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M Davies

Publications and source records attributed to M Davies.

At least 145 records · Page 8Linked to original sources
PubMed1998

A sensitive and robust method for measles RNA detection.

The aim of this study was to compare measles RNA amplification methods and to develop and select the most rapid, sensitive and robust procedure. The use of hybrid capture for measles RNA isolation was evaluated, and three RNA amplification detection techniques were compared. These were: (a) reverse transcription followed by nested polymerase chain reaction (RT-PCR) with MMLV reverse transcriptase and Taq polymerase; (b) a combined RT-PCR reaction using rTth polymerase; and (c) NASBA. An internal positive control was also developed. The sensitivities of the detection methods were quantified by using a dilution series of a known amount of total RNA from measles-infected Vero cells or by calculation of the number of transcript molecules (produced from a recombinant plasmid containing an insert measles nucleoprotein DNA) present in each amplification reaction, respectively. The results indicated that hybrid capture followed by combined RT-PCR with rTth polymerase was the most reproducibly robust and sensitive protocol and could detect as few as 10(4) synthetic measles RNA transcripts added to tissue homogenates. However, NASBA proved to be the most sensitive method for measles RNA detection in water.

Animals↗
PubMed1998

Signal pathways that transduce growth factor-stimulated mitogenesis in bone cells.

This investigation examined which signal pathways are of relevance in growth factor-stimulated bone cell mitogenesis. Platelet-derived growth factor (PDGF) and insulin-like growth factor-II (IGF-II) were potent mitogens for both the MG-63 osteoblast cell line and for primary cultures of human osteoblasts (HObs). The mitogenic action of both IGF-II and PDGF was attenuated by pertussis toxin (Ptx), by indomethacin, and by the lipoxygenase inhibitors BW755C74 and BW4AC. A combination of Ptx and indomethacin caused much greater inhibition but failed to abolish mitogenesis completely. PDGF significantly elevated inositol phosphates levels in both cell types; IGF-II had no effect on this pathway. In MG-63 cells, we demonstrated tyrosine phosphorylation of high-molecular-weight substrates elicited by both PDGF and IGF-II. Genistein inhibited the phosphorylation and mitogenic response to PDGF, but had no effect on IGF-II-induced tyrosine phosphorylation or mitogenesis. Another inhibitor of tyrosine kinases, methyl 2,5-dihydroxycinnamate, (MDHC), inhibited PDGF-stimulated mitogenesis effectively in both cell types but only blocked IGF-II-induced mitogenesis in MG-63 cells. The specificity of these inhibitors suggests that particular tyrosine kinases may regulate growth factor-induced stimulation of bone cells.

Cell Division↗
PubMed1998

Detection of canine distemper virus in 100% of Paget's disease samples by in situ-reverse transcriptase-polymerase chain reaction.

Previous evidence implicating paramyxoviruses in the aetiopathology of Paget's disease of bone has been controversial. While several groups have demonstrated the presence of paramyxoviruses using electron microscopy, immunohistochemistry, and molecular biological techniques, others have found no evidence of viruses using reverse transcriptase-polymerase chain reaction (RT-PCR). We have previously provided evidence that canine distemper virus (CDV) is present in approximately 65% of samples of pagetic bone, using in situ hybridization and RT-PCR; however, these results have been criticized. To further investigate the possible Role of CDV, we have now developed the technique of in situ-RT-PCR (IS-RT-PCR) to examine for the presence of CDV-nucleocapsid (CDV-N) ribonucleic acid (RNA) in pagetic bone. Control samples consisted of uninvolved sites from patients with the disease, normal bone, and several active remodeling states. IS-RT-PCR was optimized to detect CDV-N using distemper-infected vero cells. The specificity of the technique was confirmed using vero cells infected with CDV, which showed amplified signal following IS-RT-PCR, and cells infected with measles virus (MV), in which no positive signal for CDV was detected by IS-RT-PCR. Following conventional in situ hybridization, CDV-N was detectable in 10 of 15 pagetic bone samples. However, after five, and particularly 10, cycles of IS-RT-PCR, CDV-N was found in all 15 samples. There was no evidence of CDV in four samples from uninvolved sites from pagetic patients, or in any of the other control samples. In this study, using the novel technique of IS-RT-PCR, CDV was found to be present in 100% of pagetic samples examined. There was no evidence of the virus in any of the control samples, including samples of bone from uninvolved sites from patients with Paget's disease. These results provide additional proof that CDV is present within pagetic bone and further support the hypothesis that paramyxoviruses are involved in the etiopathology of Paget's disease.

Animals↗
PubMed1998

Emotional intelligence: in search of an elusive construct.

