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PubMed1994

A cloning and epsilon-epitope-tagging insert for the expression of polymerase chain reaction-generated cDNA fragments in Escherichia coli and mammalian cells.

An intercompatible gene-tagging insert sequence was designed to conveniently introduce epitope-tagged polypeptides into bacteria and mammalian cells. The presence of rare restriction enzyme sites located between the ATG codon and the sequence encoding the introduced epsilon-tag creates a general cloning site which allows efficient cloning of virtually any desired cDNA fragment produced by the polymerase chain reaction (PCR). The tagging insert sequence encodes a KGF-SYFGEDLMP peptide, derived from the last 12 amino acids of the protein kinase C epsilon gene, to serve as a C-terminal epitope tag of the expressed protein. While the insert can be readily adapted for insertion into any expression vector, this paper details the introduction and characterization of the epsilon-epitope-tagging insert into the bacterial pTrcHis A (epsilon TrcHis A) vector and into the metallothionein promoter-driven eukaryotic (epsilon MTH) expression vector. The expressed epsilon-tagged proteins can be readily detected with a commercially available antibody specific for the epsilon-peptide. Immunoscreening of Escherichia coli colonies transformed with the PCR-generated cDNA inserted into the epsilon TrcHis A vector enables rapid, direct biochemical characterization of the PCR product. The biochemically characterized gene constructs from the epsilon TrcHis A plasmid can be inserted into the epsilon MTH vector by a single subcloning step using the introduced compatible cohesive ends. This epsilon-epitope-tagging insert provides investigators with a versatile, uncomplicated, and reliable method of expressing an epitope-tagged PCR product in the cell type of interest.(ABSTRACT TRUNCATED AT 250 WORDS)

3T3 Cells↗

PubMed1998

Co-insertional replication is responsible for tandem multimer formation during plasmid integration into the Dictyostelium genome.

We investigated the establishment of integrating transformation vectors in the genome of Dictyostelium discoideum to gain insight into the formation of the plasmid insertions and to investigate the conditions that determine the number of plasmid copies present in such insertions. Transformation vectors conferring resistance to neomycin and/or blasticidin were introduced into the cell as a calcium phosphate coprecipitate or by electroporation. The integration of the plasmid DNA was based on either recombinational integration of plasmids or restriction enzyme-mediated integration. The genomic DNA of the resulting transformants was examined by Southern blot analysis of pulsed-field gels and by the recently published method of direct electroporation into Escherichia coli. The number of insertion sites was found to be dependent on the transformation method used, and the minimum number of plasmid copies per insertion site required for resistance depended on the type and the concentration of the selective drug. Cotransformation studies revealed a strictly homogeneous composition of vector multimers from any given insertion site. This suggests that multimers arise by co-insertional replication of a single plasmid monomer, rather than by subsequent additional insertion events involving homologous recombination. The multimerization of the integrated vector only occurred when the insertion was established by homologous recombination. Moreover, the number of plasmid copies appeared to be random, was established at the time of the transformation, and did not change with subsequent alterations to the selection regime.

Animals↗

PubMed1991

Tendinous insertions in the human thyroid cartilage plate: macroscopic and histologic studies.

The zones of tendinuous insertion and origin of the sternothyroid muscle, the thyrohyoid muscle, the inferior constrictor muscle of the pharynx and the external part of the cricothyroid muscle were studied in adult larynges by macroscopy and light microscopy. The sternothyroid muscle is inserted in the superior and inferior thyroid tubercula and also in a tendinous arch, which extends between the two tubercula. In contrast to the descriptions found in most textbooks, the sternothyroid muscle has no attachment to the oblique line. The thyrohyoid muscle and the thyropharyngeal part of the inferior constrictor muscle of the pharynx originate in ventral and dorsal symmetry at the oblique line. X-rays permit a measurement of their original angles, resulting in a mean value of 36 degrees. According to these measurements, and electromyographic findings by other authors, both muscles can be regarded as a bipennate muscle from a functional point of view. Histologic studies indicate that the oblique line's zone of origin structurally resembles an areal periosteal-diaphysary tendinous insertion. In the non-ossified thyroid cartilage, the insertions in the region of the thyroid tubercula are similar to chondral-apophysary insertions of tendons in the limb skeleton. After ossification of the thyroid cartilage, they show the shape of circumscribed periosteal-diaphysary insertions. Osteogenesis of the laryngeal skeleton therefore affects the structure of the thyroid tubercula's tendinous insertions. From a mechanical point of view, the insertions in the thyroid cartilage function as extension-checking mechanisms, and also serve to balance the different elastic modules of the tendinous tissue and the cartilaginous or bony tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Intrachromosomal insertions: a case report and a review.

