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At least 973 records · Page 54Linked to original sources
PubMed1979

Transposon-insertion mutants of Escherichia coli K12 defective in a component common to galactose and ribose chemotaxis.

From a collection of 8,000 transposon-insertion mutants of Escherichia coli K12 we identified two mutations, trg-1::Tn5 and trg-2::Tn10, that simultaneously eliminate chemotactic response to ribose and galactose, two attractants recognized by independent receptors. We show that these transposon-insertions confer a Trg phenotype, indicating that this specific pattern of tactic defects is a null phenotype. The two mutation sites are cotransductionally linked to an extend consistent with placement in the same gene. The Trg phenotype of a family of deletion mutants produced by curing trg-2::Tn10 implies that trg is a single gene. Experiments with appropriate F-primes and Hfr's locate the trg locus at approximately 31 min on the linkage map, with a marker order: pyrF-rac-(P.O. 43)-trg-man. We also found one trg mutant whose Trg phenotype was not linked to a transposon-insertion but is probably the result of a mutator activity in the parent strain. Selection of transposon-insertions near, but not in trg allowed demonstration of a very close linkage between the spontaneous trg-3 and the transposon-generated trg's, indicating all three mutations are probably in the same gene. In our manipulations of transposon-insertions we found that Tn5 had a tendency to translocate from its initial site of insertion while Tn10 was relatively stable. The trg-product is probably a chemotactic signal transducer, which interacts directly with two independent receptor proteins and transmits information to the central chemotactic machinery.

Chemotaxis↗
PubMed1981

Inactivation of the Serratia marcescens gene for the lipoprotein in Escherichia coli by insertion sequences, IS1 and IS5; sequence analysis of junction points.

A pBR322-derived plasmid pKEN221 carrying a Serratia marcescens lpp gene overproduces the outer membrane lipoprotein in an Escherichia coli lpp- cell. However, when this strain was continuously cultured in a rich medium for about thirty generations, many Lpp- mutants were accumulated. Out of six mutants analyzed, three were found to carry insertion mutation in the lpp gene in pKEN221. From resistance enzyme mapping and hybridization analysis of the mutant plasmid DNA, it was found that two mutants were caused by insertion sequence IS1 and one by IS5. Nucleotide sequence analysis of these mutant DNAs revealed that both IS1 and IS5 insertions occurred in the A-T rich 5' untranslated region of the lpp gene. While the IS1 insertion resulted in a direct duplication of a nine-base-pair sequence in the original pKEN221 DNA at the junction with IS1, the IS5 insertion resulted in a direct duplication of a four-base-pair sequence. IS5 was found to contain inverted-repeat sequences of twelve nucleotides at its exact ends. This is the first example of the nucleotide sequence analysis of an IS5 insertion mutation. By Southern blot hybridization, the E. coli chromosomal DNA was found to contain about ten copies of IS5.

Bacterial Proteins↗
PubMed1986

Mutagenesis by random linker insertion into the lamB gene of Escherichia coli K12.

Gene lamB encodes an outer membrane protein involved in maltose and maltodextrin transport as well as phage adsorption. The active form is a trimer. We characterized 11 mutations in lamB, obtained after random insertion of a BamH1 linker and screening for stable immunodetectable mutant proteins. Six mutations resulted in the loss of the distal part of the LamB protein either by deletion (five cases) or frameshift (one case). The six corresponding proteins had all lost the ability to confer phage sensitivity and the capacity to grow on dextrins, and to yield immunodetectable oligomers. Induction of a high level of the four longest of these proteins was toxic to the cell. Five other mutations were due to in-frame insertions. In four cases, the corresponding proteins still had the ability to yield immunodetectable oligomers, to confer phage sensitivity and the capacity to grow on dextrins and were not toxic on induction. In one case (AJC73), the mutant protein had lost the first three properties and was toxic on induction. Deletions and duplications between some of the inserts were also constructed and studied. To account for our results we present a hypothetical scheme in which trimerization would not only be needed for phage sensitivity and growth on dextrins but also for proper insertion into the outer membrane. The C-terminus of the protein, as well as other regions such as the site of mutation AJC73, would be required for the formation of stable trimers. We tentatively interpret toxicity as due to improper insertion into the outer membrane. Our results also show that it is possible to insert several amino acids (up to 11 in one case) at a number of positions in LamB without appreciably affecting its export and activities.

