PubMed Health⌕ Search

Biomedical subjects

K Stuart

Publications and source records attributed to K Stuart.

142 records · Page 8Linked to original sources
PubMed1982

The maxicircle of Trypanosoma brucei kinetoplast DNA hybridizes with a mitochondrial gene encoding cytochrome oxidase subunit II.

A restriction endonuclease fragment of the maxicircle of Trypanosoma brucei brucei kinetoplast DNA hybridizes with a cloned mitochondrial DNA sequence which encodes cytochrome oxidase subunit II of Zea mays. A cloned mitochondrial DNA sequence encoding cytochrome oxidase subunit II of Saccharomyces cerevisiae also hybridized with kDNA, but exhibits less homology with the maxicircle than does the maize gene. The hybridizing maxicircle DNA was localized to a 2.8 kbp segment which is bounded by TaqI restriction endonuclease sites and nearby HindIII and EcoRI restriction sites. The TaqI restriction fragment is conserved between T. brucei brucei, T. brucei rhodesiense and T. brucei gambiense and hybridizes with the Zea mays probe in each case.

Animals↗
PubMed1981

The community control of rheumatic fever and rheumatic heart disease: report of a WHO international cooperative project.

The feasibility and effectiveness of a programme for the community control of rheumatic fever and rheumatic heart disease were studied in a cooperative multicentre project initiated and coordinated by the World Health Organization. The programme was carried out in seven centres in various developing countries of Africa, America, and Asia according to a common protocol, and is under way in a further eight countries in Latin America. Pilot community programmes were shown to be practicable and effective in reducing the burden of rheumatic heart disease in developing countries and their extension to cover entire populations should be encouraged.

Adolescent↗
PubMed1980

Structural analysis of variant and invariant genes in trypanosomes.

Variant surface antigens have been purified from variants of a newly developed serodeme of Trypanosoma brucei 164, and found to be distinct by immunological and molecular criteria. cDNA clones containing variant and invariant gene sequences were isolated by using RNA from different variants and cloned DNAs from other systems as probes. These trypanosome and heterologous cloned DNAs were used as probes of trypanosome gene structure and activity. Regulation of variant antigen gene expression is at the level of transcription, and the variant antigen genomic sequences differ in their arrangement between the variants. Chick alpha- and beta-tubulin sequences hybridize to trypanosome-tubulin gene sequences, while chick beta-actin sequences do not. A 1650 bp alpha-tubulin trypanosome cDNA has been isolated. The trypanosome alpha- and beta-tubulin sequences appear to be clustered in the genome. Sequence rearrangement of tubulin genes does not occur during antigenic variation.

Animals↗
PubMed1980

Kinetoplast DNA of normal and mutant Trypanosoma brucei.

Kinetoplast DNA (kDNA) sequence organization, transcription, and alterations in dyskinetoplastic (Dk) mutants were examined in Trypanosoma brucei, using physically isolated and recombinant kDNA sequences. Maxicircles renatured as a single sequence class and had no homology with minicircles. Total minicircle complexity was greater than 300 kb. Minicircle sequence organization is complex. Different minicircles have sequences in common and comprise varying fractions of the kDNA network. Transcripts of the same maxicircle restriction fragments, representing most of the maxicircle, were detected in both bloodstream and cultured procyclic form RNA. Presumptive mitochondrial ribosomal RNA coding sequences were localized to a specific maxicircle segment. No minicircle transcription was detected. All Dk mutants examined had substantial reduction of kDNA sequences. No kDNA sequences could be detected in one mutant examined in detail. Another Dk mutant was found to contain sequences homologous to kDNA. These DNA sequences had the same electrophoretic mobility as maxicircle and minicircle restriction fragments.

Animals↗
PubMed1975

Mitochondrial and cytoplasmic ribosomes and their activity in blood and culture form Trypanosoma brucei.