We describe the phenotype of a child having a recombinant chromosome 3 with a duplication 3q13.2----q25 derived from a paternal inv ins(3)(p25.3q25q13.2). A review of 27 reported cases of intrachromosomal insertions has revealed that for a carrier of intrachromosomal insertion the risk of a child with an unbalanced karyotype is 15%. This risk may be higher for particular insertions. The recombinant chromosome can have a duplication or a deletion of different segments depending on whether the insertion is direct or inverted, paracentric or pericentric, and whether there is meiotic crossing over in the inserted or the interstitial non-inserted segment. Several of the insertions have been difficult to interpret and some of them have been mistaken for paracentric inversions. Caution is therefore indicated in interpreting parental karyotypes of a child with a deletion or a duplication, particularly if it is interstitial. This is because, whereas a risk of recurrence of a child with an unbalanced karyotype is low in de novo cases and for carriers of paracentric inversions, it is high for carriers of insertions.

Abnormalities, Multiple↗

PubMed1976

Reversion of the gal3 mutation of Escherichia coli: partial deletion of the insertion sequence.

The gal3 mutation of E. coli is an insertion of a DNA sequence, 1,100 base pairs in length, into the operator-promoter region of the galactose operon. This mutation reverts spontaneously to gal+ by excision of the insertion to produce stable, inducible revertants, or by tandem duplications of the gal operon to produce unstable, constitutive revertants. The nature of a third class of revertants, which are stable and constitutive, is the subject of the present study. The stable, constitutive class of revertants included approximately 30% of all gal+ revertants obtained from a gal3 (lambda) strain. Although the constitutive reversions could be transduced by lambda, the efficiency was found to be extremely poor and the rare transductants which did appear seemed to originate from abnormal transducing particles. It was concluded that these reversions were not normally packaged by lambda. In order to facilitate the packaging of these reversions, the chlD-pgl region was deleted from the parent gal3 (lambda) strain. Unexpectedly, the gal3 mutation in the majority of these deletions reverted to produce stable, constitutive reversions exclusively. The explanation proposed was that the chlL-pgl deletions had also removed part of the gal operator-promoter. These revertants were not considered to be true representatives of the stable, constitutive class. The specificity of deletion end-points at the insertion was found only in the gal3 (lambda) strain, and not in gal+, gal+(lambda), or gal3 strains. Moreover, the frequency of spontaneous chlD-pgl deletions increased 10- to 15-fold in presence of the gal3 insertions. A lambdagal phage bearing a true stable, constitutive reversion (galc200) was isolated from the revertant strain by subsequent deletion of the chlD-pgl segment (delta31). Electron micrographs of lambdagal+ and lambdac200 delta31(chlD pgl) DNA heteroduplexes were interpreted to indicate that the stable, constitutive reversion had arisen by a deletion of 3/4 of the gal3 insertion sequence. The main conclusions are: (i) the stable, constitutive reversions of gal3 can arise by partial deletions of the insertion sequence, apparently by elimination of the nucleotide sequence which causes polarity; (ii) the chlD-pgl deletions may exhibit preferential termination at the right extremity of the gal3 insertion in presence of prophage lambda; and (iii) the gal3 insertion appears to inhibit the production of lambdagal particles by providing a nucleotide sequence which is recognized and degraded by a specific endonuclease. It is suggested that inhibition of transducing particle formation by gal3 and the preferred termination of deletions at gal3 might represent related phenomena.

