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Biomedical subjects

J Chambers

Publications and source records attributed to J Chambers.

At least 37 records · Page 2Linked to original sources
PubMed2001

The interaction of perceived maternal and paternal parenting styles and their relation with the psychological distress and offending characteristics of incarcerated young offenders.

A shortened form of the Parental Bonding Instrument (PBI) (Pederson, 1994) was used to examine the relationship between parenting styles and the psychological distress and offending patterns of a group of young male offenders held in custody in Scotland. High levels of psychological distress were linked with low parental care, but there was no association between psychological distress and parental control. Parental care was not a distinguishing factor in offending patterns, although high paternal control was linked with a younger age of first arrest. When interactions of paternal and maternal parenting styles were examined, young offenders who perceived poor parenting (i.e. neglectful parenting or affectionless control) from both parents had the highest levels of psychological distress overall.

Adolescent↗
PubMed2001

A cybernetic theory of morality and moral autonomy.

Human morality may be thought of as a negative feedback control system in which moral rules are reference values, and moral disapproval, blame, and punishment are forms of negative feedback given for violations of the moral rules. In such a system, if moral agents held each other accountable, moral norms would be enforced effectively. However, even a properly functioning social negative feedback system could not explain acts in which individual agents uphold moral rules in the face of contrary social pressure. Dr. Frances Kelsey, who withheld FDA approval for thalidomide against intense social pressure, is an example of the degree of individual moral autonomy possible in a hostile environment. Such extreme moral autonomy is possible only if there is internal, psychological negative feedback, in addition to external, social feedback. Such a cybernetic model of morality and moral autonomy is consistent with certain aspects of classical ethical theories.

Cybernetics↗
PubMed2001

Prediction of symptom-onset in aortic stenosis: a comparison of pressure drop/flow slope and haemodynamic measures at rest.

To compare the pressure drop/flow slope with peak and mean pressure drop, effective orifice area and aortic valve resistance for the prediction of symptom-onset we performed resting and dobutamine stress echocardiography in 49 asymptomatic patients with aortic stenosis (peak aortic velocity>2.5 m/s). The end-point was progression to symptoms requiring surgery and patients were followed for a mean 21.2 (5.2) months. A total of 23 (47%) patients progressed to symptoms requiring aortic valve replacement and 26 remained asymptomatic. There was no significant difference in age, gender, fractional shortening or the presence or absence of coronary artery disease between these groups. There were differences in peak aortic velocity (P<0.0001), peak and mean pressure drop (P<0.0001), effective orifice area (P=0.03), aortic valve resistance (P=0.001) and pressure drop/flow slope (P<0.0001). On Cox regression analysis, the pressure drop/flow slope (P<0.0001), peak aortic velocity (P=0.005) and peak pressure gradient (P=0.02) were independent predictors. Mean event-free survival at 2 years for peak velocity >4.0 m/s was 17% and for pressure drop/flow slope >0.10 mmHg/ms(-1) was 20%. Of 13 patients reporting symptoms during dobutamine stress, 10 (77%) developed spontaneous symptoms during follow-up compared with 13 of 36 (36%) with no symptoms (P=0.11). The pressure drop/flow slope is a better independent predictor of symptom onset than resistance, mean pressure difference and effective orifice area, but is similar to peak velocity.

Adult↗
PubMed2001

Maternal left ventricular mass and diastolic function during pregnancy.

OBJECTIVE: To evaluate changes in left ventricular mass and diastolic function during normal pregnancy. METHODS: This was a cross-sectional study of 125 pregnant women at 9-42 weeks of gestation and 19 non-pregnant female controls. Two-dimensional and M-mode echocardiography of the maternal left ventricle and left atrium was performed. RESULTS: During pregnancy left ventricular mass increased by 52%. There was an increase in left ventricular end-diastolic and end-systolic diameters (12% and 20%, respectively), left ventricular posterior wall diameter during diastole and systole (22% and 13%, respectively) and left intraventricular septum during diastole and systole (15% and 19%, respectively). Mitral valve A-wave maximum velocity increased during pregnancy by 19%, while mitral valve E-wave maximum velocity and the ratio of E-wave/A-wave velocities increased early in pregnancy by about 14% and 6%, respectively, with a subsequent decline to 4% and 10%, respectively, below non-pregnant levels. CONCLUSION: Left ventricular mass increases during pregnancy, while left ventricular diastolic function, as demonstrated by the changes in mitral valve flow velocities, increases in the first two trimesters but declines in the third trimester.

