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Biomedical subjects

C J Thompson

Publications and source records attributed to C J Thompson.

At least 91 records · Page 5Linked to original sources
PubMed1996

Dysrhythmia formation in the older adult.

Cardiac dysrhythmia in the older patient is a common finding during critical illness. Changes in the functional anatomy and physiology of the cardiac conduction system are associated with the direct and indirect effects of aging. The pathophysiology and clinical manifestations related to changes in cardiac cellular and neural structures are presented. Knowledge of these changes will guide the critical care nurse in planning care aimed at producing positive patient outcomes.

Adult↗
PubMed1996

How have patients reacted to the implications of the DCCT?

OBJECTIVES: To assess the reactions of people with insulin-treated diabetes (ITD) to the results of the Diabetes Control and Complications Trial (DCCT). RESEARCH DESIGN AND METHODS: A leaflet documenting the purpose and results of the DCCT was circulated to all 771 patients ages 15-60 years with ITD attending our clinic. Patients were invited to complete and return a questionnaire on their responses. RESULTS: Of 550 respondents, 330 felt encouraged to improve glycemic control. Female respondents (P = 0.003) and younger age-groups (15-25 years, P = 0.001) were most likely to want to improve control. Patients with long duration of diabetes (> 20 years, P = 0.00001), hypoglycemia unawareness (P = 0.0001), or previous severe hypoglycemia (P = 0.001) were less likely to want to improve their control. Fear of hypoglycemia concerned all age-groups, whereas female respondents were most likely to be worried about the potential for weight gain (P = 0.00006). CONCLUSIONS: Knowledge of the results of the DCCT encourages significant numbers of patients to want to improve glycemic control. Fear of hypoglycemia and, in women, weight gain may prove significant impediments to the clinical implementation of the results of the DCCT.

Adolescent↗
PubMed1995

Construction of thiostrepton-inducible, high-copy-number expression vectors for use in Streptomyces spp.

A high-copy-number plasmid expression vector (pIJ6021) was constructed that contains a thiostrepton-inducible promoter, PtipA, from Streptomyces lividans 66. The promoter and ribosome-binding site of tipA lie immediately upstream from a multiple cloning site (MCS) which begins with a NdeI site (5'-CATATG) that includes the tipA translational start codon (ATG), allowing the synthesis of native proteins. Transcriptional terminators occur just upstream from PtipA and immediately downstream from the MCS. To demonstrate the utility of pIJ6021, two streptomycete genes and a growth hormone-encoding gene from flounder (Paralichthys olivaceus) were cloned in the vector and expressed in S. lividans or S. coelicolor A3(2). A derivative of pIJ6021, pIJ4123, has a unique NdeI site positioned downstream from a nucleotide sequence that encodes a His6 sequence and thrombin cleavage site. pIJ4123 can be used to produce His-tagged fusion proteins that can be readily purified by Ni(2+)-affinity chromatography; if necessary, the His6 tag can be removed by digestion with thrombin. The vectors contain a kanamycin-resistance-encoding gene for the selection of transformants.

Amino Acid Sequence↗
PubMed1995

Bialaphos.

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Anti-Bacterial Agents↗
PubMed1995

Denervation of the transplanted heart: nursing implications for patient care.

The denervated heart requires significant changes in planning and implementing care. The loss of direct neural compensation in response to the body's demands is replaced by the denervated heart's reliance on preload augmentation to maintain cardiac output, stimulation of cardiac adrenergic receptor sites to promote inotropic and chronotropic responses, and the nurse's knowledge of transplant physiology to choose and administer directacting cardiovascular pharmacologic agents to treat common posttransplant complications and to safely and effectively manage the patient's care.

Denervation↗
PubMed1995

Developmental control of the heat-shock stress regulon in Streptomyces coelicolor.

