PubMed Health⌕ Search

Biomedical subjects

A Edwards

Publications and source records attributed to A Edwards.

At least 55 records · Page 3Linked to original sources
PubMed2002

Carney's syndrome: complex myxomas. Report of four cases and review of the literature.

Cardiac myxomas are rare tumors. They usually appear as a sporadic isolated condition in the left atrium of middle-aged women with no other coincidental pathology. Carney and others have described in young people a special complex group of cardiac myxomas associated to a distinctive complex pathology, giving identity to the "Syndrome Myxoma" or "Carney's Syndrome". Four additional cases of this syndrome, treated from 1977 to 1999 at the Hospital Clínico de la Universidad de Chile are presented here with a comprehensive review of the literature, accumulating 100 cases. The main features of our cases include the presence of malignant non cardiac tumors, a familial trend, follow-up of 23 years and an iterative recurrence in the elder case. To date all patients are tumor free. Reviewing the literature, patients with Carney's Syndrome were younger, with a mean age of 26 years and female predominance (62%). Cardiac myxomas affected the four chambers of the heart: 64% the left atrium; 44% the right atrium; 14% the left ventricle and 12% the right ventricle. They were multiple tumors in 41% and involved more than one chamber in 31%, being synchronous or metachronous. There was a marked familial trend (52%), a high incidence of recurrence (20%), with more than one occurring in half the cases. Extra-cardiac involvement consisted of: 68% pigmented skin lesions, 40% cutaneous myxomas, 37% adrenal cortical disease, 27% myxoid mammary fibroadenoma and 34% male patients with testes tumors. A low percentage had pituitary adenoma, melanotic schwannomas and thyroid disease. The diagnosis is made when two or more of these criteria are present. In agreement with these findings the four chambers of the heart should be examined at surgery for atypical myxoma locations, right atriotomy and combined superior-transseptal approach improve exposure of the cavities, careful screening of the first degree family members should be conducted, and closed short and long term follow up controls are important. Complex myxoma appears as a multi-systemic disorder, occasionally having an ominous prognosis and malignant potentiality, and is still undergoing investigation for better understanding and identification.

Adolescent↗
PubMed2002

Changes in fetoplacental vessel flow velocity waveforms following maternal administration of betamethasone.

OBJECTIVE: To determine the timing of the onset of the umbilical artery flow velocity waveform changes following maternal administration of betamethasone in pregnancies complicated by umbilical artery absent end-diastolic flow, and to explore whether these changes are associated with flow velocity waveform changes in other fetoplacental vessels. SUBJECTS AND METHODS: This was a prospective study of 12 women with pregnancies complicated by umbilical artery absent end-diastolic flow. Flow velocity waveforms were recorded from the umbilical artery, fetal middle cerebral artery, renal artery, aorta and ductus venosus, before and after maternal betamethasone administration, using real-time pulsed wave Doppler. RESULTS: In all 12 pregnancies, the administration of maternal betamethasone was followed by the return of end-diastolic flow within 24 h. End-diastolic flow was first observed at 4 h and was present in all women studied at 8 h. In addition, there was a statistically significant decrease in the pulsatility index in the fetal aorta at 8 h and the middle cerebral artery at 24 h. No change was observed in the ductus venosus or the renal artery flow velocity waveforms. CONCLUSION: The findings suggest that, in pregnancies complicated by absent end-diastolic flow in the umbilical artery, maternally administered betamethasone induces a return in umbilical artery end-diastolic flow as early as 4 h, along with widespread vasodilatation throughout the fetoplacental vasculature.

Betamethasone↗
PubMed2002

Intercomparison of translocation and dicentric frequencies between laboratories in a follow-up of the radiological accident in Estonia.