Base Sequence↗

PubMed1994

Organization of heterologous DNA inserts on the mouse meiotic chromosome core.

With simultaneous immunofluorescence and fluorescent in situ hybridization, we have determined the organization of native and heterologous DNA sequences relative to the cores of meiotic prophase chromosomes. The normal chromatin organization is demonstrated with probes of mouse sequences: a cosmid probe that identifies unique sequences and a 720 kb yeast artificial chromosome (YAC) probe that recognizes a specific region of the chromatin domain. The heterologous DNA consists of a 1.8 Mb insertion of 40 tandem head-to-tail phage lambda LIZ vectors and of 11.4 Mb of bacterial/mouse DNA repeats. The lengthy lambda insert is unusual in that it is not contained in the chromatin domain of chromosome 4 and in that it fails to form direct attachments to the chromosome core. The ends are attached indirectly, probably by means of the flanking mouse sequences. At late stages of meiotic prophase, while the terminal attachments remain the same, the lambda DNA becomes highly compacted. Apparently, higher order condensation and core attachment are independent processes. The condensed inserts relax precociously at metaphase I. In the mouse heterozygous for the insert, the two sister inserts are usually merged, as are all four inserts in the homozygous mouse. Evidently chromatin loops with identical sequences can become associated during meiotic prophase. Mouse sequences within a heterologous DNA insert (repeats of bacterial plasmid pBR322 with a mouse beta-globin insert) were observed to restore some degree of core attachment.

Animals↗

PubMed1990

Genetics of factors affecting the life history of Drosophila melanogaster. IV. Cytoplasmic/maternal factors affect egg insertion behavior.

The genetic basis of insertion behavior of laboratory strains of Drosophila melanogaster was examined. Reciprocal crosses among five strains revealed a significant effect of interaction between cytoplasmic/maternal factors and the chromosomal genotype in determining the insertion tendency, thus complicating the characterization of the dominant/recessive nature of the insertion genes. The majority of heterozygous combinations demonstrated dominance or partial dominance for the higher insertion tendency over low insertion, while a few combinations produced results to the contrary. These could be due to a more complex genetic basis of insertion behavior than a simple dominant/recessive relationship or else to the cytoplasmic/maternal-chromosome interactions. Examination of the effects of each chromosome revealed the greatest contributions to insertion tendency from the second and third chromosomes, with a significant effect of interaction or nonadditivity of the insertion genes in these two chromosomes in the genotypes tested. The X and fourth chromosomes appear to contribute a small effect in some strains.

Animals↗

PubMed1985

Postpartum IUD insertions in Manila, Philippines.

In comparative IUD trials conducted in the Philippines, IUDs were inserted immediately postpartum (within ten minutes postplacenta). The first study was designed to compare the IPCS-52 mg (Intrauterine Progestasert Contraceptive System) IUD with the TCu200 when inserted either by hand or with an inserter. Follow-up continued for three years because the IPCS model was designed to release progesterone for this length of time. There was one suspected pregnancy for which the IUD was removed during the study period. The expulsion rates were higher in the IPCS groups than in the TCu groups (p less than or equal to 0.05) and they were higher in the hand insertion groups than in the inserter groups (p less than or equal to 0.05). The second study was a comparison of the Lippes Loop D and a Delta Loop, modified by the addition of three biodegradable suture projections (made of Ethicon #2 chromic material) on the upper arms of the device. The purpose of this modification was to lower the expulsion rates associated with postpartum insertions. The expulsion rates for these two devices were comparable. There were no difficulties during insertion in either study, and few complaints were reported at follow-up. These two studies demonstrated that immediate postpartum IUD insertion proved a safe, effective means of postpartum contraception.

