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Biomedical subjects

M Barclay

Publications and source records attributed to M Barclay.

At least 19 recordsLinked to original sources
PubMed2004

Reasons for failure to diagnose colorectal carcinoma at colonoscopy.

BACKGROUND AND STUDY AIMS: Colonoscopy can produce false-negative results, and the reasons for this remain obscure. The aim of this study was to examine why cancers are missed at colonoscopy. PATIENTS AND METHODS: All colonoscopies carried out at Christchurch Hospital, New Zealand, over a 43-month period (1 October 1997 - 30 April 2001) were retrospectively analyzed (the data having been prospectively collected). All cases of colorectal carcinoma during the period 1 October 1997 - 30 July 2001 (3 months longer, to capture delayed diagnoses) were also identified. The two databases were then compared, and all cases in which a colonoscopy had been performed more than 6 weeks before a colorectal carcinoma specimen being received by the pathology department were identified and analyzed. RESULTS: A total of 5055 colonoscopies were undertaken in 4598 patients. Over this period, 630 colorectal carcinomas were identified in the pathology database; 286 of the patients affected were in the colonoscopy and pathology database. Sixty-six patients had had a colonoscopy performed more than 6 weeks before the diagnosis of colorectal carcinoma. Carcinoma was identified in 48 of these 66 patients, and management was being provided. Seventeen cancers (5.9 %) were missed at colonoscopy, and the patients had had an incomplete colonoscopy in nine of these cases. In seven of the 17, an alternative benign cause was recorded. In four patients, a lesion was seen and thought to be benign, although subsequently proven not to be. In another four cases, the cancer was not diagnosed despite adequate bowel preparation and what was thought by the colonoscopist to be an adequate colonoscopy. CONCLUSIONS: Colonoscopy missed 17 of 286 cancers (5.9 %). The reasons why cancers were missed relate to incomplete colonoscopy, poor bowel preparation, misinterpretation of what was seen, failure to carry out adequate biopsy (and follow-up) of lesions seen, and systems failures related to follow-up investigations in patients who had an incomplete colonoscopy. The fact that colonoscopy and barium enema investigations may fail to diagnose cancers has important medicolegal implications. The recognition that colonoscopy may miss a cancer should encourage doctors to reinvestigate patients when there is a lack of correlation between the clinical and investigative findings.

Aged↗
PubMed2002

Substrate-regulated cyanide hydratase (chy) gene expression in Fusarium solani: the potential of a transcription-based assay for monitoring the biotransformation of cyanide complexes.

The fungus Fusarium solani detoxifies cyanide through induction of the cyanide hydratase gene activity (chy) in the presence of either KCN or the metal-complexed cyanides, K2Ni(CN)4 or K4Fe(CN)6, at pH 7.0 and 4.0 respectively. Sequence analysis of the chy gene identified primers for reverse transcriptase-polymerase chain reaction (RT-PCR)-directed analysis of mRNA transcripts, which demonstrated that activity correlated to the substrate-specific induction of gene expression. chy transcription was initiated 30-60 min after exposure of F. solani cultures to cyanide complexes. Maximum expression was detected within 4.5 h, after which chy mRNA synthesis declined below the limits of detection within 26 h. A lag period of approximately 2 h, following initial transcription, was recorded before cyanide complexes were converted to formamide. mRNA transcripts of chy were not detected in the absence of cyanide or cyanide complexes. The presence of introns within the gene resulted in a difference in size of 100 bp for DNA compared with mRNA of the corresponding 5' region. This size difference facilitated PCR detection of gene and transcript respectively. Comparisons of the predicted amino acid sequence of the F. solani chy gene and those of Gloeocerospora sorghi, Fusarium lateritium and Leptosphaeria maculans demonstrate that cyanide hydratase genes are highly conserved and of a similar evolutionary origin. These data predict that the functional assay described here to monitor the induction of chy gene expression and, potentially, cyanide degradation would be applicable to a variety of polluted environments.

Amino Acid Sequence↗
PubMed2002

A rule driven bi-directional translation system for remapping queries and result sets between a mediated schema and heterogeneous data sources.

As the number of online biomedical data sources increases, so too do the number of ways to access such data. The research described herein focuses on creating a data access system that provides bi-directional translation and mapping of data between heterogeneous databases and a mediated schema. Semantic mapping rules stored in a knowledge base are used by our generalized software to convert XML query results obtained from each data source to a common schema representing a single ontology. We apply this approach to the domain of online genetic databases, demonstrating the system's scalability and integratability.