PURPOSE: To perform an interlaboratory comparison of FISH chromosome painting and to study the time-course of translocations and dicentrics in three accident victims exposed to radiation. Also, to use the data in the validation of the FISH technique as a retrospective dosimeter. MATERIALS AND METHODS: Twelve blood samples were collected during 4 years from three subjects exposed to radiation in an accident in Estonia in 1994 involving gamma-radiation from a 137Cs source. Two of the subjects were exposed during approximately 7 h, both receiving a protracted dose of about 1 Gy and also localized exposure. The third subject received a protracted whole-body dose of 2.7 Gy during 4 weeks as well as a short-term partial-body dose. Preparations from 48-h metaphase cultures were painted by the FISH technique using routine methods and probe cocktails in four laboratories. Samples from each subject were analysed in two different laboratories that used different combinations of whole chromosome probes. The PAINT nomenclature was applied when recording chromosome aberrations. RESULTS: The intercomparison of FISH analysis data showed reasonable similarities between laboratories, the largest discrepancy being 21% in the frequency of two-way translocations in subject 3. Half-time calculations, based on combined data sets from two laboratories, showed that dicentrics decreased rapidly with half-times of approximately 2 years. In all cases, the initial dicentric yields were lower than the initial translocation yields. During the 4-year follow-up, the frequencies of all translocations in cells containing only simple rearrangements fell on average to about 65% of their initial value. Two-way translocations were slightly more persistent than all translocations. The average half-time was about 8 years for two-way translocations and around 6 years for all translocations. Cells containing complex rearrangements were few in number and they disappeared with time. In general, the inclusion of complex cells caused a more rapid fall in aberration yield. CONCLUSIONS: In general, the results imply that relatively consistent scoring data were obtained with different chromosome painting protocols. They also support the idea that the reduction of translocations with time is associated with partial-body irradiation.

Adolescent↗
PubMed2002

Choosing metaphases for biological dosimetry by fluorescence in situ hybridization (FISH).

Data are presented for a subset of lymphocytes characterized by FISH as missing painted chromosomal material. These lymphocytes occur in both control and irradiated subjects. These cells have a much greater frequency of one-way translocations than cells in which all of the painted chromosomal material is present. Their presence contributes to interindividual variability in control translocation yields. These cells do not appear to be more prevalent in persons exposed to high radiation doses. It is suggested that their exclusion when selecting cells for analysis may improve the sensitivity of FISH as a biological dosimeter at low doses. Mechanisms for the production of these one-way translocations in vivo are also discussed, with a proposal that their variable frequency in individuals may be consistent with exposure to chemical clastogens.

Adolescent↗
PubMed2001

Decision analysis in patient care.

To help patients to fully participate in shared decision making is becoming an important goal in clinical practice and one which is receiving increasing attention in terms of the requisite skills and technological development. We discuss the potential application of decision analysis-a specific technology that has been introduced into clinical practice but to date only within research contexts-and examine the usefulness and feasibility of the technique for patients, particularly in settings where clinical presentations are diverse and characterised by uncertainty.

Decision Support Techniques↗
PubMed2001

Analysis of loss of heterozygosity in lymphoma and leukaemia arising in F1 hybrid mice locates a common region of chromosome 4 loss.

Previous studies have identified five lymphoma-related tumour suppressor gene regions on murine chromosome 4. Using detailed allelotype analysis on a range of lympho-haematopoietic tumour types arising in F1 hybrid mice, we now show a consistent pattern of loss of heterozygosity (LOH) which identifies a common region of loss delineated by microsatellites D4Mit21 and D4Mit53 on proximal chromosome 4. This critical segment corresponds to the thymic lymphoma tumour suppressor region 5 (TLSR5) identified in an earlier study. Tumours of this type have also been reported as showing allelic loss from the Trp53 and Ikaros regions on chromosome 11. In the present study, only a small fraction of tumours showed LOH in the Ikaros region, while a minority of lymphomas, but not acute myeloid leukaemias, showed allelic loss of the chromosome 11 segment encoding Trp53. These and other data indicate strongly that the genomic regions identified as showing recurrent LOH depend on the genetic background of the mice. Overall, the results indicate a key role for a tumour suppressor gene(s) encoded in an approximately 3 cM segment on proximal chromosome 4 and provide an experimental basis for the further investigation of the functional role of candidate genes which include Pax5 and Tgfbr1.