Adult↗

PubMed1995

Circulatory responses to laryngeal mask airway insertion or tracheal intubation in normotensive and hypertensive patients.

The effects of laryngeal mask airway (LMA) insertion and tracheal intubation on circulatory responses were studied in normotensive (n = 24) and hypertensive (n = 22) patients. In a randomized, double-blind manner, LMA insertion or tracheal intubation was performed after induction of anaesthesia with thiopentone and muscle relaxation with succinylcholine. In both normotensive and hypertensive patients, heart rate (HR), mean arterial pressure (MAP) and rate-pressure product increased after tracheal intubation or LMA insertion compared with baseline (P < 0.05). The haemodynamic changes were greater after intubation than after LMA insertion (P < 0.05). Following intubation of the trachea or insertion of the LMA, HR increased more markedly in hypertensive patients than in normotensive patients (P < 0.05). Plasma adrenaline and noradrenaline concentrations after tracheal intubation or LMA insertion increased compared with baseline values (P < 0.05) in normotensive and hypertensive patients. The increase in noradrenaline concentration after tracheal intubation was greater than that after LMA insertion (P < 0.05). No patient revealed ECG evidence of myocardial ischaemia. We conclude that insertion of LMA is associated with less circulatory responses than tracheal intubation in both normotensive and hypertensive patients.

Adult↗

PubMed2006

Easier node dissection after chemoradiotherapy for lung cancer with collagen insertion at mediastinoscopy.

OBJECTIVE: Induction chemoradiotherapy followed by anatomical resection is a current therapeutic strategy for non-small-cell lung cancer with mediastinal node involvement. Dense peritracheal fibrosis and sclerosis after chemoradiotherapy cause difficult mediastinal node dissection. We evaluated a novel technique to make the mediastinal node dissection easier after induction therapy. METHODS: At the end of mediastinoscopic node biopsy for staging of lung cancer, cotton-type collagen was inserted anterior and lateral to the trachea in patients with pathologically confirmed mediastinal node involvement (n=45). The induction therapy consisted of concurrent use of platinum-based chemotherapy and hyperfractionated radiotherapy. After the chemoradiotherapy all patients underwent a pulmonary resection with complete mediastinal node dissection 7-12 weeks after the collagen insertion. Surgical findings of the mediastinum and the time for node dissection were compared with those without collagen insertion at mediastinoscopy after chemoradiotherapy (n=5). RESULTS: All five patients without collagen insertion showed sclerotic and fibrotic change of mediastinal nodes with severe adhesion to the trachea. In 42 of 45 patients with collagen insertion (93.3%) the collagen remained unabsorbed and separated the mediastinal nodes from the trachea. Mediastinal node dissection was easily accomplished by removing mediastinal tissues lateral and anterior to the collagen. The rate of mediastinal node separation was significantly higher with collagen insertion than without (p<0.0001). The times for node dissection in patients with and without collagen insertion showed no significant difference. CONCLUSION: Cotton-type collagen insertion at staging mediastinoscopy for lung cancer separates the mediastinal nodes from the trachea and makes the node dissection easier after induction chemoradiotherapy.

Adult↗

PubMed2006

Soft tissue graft interference fit fixation: observations on graft insertion site healing and tunnel remodeling 2 years after ACL reconstruction in sheep.

