Search PubMed⌕ Search

Biomedical subjects

B Thomas

Publications and source records attributed to B Thomas.

At least 73 records · Page 4Linked to original sources
PubMed2000

Arachidonic and docosahexaenoic acids are strongly associated in maternal and neonatal blood.

BACKGROUND: The red cell membrane fatty acid composition has frequently been used as an index of essential fatty acid (EFA) nutrition. After birth there is a decline in plasma arachidonic acid (AA) and docosahexaenoic (DHA) acids in babies fed on conventional formula which contains only the parent linoleic and alpha-linolenic acids. In human studies, the red cell phosphoglyceride composition appears to be more constant than that of plasma. In infants fed fish oil without AA, the AA proportions fall in the plasma but much less so in the red cells. This result might be considered to mean that there is no need for preformed AA. On the other hand, in a study where the levels of AA fell there was reduction of infant growth. Indeed, where cell membrane composition does change there is often an associated alteration in physiological functions of membranes. We therefore felt it worth investigating the balance between AA and DHA in a physiological situation where plasma levels are known to change, namely in pregnancy. PURPOSE: The aim of the study was to investigate a relationship between blood phosphoglyceride AA and DHA in pregnant women and neonates. SUBJECTS: Health pregnant women from London, England (n=193) and their term babies (n=45); healthy pregnant women from Seoul, South Korea (n=40) and their term babies (n=40); and preterm neonates (n=72) from London. METHOD: Blood samples were taken from British and Korean pregnant women during the third trimester, and from term and preterm babies at birth. These samples were taken for routine monitoring purposes in Korea and were a part of a study on pregnancy outcome for which ethical permission was granted from the East London and The City Health Authority and Lambeth, Southwark and Lewisham Health Authority. Approval was also obtained from the Ethical Committee of the Asan Medical Centre, Seoul, South Korea. RESULTS: AA and DHA correlated in plasma choline phosphoglycerides (CPG) of the British mothers (r=0.52 P<0.0001). The correlation coefficients and significance were much stronger in the red cell CPG and even more so in the term and preterm infant red cell CPGs ( r=0.75, 0.80 and 0.88, respectively). Similarly, AA and DHA correlated in red cell CPGs of the Korean women and their term babies. There was also a significant relationship between the two fatty acids in red cell ethanolamine phosphoglycerides in the mothers and their babies. Both linoleic (LA) and alpha-linolenic acids (ALA) were inversely associated with AA and DHA in some of the phosphoglyceride fractions of the mothers and babies. CONCLUSIONS: Although AA and DHA have different primary dietary origins, there were significant relationships between AA and DHA in the phosphoglycerides of the red cell membrane. This finding seems surprising if the red cell composition is determined by diet. These results suggest a physiological mechanism which attempts to maintain an appropriate balance between AA and DHA. It is plausible that there is an optimum balance between AA and DHA for membrane stability, deformability, enzyme and receptor function. SPONSORSHIP: The British Diabetic Association, March of Dimes Birth Defects Foundation and The Christopher H.R. Reeves Charitable Trust. European Journal of Clinical Nutrition (2000) 54, 50-56

Adult↗
PubMed2000

Phytochrome A resets the circadian clock and delays tuber formation under long days in potato.

Transgenic potatoes (Solanum tuberosum) with either increased (sense transformants) or reduced (antisense transformants) phytochrome A (phyA) levels were used, in combination with specific light treatments, to investigate the involvement of phyA in the perception of signals that entrain the circadian clock. Far-red or far-red plus red light treatments given during the night reset the circadian rhythm of leaf movements in wild-type plants and phyA over-expressors, but had little effect in phyA under-expressors. Far-red light was also able to reset the rhythm of leaf movement in wild-type Arabidopsis thaliana but was not effective in mutants without phyA. Blue light was necessary to reset the rhythm in phyA-deficient potato plants. Resetting of the rhythm by far-red plus red light was only slightly affected in transgenic plants with reduced levels of phytochrome B. The production of tubers was delayed by day extensions with far-red plus red light, but this effect was reduced in transgenic lines deficient in phyA. We conclude that phyA is involved in resetting the circadian clock controlling leaf movements and in photoperiod sensing in light-grown potato plants.