Ribosomes of Trypanosoma brucei, a parasitic, flagellated protozoan (order Kinetoplastida), were identified on sucrose density gradients by their radioactively labeled nascent peptides. Ultraviolet absorption revealed only cytoplasmic ribosomes which served as internal sedimentation markers. Synthesis on cytoplasmic ribosomes was completely inhibited by cycloheximide. In the presence of this antibiotic, nascent peptides were associated with ribosomes of lower sedimentation coefficient than the cytoplasmic ribosomes. Chloramphenicol blocked synthesis on these ribosomes which are probably the mitochondrial ribosomes. These ribosomes differed from the cytoplasmic ribosomes in several ways. Their sedimentation coefficient was about 72S rather than 84S. The stability of the 72S ribosomes was less sensitive to pancreatic ribonuclease and low Mg-++ concentrations, dissociating below 0.1 mM Mg++. The 72S ribosomes were more sensitive to elevated KCl concentrations, dissociation above 0.25 M. Protein synthetic activity associated with the 72S class of ribosomes was found in trypanosomes grown in rats. Under these conditions no cytochromes or fully active Krebs cycle is present in these cells and respiration is insensitive to cyanide.

Animals↗
PubMedDate not supplied

Hepatic chemoembolization: effect of intraarterial lidocaine on pain and postprocedure recovery.

PURPOSE: To determine if intraarterial lidocaine reduces pain during and after chemoembolization, and whether it influences postprocedure recovery. METHODS: Two patient cohorts undergoing selective hepatic chemoembolization were compared. Chemoembolization was performed without lidocaine (control group) in 27 patients and intraarterial lidocaine was used (lidocaine group) in 29 similar patients. Objective changes in patient management were assessed. Pain reduction in 31 more procedures with lidocaine (total 60) was assessed and related to tumor type. RESULTS: During chemoembolization, intraarterial lidocaine reduced the need for additional intravenous analgesics from 69% to 19%. After chemoembolization the mean Dilaudid dose in the first 24 hr was reduced from 9.5 mg to 4.15 mg; accordingly, the mean length of hospital stay was reduced from 67.5 to 53.5 hr. During the day of chemoembolization, the mean oral fluid intake increased from 420 ml (control group) to 487 ml (lidocaine group); the percentage of patients taking solid food on the day of chemoembolization increased from 3% to 43%. CONCLUSION: Intraarterial lidocaine during chemoembolization reduces the severity and duration of pain after chemoembolization resulting in faster recovery thus reducing the length of hospitalization.

Anesthetics, Local↗
PubMedDate not supplied

Self-efficacy, health locus of control, and smoking cessation.

This article examines the predictive value of measures of health locus of control and self-efficacy as predictors of outcomes of a widely disseminated, group-facilitated smoking cessation program. Outcomes studied were cessation for at least 1 day by the end of the program, end of program smoking status (abstinence), and smoking status at 6 months follow-up. Subjects were 257 participants in the smoking cessation program, of whom 207 made attempts to quit and 126 who were not smoking at the end of the treatment. Both pretreatment self-efficacy and health locus of control variables emerged as significant predictors of making an attempt and end of treatment abstinence. Only posttreatment self-efficacy predicted maintenance at 6 months. The results indicate the high self-efficacy is inversely related to making attempts to quit, but positively related to the success of attempts. The role of Health Locus of Control is complex and needs further investigation.

Adult↗
PubMedDate not supplied

Hepatic arterial chemoembolization for metastatic endocrine tumors.

PURPOSE: In patients with hepatic metastases from endocrine tumors, the safety and effectiveness of chemoembolization with ethiodized oil was determined and compared with those of embolization with particulate matter alone. PATIENTS AND METHODS: Twenty patients with hepatic islet cell or carcinoid tumor metastases were treated with selective hepatic artery injection of doxorubicin and iopamidol emulsified in ethiodized oil, followed by gelatin foam powder embolization. RESULTS: In 16 patients with hormonally active tumors, hormone secretion decreased 90% (range, 69%-98%) in 10 days, with relief of symptoms in all patients. Average tumor size decrease was 84%; average hospitalization was 8 days. Seventeen patients are alive 6-27 months after embolization, and all are asymptomatic. Three patients died within 1 year after embolization of progressive disease outside the liver. CONCLUSION: Chemoembolization with doxorubicin emulsified in ethiodized oil and iopamidol is effective in the treatment of hepatic metastases from endocrine tumors. This technique appears to result in less morbidity than particulate embolization alone.