Using soft tissue grafts for anterior cruciate ligament (ACL) reconstruction, insertion site healing plays a crucial role in the long-term fate of the graft. It has been shown in an experimental animal study that using a soft tissue graft and anatomic graft fixation, a direct ligamentous insertion alike the native ACL developed 24 weeks postoperatively. Yet there are no reports on the long-term insertion site healing of anatomically fixed soft tissue grafts. The objective of this study was to evaluate graft insertion site healing, the intra-tunnel fate of the graft and its osseous replacement 2 years after ACL reconstruction in sheep. The left ACLs of six sheep were replaced by an autologous flexor tendon split graft and anatomically fixed with biodegradable poly-(D, L-lactide) interference screws. Animals received polychromic sequential labeling at different points in time to determine bone apposition per period. For evaluation of the insertion site healing and intra-tunnel changes, MRI scans were taken in vivo. Following sacrifice, radiographic imaging, conventional histology and fluorescence microscopy was undertaken. Most of the specimens showed a wide direct ligamentous insertion. It showed patterns alike the direct ligament insertion seen in intact ACLs. The intra-tunnel part of the graft had completely lost its tendon-like structure and in two cases, it was separated from the graft insertion by a thick bony layer. The biodegradable interference screw was fully degraded in all specimens. Ossification of the former drill tunnels was intense, showing only partial-length tunnel remnants in one femoral and three tibial specimens. As the graft heals to the joint surface and the aperture site is closed with soft tissue, mechanical stress of the intra-tunnel part of the graft is eliminated and the bone tunnel is protected from synovial fluid, resulting in osseous bridging of the tunnel aperture site, accelerated intra-tunnel graft resorption and its osseous replacement.

Animals↗

PubMedDate not supplied

Fluoroscopically guided feeding tube insertion for relief of postoperative gastrointestinal anastomotic obstruction and leakage.

PURPOSE: To evaluate the feasibility and effectiveness of feeding tube insertion and enteral feeding for the treatment of postoperative gastrointestinal anastomotic obstruction and leakage. MATERIALS AND METHODS: From June 1999 to June 2002, thirty-four cases of postoperative gastrointestinal anastomotic obstruction and leakage after surgery for gastric carcinoma were treated by insertion of a feeding tube under fluoroscopic guidance. Twenty-one patients were male and 13 were female. The patients' ages ranged from 39 to 74 years (mean age: 61 years). All the patients experienced vomiting, and 15 patients had anastomotic site or duodenal stump leakage. We evaluated the feasibility of feeding tube insertion for enteral feeding to improve the obstruction and facilitate leakage site closure, and the patients' nutritional benefit was also evaluated by checking the serum albumin level between pre- and post-enteral feeding via the feeding tube. RESULTS: Thirty-two patients (94%) were successfully managed by feeding tube insertion, but the remaining two were not managed, and this was due to severe angulations at the anastomotic site. The procedure times for feeding tube insertion ranged from 15 to 60 minutes (mean time: 45 minutes). Twenty-eight patients experienced symptomatic relief of gastrointestinal obstruction, and they were able to resume a normal regular diet after feeding tube removal. Three patients underwent stent insertion due to recurrent symptoms, and one patient underwent jejunostomy feeding due to the presence of a persistent leakage site. Eleven patients achieved leakage site closure after enteral feeding via a feeding tube. The serum albumin level was significant, increased from pre-enteral feeding (2.65 +/- 0.37 g/dL) to the post-enteral feeding (3.64 +/- 0.58 g/dL) via the feeding tube (p < 0.001). The duration of follow-up ranged from one to 53 months (mean: 23 months). CONCLUSION: The insertion of a feeding tube for enteral feeding under fluoroscopic guidance is safe, and it provides effective relief from gastrointestinal anastomotic site obstruction and leakage after gastric surgery. Moreover, our findings indicate that feeding tube insertion for enteral feeding may be used as the primary procedure to treat postoperative anastomotic obstruction and leakage.

Adult↗

PubMed2001

The ROSA26 LacZ-neo(R) insertion confers resistance to mammary tumors in Apc(Min/+) mice.