Arabidopsis Proteins↗
PubMed2000

Critical role of C/EBPdelta and C/EBPbeta factors in the stimulation of the cyclooxygenase-2 gene transcription by interleukin-1beta in articular chondrocytes.

The activity of the [-831; +103] promoter of the human cyclooxygenase-2 gene in cultured rabbit chondrocytes is stimulated 2.9 +/- 0.3-fold by interleukin-1beta and this stimulation depends on [-132; -124] C/EBP binding-and [-223; -214] NF-kappaB binding-sites. The C/EBPbeta and C/EBPdelta factors bind to the [-132; -124] sequence. The [-61; -53] sequence is also recognized by C/EBPbeta and C/EBPdelta as well as USF. Mutation of the whole [-61; -53] sequence abolished the stimulation of transcription but single mutations of the C/EBP or USF site did not alter the activity of the promoter, suggesting that the factors bound to the proximal [-61; -53] sequence interact with different members of the general transcription machinery. The [-223; -214] site binds only the p50/p50 homodimer and a non-rel-related protein, but not the transcriptionally active heterodimer p50/p65. The p50/p50 homodimer could interact with the C/EBP family members bound to the [-132; -124] sequence for full stimulation of the COX-2 transcription by interleukin-1beta in chondrocytes. By contrast, the [-448; -449] sequence binds with a low affinity both the p50/p50 homodimeric and p50/p65 heterodimeric forms of NF-kappaB but has no role in the regulation of the human COX-2 promoter in chondrocytes.

Animals↗
PubMed2000

Developing a programme-review process for a baccalaureate nursing programme in Jordan.

Programme review is one way of monitoring the quality of a programme of study and promoting the growth of nursing education. The Faculty of Nursing at the Jordan University of Science and Technology (JUST) demonstrated its professional maturity by participating in an international collaborative project with the University of Windsor in Canada, to review its baccalaureate programmes. This article outlines the rationale for undertaking a programme review and discusses key principles for inclusion in the development of such a process. It highlights some strategies for success, and suggests ways in which programmes can benefit from reviews and evaluations. This process has the potential to be used as a prototype for future reviews.

Education, Nursing, Baccalaureate↗
PubMed2000

The hemodynamic and adrenergic effects of perioperative dexmedetomidine infusion after vascular surgery.

UNLABELLED: We tested dexmedetomidine, an alpha(2) agonist that decreases heart rate, blood pressure, and plasma norepinephrine concentration, for its ability to attenuate stress responses during emergence from anesthesia after major vascular operations. Patients scheduled for vascular surgery received either dexmedetomidine (n = 22) or placebo (n = 19) IV beginning 20 min before the induction of anesthesia and continuing until 48 h after the end of surgery. All patients received standardized anesthesia. Heart rate and arterial blood pressure were kept within predetermined limits by varying anesthetic level and using vasoactive medications. Heart rate, arterial blood pressure, and inhaled anesthetic concentration were monitored continuously; additional measurements included plasma and urine catecholamines. During emergence from anesthesia, heart rate was slower with dexmedetomidine (73 +/- 11 bpm) than placebo (83 +/- 20 bpm) (P = 0.006), and the percentage of time the heart rate was within the predetermined hemodynamic limits was more frequent with dexmedetomidine (P < 0.05). Plasma norepinephrine levels increased only in the placebo group and were significantly lower for the dexmedetomidine group during the immediate postoperative period (P = 0.0002). We conclude that dexmedetomidine attenuates increases in heart rate and plasma norepinephrine concentrations during emergence from anesthesia. IMPLICATIONS: The alpha(2) agonist, dexmedetomidine, attenuates increases in heart rate and plasma norepinephrine concentrations during emergence from anesthesia in vascular surgery patients.

Adrenergic alpha-Agonists↗
PubMed2000

Regulation of transcript levels of a potato gibberellin 20-oxidase gene by light and phytochrome B.

