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Biomedical subjects

M A Gregory

Publications and source records attributed to M A Gregory.

At least 37 records · Page 2Linked to original sources
PubMed1990

Pharmacokinetics of propofol in women undergoing elective caesarean section.

We have compared the pharmacokinetics of a bolus induction dose of propofol 2 mg kg-1 in 10 Chinese women undergoing elective Caesarean section with those in six non-pregnant Chinese women having laparoscopic sterilization. Blood propofol concentrations were measured using high pressure liquid chromatography with fluorimetric detection. Pharmacokinetic data were analysed by a model independent method based on statistical moment theory. Data from the laparoscopy group also underwent compartmental analysis, which produced similar kinetic results. Non-compartmental analysis estimated that the women undergoing Caesarean section had a similar elimination half-life (mean 81.27 (SD 18.87) min) and apparent volume of distribution at steady state (2.66 (0.63) litre kg-1) as non-obstetric patients (99.45 (29.40) min and 3.36 (1.87) litre kg-1). Clearance was more rapid in the Caesarean section group (39.32 (8.07) ml min-1 kg-1 vs 29.40 (8.72) ml min-1 kg-1) (P less than 0.05). The increased total body clearance may result from blood loss and delivery of the fetus and placenta at operation, although an increase in extrahepatic clearance is also possible.

Adult↗
PubMed1990

Effect of adrenaline on venous plasma concentrations of bupivacaine after interpleural administration.

Bupivacaine 2.5 mg kg-1 (0.5 ml kg-1 of 0.5% solution), with or without adrenaline 5 micrograms ml-1, was administered by interpleural injection to 12 patients after elective cholecystectomy. Noncompartmental analysis indicated that the addition of adrenaline had no effect on total body clearance, apparent volume of distribution at steady state or elimination half-life of bupivacaine. However, peak plasma concentrations were lower in the adrenaline group (mean (SD) [range]: 2.57 (0.61) [1.52-3.11] vs 3.22 (0.27) [2.84-3.53] micrograms ml-1, P less than 0.05) and the time to maximum concentration was delayed (median [range]: 25 [15-30] vs 15 [10-20] min, P less than 0.05). Analgesia was variable and no differences were detected between the two groups. The addition of adrenaline appears prudent to minimize possible bupivacaine toxicity.

Analgesia↗
PubMed1990

Obstetric epidural analgesia with mixtures of bupivacaine, adrenaline and fentanyl.

We performed a double-blind comparison of six solutions for epidural analgesia in 90 healthy Chinese women with uncomplicated pregnancies. Patients were randomly allocated to receive 10 ml bupivacaine 0.125% or 0.25% plain, bupivacaine 0.125% with adrenaline 1.25 micrograms/ml, bupivacaine 0.25% with adrenaline 2.5 micrograms/ml or the latter two solutions with added fentanyl 50 micrograms. Analgesia was unsatisfactory in 30% of the bupivacaine 0.125% groups without fentanyl. The addition of adrenaline, compared with bupivacaine 0.25% plain, gave faster onset and longer duration of analgesia (p less than 0.05) which was similar to that found in both fentanyl groups. There were no differences in method of delivery or neonatal Apgar scores among groups. The least concentrated mixture that gave the best analgesia was the combination of bupivacaine 0.125% with adrenaline 1.25 micrograms/ml and fentanyl 50 micrograms.

Adult↗
PubMed1990

The haemodynamic effects of propofol and thiopentone for induction of caesarean section.

Forty Chinese women for elective caesarean section received either propofol 2 mg.kg-1 or thiopentone 4 mg.kg-1 for induction of general anaesthesia. Systolic, mean and diastolic arterial pressures and heart rate were recorded non-invasively every minute for ten minutes. Post-induction arterial pressures were similar to pre-induction values with no differences between thiopentone and propofol. Following intubation, the rise in systolic arterial pressure was greater in the thiopentone group, 32.1 mmHg (SD 23.7) compared with the propofol group, 17.4 mmHg (SD 23.8), (P less than 0.05). In the thiopentone group, arterial pressures were slower in returning to baseline values. Heart rate was initially elevated in both groups to the same degree. At caesarean section, induction with propofol causes less variation in arterial pressure than thiopentone. Hypotension is probably prevented by the coincident stimulus of rapid sequence induction. Neonatal Apgar scores were similar between the two groups.