Amino Acid Sequence↗
PubMed1986

Clinico-pathological study of fallopian tubes after transcervical insertion of quinacrine hydrochloride pellets.

This study lends support to others indicating the apparent safety and effectiveness of multiple transcervical insertions of quinacrine hydrochloride as pellets in 240 mg dosage to achieve permanent sterilization. In order to study the effects of the number of quinacrine pellet insertions and the site of placement of the pellets in the uterus of prehysterectomy volunteers, a scoring system of histological changes in the Fallopian tube was designed. Quinacrine pellets were deposited at the fundus using a straight inserter in 16 women, and at the cornua using a curved inserter in 17 women. Each group had at least five women receiving one, two or three insertions at one-week intervals. Results indicate that neither the number of insertions nor the place of deposition of the pellets affects the degree of tubal inflammation and fibrosis.

Adult↗
PubMed1988

IUD insertion forces: effects of recent childbirth and lactation.

This investigation compared the force required to insert an IUD in women who were breastfeeding and who had recently delivered a child with that required in control women who were not breastfeeding and who had not recently delivered. Twenty-eight women who had recently delivered and who were breastfeeding were compared with twenty-eight controls. The women were matched for age and parity and for the type of IUD used. The mean IUD insertion force in the breastfeeding, recently-delivered women was 1.75 newtons (N) as compared to 2.80 N in the controls. The difference was statistically highly significant (paired t-test, p less than 0.01). Recent childbirth and lactation are associated with a reduction in IUD-related insertion pain, probably due to a reduction in the force required for insertion. This reduction in IUD insertion force is not necessarily related to lower uterine perforation rates in IUD insertion in this group. A number of physiological mechanisms may be responsible for this finding.

Adult↗
PubMed1991

Spontaneous insertion of plant plasma membrane (H+)ATPase into a preformed bilayer.

The purified (H+)ATPase from corn roots plasma membrane inserted spontaneously into preformed bilayer from soybean lipids. The yield of the protein insertion, as measured from its H(+)-pumping activity, increased as a function of lipids and protein concentrations. In optimum conditions, all the (H+)ATPase molecules were closely associated with liposomes, exhibiting a high H(+)-pumping activity (150,000% quenching min-1.mg-1 protein of the probe 9-amino-6-chloro-2-methoxyacridine). The insertion was achieved within a few seconds. No latency of the (H+)ATPase hydrolytic activity was revealed when lysophosphatidylcholine was added to permeabilize the vesicles. This indicated that the (H+)ATPase molecules inserted unidirectionally, the catalytic sites being exposed outside the vesicles ("inside-out" orientation), and thus freely accessible to Mg-ATP. The nondelipidated (H+)ATPase could also functionally insert into bilayer from PC:PE:PG or PC:PE:PI, due to the presence of both hydrophobic defects promoted by PE, and negative phospholipids specifically required by the (H+)ATPase from corn roots. The detergent octylglucoside facilitated the delipidated (H+)ATPase reinsertion probably by promoting both a proper protein conformation and hydrophobic defects in the bilayer. Lysophosphatidylcholine facilitated the delipidated protein insertion only when hydrophobic defects were already present, and thus seemed only capable to ensure a proper protein conformation.

Adenosine Triphosphate↗
PubMed1996

Comparison of insertion rate of L1 retroposon into intron 30 of the neurofibromatosis type 1 gene in seven Asian and Pacific populations.