Up to three gibberellin (GA) 20-oxidase genes have now been cloned from several species including Arabidopsis, bean (Phaseolus vulgaris), and potato (Solanum tuberosum). In each case the GA 20-oxidase genes exhibit different patterns of tissue expression. We have performed extensive northern analysis on one of the potato GA 20-oxidase genes (StGA20ox1), which is the only one that shows significant transcript levels in leaves. We show that levels of StGA20ox1 transcript are elevated in transgenic antisense plants that have reduced levels of phytochrome B (PHYB) compared with wild-type plants, implicating PHYB in the control of GA biosynthesis. We show that StGA20ox1 transcript levels vary in leaves of different age throughout the plant and cycle throughout the day, furthermore they are up-regulated by light and down-regulated in the dark. The degree of the response to the light-on signal is similar in potato plants deficient in phytochrome A or PHYB and wild-type plants. The induction of StGA20ox1 by blue light raises the possibility that a blue light receptor may be involved in the control of this gene by light.

Antisense Elements (Genetics)↗
PubMed2000

Prevalence of Chlamydia trachomatis in young men in north west London.

BACKGROUND: Chlamydia trachomatis is the most common, treatable, bacterial sexually transmitted infection in England and Wales. Among men, chlamydial infection is an important cause of non-gonococcal urethritis, epididymitis, and proctitis. The case for wider screening among women has been accepted by an expert advisory group. In the absence of estimates of the prevalence of infection in men, its potential impact at the population level is difficult to assess. OBJECTIVE: To estimate the prevalence of Chlamydia trachomatis in young men in clinic and community based samples in north west London. METHOD: Cross sectional survey in healthcare centres and general practices in north west London. 1002 males aged 18-35 years, living in north west London, were recruited by staff in occupational health departments, general practices, student health services, and a "well man" clinic and by postal recruitment in four GP practices. The men were tested for C trachomatis using the ligase chain reaction assay on urine samples. The main outcome measure was prevalence of C trachomatis infection in men aged 18-35 years. RESULTS: The overall response rate was 51%. Prevalence of confirmed infection was 1.9% (95% CI: 1.14% to 2.96%) in all men. Best estimated minimum prevalence of infection was 1% (95% CI: 0.58% to 1.50%). Estimated prevalence was highest among men aged over 30 years. CONCLUSIONS: The estimated prevalence among men is commensurate with that described for female populations in London. The results suggest that recruitment of men to screening programmes would be difficult. However, a higher proportion of chlamydial infection may be detected in men than in women by existing approaches to control through genitourinary medicine clinic based case finding and contact tracing. Screening of young women and the contact tracing of the male partners of positive females may be an efficient approach to improving chlamydia control.

Adolescent↗
PubMed2000

Epithelial Dlx-2 homeogene expression and cementogenesis.

The Dlx-2 (distal-less gene) homeoprotein transcription factor controls early tooth development but has not been studied during the late stages of biomineralization. Transgenic mice containing a Dlx-2/LacZ reporter construct were used to map the Dlx-2 expression pattern in cementoblasts, the dental cells most closely related to bone cells and therefore suggested to be uniquely positioned osteoblasts. During initial root formation, marked expression of Dlx-2 was evident in molar and incisor root epithelium, whereas dental papilla and follicle were negative. Dlx-2 was expressed in this epithelium from the apical loop to the area of its disruption. During acellular cementum formation in both incisors and molars, Dlx-2 expression was observed in the majority of differentiated cementoblasts from the apical region to the erupting zones. During cellular cementum formation, the presence of which characterizes growth-limited molars, Dlx-2 expression was restricted to the innermost cementoblasts and entrapped cementocytes. These data further support the hypothesis of a complex origin and fate of cementum-forming cells, as previously suggested by the expression patterns of a set of mesenchymal and epithelial markers, notably ameloblastin as shown here. Dlx-2 expression might constitute a landmark of cementoblast subpopulations of epithelial origin. (J Histochem Cytochem 48:277-283, 2000)

Aging↗
PubMed2000

Biomineralization, life-time of odontogenic cells and differential expression of the two homeobox genes MSX-1 and DLX-2 in transgenic mice.