Adult↗
PubMed1990

Maternal and fetal levels of propofol at caesarean section.

Twenty women were given a bolus induction of propofol 2.0 mg.kg-1 for elective caesarean section. Induction to delivery times ranged from five to fourteen minutes. At delivery the maternal venous (MV) concentrations of propofol ranged from 0.53 to 1.48 micrograms.ml-1 umbilical vein (UV) 0.39 to 1.4 micrograms.ml-1 and umbilical artery (UA) 0.34 to 0.68 micrograms.ml-1 MV propofol concentrations were always higher than corresponding UV concentrations. The mean (95% confidence interval) UV/MV ratio was 0.65 (0.56-0.74) and the mean UA/UV ratio was 1.07 (0.99-1.15). Neither ratio was shown to be correlated with induction to delivery time. Distribution of propofol is rapid across the placenta and in the fetus. Apgar scores were higher with shorter incision to delivery times but were not correlated to umbilical levels of propofol.

Adult↗
PubMed1990

The addition of fentanyl to epidural bupivacaine in first stage labour.

Epidural analgesia was studied in 100 healthy Chinese women with uncomplicated pregnancies in first stage labour. Patients were randomly allocated to receive 8 ml of one of the following five solutions: bupivacaine 0.125% with fentanyl 50 micrograms or fentanyl 100 micrograms, bupivacaine 0.25% plain, bupivacaine 0.25% with fentanyl 50 micrograms or fentanyl 100 micrograms. There was no difference in quality of analgesia among groups as measured by the reduction of visual analogue pain scores 20 minutes after the epidural dose. The duration of analgesia was similar among groups with the overall median duration being 105 minutes. There was no difference in method of delivery or neonatal Apgar scores. The least concentrated mixture providing good quality analgesia for the first stage of labour was the combination of bupivacaine 0.125% with fentanyl 50 micrograms.

Adult↗
PubMed1990

A morphological control for ventricular pathology in man: a morphometric and morphologic assessment of LV myofibres in secundum ASD.

Ethical considerations preclude the biopsy of normal human myocardium. As a consequence, morphological investigations of diseased human heart muscle are hampered by a lack of suitable normal control tissue. The left ventricular (LV) myocardium of patients with isolated secundum atrial septal defect (ASD) is considered to be normal. This study was designed to investigate the possibility that the fine-structure of LV myofibres in hearts with ASD could be used as normal controls for myofibre pathomorphology. Wedge biopsies from the LV of four adults undergoing elective surgery for the repair of ASD were examined by light and electron microscopy. Bivariant myofibre morphometry showed that the LV myocardium of one specimen was 'normal' while three specimens exhibited varying degrees of hypertrophy. There was a correlation between the diameter (FD) and morphology of individual myofibres within and between specimens. In general, myofibres with FD less than 25 microns were similar in fine-structural appearance to those described as morphologically normal in animal models whereas those with FD greater than 25 microns exhibited hypertrophic features that increased in 'severity' with increase in myofibre size. It is proposed that although the LV myocardium in ASD may be mildly hypertrophied, myofibres with FD less than 25 microns are probably normal and may be used as fine-structural controls for myofibre pathomorphology in hearts suspected of disease.

Adult↗
PubMed1989

Morphometric analysis to detect suspected myocardial disease. A pilot study.

Myofibres in the normal left ventricle (LVs) of 24 healthy young accident victims and the diseased LVs of 10 subjects who died from constrictive pericarditis or congestive (African) cardiomyopathy were subjected to morphometric evaluation. Each myofibre was represented by a pair of measurements: cross-nuclear fibre (FD) and nuclear (ND) diameters. Using a VIDS image analyser interfaced with a light microscope, 150 paired measurements were determined for each of the 34 specimens. The bivariate relationship between FD and ND for each group of specimens were expressed as linear regressions. The limits for the group distribution of normal specimen FD/ND means were calculated and graphically depicted in the form of an ellipse. Disease specimens were plotted for comparison. Of the normal specimens, 23/24 FD/ND coordinates fell within the "normal' ellipse whereas the altered relationship between FD and ND in pathological myocardia caused all 10 specimen means to be plotted outside the ellipse and their regression lines to be displaced from normal. It is suggested that the normal data define the morphometric parameters of LV myofibres in healthy hearts and create a graphic standard by which myofibre pathology in hearts suspected of disease can be detected.

