A technique to retrieve stents dislodged in the coronary artery followed by fixation in the iliac artery by means of balloon angioplasty and peripheral stent deployment

An unwelcome complication of the increasingly applied technique of coronary stenting is stent dislodgment, which may cause arterial occlusion or distal embolization, both with potentially adverse sequel. Stent dislodgment tends to occur when negotiating a tortuous artery with a balloon-mounted stent, especially if the artery is irregularly calcified or when applying a rigid stent. We have successfully applied in several patients at our laboratory a technique to retrieve a dislodged stent from the coronary artery, tow it to the iliac artery, and then deploy it locally by a peripheral balloon when retrieval through the vascular sheath seems impossible. Finally, the retrieved stent is secured by local anchoring with a peripheral stent. This technique was found to be useful and may prevent further complications and more costly interventions and hence result in a more benign clinical course. Cathet. Cardiovasc. Intervent. 49:77-81, 2000.

Peptide nucleic acid (PNA) binding-mediated induction of human gamma-globin gene expression

Peptide nucleic acids (PNAs) can bind to homopurine/homopyrimidine sequences of double-stranded DNA targets in a sequence-specific manner and form [PNA]2/DNA triplexes with single-stranded DNA D-loop structures at the PNA binding sites. These D-loop structures have been found to have a capacity to initiate transcription in vitro. If this strategy can be used to induce transcription of endogenous genes, it may provide a novel approach for gene therapy of many human diseases. Human [beta] globin disorders such as sickle cell anemia and beta-thalassemia are very common genetic diseases that are caused by mutations in the beta-globin gene. When gamma-globin genes are highly expressed in sickle cell patients, the presence of high levels of fetal hemoglobin (HbF, alpha2gamma2) can compensate for the defective beta-globin gene product and such patients have much improved symptoms or are free of disease. However, the gamma-globin genes are developmentally regulated and normally expressed at very low levels (>1%) in adult blood cells. We have investigated the possibility of inducing gamma-globin gene expression with PNAs. Using PNAs designed to bind to the 5' flanking region of the gamma-globin gene, induction of expression of a reporter gene construct was demonstrated both in vitro and in vivo. More importantly, PNA-mediated induction of endogenous gamma-globin gene expression was also demonstrated in K562 human erythroleukemia cells. This result suggests that induction of gamma-globin gene expression with PNAs might provide a new approach for the treatment of sickle cell disease. PNA-induced gene expression strategy also may have implications in gene therapy of other diseases such as genetic diseases, cancer and infectious diseases.

BFU-E colony growth in response to hydroxyurea: correlation between in vitro and in vivo fetal hemoglobin induction

Patients with sickle-cell anemia treated with hydroxyurea may have significant reduction in frequency and severity of pain episodes. However, previous clinical trials show a variable response to hydroxyurea. Criteria which can be used to select patients who are likely to respond to hydroxyurea treatment would be useful. Our laboratory has previously demonstrated an inverse linear relationship between the total number of burst-forming unit-erythroid (BFU-E) colonies and fetal hemoglobin levels in sickle-cell patients treated with hydroxyurea. In the present report, an in vitro cell culture system was established to evaluate the effects of hydroxyurea on BFU-E colony growth and induction of fetal hemoglobin production. Five Hb SS patients who were not previously treated with hydroxyurea and three Hb SS patients who failed to respond to hydroxyurea treatment were included in the study. The results show that the number of BFU-E colonies is decreased from 153.7 to 7.2 per 3 x 10(5) mononuclear cells, whereas fetal hemoglobin levels were increased from 5.1 to 19.4% in the presence of hydroxyurea in vitro in cultured erythroid progenitors, which were derived from 5 patients before treatment. The number of BFU-E colonies decreased from 153.7 to 2.0 per 3 x 10(5) mononuclear cells in the in vitro cultures obtained from serial peripheral blood samples over a 9- to 20-week period of oral hydroxyurea therapy. A simultaneous rise in fetal hemoglobin level from 10.2 to 28.6% in the peripheral blood over the same period of hydroxyurea therapy was also observed. Our results demonstrate that the increase in fetal hemoglobin levels in cells treated with hydroxyurea in vitro is comparable to the rise of fetal hemoglobin production following hydroxyurea therapy in these patients. On the contrary, these findings were not observed in three previously non-responsive sickle-cell patients. These results suggest that the changes in number of BFU-E colonies and fetal hemoglobin levels after in vitro exposure to hydroxyurea may be a useful approach to select sickle-cell patients who will respond to hydroxyurea therapy.

