Analysis of insertion mutants reveals two new genes in the pNRC100 gas vesicle gene cluster of Halobacterium halobium

The archaebacterium, Halobacterium halobium, achieves buoyancy through synthesis of intracellular gas-filled vesicles. The plasmid-encoded gene (gvpA) specifying the major structural gas vesicle protein has previously been cloned and sequenced allowing the analysis of high-frequency mutations to the vesicle negative phenotype. Among eighteen gas vesicle mutants analyzed, four were observed to contain insertion elements 0.2 to 2 kb upstream of the structural gene. To explain the phenotype of these mutants, the upstream area was analyzed by DNA sequencing and transcriptional mapping. This analysis showed the presence of two open reading frames, gvpD and gvpE, which are of opposite transcriptional orientation to gvpA (gene order gvpA-D-E). gvpD begins 201 nucleotides from the gvpA structural gene and is 1608 nucleotides long while gvpE begins two nucleotides from the 3'-end of gvpD and is 573 nucleotides long. Primer extension analysis showed the occurrence of divergent promoters in the gvpA-gvpD intergenic region with the transcription start sites separated by 109 nucleotides. The sites of three insertion sequences in gas vesicle mutants mapped within gvpE while the fourth insertion site mapped near the N-terminal coding region of gvpD. Homology between the gvpDE gene region and a chromosomal site in a H. halobium NRC-1 derivative and in several other Halobacterium strains was identified by Southern hybridization.

Phosphorylation of the carotenoid droplet protein p57 by the catalytic subunit of cyclic adenosine monophosphate-dependent protein kinase and the effect of fluoride

We have previously shown that the dispersion and aggregation of carotenoid droplets in goldfish xanthophores are regulated, respectively, by phosphorylation and dephosphorylation of a carotenoid droplet protein p57. There is a basal level of p57 phosphorylation of p57 in unstimulated cells, which is greatly stimulated by adrenocorticotropic hormone (ACTH) or cyclic adenosine monophosphate (cAMP) acting via cAMP-dependent protein kinase. We have also observed that, in permeabilized xanthophores, pigment dispersion can be induced when cAMP is replaced by fluoride. Since p57 has multiple phosphorylation sites, there is the question of whether all p57 phosphorylation is by cAMP-dependent protein kinase or whether phosphorylation by cAMP-independent protein kinase coupled with inhibition of phosphatase activity by fluoride can replace cAMP-dependent protein kinase and that the ability of fluoride to replace cAMP for pigment dispersion in permeabilized cells is probably due to activation of adenylcyclase. We also show that ACTH causes an approximately threefold increase in the level of cAMP in these cells.

Transcatheter arterial chemoembolization for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) was treated with transcatheter arterial chemoembolization (TACE) in a sample of 129 patients. The cumulative survival rate was 49% at 1 year and 22% at 2 years. The median survival time was 11.9 months. The survival rates at 1 year of 84 patients in Child's group A and 27 in Child's group B were 56% and 40%; out of 52 HCC patients with portal vein patent and 77 with portal vein invasion 75% and 40% survived, and the 1-year survival rates for 33 HCC patients with capsule intact, 14 with capsule broken and 82 with no capsule were 85%, 65% and 40% respectively. From the above results there were statistically significant differences in survival time in those with good clinical performance status by Child's classification, those showing patency of the portal vein and those where the capsule was present. Therefore, we would like to recommend, TACE of HCC in well-selected patients presenting with good clinical status, patency of the portal vein and without broken capsule, in order to achieve better clinical results.

Inhibitory effect of l-ascorbic acid on the growth of astrocytes in cell culture

The effect of l-ascorbic acid on the growth of astrocytic cells in culture was investigated. l-Ascorbic acid produced a concentration-dependent reduction of the growth of astrocytes, both in normal and tumor cells. The effect of l-ascorbic acid was similar to that of the relative acidification of the medium, except in treated concentrations greater than 10(-6) M. The effects produced by both l- and d-forms of ascorbic acid were the same. The inhibitory effect of l-ascorbic acid at greater concentrations was partially prevented by oxidized glutathione and increased by the large concentration of reduced glutathione. This result suggests that l-ascorbic acid possesses the ability to inhibit the growth of astrocytic cells in culture through the acidification of the medium at small concentrations and/or the antioxidative properties of this compound at larger concentrations.

Analysis of RNA synthesis of type 1 poliovirus by using an in vitro molecular genetic approach

Membranous crude replication complexes (CRC) were isolated from poliovirus-infected HeLa cells as recently described (N. Takeda, R.J. Kuhn, C.-F. Yang, T. Takegami, and E. Wimmer, J. Virol. 60:43-53, 1986). Viruses used to produce the CRC were poliovirus type 1 (Mahoney), [PV-1(M)], poliovirus type 1 (Sabin) [PV-1(S)], and four in vitro recombinants that were constructed from infectious cDNA clones. RNA synthesis in CRC was studied. No end-linked, full-length double-stranded poliovirus RNA was detected in CRC regardless of whether nonionic detergent (Nonidet P-40) was added prior to incubation. Synthesis of VPg-pU and VPg-pUpU, two nucleotidyl proteins presumed to be involved in the initiation of RNA synthesis, was slower at 30 degrees C in CRC induced by PV-1(S) than by PV-1(M). This observation was used to design a pulse-chase experiment whose result suggested that synthesis of VPg-pUpU occurred by uridylylation of VPg-pU. Synthesis of VPg-pU(pU) was thermosensitive in CRC induced by PV-1(S). With CRC of recombinant viruses, the thermosensitive block covaried to nucleotide substitutions in PV-1(S) that mapped to the virus-induced RNA polymerase 3Dpol. We conclude that plus-stranded RNA synthesis in CRC does not proceed via hairpin structures. The results of VPg-pU----VPg-pUpU synthesis are consistent with a model in which VPg-pU is the primer of RNA synthesis mediated by 3Dpol. The data suggest that uridylylation of VPg or a precursor thereof may be catalyzed by 3Dpol itself, a mechanism resembling events occurring in adenovirus DNA replication.