Adolescent↗
PubMed1987

Variations in the morphology of villous epithelial cells within 8 mm of untreated duodenal ulcers.

In order to investigate the bio-mechanics of duodenal ulcerogenesis and compare the 'quality' of drug mediated mucosal healing, it is necessary to define the morphological appearance of ulcerative mucosae. This report describes the morphological appearance of pre-therapy, juxta-duodenal ulcer (DU) villous epithelia. Biopsies made at endoscopy from the first part of the duodenum in four healthy volunteers and 3-8 mm from the edge of the DU in 97 patients were examined by light and electron microscopy. Irrespective of whether biopsies were made from the normal or juxta-DU mucosa, the villous epithelium was populated by one, or more, of six, morphologically identifiable cell types. Control epithelia were populated with normal goblet and absorptive cells. Based on the fine-structural characteristics of the predominant cell type, pathological specimens were divided into two groups: metaplastic (Group 1) and non-metaplastic (Group 2). Group 1 specimens were either exclusively populated with fully differentiated metaplastic gastric surface mucus secreting cells (GMC) (Group 1A), or GMC in various phases of metaplastic differentiation together with abnormal goblet cells (Group 1B). Group 2 specimens were populated with 'pathological' absorptive and normal goblet cells. It is postulated that the group variations in pre-therapy juxta-DU morphology represent various phases in the natural history of duodenal ulcerogenesis and healing.

Duodenal Ulcer↗
PubMed1986

Perspective graphics as a means of portraying the distribution of radiolabelled ligands in the spinal cord--a pilot study using intrathecally administered 3H morphine.

Tritium-labelled morphine sulphate was injected into the lumbar (L4-5) subarachnoid space of an adult male baboon. Three hours after injection, the animal was sacrificed. Using quantitative light microscopic autoradiographic mapping techniques, contour and perspective diagrams were prepared that described the position of radiolabel and by inference the distribution of morphine binding sites within the spinal cord. High concentrations of 3H was found in the medial regions of laminae I, II (substantia gelatinosa) and III of the dorsal horns. Smaller, but significant levels were seen bilaterally in the spinal anterolateral quadrant. Minimal 3H activity was seen in the remainder of the spinal cord with the lowest level being recorded in the spinal canal. Perspective graphics proved a precise and attractive method for locating the position and quantifying the concentration of radiolabel in baboon spinal cord.

Animals↗
PubMed1986

Preparation of the community-medical dietitian: a survey of graduates.

The 1984 Study Commission on Dietetics reports that dietetics education needs greater emphasis/depth on management, communications, and the scientific principles of nutrition, with a broader base in the behavioral sciences. This recommendation is supported by recent graduates and their employers. The skill area identified as deficient by the most employers was the ability to delegate or direct. At least 20% of these graduates felt a need to strengthen their role as interpreter of nutrition science and the curricular areas related to nutrient metabolism, educational methods, and behavior modification. Changes projected for the dietetics profession in the future include an increase in patient care outside the hospital; an increase in the need for nutrition services in independent medical practice associations, gerontology centers, and fitness centers; and an increase in opportunities in the business world. Educational programs must be sensitive to the new skills needed for practice in both clinical and community dietetics. They must continue to assess their effectiveness in providing these, because the dietitian best prepared with skills in both areas will be best prepared for the future.

Community Health Services↗
PubMed1985

Morphine concentration in brain and spinal cord after subarachnoid morphine injection in baboons.

Tritium-labeled morphine was injected into the lumbar (L4-5) subarachnoid space of three baboons. The animals were sacrificed 3, 6, and 24 hr thereafter. Morphine concentrations were measured at five predetermined positions within the spinal cord, medulla oblongata, and frontal lobes of the brain by scintillation-count assay. The results revealed that morphine ascends in the subarachnoid space and is absorbed into the spinal cord and medulla oblongata in a time-dependent fashion. Ventilation was most depressed and maximal concentrations of morphine were detected in the medulla six hours after injection. Delayed respiratory depression, occasionally reported after intraspinal morphine injection, may therefore be caused as a result of the affinity of morphine for binding sites, possibly opiate receptors, situated within the vital respiratory and cardiovascular neuronal complexes of the medulla.