alpha-Amino butyric acid cannot reactivate the silenced gamma gene of the beta locus YAC transgenic mouse

Butyric acid, a naturally occurring fatty acid, has been shown to increase fetal hemoglobin in BFUe cultures, in primates, and in patients with beta chain hemoglobinopathies. The precise mechanism of gamma gene induction by butyrate is unknown. Butyrate may induce fetal hemoglobin production in vivo by reactivation of silenced gamma globin genes, by inhibiting the silencing of gamma genes, or by both mechanisms. We examined the effects of butyrate on gamma gene expression in transgenic mice carrying three types of constructs: microLCRA gamma mice, which continue to express the gamma gene in the adult stage of development at a level of one-third to one-fifth of the expression in the fetus; microLCRA gamma psi beta delta beta mice, which display correct developmental regulation of gamma and beta human globin genes and have low level gamma globin expression in the adult; and beta locus YAC mice, which display correct developmental regulation of epsilon, gamma, and beta globin genes and have a totally silenced gamma gene in the adult stage. Animals were treated with a continuous infusion of alpha-amino butyric acid (alpha-ABA) for 7 days. In microLCRA gamma mice alpha-ABA produced up to a 43-fold induction of gamma and 9-fold induction of mouse alpha globin genes. In contrast, butyrate did not induce gamma globin expression in the beta locus YAC mice. However, the gamma globin genes of beta locus YAC mice were activated after administration of 5-azacytidine (5-azaC), and the level of gamma globin expression was further increased by administration of alpha-ABA. These results suggest that butyrate cannot reactivate a totally silenced gamma gene and that induction of fetal hemoglobin by this compound may require the presence of preactivated gamma globin genes.

Fetal hemoglobin induction by acetate, a product of butyrate catabolism

Butyrate induces fetal hemoglobin (HbF) synthesis in cultures of erythroid progenitors, in primates, and in man. The mechanism by which this compound stimulates gamma-globin synthesis is unknown. In the course of butyrate catabolism, beta oxidation by mitochondrial enzymes results in the formation of two acetate molecules from each molecule of butyrate. Studies were performed to determine whether acetate itself induces HbF synthesis. In erythroid burst-forming unit (BFU-E) cultures from normal persons, and individuals with sickle cell disease and umbilical-cord blood, dose-dependent increases in gamma-globin protein and gamma mRNA were consistently observed in response to increasing acetate concentrations. In BFU-E cultures from normal adults and patients with sickle cell disease, the ratio of gamma/gamma + beta mRNA increased twofold to fivefold in response to acetate, whereas the percentage of BFU-E progeny staining with an anti-gamma monoclonal antibody (MoAb) increased approximately twofold. Acetate-induced increases in gamma-gene expression were also noted in the progeny of umbilical cord blood BFU-E, although the magnitude of change in response to acetate was less because of a higher baseline of gamma-chain production. The effect of acetate on HbF induction in vivo was evaluated using transgenic mouse and primate models. A transgenic mouse bearing a 2.5-kb mu locus control region (mu LCR) cassette linked to a 3.3-kb A gamma gene displayed a near twofold increase in gamma mRNA during a 10-day infusion of sodium acetate at a dose of 1.5 g/kg/d. Sodium acetate administration in baboons, in doses ranging from 1.5 to 6 g/kg/d by continuous intravenous infusion, also resulted in the stimulation of gamma-globin synthesis, with the percentage of HbF-containing reticulocytes (F reticulocytes) approaching 30%. Surprisingly, a dose-response effect of acetate on HbF induction was not observed in the baboons, and HbF induction was not sustained with prolonged acetate administration. These results suggest that both two-carbon fatty acids (acetate) and four-carbon fatty acids (butyrate) stimulate synthesis of HbF in vivo.