Databases as Topic↗
PubMed2001

Teaching students to break bad news.

BACKGROUND: Physicians typically learn to communicate bad news to patients through trial and error or observation of more senior physicians. To give medical students initial instruction and experience in this area, we developed two standardized patient instructor (SPI) experiences in "breaking bad news." METHODS: Twenty-one junior medical students had an SPI experience discussing a new diagnosis of rectal cancer or pregnancy loss. These 21 students, and 17 students having neither experience, interviewed the pregnancy loss SPI on the clinical performance examination (CPE) at the end of the junior year. RESULTS: Students who had previously had a "breaking bad news" SPI experience performed significantly better on the CPE pregnancy loss station than students without this experience. There was no significant difference in performance between students who had previously had the pregnancy loss versus rectal cancer SPI. CONCLUSIONS: This research provides evidence for the effectiveness of bad news communication skills teaching, and its potential for transfer across content areas.

Abortion, Spontaneous↗
PubMed2001

Small intestinal motor patterns in critically ill patients after major abdominal surgery.

OBJECTIVES: In patients who have had major surgery or trauma, early enteral feeding is safer and more effective than parenteral or nasogastric feeding but is frequently associated with diarrhea. Limited recordings have shown that the patterning of duodenal interdigestive motor activity is frequently abnormal after surgery or in patients who are critically ill. The aims of this study were to evaluate the effects of major abdominal surgery on small intestinal motility, and to elucidate the motor patterns that occur postoperatively in critically ill patients in response to enteral feeding. METHODS: The effects of elective aortic aneurysm repair on small intestinal motility were studied in 11 patients aged 63-77 yr. A 3.5-mm diameter multilumen extrusion was used to monitor pressures at 12 points, distributed between the antrum and 100 cm distal to the pylorus. An additional lumen allowed enteral feeding into the duodenum. Recordings commenced immediately postoperatively and continued for up to 4 days. Data are given as means and SEMs. RESULTS: Bursts (frequency > 10/min) of small intestinal pressure waves that resembled phase III interdigestive motor activity occurred in all patients immediately after surgery. During mechanical ventilation, the timing of bursts along the segment evaluated was frequently abnormal for true interdigestive phase III activity, with simultaneous onset in multiple channels (46%), multiple or distal origins (8%), or retrograde migration (20%). When patients were not being ventilated, the migration pattern of the bursts was more typical of interdigestive phase III activity. The interval between bursts was unusually short for interdigestive motor activity, although it increased from 30+/-12 min on day 1 to 41+/-18 min on day 3 (p < 0.05). A phase II pattern of pressure waves was virtually absent in all patients on all study days. In six patients who received postoperative enteral nutrition, the bursts of pressure waves were not abolished by feeding, contrary to normal phase III activity. CONCLUSIONS: Small intestinal pressure wave bursts are seen immediately after elective aortic aneurysm repair, but the migration of these bursts is frequently abnormal for phase III interdigestive activity. Duodenal nutrient delivery did not interrupt the occurrence of these bursts. Persistence of pressure wave bursts in this setting may be important in the delivery of enteral nutrition.

Aged↗
PubMed1998

Lower oesophageal sphincter tone increases after induction of anaesthesia in pigs with full stomach.

PURPOSE: The lower oesophageal sphincter (LOS) is the man mechanism that prevents gastro-oesophageal regurgitation during anaesthesia. The aim of this study was to assess the effect on lower oesophageal sphincter pressure (LOSP) of rapid sequence induction in pigs with full stomachs. METHODS: Lower oesophageal sphincter pressure and oesophageal barrier pressure (BrP = LOSP minus gastric pressure) were measured using a water-perfused manometric catheter method in 12 pigs after gastric filling with 500 ml of liquid nutrient mixture. Six pigs were randomly allocated to receive 5 mg.kg-1 propofol and 3 mg.kg-1 succinylcholine i.v. and six pigs received 8 mg.kg-1 thiopentone and 3 mg.kg-1 succinylcholine i.v. RESULTS: After induction, mean LOSP increased during the period with fasciculations from 19 +/- 4 mmHg to 28 +/- 5 mmHg in the propofol-succinylcholine group and from 23 +/- 6 mmHg to 36 +/- 7 mmHg in the thiopentone-succinylcholine group. The LOSP remained elevated after the fasciculations. LOSP and BrP were not different between the groups. CONCLUSIONS: Induction of anaesthesia with propofol-succinylcholine or thiopentone-succinylcholine increases LOSP and, consequently, BrP in pigs with a full stomach. This increase begins before fasciculations and remains elevated for the period when intubation would occur.