Adult↗
PubMed2001

Maternal left ventricular transverse and long-axis systolic function during pregnancy.

OBJECTIVES: Circumferential fiber shortening has been the dominant basis for conventional analysis by echocardiography of left ventricular systolic function during pregnancy. Results in the literature have been conflicting due mainly to the fact that geometric assumptions for the calculation of these indices are made that may not be valid due to changes in left ventricular shape during pregnancy. Left ventricular long-axis displacement is expected to be a useful index of systolic function, independent of the changes in left ventricular geometry. The aim of this study was to compare circumferential to long-axis shortening during left ventricular contraction in pregnant women. METHODS: This was a cross-sectional study of 125 pregnant women at 9-42 weeks of gestation and 19 non-pregnant female controls. Two-dimensional and M-mode echocardiography of the left ventricle was performed including measurement of left ventricular long-axis displacement and activation time on the lateral, septal, anterior and inferior sides of the mitral annulus. Activation time was assessed as the time from the start of the Q-wave of the electrocardiogram to the onset of left ventricular long-axis shortening. RESULTS: Mean arterial pressure and activation time decreased during pregnancy, reaching a nadir at about 19 weeks' gestational age of 4% and 13%, respectively, below non-pregnant values; they subsequently increased towards term. Left ventricular long-axis displacement mirrored the changes in mean arterial pressure and activation time and increased with gestational age at all four sites of the atrioventricular plane reaching a peak at about 23 weeks (+ 12% compared to non-pregnant levels). The ejection fraction and fractional shortening remained stable until 30 and 32 weeks, respectively, and then decreased towards term. CONCLUSION: Changes in left ventricular long-axis performance during pregnancy occur earlier than do measures of transverse function.

Adult↗
PubMed2001

Active control of the volume acquisition noise in functional magnetic resonance imaging: method and psychoacoustical evaluation.

Functional magnetic resonance imaging (fMRI) provides a noninvasive tool for observing correlates of neural activity in the brain while a subject listens to sound. However, intense acoustic noise is generated in the process of capturing MR images. This noise stimulates the auditory nervous system, limiting the dynamic range available for displaying stimulus-driven activity. The noise is potentially damaging to hearing and is distracting for the subject. In an active noise control (ANC) system, a reference sample of a noise is processed to form a sound which adds destructively with the noise at the listener's ear. We describe an implementation of ANC in the electromagnetically hostile and physically compact MRI scanning environment. First, a prototype system was evaluated psychoacoustically in the laboratory, using the electrical drive to a noise-generating loudspeaker as the reference. This system produced 10-20 dB of subjective noise-reduction between 250 Hz and 1 kHz, and smaller amounts at higher frequencies. The system was modified to operate in a real MR scanner where the reference was obtained by recording the acoustic scanner noise. Objective reduction by 30-40 dB of the most intense component in scanner noises was realized between 500 Hz and 3500 Hz, and subjective reduction of 12 dB and 5 dB in tests at frequencies of 600 Hz and at 1.9 kHz, respectively. Although the benefit of ANC is limited by transmission paths to the cochlea other than air-conduction routes from the auditory meatus, ANC achieves worthwhile attenuation even in the frequency range of maximum bone conduction (1.5-2 kHz). ANC should, therefore, be generally useful during auditory fMRI.

Auditory Perception↗
PubMed2001

Biochemical markers in the management of suspected acute myocardial infarction in the emergency department.

OBJECTIVES: To compare cardiac troponin T, myoglobin, CK, CKMB activity, CKMB mass and the initial electrocardiogram in the early diagnosis of myocardial infarction in the emergency department. Methods-Biochemical markers were measured at presentation in patients with a possible diagnosis of acute myocardial infarction. Based on the clinical notes, patients were grouped as "definite myocardial infarction" (n = 50), "definite no myocardial infarction" (n = 81) and "uncertain" (n = 96). Sensitivity and specificity and positive and negative predictive values were calculated using the 131 patients with definitely present or absent myocardial infarction. RESULTS: The initial electrocardiogram was more sensitive than any of the markers in the first six hours from symptom onset-sensitivity 74% (95%CI 61% to 88%). The positive predictive value of the initial electrocardiogram was 97% in the first six hours; the markers ranged from 47% to 67%. The negative predictive value of the initial electrocardiogram was 85% in the first six hours; the markers ranged from 61% to 70%. Four patients with non-diagnostic electrocardiograms presenting beyond six hours after pain onset had a myocardial infarct detected by at least three of the biochemical markers in each case. CONCLUSIONS: The electrocardiogram is of more diagnostic use than biochemical markers in the first six hours after the onset of pain, but biochemical markers give additional positive diagnostic information in patients presenting later than this. The negative predictive accuracy of biochemical markers is too low for a single sample to be useful for excluding myocardial infarction in the first six hours after onset of symptoms.