The allele frequency of a L1 retroposon insertion into intron 30 of the neurofibromatosis type 1 (NF1) gene was determined by analyzing amplified fragment lengths in seven Asian or Pacific population; namely, Japanese, Chinese. Indian, Malay, Filipino, Indonesian and New Guinean. Nearly 100 chromosomes from each group were analyzed. The presence of the L1 insertion was identified by the appearance of an abnormally large PCR-amplified product. The insertion frequency varied from 0.45 to 0.75, depending on the population group. Malay and Indonesian populations were found to have the highest insertion frequencies (0.75 and 0.72, respectively), while the wild-type genotype was more prevalent in Indians. The lowest insertion frequency (0.45), observed in Indians, was nearest to that reported in Westerners (0.35). The different L1 insertion frequencies found in Asian and Pacific groups reflect a major divergence in these human populations. Japanese and Chinese populations showed the highest heterozygosity (0.50), suggesting the usefulness of this polymorphism in linkage analysis in these populations.

Alleles↗
PubMed1984

Conformational changes in the globin family during evolution. 1. Analysis of the evolutionary role of insertions and deletions.

Conformational restrictions imposed on the fixation of insertions and deletions by the three-dimensional structure of globins during evolution are analyzed. An evolutionary tree for the primary structure of 38 taxonomically distant globins was constructed by a computer method. Based on this tree, the calculated fixation frequency of point mutations was 50-fold higher than that established jointly for deletions and insertions, and the fixation frequency of deletions was more than three times that established for insertions. It was also found that deletions and insertions are predominantly fixed in the interhelical sections and at the ends of the alpha-helices of the globin molecules. Conformational analysis of the packing of the alpha-helices in the spatial structure of globins demonstrated that the fixation of deletions and insertions in the center of an alpha-helix produces a marked distortion of their normal packing. The possible role of deletions and insertions in the evolution of protein families is discussed.

Animals↗
PubMed1996

Isolation and characterization of human hepatoma cells with targeted insertions of a gpt selectable marker in the alpha 1-antitrypsin locus.

The bacterial xanthine-guanine phosphoribosyl transferase (gpt) gene was inserted by homologous recombination into the chromosomal alpha 1-antitrypsin (alpha 1AT) gene of HPRT-deficient human hepatoma cells. These insertions encoded chimeric alpha 1AT-gpt mRNAs that were expressed in the modified cells. Six targeted integrations were obtained, but only two of these harbored simple insertion events. The remaining four homologous insertions contained additional DNA sequences 3' of the gpt coding cassette. Variant cell lines deficient for gpt expression were isolated from transfectants containing either homologous or non-homologous gpt insertions by selection in media containing 6-thioguanine. These variant cell lines expressed alpha 1AT but not alpha 1AT-gpt mRNAs, indicating that they contained expression defects in cis. Genotypic analyses suggested that the predominant mechanism by which the variants were generated was by nondisjunctive loss of chromosomes containing the modified alpha 1AT-gpt alleles. Somatic cell hybrids formed by fusing hepatoma cells containing targeted alpha 1AT-gpt insertions with fibroblasts exhibited extinction of both modified and unmodified alpha 1AT alleles.

Base Sequence↗
PubMed1990

Fluid through the epidural needle does not reduce complications of epidural catheter insertion.

Epidural catheter insertion may be associated with blood vessel trauma or nerve root irritation. The purpose of this study was to assess whether the injection of small amounts of fluid through the Tuohy needle prior to catheter insertion reduced the incidence of these and other minor complications. Two hundred patients in labour, requesting epidural analgesia, were randomly assigned to one of three groups: Group I--the catheter was inserted without previous injection of fluid; Group II--3 ml, 1.5 per cent lidocaine hydrochloride was injected through the needle prior to catheter insertion; Group III--3 ml, saline was injected prior to catheter insertion. There were no differences among the groups in the incidence of blood vessel trauma or paraesthesiae. We conclude that there is no advantage in injecting of fluid routinely into the epidural space prior to catheter insertion.