Msx and Dlx homeobox genes encode for transcription factors that control early morphogenesis. More specifically, Msx-1, Msx-2, and Dlx-2 homeobox genes contribute to the initial patterning of the dentition. The present study is devoted to the potential role of those homeobox genes during the late formation of mineralized tissues, using the rodent incisor as an experimental system. The continuously erupting mandibular incisor allows (1) the coinvestigation of the whole sequences of amelogenesis and dentinogenesis, aligned along the main dental axis in a single sample in situ and (2) the differential characterization of transcripts generated by epithelial and ectomesenchymal odontogenic cells. Northern blot experiments on microdissected cells showed the continuing expression of Msx-2 and Dlx-2 in the later stages of dental biomineralization, differentially in epithelial and ectomesenchymal compartments. Transgenic mice produced with LacZ reporter constructs for Dlx-2 and Msx-1 were used to detect different components of the gene expression patterns with the sensitive beta-galactosidase histoenzymology. The results show a prominent epithelial involvement of Dlx-2, with stage-specific variations in the cells involved in enamel formation. Quantitative analyses identified specific modulations of Dlx-2 expression in ameloblasts depending on the anatomical sites of the incisor, showing more specifically an inverse linear relationship between the Dlx-2 promoter activity level and enamel thickness. This investigation extends the role of homeoproteins to postmitotic stages, which would control secretory cell activity, in a site-specific manner as shown here for Dlx-2.

Animals↗
PubMed2000

Screening for acute myocardial injury: creatine kinase is comparable to myoglobin.

During the last decade, there have been many studies comparing myoglobin and the troponins to creatine kinase MB. Myoglobin was introduced as an early marker, but most studies have not directly compared it to total creatine kinase in any detail. We retrospectively (9/98-5/99) examined 1772 paired samples from 1572 patients drawn in the emergency department to assess the optimum decision limits, sensitivity, specificity, positive predictive values (PPV), and negative predicitve value (NPV) for creatine kinase and myoglobin in predicting acute myocardial injury. Of the admitted patients, 114 had acute myocardial injury, 166 had angina and 89 had non-cardiac chest pain; 1203 patients were discharged. Initially low creatine kinase (<100 IU/l; minimum 19 IU/l) and myoglobin (<100 microg/l; minimum 9.5 microg/l) results were identified in 63.5% and 88.3% of patients, respectively, emphasizing the importance of serial sampling. Receiver operator characteristic analysis demonstrated optimum decision limits at 100 IU/l and 70 microg/l, respectively. These levels were associated with sensitivity/specificity/PPV/NPV of 66/66/13/96 for creatine kinase and 54/85/22/96 for myoglobin. We conclude that both tests are comparable for initial screening of patients with chest pain in the emergency department. Since creatine kinase is faster, cheaper, and more widely available, it is the test of choice for our institution.

Creatine Kinase↗
PubMed2000

Working women identify influences and obstacles to breast health practices.

PURPOSE/OBJECTIVES: To identify factors contributing to participation in breast screening in working women to drive health education planning and implementation. DESIGN: Survey. SETTING: Automotive plants in southern Canada. SAMPLE: Union and nonunion women working in the plants. METHODS: Survey using "Health Care Practices: A Worksite Survey," modified for Canadian population. MAIN RESEARCH VARIABLES: Age, education, breast health practices, influences on decision to participate in breast screening, and physician gender. FINDINGS: Differences were noted among three age groups (under 30 years, 30-49 years, 50 years or older) in terms of influences and perceived barriers to the different modalities of breast screening. For clinical breast exams, women preferred an expert in breast health, regardless of whether the professional was a physician or a nurse. In all groups, the physician was noted as being very influential; however, perceptions of encouragement from the physician varied across the age groups. Perceptions of barriers to breast screening differed among the age groups and between women with male physicians and those with female physicians. Coworkers were identified as being a strong influence in the older group, whereas friends and family were identified as being more influential in the younger groups. CONCLUSIONS: Health promotion and education strategies may need to be stratified for different age groups. IMPLICATIONS FOR NURSING PRACTICE: Breast health education may need to be seen as an ongoing educational process, with the target groups being both the women and the primary healthcare professionals. The worksite has strong potential as a setting for health promotion activities.