Creatine Kinase↗
PubMed2001

Long axis excursion in aortic stenosis.

OBJECTIVES: To examine long axis excursion in patients with all grades of aortic stenosis and preserved transverse systolic function, and to compare long axis excursion in symptomatic with that in asymptomatic severe aortic stenosis. DESIGN: Prospective comparative study. SETTING: Regional cardiothoracic centre. PATIENTS: 78 patients with all grades of aortic stenosis and normal fractional shortening and ejection fraction were studied. There were two comparison groups, 10 age matched normal subjects and 14 patients with aortic stenosis and fractional shortening < 26%. METHODS: Aortic valve function and left ventricular mass were assessed echocardiographically. M mode measurements of long axis excursion at the septal and lateral sides of the mitral annulus were taken. RESULTS: There were significant differences between the groups in long axis excursion at both the septal (p < 0.0001) and lateral sides of the mitral annulus (p = 0.002 by analysis of variance). Long axis excursion was independently related to both left ventricular mass index (p = 0.001) and the grade of aortic stenosis (p = 0.002). Comparing patients with severe aortic stenosis with and without symptoms, there were significant differences in effective orifice area (p = 0.02 ) and long axis excursion at the lateral side of the mitral annulus (p = 0.04), but not in fractional shortening, ejection fraction, or peak or mean pressure difference. CONCLUSION: In patients with aortic stenosis, long axis excursion is reduced even in the presence of normal fractional shortening or ejection fraction. It is lower in patients with symptomatic compared with asymptomatic severe aortic stenosis and may be of use in predicting the onset of symptoms.

Acute Disease↗
PubMed2001

The clinical and diagnostic features of mitral valve disease.

Mitral valve disease remains common, and requires regular clinical and echocardiographic review. Surgery is indicated soon after the development of symptoms or at the first sign of left ventricular decompensation in mitral regurgitation or of the right ventricle in mitral stenosis.

Echocardiography↗
PubMed2001

Patent foramen ovale in elderly stroke patients.

The aim of this study was to determine the incidence of echocardiographically detectable patent foramen ovale (PFO) in elderly patients who have strokes from cerebral infarction, as well as to assess the association between PFOs and other risk factors for stroke disease. Forty-three patients aged > or = 65 years admitted consecutively with cerebral infarction shown on computerised tomography of the brain were assessed using transoesophageal echocardiography. A PFO was present in 8 (19%) of the 43 patients. Four patients (50%) in this PFO group had stroke risk factors. Two were in atrial fibrillation and, of the six patients in sinus rhythm, a risk factor was present in two, both of whom had diabetes mellitus. A PFO was not detected in 35 patients. Twenty-nine (83%) of the patients in this group had risk factors, with 18 having two or more. Seven patients were in atrial fibrillation. Of the 28 patients in sinus rhythm, risk factors were present in 22 (78%).

Aged↗
PubMed2000

Immunohistochemical localization of the P2Y1 purinergic receptor in Alzheimer's disease.

The biological actions of extracellular nucleotides are mediated by two distinct classes of P2 receptor, P2X and P2Y. The G protein-coupled P2Y receptors comprise five mammalian subtypes, P2Y(1-11). The P2Y1 subtype is expressed abundantly throughout the human brain and is specifically localized to neuronal structures. In the present study, the distribution of the P2Y1 receptor was investigated in Alzheimer's disease (AD) brains. In contrast to control human brain, the P2Y1 receptor was localized to a number of characteristic AD structures such as neurofibrillary tangles, neuritic plaques and neuropil threads. Immunoblot analysis showed that this specific immunostaining observed over tangles was not a result of cross-reactivity between the anti-P2Y1 antiserum and abnormal tau protein, the major constituent of tangles. The significance of this altered P2Y1 cellular distribution in AD brains is at present unclear.

Adenosine Diphosphate↗
PubMed2000

Regional and cellular distribution of the P2Y(1) purinergic receptor in the human brain: striking neuronal localisation.

