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B Lowe

Publications and source records attributed to B Lowe.

At least 55 records · Page 3Linked to original sources
PubMed1992

Active Mutator elements suppress the knotted phenotype and increase recombination at the Kn1-O tandem duplication.

The KNOTTED-1 (KN1) locus is defined by a number of dominant mutations that affect leaf development. The Kn1-O mutation is characterized by outpocketings of tissue along lateral veins of the maize leaf and by displacement of ligule tissue from the junction of the blade and sheath into the blade. Kn1-O results from a tandem duplication of 17 kb; each repeat includes the entire 8-kb KN1 transcription unit. Mutator (Mu) transposable elements inserted at the junction of the two repeats diminish the mutant phenotype. The Mu insertions affect the Kn1-O mutation in several distinctive ways. (1) Two of the three Mu elements, a Mu1 and a Mu8 element, diminish the mutant phenotype only when active as indicated by hypomethylation; when methylated or inactive, the phenotype is comparable to the Kn1-O progenitor. (2) Additional rearrangements have arisen in these derivatives that further reduce the mutant phenotype. (3) A 100-2000-fold increase in the loss of one repeat occurs in the presence of Mu elements as compared to Kn1-O without elements. The high frequency of loss only occurs when the Mu elements are hypomethylated. The frequency is also influenced by the specific allele carried at the same locus on the homologous chromosome. Reciprocal exchange of flanking markers does not accompany the loss events. Various recombination models that address the events occurring at Kn1-O are presented.

Alleles↗
PubMed1990

Amplification of genomic sequences flanking transposable elements in host and heterologous plants: a tool for transposon tagging and genome characterization.

The isolation of sequences flanking integrated transposable elements is an important step in gene tagging strategies. We have demonstrated that sequences flanking transposons integrated into complex genomes can be simply and rapidly obtained using the polymerase chain reaction. Amplification of such sequences was established in a model system, a transgenic tobacco plant carrying a single Ac element, and successfully applied to the cloning of a specific Spm element from a maize line carrying multiple Spm hybridizing sequences. The described utilization of methylation sensitive restriction enzymes (including those with degenerate recognition sequences) in the generation of templates for amplification will simplify the cloning and mapping of genomic sequences adjacent to transposable elements.

Base Sequence↗
PubMed1989

Absorption of Tc-99m pertechnetate from the augmented bladder during direct nuclear cystography.

A retrospective review comparing bladder absorption of pertechnetate and Tc-99m sulfur colloid from the augmented bladder was performed. Based upon the author's findings, the routine use of Tc-99m sulfur colloid in this patient population is recommended to prevent the erroneous diagnosis of vesicoureteral reflux and miscalculation of GFR due to the presence of background soft-tissue and blood activity.

Glomerular Filtration Rate↗
PubMed1989

Fertilization of human oocytes in vitro by spermatozoa from oligozoospermic and normospermic men.

Sperm were isolated from the semen of oligozoospermic (less than 20 x 10(6) sperm/ml) and normospermic (greater than or equal to 20 x 10(6) sperm/ml) men in an in-vitro fertilization (IVF) programme. Oocytes from the female partners were inseminated with either 75 or 100 x 10(3) motile sperm and checked for fertilization after 16-20 h. A significant reduction in the overall fertilization rate of oocytes was seen for the oligozoospermic group compared to the normospermic group, at both insemination concentrations. In the oligozoospermic group, a fertilization rate of 31% (19/61) was achieved when oocytes were inseminated with 75 x 10(3) sperm, and 38% (9/24) when inseminated with 100 x 10(3) sperm. This compared with rates of 57% (397/696) and 64% (650/1018), respectively, for normospermic cases at both insemination concentrations. No evidence of fertilization was seen in 36% (4/11) and 67% (4/6) of oligozoospermic cases when 75 or 100 x 10(3) sperm were used, compared with values of 13% (17/133) and 9% (20/212), respectively, in normospermic cases. After excluding zero cases, the fertilization rate of oocytes for the oligozoospermic group (75%; 9/12) was similar to the normospermic group (70% 650/935) when 100 x 10(3) sperm were used. However, when 75 x 10(3) sperm were used, the fertilization rate for the oligozoospermic group (41%; 19/46) was significantly lower than that of the normospermic group (62%; 397/645). Following the transfer of embryos into the female partner, clinical pregnancies were diagnosed in 2/7 (29%) oligozoospermic cases and 27/267 (10%) normospermic cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗
PubMed1988

Factors associated with accidental fractures of the zona pellucida and multipronuclear human oocytes following in-vitro fertilization.

A total of 101 multipronuclear oocytes (7.4% of fertilizations) were retrospectively identified in this in-vitro fertilization programme. The use of a manual syringe suction system, instead of an electric pump, to aspirate follicles, was associated with a significant increase in the proportion of oocytes with fractured zonae pellucidae (P less than 0.001), a lower normal fertilization rate (P less than 0.05) and a higher proportion of multipronuclear fertilizations (P less than 0.001). Irrespective of the mode of follicular aspiration, significantly more multipronuclear fertilizations occurred following stimulation with a combination of clomiphene and human menopausal gonadotrophin, than after clomiphene alone (P less than 0.05). It was concluded that the aspiration pressures, created by syringe suction, were more likely to rupture the zona pellucida of some oocytes, while in others it predisposed to an increased multipronuclear fertilization rate.

Female↗
PubMed1987

Relapsing Kawasaki's disease.

An 18-month-old child with Kawasaki syndrome twice developed severe recurrence of symptoms when the acetylsalicylic acid (Aspirin) dosage was decreased from 80 mg/kg/day. Care of the patient with Kawasaki disease should be directed toward control of symptoms as well as monitoring for cardiac involvement.