Adolescent↗
PubMed2000

Phytochrome regulation of phytochrome A mRNA levels in the model short-day-plant Pharbitis nil.

The exposure of dark-grown Pharbitis nil seedlings to continuous R induces a rapid decrease in PHYA mRNA abundance with a half-life of about 2 h. A 5 min R pulse also induces this decline, and the effect is partially reversible by subsequent FR irradiation, confirming that the regulation of expression is mediated via the Pfr form of a phytochrome. When de-etiolated seedlings are returned to darkness after a W photoperiod, PHYA mRNA slowly reaccumulates from 20% to 50% of the dark level within 24 h. The rate of reaccumulation is greatly accelerated by the removal of Pfr with a FR pulse, resulting in reaccumulation to 100% within approximately 11 h. Without FR irradiation PHYA mRNA expression remains fully repressed for at least 11 h after the end of the photoperiod, suggesting that the controlling Pfr is highly stable.

Amino Acid Sequence↗
PubMed1999

Modulation of E2F activity in primary mouse B cells following stimulation via surface IgM and CD40 receptors.

Since signals via CD40 and the B cell receptor are known to synergize to induce B cell activation, we have analyzed the pocket protein/E2F complexes in mouse B lymphocytes following stimulation by anti-IgM, anti-CD40, alone or together. We find that E2F4 and DP1 form the predominant E2F heterodimers in the G0 and G1 phases of the cell cycle, complexed with hypophosphorylated p130. During late G1 and S phase this complex is replaced by at least three different E2F complexes, one of which is an E2F complex containing p107 or pRB as well as two "free" E2F complexes consisting of E2F4/DP1 and E2F1-3/DP1. These effects were mirrored by the levels and phosphorylation status of the three pocket proteins. We also observed an increase in electrophoretic mobility of DP1 and E2F4 as B cells progressed from G0 into early G1, resulting from their dephosphorylation. This is known to correlate with a decrease in DNA binding capacity of these proteins and could also be important for derepression of genes negatively regulated through E2F sites in their promoters. These results therefore indicate that the pRB/E2F pathway integrates proliferative signals emanating from the sIgM and CD40 receptors.

Animals↗
PubMed1999

Molecular abnormalities associated with endocrine tumors of the uterine cervix.

Objective. We studied the molecular abnormalities involved in the pathogenesis of endocrine tumors of the uterine cervix. Methods. We obtained DNA from precisely microdissected archival tissue from 15 endocrine tumors of the uterine cervix, consisting of 5 carcinoids (1 typical, 4 atypical), 2 large cell neuroendocrine carcinomas, and 8 small cell carcinomas. We investigated the presence of high-risk (types 16 and 18) and intermediate-risk (types 31 and 33) human papilloma virus (HPV) sequences, TP53 and K-ras gene mutations, and loss of heterozygosity (LOH) at 9 genes/chromosomal regions, including 3p14.2/FHIT, 3p14-p21, 3p21, 3p22-p24, 5q21-q22/APC-MCC region, 9p21/CDKN2, 11q23/MEN1, 13q/RB, and 17p/TP53. Results. HPV sequences were detected in 8 (53%) tumors, HPV 16 in 2 cases, and HPV 18 in 2 cases. LOH at 9p21 (43%) and localized 3p deletions (47%) were the most frequent allelic losses found. Allelic losses at 5q21-q22/APC-MCC region, 11q23/MEN1, and 13q/RB were infrequent. TP53 gene mutations were detected in 7 (47%) tumors (1 atypical carcinoid and 6 carcinomas). HPV sequences were demonstrated in 4 of the 7 cases with TP53 gene mutations. No K-ras mutations were detected. Conclusion. The molecular changes present in endocrine tumors of the uterine cervix have distinct features. They incorporate those present in the neuroendocrine tumors of the lung (high frequency of TP53 gene abnormalities and 9p21 deletions) with those detected in squamous cell carcinomas of the cervix (high-risk HPV sequences and localized 3p deletions).