In the differentiating eubacterium Streptomyces coelicolor, nutritional imbalances activate a developmental programme which involves the heat-shock stress regulon. In liquid batch cultures, the growth curve could be separated into four components: rapid growth 1 (RG1), transition (T), rapid growth 2 (RG2) and stationary (S). Patterns of gene expression in cultures subjected to heat shock in various phases were recorded on two-dimensional gels and analysed using advanced statistical methods. The responses of all heat-shock proteins (HSPs) were highly dependent upon growth phase, thus demonstrating that the four phases of growth were physiologically distinct. For many HSPs, the level of thermal induction attained were closely related to growth stage-determined levels of synthesis before heat shock, thus supporting the idea that developmental and thermal induction of this stress regulon have common control elements. Cluster analysis identified five groups of HSPs displaying similar kinetics of heat- and developmentally induced synthesis, probably reflecting the influence of major regulatory systems. Methods introduced here to analyse the response of groups of genes to multiple simultaneous stimuli should find broad applications to studies of other prokaryotic and eukaryotic regulons.

Bacterial Proteins↗
PubMed1995

Molecular characterization and transcriptional analysis of a multidrug resistance gene cloned from the pristinamycin-producing organism, Streptomyces pristinaespiralis.

A multidrug resistance gene (mdr) has been cloned from Streptomyces pristinaespiralis, a producer of two antibiotics having synergistic activities together known as pristinamycin. This gene, ptr, provides resistance not only to two structurally dissimilar compounds (pristinamycin I, PI; pristinamycin II, PII) and the natural pristinamycin mixture but also to rifampicin. Mutagenesis and subcloning of ptr localized it to a 2 kb region which was sequenced and analyzed. It contained an open reading frame of 1506 bp which encoded a putative membrane protein with 14 hydrophobic domains, and showed sequence similarity to a superfamily of bacterial proteins that employ transmembrane electrochemical gradients to catalyse active efflux of various antibiotics and toxic compounds. Ptr was most similar to a subfamily which included other mdr genes and antibiotic transport genes associated with antibiotic biosynthetic gene clusters in actinomycetes. In vitro coupled transcription-translation experiments were used to identify the ptr gene product. Analysis of the upstream region did not reveal a divergently transcribed repressor gene, as is the case for several related resistance determinants involved in antibiotic transport, suggesting that ptr is regulated by a different mechanism. Transcriptional analyses of this gene, carried out in both S. pristinaespiralis and Streptomyces lividans, indicated the same transcriptional start point and predicted -10 and -35 hexamers which were somewhat similar to Streptomyces vegetative-type promoters.

Amino Acid Sequence↗
PubMed1995

Stress-activated expression of a Streptomyces pristinaespiralis multidrug resistance gene (ptr) in various Streptomyces spp. and Escherichia coli.

A promoter which controls expression of the pristinamycin multidrug resistance gene (ptr) in Streptomyces pristinaspiralis could be induced by physiological stresses in both Streptomyces spp. and Escherichia coli. In S. pristinaspiralis, the ptr promoter (Pptr) was induced by pristinamycin I (PI) or pristinamycin II (PII). Streptomyces lividans was adopted as a convenient heterologous host for studies of Pptr regulation since it has no known pristinamycin biosynthetic genes. Two key regulatory features were documented in these studies: many (19 of 70) antibiotics and chemicals with no common targets or structural features induced the Pptr; induction with PI was most efficient during a transition phase when antibiotic biosynthetic genes are switched on. In Streptomyces coelicolor, Pptr activity was similarly inducible by PI and not dependent on sigma factors HrdA, HrdC, or HrdD. In E. coli, Pptr cloned in the bifunctional promoter probe vector pIJ2839 was functional and activated upon entry into stationary phase in the absence of exogenous inducer. Finally, gel-retardation studies demonstrated a Pptr-binding protein in S. lividans (where its activity was PI-inducible), S. coelicolor and S. pristinaespiralis. The fact that this activity was not detected in E. coli suggested the existence of another regulatory system perhaps also present in Streptomyces.

Anti-Bacterial Agents↗
PubMed1995

Unusual regulatory mechanism for a Streptomyces multidrug resistance gene, ptr, involving three homologous protein-binding sites overlapping the promoter region.