Adult↗
PubMed1999

Propofol or sevoflurane for laryngeal mask airway insertion.

PURPOSE: Sevoflurane is a volatile anesthetic agent, which combines rapid, smooth inhalational induction of anesthesia with rapid recovery, making it particularly suitable for day case anesthesia. The laryngeal mask airway is often also used in ambulatory anesthesia, with intravenous propofol being the agent of choice for its insertion. Our objective was to compare the conditions for laryngeal mask airway (LMA) insertion obtained by modified vital capacity breath sevoflurane inhalational induction of anesthesia with propofol intravenous induction. METHODS: Eighty-eight patients, aged 18-65 yr, ASA I-II, undergoing general anesthesia for elective surgery were randomized into two groups in a prospective, single-blind study. Patients in Group P (n=44) received 2.5 mg x kg(-1) propofol i.v. and in Group S (n=44) received sevoflurane 8% in nitrous oxide 50% and oxygen. Ventilation was not assisted. Laryngeal mask airway insertion was attempted at one minute intervals from loss of both verbal response and eyelash reflex, by an anesthesiologist unaware of the induction technique. Complications, such as coughing and head movement, were also noted at each attempt. RESULTS: Mean time to successful LMA insertion was 1.3 (1-3) min in P and 2.2 (1-3) min in S, P < 0.05. Eleven patients in Group P, (25%) required additional propofol compared with four (9%) in S, P < 0.05. Incidence of complications was similar in both groups and by 3 min, LMA was successfully inserted in all patients. CONCLUSION: Modified vital capacity breath inhalational induction with sevoflurane 8% is efficient for LMA insertion in most cases, but takes slightly longer than propofol.

Adolescent↗
PubMed1999

Anesthesia for insertion of a Dumon stent in a patient with a large tracheo-esophageal fistula.

PURPOSE: To present the anesthetic management for the insertion of a Dumon silicon stent to the trachea of a patient with a large tracheo-esophageal fistula. The aim of the stent insertion was to seal the fistula in order to prevent aspiration of esophageal content and subsequent pneumonitis. CLINICAL FEATURES: A 45-yr-old man with a large tracheo-esophageal fistula was scheduled for the insertion of the Dumon stent. Since placement of the stent necessitates the insertion of a rigid bronchoscope, under general anesthesia, with its tip just proximal to the fistula, controlled ventilation was expected to be difficult to achieve because of the diversion of oxygen through the large fistula to the esophagus. We successfully ventilated the lungs, after the fistula was sealed using a large balloon which was inserted in the esophagus, and the stent insertion was completed uneventfully. CONCLUSION: Anesthesia for procedures involving the central airway is challenging. This report describes a simple and practical method to facilitate ventilation by temporary seal of a tracheo-esophageal fistula using a modified esophageal balloon.

Anesthesia, General↗
PubMed2002

A DNA sequence evolution analysis generalized by simulation and the markov chain monte carlo method implicates strand slippage in a majority of insertions and deletions.

To study the mechanisms for local evolutionary changes in DNA sequences involving slippage-type insertions and deletions, an alignment approach is explored that can consider the posterior probabilities of alignment models. Various patterns of insertion and deletion that can link the ancestor and descendant sequences are proposed and evaluated by simulation and compared by the Markov chain Monte Carlo (MCMC) method. Analyses of pseudogenes reveal that the introduction of the parameters that control the probability of slippage-type events markedly augments the probability of the observed sequence evolution, arguing that a cryptic involvement of slippage occurrences is manifested as insertions and deletions of short nucleotide segments. Strikingly, approximately 80% of insertions in human pseudogenes and approximately 50% of insertions in murids pseudogenes are likely to be caused by the slippage-mediated process, as represented by BC in ABCD --> ABCBCD. We suggest that, in both human and murids, even very short repetitive motifs, such as CAGCAG, CACACA, and CCCC, have approximately 10- to 15-fold susceptibility to insertions and deletions, compared to nonrepetitive sequences. Our protocol, namely, indel-MCMC, thus seems to be a reasonable approach for statistical analyses of the early phase of microsatellite evolution.