Uridylylation of the genome-linked protein of poliovirus in vitro is dependent upon an endogenous RNA template

The properties of an in vitro replication system derived from a membrane fraction (crude replication complex, CRC) of poliovirus-infected HeLa cells were examined. This system was capable of producing the nucleotidyl-proteins VPg-pU and VPg-pUpU. Due to high intrinsic phosphoesterase(s) activity and endogenous nucleoside triphosphate pools the yield of labeled product was low. Treatment of CRC with DEAE-cellulose and addition of an ATP generating system resulted in a dramatic increase in the level of nucleotidyl-proteins formed. The capacity to form VPg-pU and VPg-pUpU could be completely abolished by pretreatment of CRC with nuclease, an observation suggesting that the uridylylation of VPg is a template-dependent reaction.

Vessel, plaque, and lumen morphology after transluminal balloon angioplasty. Quantitative study in distended human arteries

We performed transluminal balloon angioplasty in 24 cadaver and nine amputated limb superficial femoral arteries under controlled experimental conditions. The cadaver arteries were excised, restored to in situ length, redistended, and maintained at 100 mm Hg intraluminal pressure at 37 degrees C throughout the angiographic and dilation procedure and during fixation. The amputated limb arteries were dilated and pressure perfusion-fixed after dilation. Quantitative analysis of cadaver vessels revealed that arteries with prominent atherosclerotic lesions had the same internal elastic lamina (IEL) circumference (15.6 +/- 1.0 mm) as those with little or no stenosis (16.8 +/- 0.5 mm) but lumen area (8.8 +/- 1.7 mm2) was markedly reduced compared to nonstenotic sites (20.0 +/- 1.9 mm2, p less than 0.01). Lesions occupied 49 +/- 6% of the area circumscribed by the IEL in cadaver arteries with prominent plaques. After dilatation, lumen areas at stenotic sites were enlarged 43% on histologic sections (12.6 +/- 1.8 mm2 vs 8.8 +/- 1.7 mm2, p less than 0.01) and 31% as determined by angiography (p less than 0.05) when compared to immediately adjacent nondilated regions. The increased lumen area was associated with splitting of the intima near the edges of the plaque, separation of the edges of the plaque from the media, and stretching of the media and adventitia, often with accompanying rupture of the media. There was no evidence of plaque compression, fragmentation, deformation, modeling, or herniation into the media. The detached wedge-shaped edges of the lesions formed flaps projecting into the lumen, resulting in a marked increase in lumen irregularity on cross-section.(ABSTRACT TRUNCATED AT 250 WORDS)

Initiation of poliovirus plus-strand RNA synthesis in a membrane complex of infected HeLa cells

An in vitro poliovirus RNA-synthesizing system derived from a crude membrane fraction of infected HeLa cells was used to analyze the mechanism of initiation of poliovirus plus-strand RNA synthesis. This system contains an activity that synthesizes the nucleotidyl proteins VPg-pU and VPg-pUpU. These molecules represent the 5'-terminal structure of nascent RNA molecules and of virion RNA. The membranous replication complex is also capable of synthesizing nucleotidyl proteins containing nine or more of the poliovirus 5'-proximal nucleotides as assayed by the formation of the RNase T1-resistant oligonucleotide VPg-pUUAAAACAGp or by fingerprint analysis of the in vitro-synthesized RNA. Incubation of preformed VPg-pUpU with unlabeled nucleoside triphosphates resulted in the formation of VPg-pUUAAAACAGp. This reaction, which appeared to be an elongation of VPg-pUpU, was stimulated by the addition of a soluble fraction (S-10) obtained from uninfected HeLa cells. Preformed VPg-pU could be chased into VPg-pUpU in the presence of UTP. Our data are consistent with a model that VPg-pU can function as a primer for poliovirus plus-strand RNA synthesis in the membranous replication complex and that the elongation reaction may be stimulated by a host cellular factor.

Percutaneous transluminal angioplasty for limb salvage

Thirty patients with end-stage atherosclerosis, being considered for amputation, were treated by percutaneous transluminal angioplasty (PTA). All had very poor run-off, and none was a candidate for arterial reconstruction. Occluded segments of the iliac, femoral, popliteal, and tibial arteries measuring up to 21 cm were recanalized, resulting in an increased ankle/brachial systolic pressure index despite significant distal occlusive disease. Ischemic symptoms were relieved in 22 patients, and the overall limb salvage rate (2- to 17-month follow-up) was 73%.

Long-segment arterial occlusion: percutaneous transluminal angioplasty

In cases of occlusion of the superficial femoral artery exceeding a length of 10 cm, accompanied by involvement of the popliteal artery and poor runoff, percutaneous transluminal angioplasty is unfavorable. However, when such advanced occlusive disease is present in patients for whom vascular surgery is not feasible, this technique can be of value by averting or at least postponing amputation. Percutaneous transluminal angioplasty was used to recanalize long segments (10-36 cm) of occluded or stenotic femoropopliteal arteries in 21 patients. Results were evaluated by means of pre- and postangioplasty arteriograms and measurements of pressure indices. The initial success rate was 76%; the success rate on 5-24 month follow-up was 67%. The long-term benefit can be improved by other measures, such as stopping cigarette smoking, exercise, long-term anticoagulation therapy, and early detection and treatment of restenosis.