The biological actions of extracellular nucleotides are exerted via two families of P2 receptors, P2X and P2Y. The metabotropic P2Y receptors comprise at least 7 distinct subtypes, which have been cloned from a number of species. However, none of the P2Y receptor proteins have been visualised yet in human brain. In the present study, the regional and cellular distribution of the P2Y(1) receptor was investigated in the human brain by using immunohistochemistry. Polyclonal antibodies were raised against a synthetic peptide from the C-terminus of the P2Y(1) protein. Immunoblot analysis demonstrated that P2Y(1) antiserum specifically recognised a 63-kDa band in human and rat brain membranes. Similarly, the antiserum specifically detected the human P2Y(1) receptor in transfected 1321N1 cells. Immunohistochemical analysis on perfusion-fixed human brain tissue showed a widespread distribution for this receptor throughout the brain. At the cellular level, the P2Y(1) receptor was strikingly localised to neuronal structures of the cerebral cortex, cerebellar cortex, hippocampus, caudate nucleus, putamen, globus pallidus, subthalamic nucleus, red nucleus, and midbrain. Expression of the P2Y(1) receptor was not detected in other non-neuronal cell types. These results provide the first characterisation of the cellular distribution of a P2Y receptor in the human brain. The widespread and abundant distribution of the P2Y(1) receptor suggests its involvement in a number of important functions within the human brain. The neuronal localisation of this receptor points towards a possible role in neurotransmission, and also highlights a major role for extracellular nucleotides as signaling molecules within the brain.

Animals↗
PubMed2000

Heterozygous MDR3 missense mutation associated with intrahepatic cholestasis of pregnancy: evidence for a defect in protein trafficking.

Intrahepatic cholestasis of pregnancy (ICP) is a liver disease of pregnancy with serious consequences for the mother and fetus. Two pedigrees have been reported with ICP in the mothers of children with a subtype of autosomal recessive progressive familial intrahepatic cholestasis (PFIC) with raised serum gamma-glutamyl transpeptidase (gamma-GT). Affected children have homozygous mutations in the MDR3 gene (also called ABCB4 ), and heterozygous mothers have ICP. More frequently, however, ICP occurs in women with no known family history of PFIC and the genetic basis of this disorder is unknown. We investigated eight women with ICP and raised serum gamma-GT, but with no known family history of PFIC. DNA sequence analysis revealed a C to A transversion in codon 546 in exon 14 of MDR3 in one patient, which results in the missense substitution of the wild-type alanine with an aspartic acid. We performed functional studies of this mutation introduced into MDR1, a closely related homologue of MDR3. Fluorescence activated cell sorting (FACS) and western analysis indicated that this missense mutation causes disruption of protein trafficking with a subsequent lack of functional protein at the cell surface. The demonstration of a heterozygous missense mutation in the MDR3 gene in a patient with ICP with no known family history of PFIC, analysed by functional studies, is a novel finding. This shows that MDR3 mutations are responsible for the additional phenotype of ICP in a subgroup of women with raised gamma-GT.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed2000

Does the multidimensional nature of Super Profiles help district health authorities understand the way social capital affects health?

BACKGROUND: Social capital describes the notion that the social processes in an area can lead to benefits in health. As Super Profiles describe the social character of an area and they are easy for health authorities to use, they could provide a simple method for local assessment of how social organization affects health. METHODS: We calculated the expected mean birthweight for the enumeration districts of Birmingham based upon marital status, registration details of the child, year of birth, the mother's country of birth, fetal sex and deprivation as judged by the Townsend score using data from 138,696 live-born singleton births for the years 1986-1996 inclusive. We classified enumeration districts into Target Markets, derived from Super Profiles. For each Target Market, we calculated the observed mean birthweight and the difference and 95 per cent confidence interval between the observed and expected birthweights. We used information in Super Profiles to speculate about the social processes that led to some Target Markets having mean birthweights that were significantly different from those expected. RESULTS: Fifteen of the 40 Target Markets had significant differences between predicted and observed mean birthweight, but these differences were less than 50 g. There were no common characteristics of Target Markets that were consistently advantageous for birthweight and none that were disadvantageous. CONCLUSION: The information in the Super Profiles does not illuminate the way that social processes affect health, and the variation in mean birthweight between areas explained by social processes as measured by Super Profiles is small.

Birth Certificates↗