Base Sequence↗
PubMed1999

Differences in endothelial injury after balloon angioplasty, insertion of balloon-expanded stents or release of self-expanding stents: An electron microscopic experimental study.

PURPOSE: To evaluate which of six different commonly available stents inserted into an artery without percutaneous transluminal angioplasty (PTA) causes the least endothelial damage. To compare the degree of endothelial injury after insertion of such a stent with injury caused by PTA. METHODS: Twelve healthy pigs were used in the experiments. In the first part of the study six different types of stents were inserted into the common iliac arteries. In the second part of the study self-expanding stents with large spaces between the wires were used. PTA was performed in the contralateral iliac artery. The pigs were killed immediately after the procedure and resected specimens examined after fixation, using scanning electron microscopy. RESULTS: All procedures but two were accomplished successfully. More endothelium was preserved after insertion of self-expanding stents with large spaces between the wires, compared with stents with small spaces and balloon-expanded stents. After insertion of self-expanding stents with large spaces, 50.1% +/- 16.4% of the endothelium remained intact, compared with only 5.6% +/- 7.7% after PTA. The difference was statistically significant (p < 0.001). CONCLUSION: Self-expanding stents with large spaces between the wires, inserted without PTA, cause less damage to the endothelium than other stents and significantly less damage than PTA.

Angioplasty, Balloon↗
PubMed2006

Morphometric side-to-side differences in human cruciate ligament insertions.

Graft placement in cruciate ligament reconstruction is known to significantly influence postoperative knee stability and range of motion. Improvement of bone tunnel positioning has been advocated by computer-assisted surgical procedures that require reliable input and reference data. This study validates the hypothesis that morphometric reference data can be obtained from the uninjured controlateral knee for accurate bone tunnel and graft positioning. Thirty pairs of human cadaver knees were dissected and the femoral and tibial footprints of the anterior and posterior cruciate ligaments (PCL) were radiopaquely marked. Radiographs were taken of the corresponding left- and right-sided femora and tibiae, and digitally processed. Controlateral specimens were mirrored and overlapped precisely, the areas and intersections of ligament insertion were digitally determined. There were no significant differences in the total area of cruciate ligament insertion between left and right knee specimens or between female and male specimens. Intersection areas (IAs) in femoral and tibial anterior cruciate ligament (ACL) insertions averaged 31.3 and 33.4% of the total insertion area, respectively. The center of gravity for the femoral and tibial ACL footprint differed by 4.7 and 4.5 mm between left and right knees, respectively. IAs in femoral and tibial PCL insertions averaged 46.1 and 61.3% of the total insertion area, respectively. The center of gravity for the femoral and tibial PCL footprint differed by 4.5 and 2.4 mm between left and right knees, respectively. Our study does not support the concept of obtaining morphologic reference data from the uninjured controlateral knee for individual bone tunnel placement.

Aged↗
PubMed2006

Efficacy of computer-assisted pedicle screw insertion for cervical instability in RA patients.

We evaluated the efficacy of the computer-assisted cervical pedicle screw insertion, compared with those inserted without the help of the system on the cervix of rheumatoid arthritis (RA) patients. Eighty-six cervical pedicle screws were inserted without the help of the system. Of the 86, 59 screws were in non-RA patients with degenerative spine, and 27 were in RA patients. The accuracy of the screw insertions was evaluated by a CT-based method. Then, 25 screws were inserted with the system into the cervical spines between C2 and C6 in RA patients (Navigation group). The efficacy of the system was assessed by the CT-based method, compared with 27 screws inserted without the system (Conventional group). The screws in RA patients tended to be more deviated than those in non-RA patients. In Conventional group, four screws (15%) were placed far laterally, and two (7%), far medially. In contrast, no screw was placed far laterally or medially in Navigation group (P < 0.05).