Aspirin↗
PubMed1987

Fear of failure: a place for the trial of instrumental delivery.

The safety of performing potentially difficult midcavity forceps or vacuum extractions, as trials of instrumental delivery was assessed retrospectively. Successful vaginal delivery was achieved in 61% of 122 patients with delay in the second stage who had a trial of instrumental delivery performed in an operating theatre with full preparations to proceed to caesarean section. The outcome was compared with that in 42 patients who were delivered for the same indication, by primary caesarean section, without prior instrumentation. Transient fetal trauma occurred only in the trials of instrumental delivery, and there was no significant difference in immediate neonatal or maternal morbidity. In another group of 61 patients instrumental delivery was attempted without full preparations for possible caesarean section and when unexpected difficulty arose, the forceps or vacuum extractor were abandoned in favour of caesarean section. Within this group of unexpected failures of instrumentation there were significantly more babies with low Apgar scores, delayed onset of respirations or needing intubation. A carefully conducted trial of instrumental delivery is an acceptable alternative to caesarean section for delay in the second stage due to a potentially difficult midcavity arrest.

Adult↗
PubMed1986

Hydatidiform moles at Waikato Women's Hospital, 1971-85.

A retrospective study was made of 61 patients who had hydatidiform moles diagnosed at Waikato Women's Hospital, from 1971 to 1985. The incidence of molar pregnancy was 1 in 700 deliveries. Following the introduction of the National Trophoblastic Disease Register in 1980, the use of a standard surveillance schedule greatly improved the completeness of follow-up. To date, of 29 patients followed-up by serum beta hCG monitoring, 3/20 (15%) classic moles and 0/9 partial moles have required chemotherapy for persistent trophoblastic activity. No cases of histologically proven postmolar choriocarcinoma were recorded.

Adult↗
PubMed1985

Limited-host-range plasmid of Agrobacterium tumefaciens: molecular and genetic analyses of transferred DNA.

A tumor-inducing (Ti) plasmid from a strain of Agrobacterium tumefaciens that induces tumors on only a limited range of plants was characterized and compared with the Ti plasmids from strains that induce tumors on a wide range of plants. Whereas all wide-host-range Ti plasmids characterized to date contain closely linked oncogenic loci within a single transferred DNA (T-DNA) region, homology to these loci is divided into two widely separated T-DNA regions on the limited-host-range plasmid. These two plasmid regions, TA-DNA and TB-DNA, are separated by approximately 25 kilobases of DNA which is not maintained in the tumor. The TA-DNA region resembles a deleted form of the wide-host-range TL-DNA and contains a region homologous to the cytokinin biosynthetic gene. However, a region homologous to the two auxin biosynthetic loci of the wide-host-range plasmid mapped within the TB-DNA region. These latter genes play an important role in tumor formation because mutations in these loci result in a loss of virulence on Nicotiana plants. Furthermore, the TB-DNA region alone conferred tumorigenicity onto strains with an intact set of vir genes. Our results suggest that factors within both the T-DNA and the vir regions contribute to the expression of host range in Agrobacterium species. There was a tremendous variation among plants in susceptibility to tumor formation by various A. tumefaciens strains. This variation occurred not only among different plant species, but also among different varieties of plants within the same genus.

DNA, Bacterial↗
PubMed1983

Unicystic ameloblastoma.

The unicystic ameloblastoma should be considered a distinct entity and treated conservatively. The following case report emphasizes the use of computerized axial tomography in the diagnosis of this lesion. The detailed histology and conservative surgical therapy is discussed.

Aged↗
PubMed1982

Comparative efficacy of 10 antimicrobial agents in experimental infections with Bacteroides fragilis.

The comparative efficacy of 10 antimicrobial agents against 15 strains of Bacteroides was examined in vivo using an experimental model of subcutaneous abscesses in mice. Results were evaluated by bacterial counts per lesion with the antimicrobial agents administered beginning 1 hr after challenge. Six drugs reduced counts (mean +/- SEM log decrease) significantly compared with values in untreated control animals: metronidazole, 6.7 +/- 0.6; clindamycin, 5.0 +/- 0.6; moxalactam, 3.8 +/- 0.5; cefoxitin, 3.5 +/- 0.5; chloramphenicol, 1.6 +/- 0.5; and carbenicillin, 1.0 +/- 0.3. Antimicrobial agents that had no significant effect compared with values in untreated control animals were cephalothin, cefoperazone, ceforanide, and rosaramicin. Evaluation of several parameters based on in vitro activity and pharmacokinetic properties at the infected site indicated that the time during which the level of antimicrobial agent exceeded the minimal inhibitory concentration correlated best with in vivo antibacterial activity. A delay in the time that treatment was initiated resulted in a marked reduction in in vivo activity.

Abscess↗
PubMed1980

Symptomatic relapse after oral vancomycin therapy of antibiotic-associated pseudomembranous colitis.

Twenty patients with antimicrobiol-associated diarrhea had a symptomatic relapse after oral vancomycin therapy. All patients had stool examinations which implicated C. difficile as the causative agent, and 16 had pseudomembranous colitis. Clinical courses were characterized by resolution of symptoms with recurrence of diarrhea at 4--21 days after vancomycin was discontinued. Studies of stools collected sequentially showed that vancomycin failed to eliminate C. difficile despite susceptibility to this agent with in vitro testing. A review of our records shows the incidence os symptomatic relapse is approximately 14%. This experience emphasizes the importance of adequate follow-up in patients treated with oral vancomycin for antibiotic-associated diarrhea or colitis due to C. difficile.

Anti-Bacterial Agents↗