Shoulder strength, power, and endurance in college tennis players

Twenty-four college tennis players were tested for bilateral shoulder internal/external rotation strength on a Cybex 340 isokinetic dynamometer; they were positioned supine with the glenohumeral joint abducted to 90 degrees. Subjects produced significantly (P less than 0.01) more torque in internal rotation at 60 and 300 deg/sec in the dominant arm compared to the nondominant arm. Subjects also produced significantly more power in internal rotation at 60 deg/sec in the dominant arm. No significant differences between the dominant and nondominant arms were seen in internal rotation power at 300 deg/sec or in the internal rotation endurance ratio. No significant differences were seen in external rotation on any measurement. By significantly increasing the strength of the dominant shoulder in internal rotation without subsequent strengthening of the external rotators, muscle imbalances may be created in the dominant arm that could possibly affect the tennis player's predisposition to injuries caused by overloading of the shoulder joint. This study suggests that external rotation strengthening exercises should be implemented in tennis conditioning programs to maintain muscle strength balance, and possibly reduce the chance of overload injury.

Evolutionary relationships among sulfur- and iron-oxidizing eubacteria

Some 37 reverse transcriptase, partial 16S rRNA sequences from sulfur- and/or iron-oxidizing eubacteria, including sequences from species of the genera Thiobacillus, Thiothrix, Thiomicrospira, Acidophilium, "Leptospirillum," Thiovulum, and Chlorobium, have been determined. In addition, 16S sequences from a number of unnamed sulfur- and/or iron-oxidizing bacteria from hydrothermal vent sites, from invertebrate-bacterial endosymbioses, and from various mineral recovery operations also have been determined. The majority of sequences place their bacterial donors in one or another of the subdivisions of the Proteobacteria. However, three unnamed facultatively thermophilic iron-oxidizing isolates, Alv, BC, and TH3, are affiliated with the gram-positive division. One H2S-oxidizer, from the genus Thiovulum, is affiliated with Campylobacter, Wolinella, and other genera in what appears to be a new subdivision of the Proteobacteria. Three "Leptospirillum"-helical vibrioid isolates, BU-1, LfLa, and Z-2, exhibit no clear phylum level affiliation at all, other than their strong relationship to each other. A picture is emerging of an evolutionary widespread capacity for sulfur and/or iron oxidation among the eubacteria.

Pulmonary manifestations of HIV infection in children

We retrospectively reviewed the spectrum, course, and outcome of pulmonary diseases in 66 children with AIDS, hospitalized between 1982 and 1988, prior to the use of zidovudine. Fifty-two of the 66 (79%) patients developed pulmonary problems. In fifty-two percent of all patients, a pulmonary problem was the first symptom of HIV infection. The most common respiratory illness requiring hospitalization was an episode of respiratory distress with normal PaO2 and unchanged X-ray with a 9.7 +/- 6.8 days mean duration of hospitalization. Bacterial pneumonia, Pneumocystis carinii pneumonia (PCP) and pulmonary lymphoid hyperplasia/lymphoid interstitial pneumonia occurred in 30%, 32% and 22% of the patients, respectively. Bacterial pneumonia and PCP were associated with a high mortality rate. Sixty-eight percent of the patients died within 24 months of the onset of pulmonary disease. In 50% of the children, pulmonary disease was a primary cause of death. The results of this study can be useful in developing prospective studies for the prevention and treatment of pulmonary complications of HIV infection.

Characterization of ribonuclease P from the archaebacterium Sulfolobus solfataricus

Ribonuclease P is the endonuclease that removes the leader fragments from the 5'-ends of precursor tRNAs. The enzyme isolated from eubacteria contains a catalytic RNA subunit. RNAs also copurify with eukaryotic RNase P, although catalysis by those RNAs has not been demonstrated. This paper reports the isolation and characterization of ribonuclease P from the thermoacidophilic archaebacterium Sulfolobus solfataricus. Archaebacteria are a primary evolutionary lineage, distinct from both eukaryotes and eubacteria. Ribonuclease P of S. solfataricus has reaction component requirements and a Km for substrate tRNA (2.5 X 10(-7) M) that are roughly similar to those reported for eubacterial and eukaryotic ribonuclease P. The temperature optimum for the reaction is 77 degrees C, reflecting the thermophilic character of the organism. The enzyme activity is not affected by treatment with micrococcal nuclease, suggesting that there is no RNA subunit or that it is protected from nuclease action. The density of the enzyme in cesium sulfate equilibrium density gradients is 1.27 g/ml, which is similar to that of protein. However, several RNAs between 200 and 400 nucleotides in size copurify with the enzyme activity on the density gradients, and one of them remains after micrococcal nuclease treatment. These properties of the S. solfataricus enzyme are compared with those of ribonuclease P from eukaryotes and eubacteria.

