrees C/min with a median temperature of intracellular ice formation (TIIF50) of -28 degrees C. The freezable water volume of untreated eggs was approximately 5.4 nl as determined by DSC. IIF in dechorionated eggs occurred over a much broader temperature range (-13 to -31 degrees C), but the incidence of IIF increased sharply below -24 degrees C, and the cumulative incidence of IIF at -24 degrees C decreased with cooling rate. In permeabilized eggs without cryoprotectants (CPAs), IIF occurred at much warmer temperatures and over a much wider temperature range than in untreated eggs, and the TIIF50 was cooling rate dependent. At low cooling rates (1 to 2 degrees C/min), TIIF50 increased with cooling rate; at intermediate cooling rates (2 to 16 degrees C/min), TIIF50 decreased with cooling rate. The total incidence of IIF in permeabilized eggs was 54% at 1 degree C/min, and volumetric contraction almost always occurred during cooling. Decreasing the cooling rate to 0.5 degree C/min reduced the incidence of IIF to 43%. At a cooling rate of 4 degrees C/min, ethylene glycol reduced the TIIF50 by about 12 degrees C for each unit increase in molarity of CPA (up to 2.0 M) in the suspending medium. The TIIF50 was cooling rate dependent when embryos were preequilibrated with 1.0 M propylene glycol or ethylene glycol, but was not so in 1.0 M DMSO. For embryos equilibrated in 1.5 M ethylene glycol and then held at -5 degrees C for 1 min before further cooling at 1 degree C/min, the incidence of IIF was decreased to 31%. Increasing the duration of the isothermal hold to 10 min reduced the incidence of IIF to 22% and reduced the volume of freezable water in embryos when intracellular ice formation occurred. If the isothermal hold temperature was -7.5 or -10 degrees C, a 10- to 30-min holding time was required to achieve a comparable reduction in the incidence of IIF.     

Expression and characterization of the tau subunit of phosphorylase kinase

A cDNA encoding the entire tau subunit of rabbit skeletal muscle phosphorylase kinase was reconstructed and inserted into a plasmid containing the Escherichia coli ptac promoter and a constructed plasmid containing the ptac promoter and bacterial chloramphenicol acetyl transferase (CAT) gene, respectively. A significant phosphorylase kinase activity was found, in the first case. In the second case, a fused protein containing 73 amino acids from the CAT protein was obtained. After renaturation, the CAT-tau subunit protein shows enzymatic activity similar to the HPLC-purified and renatured tau subunit.     

A refined linkage map for DNA markers around the pericentromeric region of chromosome 10

A refined genetic linkage map for the pericentromeric region of human chromosome 10 has been constructed from data on 12 distinct polymorphic DNA loci as well as the locus for multiple endocrine neoplasia type 2A (MEN 2A), a dominantly inherited cancer syndrome. The map extends from D10S24 (at 10p13-p12.2) to D10S3 (at 10q21-q23) and is about 70 cM long. Overall, higher female than male recombination frequencies were observed for this region, with the most remarkable female excess in the immediate vicinity of the centromere, as previously reported. Most of the DNA markers in this map are highly informative for linkage and the majority of the interlocus intervals are no more than 6 cM apart. Thus this map should provide a fine framework for future efforts in more detailed mapping studies around the centromeric area. A set of ordered cross-overs identified in this work is a valuable resource for rapidly and accurately localizing new DNA clones isolated from the pericentromeric region.