B6.129S7-Gtrosa26 (ROSA26) mice carry a LacZ-neo(R) insertion on Chromosome (Chr) 6, made by promoter trapping with AB1 129 ES cells. Female C57BL/6J Apc(Min/+) (B6 Min/+) mice are very susceptible to the induction of mammary tumors after treatment with ethylnitrosourea (ENU). However, ENU-treated B6 mice carrying both Apc(Min) and ROSA26 are resistant to mammary tumor formation. Thus, ROSA26 mice carry a modifier of Min-induced mammary tumor susceptibility. We have previously mapped the modifier to a 4-cM interval of 129-derived DNA that also contains the ROSA26 insertion. Here we report additional evidence for the effect of the ROSA26 insertion on mammary tumor formation. To test the hypothesis that the resistance was due to a linked modifier locus, we utilized two approaches. We have derived and tested two lines of mice that are congenic for 129-derived DNA within the minimal modifier interval and show that they are as susceptible to mammary tumors as are B6 mice. Additionally, we analyzed a backcross population segregating for the insertion and show that mice carrying the insertion are more resistant to mammary tumor development than are mice not carrying the insertion. Thus, the resistance is not due to a 129-derived modifier allele, but must be due to the ROSA26 insertion. In addition, the effect of the ROSA26 insertion can be detected in a backcross population segregating for other mammary modifiers.

Alleles↗

PubMed2006

A randomized controlled trial comparing simultaneous intra-operative vs sequential prophylactic ureteric catheter insertion in re-operative and complicated colorectal surgery.

OBJECTIVES: Prophylactic insertion of ureteric stents aids intra-operative identification of ureters and may allow easier visualization of any direct ureteric injury. Traditionally, ureteric catheters are inserted sequentially, before starting the abdominal part of the operation. This study determines the safety and efficacy of simultaneous intra-operative ureteric catheter insertion during complicated and re-operative colorectal surgery. MATERIALS AND METHODS: After institutional review board (IRB) approval, 24 patients were randomized into two groups, sequential (SEQ) and simultaneous (SIM) depending upon the timing of stent placement relative to abdominal incision. Time taken from induction to abdominal incision (AIT), induction to peritoneal entry (PET), catheter insertion time (CIT), and urinary tract infection rates were recorded. Degree of difficulty for stent insertion was graded on a scale of 1-10. RESULT: Demographics were similar between groups. Mean AIT (22 +/- 4 vs 41 +/- 7; p = 0.0001) and mean PET (26 +/- 4.2 vs 44 +/- 7.6; p = 0.0001) were shorter in the SIM group. There was no significant difference in mean CIT in SIM and SEQ groups (17.9 +/- 4.9 vs 17.6 +/- 5.9 min, p = 0.8). The stents were unsuccessful bilaterally in one patient in the SEQ group and unilaterally in two other patients, one in each group. The median difficulty score for catheter insertion was 3 (1-10) and 2 (1-10), (p = 0.12), respectively, in SIM and SEQ groups. There were no ureteric injuries in either group. One patient in SIM developed a urinary tract infection. CONCLUSION: Simultaneous ureteric catheter insertion during abdominal procedures reduces operating times without a significant increase in morbidity. Furthermore, this permits a policy of selective stent insertion as required by the intra-abdominal findings after laparotomy.

Adult↗

PubMed2002

Direct visual or blind insertion of the primary trocar.

BACKGROUND: We set out to assess the difference in complication rates between primary umbilical insertion by a blind trocar and insertion with an optical surgical obturator. METHODS: In a retrospective survey, we investigated the rate of severe complications by primary umbilical trocar entry. Of 1546 patients undergoing gynecological laparoscopies at a tertiary-care university hospital, 1000 cases were operated by blind umbilical insertion with a conventional primary trocar whereas 546 used an optical primary trocar. RESULTS: The rate of major complications during insertion of the primary trocar in the blind insertion group was five of 1000 (0.5%), whereas there were no major complications in the optical-guided insertion group (0.0%). CONCLUSIONS: In comparison with the blind insertion of a sharp trocar, optical guidance provides a safe and functional primary insertion method that allows to detect adhesions to be detected at an early stage, thus preventing injuries to the bowel and abdominal vessels.

Adult↗

PubMed2001

Effect of deletion and the site of insertion in double copy anti-tat retroviral vectors: viral titres and production of anti-tat mRNA.