Outcome of mechanical ventilation in children with acquired immunodeficiency syndrome

We retrospectively reviewed the records of 18 children with acquired immunodeficiency syndrome (AIDS) who required mechanical ventilation for respiratory failure. These patients represented 35% of the patients seen with pulmonary disease and AIDS. The most common causes of respiratory failure were Pnuemocystis carinii pneumonia (77%) and bacterial pneumonia (33%). Bronchial lavage by fiberoptic bronchoscopy or endotracheal tube suctioning in mechanically ventilated children with AIDS had a high yield for P. carinii. Eight of 18 (44%) children survived the episode of respiratory failure and were weaned from the ventilator. However, four of eight survivors died within 6 months. Arterial oxygen tension on admission and maximum peak inspiratory pressure on the ventilator did not differ between survivors and nonsurvivors. We conclude that children with AIDS who are mechanically ventilated can be weaned from the respirator but that the subsequent course remains poor.

Sulfur-oxidizing bacterial endosymbionts: analysis of phylogeny and specificity by 16S rRNA sequences

The 16S rRNAs from the bacterial endosymbionts of six marine invertebrates from diverse environments were isolated and partially sequenced. These symbionts included the trophosome symbiont of Riftia pachyptila, the gill symbionts of Calyptogena magnifica and Bathymodiolus thermophilus (from deep-sea hydrothermal vents), and the gill symbionts of Lucinoma annulata, Lucinoma aequizonata, and Codakia orbicularis (from relatively shallow coastal environments). Only one type of bacterial 16S rRNA was detected in each symbiosis. Using nucleotide sequence comparisons, we showed that each of the bacterial symbionts is distinct from the others and that all fall within a limited domain of the gamma subdivision of the purple bacteria (one of the major eubacterial divisions previously defined by 16S rRNA analysis [C. R. Woese, Microbiol. Rev. 51: 221-271, 1987]). Two host specimens were analyzed in five of the symbioses; in each case, identical bacterial rRNA sequences were obtained from conspecific host specimens. These data indicate that the symbioses examined are species specific and that the symbiont species are unique to and invariant within their respective host species.

The identifier concept: clinical parameters to stratify hospital patient costs within gynecology diagnosis-related groups

The purpose of this study was to analyze whether clinical variables could stratify hospital costs within gynecology diagnosis-related groups. We analyzed 3171 gynecologic admissions to a large teaching hospital and found that the parameters of nonemergency and intensive care unit admission and blood or plasma product utilization could stratify hospital costs and outcome within a gynecology diagnosis-related group. Patients with the variables had higher total hospital costs, a longer hospital length of stay, more procedures per patient, a greater proportion of outliers, and a higher mortality than patients without the variables. This study demonstrates that these four clinical variables could be used to focus cost-containment efforts on gynecologic patients incurring higher costs in the coming era of limited resources.

Role of the protein moiety of ribonuclease P, a ribonucleoprotein enzyme

The Bacillus subtilis ribonuclease P consists of a protein and an RNA. At high ionic strength the reaction is protein-independent; the RNA alone is capable of cleaving precursor transfer RNA, but the turnover is slow. Kinetic analyses show that high salt concentrations facilitate substrate binding in the absence of the protein, probably by decreasing the repulsion between the polyanionic enzyme and substrate RNAs, and also slow product release and enzyme turnover. It is proposed that the ribonuclease P protein, which is small and basic, provides a local pool of counter-ions that facilitates substrate binding without interfering with rapid product release.

The RNA component of the Bacillus subtilis RNase P. Sequence, activity, and partial secondary structure

The gene defining the catalytic RNA component of RNase P in Bacillus subtilis 168 was cloned into bacteriophage lambda and plasmid vectors. The nucleotide sequence of the gene and its surroundings was determined from the cloned DNA and by directly sequencing or reverse transcribing the RNase P RNA. The B. subtilis RNase P RNA sequence (400-401 nucleotides) is remarkably different from that of Escherichia coli (377 nucleotides) (Reed, R. E., Baer, M. F., Guerrier-Takada, C., Donis-Keller, H., and Altman, S. (1982) Cell 30, 627-636; Sakamoto, H., Kimura, N., Nagawa, F., and Shimura, Y. (1983) Nucleic Acids Res. 11, 8237-8251). At best the two are less than 50% similar in sequence. To verify that the RNase P RNA gene was analyzed, a modified, putative gene was cloned adjacent to a bacteriophage T7 promoter and various transcripts were tested for RNase P activity. The intact gene transcript, but not fragments, showed full activity. Full catalytic activity was restored upon mixing the fragments. The extensive differences between the B. subtilis and E. coli RNase P RNAs precluded full covariance analysis of secondary structure, but phylogenetically consistent foldings for portions of both molecules could be derived.

