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Biomedical subjects

M R Thomas

Publications and source records attributed to M R Thomas.

At least 73 records · Page 4Linked to original sources
PubMed1995

Echocardiographic assessment of systolic and diastolic left ventricular function using an automatic boundary detection system. Correlation with established invasive and non invasive parameters.

Systolic and diastolic left ventricular function was assessed using an echocardiographic automatic boundary detection system (ABD) in 50 unselected patients undergoing left cardiac catheterisation. Automatic boundary detection system derived parameters (fractional area change [FAC], peak positive rate of area change [+dA/dt] and peak negative rate of area change [-dA/dt]) were compared with invasively (left ventricular angiography and pressures) and non invasively (Doppler mitral filling velocities and isovolumic relaxation time) acquired conventional indices of ventricular function. Adequate detection of endocardial boundaries and subsequent measurements using the ABD system were achieved in 40/50 (80%) patients in the short axis parasternal view, in 41/50 (82%) in the apical four chamber view and in 34/50 (68%) in both views. For the whole group of patients the FAC (maximal left ventricular diastolic area--minimal left ventricular systolic area/maximal left ventricular diastolic area) estimated in the short axis view correlated with the angiographic ejection fraction (EF) measured in the right oblique projection (r = 0.51, p < 0.001). There was only a weak correlation of the FAC estimated in the apical four chamber view with the EF (r = 0.36, p < 0.01). The mean FAC (mean value of the FAC in the short axis and apical four chamber views) correlated reasonably with the EF (r = 0.62, p < 0.0001). There was no correlation between ABD derived parameters and left ventricular end diastolic pressure (LVEDP) in these patients. In a subgroup of patients with normal coronary arteries and left ventricular function (n = 17), although there was no correlation between EF and FAC, there was a strong positive correlation between FAC (apical four chamber and mean) and LVEDP (r = 0.77, p < 0.01 and r = 0.87, p < 0.01 respectively). No correlation was found in these patients between EF and LVEDP. In a further subgroup of patients with angiographically abnormal left ventricular function (EF < 45%), there was a positive correlation between FAC (short axis, apical four chamber and mean) and EF (r = 0.52, p < 0.05, r = 0.83, p < 0.0001 and r = 0.80, p < 0.001 respectively) and a negative correlation between FAC (short axis and mean) and LVEDP (r = -0.52, p < 0.05 and r = -0.60, p < 0.01 respectively). There was also a negative correlation between LVEDP and EF in the same subgroup of patients (r = -0.65, p < 0.01).(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1995

Spontaneous haemothorax as a complication of anti-coagulation following coronary angioplasty.

Haemorrhagic complications are well recognized when heparin is used during percutaneous transluminal coronary angioplasty (PTCA). We present a 74-year-old female who developed a large acute spontaneous haemothorax 20 h after coronary angioplasty. Spontaneous haemothorax has rarely been described and is predominantly associated with pulmonary embolism. In the absence of a pulmonary embolus, a spontaneous haemothorax during anti-coagulation has only been described twice in the world literature since 1862 (1). This is the first description of this complication following the use of heparin during PTCA.

Aged↗
PubMed1995

A histomorphometric study of bone changes in thyroid dysfunction in rats.