A promoter controlling expression of the pristinamycin multidrug resistance gene (ptr), originally isolated from Streptomyces pristinaespiralis, is inducible by many toxic compounds in various Streptomyces species. Studies of ptr promoter control were carried out in the heterologous host, Streptomyces lividans. In S. lividans, a regulatory protein or a protein complex (Pip), identified by its ability to bind to the ptr promoter in gel-retardation experiments, was induced by pristinamycin I (PI). In situ copper-phenanthroline footprinting analysis identified three (A, B, and C) similar Pip-binding sites having the sequence GTACA(C/G)CGTA(C/T). These sites overlapped with functionally important regions of the promoter: the 'A' site overlapped with the -35 hexamer, 'B' overlapped with the -10 hexamer and 'C' was located between the transcription start site and the Shine-Dalgarno sequence. A GT-AG dinucleotide mutation was introduced at positions 8-9 of the consensus sequence to generate seven variant promoters: three mutated in one of the three sites, three mutated in two sites, and one mutated in all three sites. Whereas these promoters had reduced antibiotic (PI)-induced activity, their levels of expression in the absence of PI was higher. This suggested an unusual regulatory mechanism in which Pip could act either as an activator or repressor. Gel shift experiments revealed Pip or its homologues in many other Streptomyces species, suggesting that it is widely employed in the regulation of antibiotic resistance genes and perhaps secondary metabolism.

Bacterial Proteins↗
PubMed1995

Abnormal insulin treatment behaviour: a major cause of ketoacidosis in the young adult.

Diabetic ketoacidosis occurs more frequently in the young adult population than in any other age group. In a 3-year retrospective casenote review of all patients admitted with ketoacidosis to this hospital, we have defined the clinical characteristics of ketoacidosis in this age group. Young adults (< 25 years) had worse preceding glycaemic control (median HbA1 14.6 vs 10.1%, p = 0.0001) and more frequent episodes of ketoacidosis in the previous 5 years (3 vs 0, p = 0.0001) than older adults (> 25 years); on admission they had lower blood urea concentrations (p = 0.0001) and had a lower incidence of systolic hypotension (6% vs 32%, p = 0.007). There were fewer complications of ketoacidosis in the young adults, and the duration of hospital stay was less than that in the older age group (4 vs 8 days, p = 0.0003). Young adults were less likely to have a proven underlying infective or other organic precipitant for ketoacidosis, but were investigated and treated in a similar way to older adults. Insulin error or manipulation was identified in 42% of young adults; abnormal insulin treatment behaviour is likely to be the major cause of ketoacidosis in this age group.

Adolescent↗
PubMed1994

Characterisation by molecular cloning of two genes from Streptomyces verticillus encoding resistance to bleomycin.

Extracts of a bleomycin (Bm)-producing Streptomyces verticillus ATCC15003 were found to possess an acetyltransferase activity which inactivates Bm in the presence of acetyl coenzyme A. DNA fragments of S. verticillus were introduced into S. lividans by cloning and transformants selected for resistance to Bm. Deletion mapping and subcloning of a 6-kb DNA fragment showed the presence of two resistance determinants, blmA and blmB. The acetyltransferase activity was encoded by blmB; nucleotide sequence analysis identified an ORF consisting of 301 amino acids (aa) proposed to be that of Bm acetyltransferase (Bat). S. lividans and Escherichia coli transformants harboring plasmids carrying blmB produced an acetyltransferase which modified and determined resistance to Bm and structurally related antibiotics; this resistance gene has potential as a selective marker in gene transfer studies. Nucleotide sequence analysis of blmA revealed an ORF encoding 122 aa that had significant sequence similarity to the gene encoding the Bm-binding protein (Shble) identified by Gatignol et al. [FEBS Lett. 230 (1988) 171-175] in Streptoalloteichus hindustanus, the tallysomycin-producer. The blmA gene was expressed in E. coli and the resulting protein, like the Shble protein, prevents in vitro Bm-induced DNA breakage.

Acetyltransferases↗
PubMed1994

Dysplastic nevi as a melanoma risk factor in patients with familial melanoma.