Animals↗
PubMed1984

Myocardial ischaemia in constrictive pericarditis--a morphometric and electron microscopical study.

Left ventricular biopsies, taken during pericardiectomy, were morphometrically and morphologically examined to determine the pathology of the myocardium in constrictive pericarditis (CP). To serve as a normal control a similar appraisal was made of tissue from the left ventricle of a patient undergoing atrial septal repair. Morphometrically, mean cross-fibre diameters at the position of the nucleus in atrial septal defect (ASD) and CP hearts were within a range previously reported as normal. In hearts from patients with CP, the range of individual myocardial fibre diameters was extended. Ultrastructurally the myocardium in ASD appeared normal. In CP, myofibres could be divided into two groups: (a) small and morphologically normal; and (b) large and oedematous. Oedematous fibres contained abnormal nuclei and sarcoplasmic organelles and myofibrillar dissolution was a prominent feature in many cells. These pathological features are among those previously used to characterize myofibre ischaemia. In CP, prolonged cardiac compression is thought to predispose the heart to atrophy due to its inability to function properly (disuse atrophy). The results of this study suggest that in CP, myocardial ischaemia is a more important factor in the aetiology of myocardial dysfunction than is atrophy which arises from enforced cardiac disuse.

Adolescent↗
PubMed1983

Characterisation of normal human myocardium by means of morphometric analysis.

A morphometric analysis of ventricular myofibres, in specimens taken at necropsy from ten normal hearts, was performed to determine the distribution of fibre and nuclear diameters and their dependence on sampling position within the heart (group a). To assess the significance of the findings, two control groups of specimens were subjected to the same analysis: b) specimens from the hearts of four patients who had died of African cardiomyopathy; c) biopsies taken from the left ventricles of two hearts undergoing surgical repair of atrial septal defects (ASD), in which the myocardium is considered normal. Although mean values for the left ventricle were 13% greater on average than those for the right, a linear correlation, independent of sampling position, was found between nuclear and fibre diameter. Mean fibre and nuclear diameters for specimens from the normal and ASD control groups followed the same correlation as for individual normal fibres, whereas there was a significant deviation in the case of the cardiomyopathy specimens. The relationship between nuclear and fibre diameters was found to distinguish between normal and pathological specimens more clearly than the mean values of either dimension considered separately. It is suggested that this relationship is a more sensitive criterion of ventricular fibre normality or pathology than the parameters used in previous studies of this nature.

Adolescent↗
PubMed1982

The effect of tri-potassium di-citrato bismuthate on the duodenal mucosa during ulceration. An ultrastructural study.

The manner in which tri-potassium di-citrato bismuthate (TDB) promotes duodenal ulcer healing is not known. Endoscopic biopsy specimens were taken from the edges of duodenal ulcers from 5 patients before and after treatment with TDB. Using the bismuth contained within this drug as an electron-dense marker, the mode of action of TDB was determined by transmission electron microscopy. TDB was found to promote ulcer healing by adhering to the ulcerative mucosa, thereby providing an effective barrier to the substances which cause and maintain ulceration.

Anti-Ulcer Agents↗
PubMed1982

An ultrastructural study of the origin and function of basophilic degeneration in human cardiac muscle--cardiac colloid. Type 1.

The myofibres in biopsies obtained from the left ventricle during cardiopulmonary bypass, in patients undergoing surgery for mitral and aortic valve replacement and the correction of atrial septal defect, contained inclusions thought to be type 1 cardiac colloid. Electron microscopy showed this material to be synthesised by and contained within a grossly dilated rough endoplasmic reticulum. The presence of membrane-bound aggregates of non-fibrillar sarcoplasmic organelles within colloid deposits, together with osmiophilic inclusions thought to be related to lipofuscin, both within and moving from this structure, suggest that type 1 cardiac colloid is an autophagic vacuole designed to degrade ageing or redundant sarcoplasmic organelles.

Adolescent↗