Clinical studies in thyrotoxicosis reveal a state of high bone turnover leading, eventually, to osteoporosis. Recently there has been concern that thyroxine (T4) treatment may have a similar effect on bone. Rat models have been used to study the effects of T4 on bone, but the majority of studies have looked at the effects of T4 after only 3 weeks of treatment. The aim of this study was to evaluate histomorphometric changes in rats after 12 weeks of thyroxine overtreatment or 12 weeks of hypothyroidism compared with untreated control animals. Animals received either T4 200 micrograms/kg per day, 0.1% propylthiouracil, or vehicle for 12 weeks. Tetracycline was administered 1 week and 3 weeks prior to killing. Iliac crest bone was used for histomorphometry. Serum T4 measurements (taken at killing) confirmed hyper- and hypothyroidism in the appropriate animal groups (between group difference p < 0.001 by ANOVA). In hyperthyroid animals there was an increase in mineral apposition rate (MAR; 0.94 vs. 0.59 microns/day, p < 0.001) and mineral formation rate (MFR/BS; 0.24 vs. 0.12 x 10(-2) micron3/micron2 per day, p < 0.001) and a slight increase in eroded surfaces (ES/BS%; 1.54 vs. 1.36, p < 0.05) compared with controls, consistent with previous in vitro and in vivo observations. In hypothyroid rats there was a marked reduction in osteoid surfaces (OS/BS%; 1.7 vs. 24.8, p < 0.001) and MAR (0.3 vs. 0.59 micrograms/day, p < 0.001), a reduction in ES/BS% (0.51 vs. 1.36, p < 0.05), and an increase in cancellous bone volume (BV/TV%; 30.29 vs. 19.6, p < 0.05), suggesting that thyroid hormones are a requirement for normal bone turnover.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1995

The laryngectomee and swimming.

Following laryngectomy patients are usually advised that swimming is no longer possible. Under supervised conditions and using a swimming aid, such as described, a laryngectomee may return to an activity previously considered unavailable, rehabilitation thus being more complete. However, for a laryngectomee to proceed a safe supervised environment is required, and the path to this goal is often long and arduous, but with persistent dedication the Laryngectomy Swimming Club may become a reality bringing rich reward.

England↗
PubMed1995

Selenate fortification improves selenium status of term infants fed soy formula.

Thirty-three healthy term infants were fed either soy formula (SF, 0.028 mumol Se/L; n = 17) or soy formula with added selenate (SF+Se, 0.17 mumol Se/L; n = 16) from birth (+4 d) to 16 wk. Selenium intakes of infants fed SF+Se were similar to the recommended dietary allowance and significantly greater than those of SF-fed infants. The SF group had significantly lower plasma, erythrocyte, and urine selenium, and lower plasma and erythrocyte glutathione peroxidase (GPx) activities at 16 wk compared to those of infants fed SF+Se. A decrease in plasma selenium was observed in SF-fed infants, whereas no differences in plasma selenium were found in infants fed SF+Se. These results indicate that selenate added to soy formula is highly available and effective at maintaining infant plasma and erythrocyte selenium concentrations and GPx activities that are greater than those of infants fed soy formula not fortified with selenium.

Double-Blind Method↗
PubMed1995

Haemorrhage as a complication of inferior turbinectomy: a comparison of anterior and radical trimming.

A study was conducted to see whether the turbinectomy technique used influenced the incidence of haemorrhage. In a group of 214 patients who underwent bilateral turbinate surgery, haemorrhage occurred in 0.9% of those who had anterior turbinectomy and 5.8% who had radical turbinectomy (P < 0.05). It is concluded that confining excision to the anterior end of the inferior turbinate offers the advantage of a lower incidence of haemorrhage.

Adolescent↗
PubMed1995

An evaluation of sequence tagged microsatellite site markers for genetic analysis within Citrus and related species.

Microsatellites, also called sequence tagged microsatellite sites (STMSs), have become important markers for genome analysis but are currently little studied in plants. To assess the value of STMSs for analysis within the Citrus plant species, two example STMSs were isolated from an intergeneric cross between rangpur lime (Citrus x limonia Osbeck) and trifoliate orange (Poncirus trifoliata (L.) Raf.). Unique flanking primers were constructed for polymerase chain reaction amplification both within the test cross and across a broad range of citrus and related species. Both loci showed length variation between test cross parents with alleles segregating in a Mendelian fashion to progeny. Amplification across species showed the STMS flanking primers to be conserved in every genome tested. The traits of polymorphism, inheritance, and conservation across species mean that STMS markers are ideal for genome mapping within Citrus, which contains high levels of genetic variability.

Alleles↗
PubMed1994

Inhibition of platelet activity by S-nitrosoglutathione during coronary angioplasty.