Anesthesia↗
PubMed1991

Cost efficiency of bone scans in breast cancer.

A total of 110 consecutive females who presented in 1987 with primary carcinoma of the breast were staged according to the UICC TNM staging system. Of these, 90 patients had bone scans at presentation, of which seven were positive. The rate of positive initial scans for Stages I-II was 3.5%. Of these only one patient subsequently had bone metastases confirmed, to diagnose which by bone scan, the estimated cost was pounds 1300. Follow-up information was obtained for 95 patients, repeat scans being performed in 22 who had symptoms suggestive of bone metastases. Ten patients with negative initial scans converted to scan-positive within a mean time of 15 months. Only four of these had radiological confirmation of bone metastases. The cost of detecting bone metastases by follow-up scan was approximately pounds 80 per patient. The false-positive rate and the false-negative rate were both calculated as 10%. The specificity of the test was calculated as 90%. It is recommended that bone scanning should be reserved for patients with Stages III and IV disease and to evaluate symptoms suggesting bone metastases.

Adult↗
PubMed1991

Patterns of presentation of breast disease over ten years in a specialised clinic.

A clinic specialising in breast disease has been surveyed over a decade. Detailed information has been collected on 3,500 women with benign breast disorders and 950 with breast cancer. Over this time, the demand for and utilisation of this facility has increased steadily. Over the ten years, there has been a trend for a higher proportion of breast cancers to be smaller in size and for fewer cancers to be locally advanced or metastatic at presentation. Critical appraisal of referral and consultation patterns indicates that the original aims of establishing this clinic have not been maintained. Paradoxically, this is a result of the success of the exercise. Measures which might lead to a higher proportion of patients with breast cancer being managed at the Breast Clinic rather than a General Surgical Outpatient Clinic are discussed.

Adult↗
PubMed1989

Court-ordered cesarean section: an analysis of ethical concerns in compelling cases.

Two previously unreported cases are presented in which court-ordered cesarean sections were considered appropriate by physicians. An analysis of the factors that compel physicians to deem court-ordered intervention appropriate is presented. When the significance of a third-trimester fetal death or a lifetime physical or mental disability is balanced against the demand to uphold maternal autonomy at all costs, the recognized ethical principles of beneficence, nonmaleficence, justice, obstetric contract keeping, and acting in the patients' best interests combine, in rare situations, to override concerns for individual maternal autonomy and justify court-ordered intervention.

Adult↗
PubMed1988

Sonographic evaluation of cervical length in pregnancy: diagnosis and management of preterm cervical effacement in patients at risk for premature delivery.

Sonographic measurement of cervical length during pregnancy can provide an objective, noninvasive assessment of anatomical shortening associated with premature labor and delivery. One hundred fifty normal women underwent serial sonographic cervical length measurements during uncomplicated pregnancy. The mean cervical length was 52 +/- 12 mm until 34 weeks' gestation, when gradual effacement and cervical length shortening began. Using these data, we managed 88 pregnant women with previous second-trimester pregnancy losses by a combination of cerclage placement for cervical length less than 40 mm and aggressive therapy for premature uterine contractions. The results showed the following: 1) 97% of women with diethylstilbestrol exposure and 80% of women with müllerian abnormalities exhibited cervical length shortening; 2) only 60% of women with a normal uterine cavity showed cervical lengths of less than 40 mm; and 3) all three groups of high-risk patients, independent of cervical length, showed significant premature uterine activity. These observations suggest that sonographic cervical length measurement may be a useful adjunct in the assessment of anatomical cervical integrity and the decision for cerclage placement. Furthermore, the presence of both premature cervical length shortening and preterm uterine activity in 65% of high-risk patients suggests that "cervical incompetence" and premature labor may not be distinct entities, but common symptoms associated with an increased risk of preterm delivery.

Cervix Uteri↗
PubMed1981

Development and critical evaluation of the food nomogram.