In attempts to further develop murine leukemia virus (MLV) based retroviral vectors for gene therapy, we investigated vector production and antisense expression from retroviral constructs with U3 deletions or insertions. Promoter elements in the U3 region of the 3' LTR of the vector pLXSN were deleted and replaced with DNA encoding the HIV anti-tat gene under control of the tRNAmet promoter to produce a double copy self inactivating vector (DC-SIN). DC-SIN constructs were compared to vectors containing the anti-tat cassette inserted at 5 different sites of the U3 region (DC-insertions). Titres of DC-SIN and DC-insertion vectors were similar but approximately 10 fold lower than parental pLXSN. Cells transduced with DC-SIN and DC-insertion vectors all expressed anti-tat mRNA. Transcripts from the MLV-LTR were detected in cells transduced with DC-insertion but not DC-SIN vectors or a vector with the anti-tat cassette between CAAT and TATA boxes of the promoter, indicating inactivation of the viral promoter in the latter vectors. Cells transduced with constructs of either design showed comparable efficacy of protection against HIV challenge. Thus, no U3 insertion site was preferred for virus production. Insertion of a tRNA promoter between CAAT and TATA boxes and the DC-SIN design which would not introduce an active RNA pol II promoter into the genome are attractive for further development of safe gene therapy agents.

Genes, tat↗

PubMed1981

Guidelines for effective and safe percutaneous intraaortic balloon pump insertion and removal.

During the 12 month period beginning February 1980, a total of 54 consecutive patients had 60 attempts at percutaneous insertion of an intraaortic balloon because of medically uncontrollable angina, cardiogenic shock either in the setting of an acute myocardial infarction or within hours of cardiac surgery and as a prophylactic measure in high risk patients before cardiac surgery. The balloon was successfully inserted in 49 patients (91 percent). In five patients the balloon could not be inserted in spite of eight attempts because of tortuosity of the iliac artery. All nine patients in whom balloon insertion was attempted without fluoroscopy had the device inserted successfully. The four insertion attempts during cardiac massage were all successful. Experience with use of the new longer introducer sheath is described. Since its acquisition there has not been a single balloon pump insertion failure in 20 consecutive patients including 6 patients in whom initial attempts through the conventional short death were unsuccessful because of iliac tortuosity. The major complications encountered in the present series were thromboembolic: femoral arterial thrombosis developed in five patients (10.2 percent) and an asymptomatic pulse loss in the contralateral foot developed in another. There were no cases of pseudoaneurysm, groin hematoma, aortic dissection or infection related to the percutaneous balloon. On the basis of this experience, several guidelines are suggested for safe and effective percutaneous insertions and removal of the intraaortic balloon pump.

Aged↗

PubMed1985

Specificity of insertion of IS1.

A systematic study of the specificity of insertion of the transposable element IS1 into small defined-sequence plasmids (pBR322 and derivatives) was conducted to determine the features of the DNA sequence that influence target site selection. We have physically mapped several collections of independent insertions of IS1 into these plasmids and have determined: (1) that about 80% of all insertions occur in the DNA segment (about 200 base-pairs) between the unique EcoRI site of pBR322 and the beginning of the beta-lactamase gene, one of the two regions of high A + T density in this plasmid; (2) that there is a strong orientation effect in this region (almost all IS1 insertions are in one orientation) that depends on both the pBR322 sequence and the environment of the transposon in the donor molecule; and (3) that the orientation effect does not depend on the strong transcription that is directed through this region in pBR322. Furthermore, we have found that insertion of a poly(dA X dT) segment into pBR322 creates an artificial hotspot for IS1 insertion, even though it is not as attractive for insertion as the above-mentioned major hotspot. Our observations suggest that an interplay between several properties of the target sequences and the sequence environment of the donor transposon is responsible for the observed specificity of position and orientation. One of the possibilities discussed here is that preferred "entry-sites", or "signal" sequences, for the transposition complex play a major role in determining the positions and orientations of IS1 insertions.

Ampicillin↗