Platelet activation is associated with acute vessel occlusion and chronic restenosis after percutaneous transluminal coronary angioplasty (PTCA). Organic nitrates, which act by releasing the vasodilator and anti-platelet agent nitric oxide (NO), have a predominantly vasodilator action and cause hypotension at doses required to inhibit platelet activation. S-nitrosoglutathione (GSNO) is an NO donor with a preferential action on platelets. We investigated platelet activation in patients undergoing PTCA and the effect of GSNO. Blood was sampled from the coronary sinus to measure platelet surface expression of P-selectin and glycoprotein IIb/IIIa as indices of platelet activation. In 7 control patients, PTCA caused a rise in platelet surface expression of P-selectin and glycoprotein IIb/IIIa, which was maximal 5 minutes after PTCA, indicating increased platelet activation despite treatment with aspirin, glyceryl trinitrate, and heparin. 6 patients received an intracoronary infusion of GSNO, starting 10 min before PTCA. GSNO significantly inhibited the PTCA-induced increase in platelet surface expression of P-selectin and glycoprotein IIb/IIIa without altering blood pressure. These findings show that platelets are activated following PTCA and that GSNO can prevent this activation.

Aged↗
PubMed1994

DNA typing of grapevines: a universal methodology and database for describing cultivars and evaluating genetic relatedness.

With established ampelographic techniques for grapevine identification it is often difficult to achieve a satisfactory, objective result. We have developed a DNA typing system using sequence-tagged microsatellite site markers as a means of differentiating cultivars of grapevine. A semi-automated analysis procedure was linked to an electronic database and found to be an objective and reliable system for cultivar identification using this simple marker type. The accumulated DNA typing data from over eighty cultivars demonstrated that cultivars that are difficult to differentiate phenotypically using ampelographic techniques can be distinguished by DNA typing. Parentage analysis uncovered errors in parent assignment or cultivar identification in specific cases. The electronic database has a conservative format to take into account the occurrence of null alleles and the possibility of missed alleles. Computer-assisted comparisons of cultivars in the database can be performed and various approaches for estimating the match probability that two unrelated cultivars have the same genotype simply due to chance are discussed. We suggest that further development of the database through international co-operation using standardised sequence-tagged site markers offers the possibility of achieving a universal grapevine identification system.

DNA, Plant↗
PubMed1994

Two cases of lateral sinus thrombosis presenting with extracranial head and neck abscesses.

Two cases of lateral sinus thrombosis in fit adults with no previous otological history are presented. One case occurred in association with Bezold's abscess and followed mastoiditis which was masked by previous antibiotic treatment. The other case occurred in association with an occipitoparietal scalp abscess and there was no obvious preceding middle ear infection. The causative bacteria were Streptococcus milleri and a variant Streptococcus intermedius. Lateral sinus thrombosis is discussed.

Abscess↗
PubMed1994

Growth and protein status of term infants fed soy protein formulas differing in protein content.

OBJECTIVE: The purpose of this study was to compare growth and protein status of healthy term infants from 2 to 112 days of age fed a commercially available soy-based formula (IS) and a similar formula (EF) containing less protein (2.91 vs 2.45 g/100 kcal). DESIGN: A controlled, randomized, blind parallel clinical trial was conducted in 32 male and 32 female infants. Infants were enrolled at 2 days of age, and their assigned formula was their only feeding to 112 days of age. At this time their weight, length, and head circumference were measured. Weight, length, and head circumference were measured and formula intake, formula intolerance and stool characteristics were recorded at 8, 28, 56, and 112 days of age. Plasma urea nitrogen (PUN), total protein, albumin, and transthyretin were determined at 56 and 112 days. RESULTS: There were no statistically significant differences in weight, length, head circumference, or gains in these measures. PUN concentration was significantly lower in infants fed EF than IS at 56 and 112 days. Plasma total protein, albumin, and transthyretin concentrations were not different between the two feeding groups at the two testing periods. Tolerance to the two formulas was similar. Stool characteristics did not differ between the two groups. CONCLUSION: A soy-based formula containing 2.45 g protein/100 kcal and approximately 640 mumol of total sulfur containing amino acids/100 kcal adequately meets the protein needs of term infants from 2 to 112 days of age.