Carcinoid Tumor↗
PubMed1999

Bioactive fragment of human interleukin-1beta (163-171) modulates the immune response to synthetic peptides of RESA of Plasmodium falciparum.

In this study a bioactive fragment, residues 163-171 of human interleukin-1beta (hu IL-1beta), that mimics the functions of the whole IL-1 molecule was chemically linked to two peptide sequences of the ring erythrocyte surface antigen (RESA), an asexual blood stage antigen of Plasmodium falciparum. The immunogenicity of different formulations was studied in different haplotypes of inbred mice. The peptide-IL-1beta conjugates delivered in liposomes showed the maximal antibody production. Antigen entrapped in liposomes at a dose of 5 microg showed antibody levels comparable to that of peptide conjugate in alum. The IgG subclass profile with different RESA peptides and its conjugates at various doses in liposomes induced predominantly IgG2a/2b isotypes while alum-delivered formulations showed both IgG1 and IgG2a/2b isotypes. In vitro studies of merozoite reinvasion showed varying degree (50-85%) of inhibition, maximum being with the peptide conjugates in liposomes (80-87%). Thus, this approach suggests that linking of hu IL-1beta is instrumental in augmenting the immune response against otherwise poorly immunogenic synthetic peptides.

Animals↗
PubMed1999

A new bipolar system for performing operative hysteroscopy in normal saline.

We evaluated the efficacy and safety of the VersaPoint bipolar vaporization system during hysteroscopic treatment of 10 women with symptomatic submucous leiomyomata, endometrial polyps, uterine septa, and synechiae in a prospective, uncontrolled pilot study at two Canadian university-affiliated teaching hospitals. Patients were two women with recurrent pregnancy loss associated with a diagnosis of uterine septa, one with infertility, one with recurrent pregnancy loss and synechiae, and six with menorrhagia associated with either leiomyomata or endometrial polyps. Electrodes were inserted through a 5F operating channel of a 15F cystoscope, and a 17 or 21F hysteroscope. Three electrodes were used: ball, twizzle, and spring. Power settings ranged from 50 W (desiccation mode) to 200 W (vapor cut mode). Normal saline was used as the distention medium in all cases. Either general anesthesia or intravenous sedation with paracervical block was used. There were no major complications such as uterine perforation, excessive bleeding, fluid overload, or thermal injury. The amount of normal saline used varied considerably from 0.5 to 20 L. The maximum amount of saline absorbed was 900 ml in a case involving resection of 4.5- and 2.0-cm leiomyomata that lasted 115 minutes. Mild cramping, vaginal bleeding, and discharge in the first 2 to 3 days were relieved by nonsteroidal antiinflammatory agents. No patients were readmitted up to 6 weeks after the procedure. Preliminary results of this pilot study support the safety of the VersaPoint bipolar vaporization system, although its long-term efficacy remains to be determined. It appears to be well tolerated by some women using conscious sedation and paracervical block. Therefore, it can potentially be used in an office setting as well as in symptomatic patients who are at risk from a general anesthetic. (J Am Assoc Gynecol Laparosc 6(3):331-336, 1999)

Adult↗
PubMed1999

Plasma vitamin A and E in preterm babies fed on breast milk or formula milk with or without long-chain polyunsaturated fatty acids.

Plasma vitamin A and E, the antioxidant nutrients copper and zinc, and magnesium were investigated in preterm babies. They were fed on their own mother's breast milk, or a formula with, or without, AA and DHA. Vitamin A (2.4 mg/d) and E (15 mg/d) supplements were also given. Vitamin A and E levels of most of the babies were sub-optimal at birth. The mean concentrations of vitamin E increased in all the groups by the expected date of delivery (EDD) (p < 0.001). Those fed on their mother's breast milk had the highest value compared with the other groups (p < 0.001). There was an increase in the mean level of vitamin A (p > 0.05) and copper (p < 0.05) and a decrease in zinc (p < 0.05) between birth and EDD. Concentrations of the two vitamins were not different (p > 0.05) between the babies fed on the formula with, and without, AA and DHA. It is concluded that the amount of AA and DHA incorporated in the formula milk did not adversely influence the plasma vitamin A and E of the babies.

Anthropometry↗