BACKGROUND: Familial melanoma has been associated with "clinically atypical moles" or "dysplastic nevi," (DN) which are markers for increased melanoma risk. In addition, melanomas in these kindreds present at a younger age, and tend to be multiple. METHODS: Melanoma incidence rates were determined for 710 members of 311 melanoma families, defined as kindreds in which melanoma had occurred in two or more blood relatives. Patients were classified either clinically or histologically as expressing DN. Melanomas that occurred before the first examination were recorded, and patients were followed prospectively for new melanomas. RESULTS: In prospective follow-up, the age-adjusted melanoma incidence rate was 1710/100,000 patient-years in family members with DN. In contrast, the rate was zero (no melanomas occurred) in family members without DN. For family members with DN, but without a history of melanoma, the age-adjusted incidence rate of melanoma was 413/100,000 patient-years, whereas the rate was 2779/100,000 patient-years in family members with DN and a history of melanoma. CONCLUSIONS: Dysplastic nevi and a history of melanoma are strong risk factors for subsequent melanoma. Prognostic factors are greatly improved for patients with melanomas diagnosed in follow-up compared with the first two melanomas in each kindred. These findings warrant surveillance of individuals with DN who are members of familial melanoma kindreds.

Adult↗
PubMed1994

Transcriptional analysis of groEL genes in Streptomyces coelicolor A3(2).

In Streptomyces coelicolor A3(2), synthesis of the groES, groES-groEL1 and groEL2 transcripts is induced either by heat shock or by undefined physiological stress signals present at a certain stage of growth. Under all conditions tested, transcription of groES and groES-groEL1 originated from a unique start site upstream of groES, whereas transcription of groEL2 originated from a unique site upstream of groEL2. RNA polymerase isolated either from heat-shocked or control mycelia allowed in vitro transcription from the P1 promoter of groES/EL1 and the P2 promoter of groEL2. The fact that these two RNA polymerase preparations both initiated transcription with equal efficiency from the same sites suggested that a heat shock-specific sigma factor is not responsible for the temperature-induced transcription of groE genes. Instead, regulation of these genes from vegetative-type promoters may be effected by a DNA-binding protein observed in gel retardation assays, which recognizes a motif found in the groE and dnaK promoter regions of many prokaryotic genes.

Base Sequence↗
PubMed1994

Characterization of two groEL genes in Streptomyces coelicolor A3(2).

Two Streptomyces coelicolor A3(2) groEL-like genes, groEL1 and groEL2, were cloned and characterized. Pulsed-field-gel electrophoresis located these genes, which were not adjacent, in the same segment of the chromosome. Nucleotide sequence analysis revealed that groEL1, but not groEL2, was preceded by a groES-like gene. Northern blots showed that heat shock induced the accumulation of transcripts corresponding to groES (0.7 kb), groES/EL1 (2.3 kb) and groEL2 (2.1 kb). Unique transcription start points and promoters were located for groES/EL1 and groEL2, having -10 and -35 hexamers similar to eubacterial vegetative promoters. Regions located 5' to the groES/EL1 or groEL2 structural genes contain 'GCACTCN9GAGTGC' motifs conserved upstream from the heat-shock genes of other bacteria.

Amino Acid Sequence↗
PubMed1994

Synthesis of ribosomal proteins during growth of Streptomyces coelicolor.

Changes in expression of ribosomal protein genes during growth and stationary phase of Streptomyces coelicolor A3(2) in liquid medium were studied. Proteins being synthesized were pulse-labelled with [35S]-methionine, separated by two-dimensional polyacrylamide gel electrophoresis, and quantified using the BioImage computer software. Most of the ribosomal proteins were synthesized throughout the life cycle. Exceptions were two proteins whose synthesis drastically decreased at the approach of stationary phase. These two proteins were identified in purified ribosomes as homologues of Escherichia coli ribosomal proteins L10 and L7/L12, using antibodies raised against fusion proteins between these ribosomal proteins and Escherichia coli beta-galactosidase. The genes (rplJ and rplL) encoding the L10 and L7/L12 proteins were contained in a 1.2 kb BamHI fragment that was cloned and sequenced. The linkage and order of the genes coincide with other L10-L7/L12 operons. However, L11 and L1 genes were not present immediately upstream of the L10 gene, as is the case for E. coli and other bacteria. Instead, two open reading frames of unknown function were found immediately upstream of the L10 gene, in an adjacent 1.9 kb BamHI fragment.

Base Sequence↗