The catalytic element of a ribosomal RNA-processing complex

The Bacillus subtilis RNase M5 complex, responsible for the terminal maturation of 5 S rRNA, includes two proteins. One of these proteins is ribosomal protein BL16 (equivalent to Escherichia coli EL18); the other, the alpha component, is required for catalysis. The RNase M5 alpha component has been purified in bulk extensively, and the active polypeptide (Mr approximately 24,000) identified following polyacrylamide gel electrophoresis. Reaction conditions (20-30% dimethyl sulfoxide) are reported which render RNase M5 activity independent of ribosomal protein BL16. This proves that alpha indeed is the catalytic element, the actual RNase M5, which normally attacks a ribonucleoprotein substrate consisting of protein BL16 in complex with the 5 S rRNA precursor. Kinetic analyses of the BL16-dependent and independent reactions suggest that any alpha-BL16 association contributes little to the energetics of the alpha-ribonucleoprotein substrate interaction. It is postulated that the BL16 protein serves as a scaffold, to lock the precursor mRNA into a conformation recognizable by the nuclease.

The ribonucleoprotein substrate for a ribosomal RNA-processing nuclease

The Bacillus subtilis RNase M5 activity, responsible for the endonucleolytic maturation of 5 S rRNA, requires two proteins, alpha and beta. The beta component has been purified to homogeneity and shown to correspond to ribosomal protein BL16. The BL16 protein evidently corresponds functionally to Escherichia coli ribosomal protein EL18, as that latter protein also will complement the B. subtilis alpha protein in the RNase M5 reaction. A filter binding assay for the formation of B. subtilis 5 S rRNA-protein complexes was characterized and used to evaluate the association of BL16 protein with some RNAs. A native precursor of 5 S rRNA, containing extra sequences at both termini of the mature domain, binds the ribosomal protein no better than the mature 5 S rRNA; the precursor sequences do not facilitate that interaction. A model is considered in which the precursor segments facilitate, by refolding, the dissociation of processing products prior to the RNase M5 step. Electrostatic versus nonelectrostatic contributions to the BL16-5 S rRNA complex formation were inspected by analyzing variation in apparent association constants as a function of ionic strength. Electrostatic interactions were seen to contribute approximately 65% to the overall binding energy.

The conserved 5 S rRNA complement to tRNA is not required for translation of natural mRNA

We have tested a putative base-paired interaction between the conserved GT psi C sequence of tRNA and the conserved GAAC47 sequence of 5 S ribosomal RNA by in vitro protein synthesis using ribosomes containing deletions in this region of 5 S rRNA. Ribosomes reconstituted with 5 S rRNA possessing a single break between residues 41 and 42, deletion of residues 42-46, or deletion of residues 42-52 were tested for their ability to translate phage MS2 RNA. Initiator tRNA binding, aminoacyl-tRNA binding, ppGpp synthesis, and miscoding were also tested. All of the measured functions could be carried out by ribosomes carrying the deleted 5 S rRNAs. The sizes and relative amounts of the polypeptides synthesized by MS2 RNA-programmed ribosomes were identical whether or not the 5 S RNA contained deletions. Aminoacyl-tRNA binding and miscoding were essentially unaffected. Significant reduction in ApUpG (but not poly(A,U,G) or MS2 RNA)-directed fMet-tRNA binding and ppGpp synthesis were observed, particularly in the case of the larger (residues 42-52) deletion. We conclude that if tRNA and 5 S rRNA interact in this fashion, it is not an obligatory step in protein synthesis.

Conserved 5S rRNA complement to tRNA is not required for protein synthesis

The notion that tRNA and 5S rRNA interact through evolutionarily conserved complementary sequences has been tested by nucleolytic modification of the 5S rRNA, using the modified rRNA to reconstitute the large ribosomal subunit, and assaying for poly(uridylic acid)-directed polyphenylalanine synthesis. The 5S rRNA sequence C-G-A-A (residues 43-46) and several residues surrounding it are not essential for protein synthesis.