The historical development and validation of the Food Nomogram is described to show the scientific basis of formulas to predict caloric need. Prediction of basal caloric need in nutritional assessment using formulas such as that represented by the Mayo Foundation Nomogram is based on surface area and standardized kilocalories per unit of surface area. Though these quantities do reflect error, major discrepancies evolve with prediction of total need, including kilocalories for activity. In spite of these limitations, predicting formulas have been valuable tools in predicting total caloric need. Three formulas are contrasted and found reliable.

Adolescent↗
PubMed1979

Serum lipoproteins in rats bearing Morris hepatomas of different degrees of differentiation.

Serum lipoproteins were measured by ultracentrifugal means in rats bearing hepatomas of different degrees of malignancy (Morris hepatomas 16, 5123TC and 7777) to determine the effect of these hepatomas on serum lipoprotein levels. Serum lipoprotein patterns were altered, especially in rats bearing hepatomas 16 and 7777, which had elevated high-density lipoproteins. (They were not elevated in serum of rats bearing hepatoma 5123TC). This increase in high-density lipoproteins seems to be specific for chemically induced hepatomas since HDL2 is usually decreased in humans and animals with types of cancer not involving the liver. It appears that hepatomas can synthesize lipoproteins, and the serum levels of the host rats are altered depending on the hepatoma. Different biochemistries appear to be associated with each hepatoma. Cholesterol and fatty acid levels of unfractionated serum and of isolated lipoproteins also indicate abnormal lipid/lipoprotein metabolism associated with these hepatomas.

Aging↗
PubMed1979

Glycosphingolipids of subcellular fractions from normal rat liver and Morris hepatoma 5123TC.

Neutral glycosphingolipids and gangliosides were quantified in lipid extracts from plasma membranes, mitochondria, microsomes, and nuclei isolated from normal rat liver and Morris hepatoma 5123TC. Results showed a higher content of glycosphingolipids, especially gangliosides, in hepatomas and differences in the distribution of glycosphingolipids among subcellular fractions. Differences in the glycosphingolipid composition of the hepatoma, namely, the absence of trisialogangliosides and an increase in the lower molecular weight gangliosides, reflected an altered metabolism of glycosphingolipids in this tumor. The results indicated that changes in membrane glycosphingolipids were not restricted to the cell surfaces of malignant cells, inasmuch as intracellular membrane fractions also exhibited altered glycosphingolipid profiles.

Animals↗
PubMed1978

Discrete separation of HDL2 from HDL3 of human serum by means of polyacrylamide gel.

A relatively short, simple procedure is presented to separate serum high-density lipoproteins discretely into the two main classes, those with densities between 1.063 and 1.125 g/ml (HDL2) and those with densities between 1.125 and 1.210 g/ml (HDL3). A 3.5% polyacrylamide gel in 10 cm glass tubes and the use of Tris/glycine buffer, pH 8.4, will accomplish this separation. The components can be identified in several different ways, examples of which are given. This procedure will give rapid and reliable estimations of both HDL2 and HDL3, and can be used to relate their levels and proportional amounts to incidence or risk of atherosclerosis, coronary-artery disease and possibly cancer.

Adult↗
PubMed1977

Alterations in glycosphingolipids of plasma membranes from Morris hepatoma 5123TC.

Neutral glycosphingolipids and gangliosides were quantified in lipid extracts from normal rat liver and Morris hepatoma 5123TC and their isolated plasma membranes to determine differences in these components in the cell surface membranes of malignant cells. Glycosphingolipids present in rat liver and hepatoma were concentrated in plasma membranes, and glycosphingolipid patterns in plasma membranes reflected those of their respective whole cells. Neutral glycospingolipids of plasma membranes from normal liver and from hepatoma consisted of ceramide mono- and dihexosides, together accounting for 83 to 86% of the total neutral glycosphingolipids and some ceramide tri- and tetrahexosides. In plasma membranes from hepatoma, the concentration of neutral glycosphingolipids was generally greater than in plasma membranes from normal liver. Gangliosides of plasma membranes from hepatoma were altered more drastically, since trisialogangliosides, present in plasma membranes from normal liver, were absent, while hematosides, monosialogangliosides, and disialogangliosides were increased an average eight-fold. These data are compatible with a concept of incomplete synthesis of trisialogangliosides in hepatoma and an accumulation precursor gangliosides.

Animals↗