Adult↗
PubMed2002

Genetic mapping of an insertional hydrocephalus-inducing mutation allelic to hy3.

The transgenic mouse line OVE459 carries a transgene-induced insertional mutation resulting in autosomal recessive congenital hydrocephalus. Homozygous transgenic animals experience ventricular dilation with perinatal onset and are noticeably smaller than hemizygous or non-transgenic littermates within a few days after birth. Fluorescence in situ hybridization (FISH) revealed that the transgene inserted in a single locus on mouse Chromosome (chr) 8, region D2-E1. Genetic crosses between hemizygous OVE459 mice and mice heterozygous for the spontaneous mutation hydrocephalus-3 (hy3) produced hydrocephalic offspring with a frequency of 22%, demonstrating that these two mutations are allelic. A genomic library was made by using DNA from homozygous OVE459 mice, and genomic DNA flanking the transgene insertion site was isolated and sequenced. A PCR polymorphism between C57BL/6 DNA and Mus spretus was used to map the location of the transgene insert to 1.06 cM +/- 0.75 proximal to D8Mit152 by using the Jackson Laboratory Backcross DNA Panel Mapping Resource. Furthermore, sequence analysis from a mouse bacterial artificial chromosome (BAC) clone, positive for unique markers on both sides of the transgene insertion site, demonstrated that the genomic DNAs flanking each side of the transgene insertion are physically separated by approximately 51 kb on the wild-type mouse chromosome.

Animals↗
PubMed2004

Transumbilical approach for shunt insertion in the pediatric population: an improvement in cosmetic results.

OBJECTIVE: In spite of the recent interest in endoscopic third ventriculostomy, ventriculoperitoneal (VP) shunt is still the gold standard in treating non-obstructive hydrocephalus in children. The peritoneal cavity remains the optimal site for cerebrospinal fluid (CSF) diversion. Shunt insertion and re-interventions carry a high risk of inaesthetic abdominal scars and long-term morbidity. We report a technique of transumbilical shunt insertion, which provides better cosmetic results and without many more complications. This approach has been performed for a long period in a wide variety of intra-abdominal conditions by pediatric surgeons. METHODS: Between March and October 2003, we inserted 12 VP shunts in children. For eight consecutively treated children the follow-up is more than 3 months. All the shunts were inserted through the umbilicus. These eight children are the subjects of this study. Indications for shunting were: communicating hydrocephalus (6 cases), subdural hematoma (1 case), and hygroma associated with an arachnoid cyst (1 case). The population consisted of 7 boys and 1 girl, ranging in age between 6 weeks and 47 months (mean age: 15 months), and their body weights varied between 2,110 g and 18,000 g (mean weight: 8,470 g). All children were examined twice a day for 3 days, and wounds were examined daily to check for the absence of sepsis or dehiscence. Clinical controls were performed 1 month after discharge. The operating surgeon was invited to comment on any difficulties encountered in making or closing this incision afterwards. RESULTS: The average length of clinical follow-up was 6 months (range 4-7 months). One infection of the VP shunt occurred. It was treated with external drainage and antibiotics. After 1 week, a second VP shunt was inserted using the same technique without particular difficulty and with a nice cosmetic result. Concerning the seven other children, the cosmetic results were optimal, with no puckered abdominal scars or wound dehiscence, and with no perioperative or long-term complications related to the umbilical approach. CONCLUSION: At this early follow-up, umbilical incision for shunt insertion is a safe and easy technique. It provides an optimal cosmetic result, even in cases of re-intervention. This minimally invasive surgery does not require long specialized training. We have not shown an increase in complications associated with a "learning curve." Longer follow-up is needed to evaluate the risk of infection.

Cerebrospinal Fluid Shunts↗