Anthropometry↗
PubMed1994

A randomised comparison of the Omniflex and Magnarail systems in recanalisation of coronary occlusions.

OBJECTIVE: The reported success rates for angioplasty of occluded coronary arteries fall some way short of the success rates for angioplasty of sub-occlusive stenoses. Two angioplasty systems used in this setting were compared. DESIGN: A prospective randomised open study comparing the Magnarail system (Schneider) and the Omniflex system (Medtronic). SETTING: A regional cardiothoracic centre performing over 300 angioplasty procedures a year. PATIENTS AND METHODS: 50 consecutive patients with occluded (thrombolysis in myocardial infarction study (TIMI) grade 0 or 1) arteries thought to be suitable for recanalisation were assigned to undergo angioplasty with either the Magnarail or Omniflex as the primary system. Twenty minutes of fluoroscopic screening was allowed with the primary randomised system before it was considered a failure. The other non-randomised system could then be used at the operators' discretion, and a further 20 minutes' screening was permitted. MAIN OUTCOME MEASURES: A patent coronary artery with a residual stenosis of < 50% with prompt distal opacification (TIMI grade 3 flow) and a reduction in collateral supply to the index artery. RESULTS: The overall success rate in recanalising occluded vessels was 72%-64% for the Magnarail system used as the primary system and 51.7% for the Omniflex (NS). The Magnarail was more successful in angioplasties of the right coronary artery (11/14 v 3/10, p = 0.02) and in mid and distal sites of occlusion (11/17 v 4/14, p < 0.05). There was a trend in favour of the Omniflex in the left anterior descending coronary artery. CONCLUSION: Both systems would seem to be suitable for angioplasty of occluded coronary arteries. The improved steerability of the Magnarail may be advantageous in distal occlusions and lesions in tortuous arteries. The relatively stiffer Omniflex may be superior for proximal occlusions. The study group was too small to confirm this unequivocally.

Angioplasty, Balloon, Coronary↗
PubMed1994

Pain and the use of health services among the elderly.

This study examined pain management strategies and the relationship of pain to the use of health services in a sample of community-resident Canadian elderly. Analyses with the Andersen-Newman framework of need, enabling and predisposing variables revealed that pain did not make an incremental contribution to explaining service use. Traditional measures of need for services accounted for the majority of explained variance in health service use. The substantial number of participants who were found to be coping with chronic, frequent pain relied on themselves as much as formal health services for dealing with their pain. The most common coping style for these pain sufferers was a combination of analgesics and accepting mild pain as part of daily life. This combination of medical intervention and attitudinal factors appears to make the coping process very manageable.

Aged↗
PubMed1994

Enrichment of microsatellites from the citrus genome using biotinylated oligonucleotide sequences bound to streptavidin-coated magnetic particles.

A method is described for the rapid isolation of microsatellite sequences using a biotin-labeled oligonucleotide attached to streptavidin-coated magnetic particles. The oligonucleotide "hook" in solution hybridizes to complementary single-stranded lengths of genomic DNA onto which have been engineered specific PCR priming sites. The final product is an enriched library of microsatellites of defined sequences. The method is applicable to any genome and in principle is adaptable to the rapid isolation of both repetitive as well as genic sequences. It is illustrated by the isolation of trinucleotide repeat (TAA)n sequences from the citrus genome.

Bacterial Proteins↗
PubMed1993

Use of an intracoronary stent to control intrapericardial bleeding during coronary artery rupture complicating coronary angioplasty.

Coronary artery rupture is a rare complication of percutaneous transvenous coronary angioplasty (PTCA) usually requiring urgent cardiac surgery and often resulting in a poor outcome including death. We report, for the first time, the use of an intracoronary stent to control intrapericardial bleeding following the development of a coronary artery rupture during PTCA. Cardiac surgery was avoided and the patient was discharged well 1 week after the procedure.

Aged↗