Animals↗
PubMed2001

Changes in plasma progesterone, estrogen, and testosterone concentrations throughout the reproductive cycle in female viviparous blue-tongued skinks, Tiliqua nigrolutea (Scincidae), in Tasmania.

Changes in mean plasma concentrations of progesterone (P4), estrogen (E), and testosterone (T) in a captive population of female viviparous skinks, Tiliqua nigrolutea, were examined. Reproductively active and quiescent individuals were present in the population concurrently, allowing a comparison between these two conditions. Mean plasma progesterone concentrations were basal (1-2 ng ml(-1)) until the start of gestation and peaked in the second trimester (12.7 +/- 1.27 ng ml(-1)), before falling significantly prior to parturition. An increase in mean plasma estrogen concentrations occurred coincident with the vitellogenic period; the mean plasma estrogen concentration peaked at 715.1 +/- 106.68 pg ml(-1) shortly before ovulation. Mean plasma testosterone concentrations in reproductively active females peaked in the periovulatory period (6.3 +/- 0.63 ng ml(-1)) and had returned to basal concentrations (<1 ng ml(-1)) 2 weeks later. Changes in mean plasma steroid concentrations were correlated with reproductive condition and are discussed in terms of potential in vivo steroid interactions and the multihormone control of reproduction.

Animals↗
PubMed2001

Measuring the involvement of patients in shared decision-making: a systematic review of instruments.

We wanted to determine whether research instruments exist which focus on measuring to what extent health professionals involve patients in treatment and management decisions. A systematic search and appraisal of the relevant literature was conducted by electronic searching techniques, snowball sampling and correspondence with field specialists. The instruments had to concentrate on assessing patient involvement in decision-making by observation techniques (either direct or using audio or videotaped data) and contain assessments of the core aspects of 'involvement', namely evidence of patients being involved (explicitly or implicitly) in decision-making processes, a portrayal of options and a decision-making or deferring stage. Eight instruments met the inclusion criteria. But we did not find any instruments that had been specifically designed to measure the concept of 'involving patients' in decisions. The results reveal that little attention has been given to a detailed assessment of the processes of patient involvement in decision-making. The existing instrumentation only includes these concepts as sub-units within broader assessments, and does not allow the construct of patient involvement to be measured accurately. Instruments developed to measure 'patient-centeredness' are unable to provide enough focus on 'involvement' because of their attempt to cover so many dimensions. The concept of patient involvement (shared decision-making; informed collaborative choice) is emerging in the literature and requires an accurate method of assessment.

Decision Making↗
PubMed2001

Structure of Thermotoga maritima stationary phase survival protein SurE: a novel acid phosphatase.

BACKGROUND: The rpoS, nlpD, pcm, and surE genes are among many whose expression is induced during the stationary phase of bacterial growth. rpoS codes for the stationary-phase RNA polymerase sigma subunit, and nlpD codes for a lipoprotein. The pcm gene product repairs damaged proteins by converting the atypical isoaspartyl residues back to L-aspartyls. The physiological and biochemical functions of surE are unknown, but its importance in stress is supported by the duplication of the surE gene in E. coli subjected to high-temperature growth. The pcm and surE genes are highly conserved in bacteria, archaea, and plants. RESULTS: The structure of SurE from Thermotoga maritima was determined at 2.0 A. The SurE monomer is composed of two domains; a conserved N-terminal domain, a Rossman fold, and a C-terminal oligomerization domain, a new fold. Monomers form a dimer that assembles into a tetramer. Biochemical analysis suggests that SurE is an acid phosphatase, with an optimum pH of 5.5-6.2. The active site was identified in the N-terminal domain through analysis of conserved residues. Structure-based site-directed point mutations abolished phosphatase activity. T. maritima SurE intra- and intersubunit salt bridges were identified that may explain the SurE thermostability. CONCLUSIONS: The structure of SurE provided information about the protein's fold, oligomeric state, and active site. The protein possessed magnesium-dependent acid phosphatase activity, but the physiologically relevant substrate(s) remains to be identified. The importance of three of the assigned active site residues in catalysis was confirmed by site-directed mutagenesis.

Amino Acid Sequence↗