Adenoma, Islet Cell↗
PubMedDate not supplied

Two mechanisms of expression of a predominant variant antigen gene of Trypanosoma brucei.

African trypanosomes evade the host immune response by periodically switching their variant surface glycoprotein (VSG) coat. The resulting, serologically distinct variant antigenic types (VATs) appear in a loosely ordered sequence and those arising early in infections are termed predominant VATs. VAT switching reflects the successive transcriptional activation of single VSG genes from a large repertoire. Activation of some VSG genes is accomplished by duplication of a previously silent basic copy (BC) gene and insertion of this expression linked copy (ELC) near a chromosomal telomere where is is expressed. However, other VSG genes, always located near a telomere, use a non-duplication activation ( NDA ) mechanism. We report here that the gene encoding the predominant IsTat 1.A VSG can be activated with or without duplication. Four of six independently derived clones activated the 1.A gene without gene duplication or detectable rearrangement. The other two contained an active 1.A ELC, possibly generated by a gene conversion extending to the end of the telomere. The ability to utilize both NDA and ELC mechanisms of gene activation and perhaps an alternative mechanism for gene duplication may account for the fact that VAT 1.A is the most predominant VAT of the IsTaR 1 serodeme .

Chromosome Mapping↗
PubMedDate not supplied

Expression of a minichromosomal variant surface glycoprotein gene in Trypanosoma brucei.

African trypanosomes contain numerous variant surface glycoprotein (VSG) genes, but express only one at a time. When different VSG genes are activated by gene duplicative or non-duplicative mechanisms, antigenic variation occurs. Although transcriptionally inactive VSG genes can have either an intra-chromosomal or a telomeric location, all expressed VSG genes so far examined are telomeric. Some VSG genes are located on minichromosomes of approximately 100 kilobases (kb), but all those thus far described are transcriptionally inactive. We have found that the single copy of the IsTat 1.1 VSG gene in the IsTaR 1 serodeme has a telomeric location on a minichromosome when inactive. When it is activated, it is not duplicated and remains on a minichromosome. These data indicate that minichromosomes contain or can acquire all the DNA sequences necessary in cis for VSG gene expression and antigenic switching. Of several sequences associated with expressed VSG genes or their transcripts, only the 76-base pair (bp) repeat element was found in minichromosomal DNA. Variant antigenic types (VATs) which occurred immediately before and after VAT-1, expressed VSG genes located on larger chromosomes. Thus, different chromosomes can act as VSG gene expression sites.

Animals↗
PubMedDate not supplied

Long-range restriction mapping of megabase-sized chromosomes that may be homologs in Trypanosoma brucei.

Trypanosoma brucei is a blood-borne pathogen that changes its variant surface glycoprotein coat, thus evading immune destruction. Restriction digestion, combined with probe hybridization studies, was used to construct long-range restriction maps of the 1.4 (M4) and 1.5 megabase (M3) chromosomes from the IsTaR1 serodeme of T. b. brucei. Comparison of the two chromosomes suggests that they are a homologous pair. Hybridization with a repetitive sequence probe also identifies several copies on the M4 chromosome and a relative paucity of cross-hybridizing repetitive sequence on the larger M3 chromosome.

Animals↗
PubMedDate not supplied

Intracellular localization of LRV1 in infected Leishmania cells and epitope conservation of the coat protein.

Polyclonal antibodies were raised against a recombinant fragment of the coat protein of LRV1-1 to determine the epitope conservation of the coat protein among LRV1 isolates, and the intracellular localization of LRV1 particles in promastigote cells of Leishmania braziliensis. Western blot analysis showed that specific epitopes of the coat protein are highly conserved among isolates from different geographic areas. Using indirect immunofluorescence assays LRV1 viral particles were observed as fluorescent granules, limited to the cytoplasm and with no apparent association to the host organelles or the cell membrane, characteristic of a persistent, non-infectious virus.

Animals↗