The view that emotional intelligence should be included within the traditional cognitive abilities framework was explored in 3 studies (total N = 530) by investigating the relations among measures of emotional intelligence, traditional human cognitive abilities, and personality. The studies suggest that the status of the emotional intelligence construct is limited by measurement properties of its tests. Measures based on consensual scoring exhibited low reliability. Self-report measures had salient loadings on well-established personality factors, indicating a lack of divergent validity. These data provide controvertible evidence for the existence of a separate Emotion Perception factor that (perhaps) represents the ability to monitor another individual's emotions. This factor is narrower than that postulated within current models of emotional intelligence.

Adolescent↗
PubMed1998

Community care for adults with Williams syndrome: how families cope and the availability of support networks.

A study of the adjustment difficulties and needs of 70 adults with Williams syndrome found that the majority continued to live at home and remained heavily dependent on their families for their self-care. Twenty-nine families (41.4%) had had no contact with a social worker in the preceding 2 years, and 34 out of the 48 families whose children still lived at home (70.8%) had no access to respite care. Advice regarding benefits, and appropriate living and occupational arrangements for the adults was also patchy. Despite progressive medical problems, and high rates of behavioural and emotional difficulties, only 20 adults (29%) were receiving regular health checks, while 21 (30%) had had some contact with a mental health service in the preceding 2 years. In the majority of cases, families continued to shoulder the main burden of care for their sons and daughters with Williams syndrome well into adulthood, with little support from statutory and voluntary agencies. The implications of these findings are considered with regard to the principles of community care.

Adaptation, Psychological↗
PubMed1998

Structural requirements for ligand interactions at the benzodiazepine recognition site of the GABA(A) receptor.

His101 of the GABA(A) receptor alpha1 subunit is an important determinant of benzodiazepine recognition and a major site of photolabeling by [3H]flunitrazepam. To investigate further the chemical specificity of the residue in this position, we substituted it with phenylalanine, tyrosine, lysine, glutamate, glutamine, or cysteine. The mutant alpha subunits were coexpressed with the rat beta2 and gamma2 subunits in TSA201 cells, and the effects of the substitutions on the binding of benzodiazepine site ligands were examined. [3H]Ro 15-4513 bound to all mutant receptors with equal or greater affinity than to the wild-type receptor. However, flunitrazepam and ZK93423 recognition was adversely affected by substitutions of the amino acid in this position. The binding of the antagonists, Ro 15-1788 and ZK93426, was also sensitive to the mutations, with the largest decreases in affinity occurring with the tyrosine, lysine, and glutamate substitutions. In all mutants that recognized flunitrazepam, GABA potentiated the binding of this ligand to a similar extent, suggesting that it is a full agonist at these receptors. The effects of GABA on the binding of Ro 15-1788 and Ro 15-4513 suggest that their efficacies may have been changed by some of the substitutions. This study further emphasizes the importance of the residue at position 101 in both ligand recognition and pharmacological effect.

Allosteric Site↗
PubMed1998

Response of the human peritoneal mesothelial cell to injury: an in vitro model of peritoneal wound healing.

BACKGROUND: The denudation of the peritoneal mesothelium and damage to the underlying interstitium is a frequent finding in patients receiving continuous ambulatory peritoneal dialysis as a treatment for end-stage renal failure. The response of the mesothelium to injury from repeated episodes of infection or from exposure to dialysis fluids has not been extensively studied. The present study describes a simple and reproducible method with which to investigate the response of human mesothelial cells to injury. METHODS: The model of peritoneal injury consists of mechanically wounding a monolayer of human peritoneal mesothelial cells with a glass probe and following the repopulation of the denuded area by time-lapse photomicroscopy. In addition immunohistochemistry was used to follow the response of marker proteins for stress fibers and focal adhesions as well as macromolecules associated with the extracellular matrix. RESULTS: Under serum-free conditions the wound (0.58 +/- 0.094 mm; mean +/- SD; N = 20) closed within 72 +/- 5 hours (N = 8). This rate of healing was enhanced by fetal calf serum, by human serum (10%) and by undiluted spent non-infected dialysate. The repair process over the first 48 hours was the result of cell migration, was independent of cell proliferation and involved the de novo synthesis of several different extracellular matrix components. An early event in the healing process was the rapid reorganization of intracellular stress fibers together with the formation of associated focal adhesions in cells at the wound edge. CONCLUSION: This in vitro model should prove invaluable in characterizing the process of wound healing within the peritoneal cavity, thus allowing a better understanding of the response to infection as well as any effect of dialysis fluids in this pattern of cell behavior.

Blood Physiological Phenomena↗
PubMed1998

Long-term (5 year) effects of transient (silent) ischaemia on left ventricular systolic function in stable angina. Clinical and radionuclide study.

AIMS: (a) to assess short (1 year) and long-term (5 year) changes in left ventricular ejection fraction in patients with stable coronary disease with or without ECG evidence of transient ischaemia during daily life on routine therapy, and (b) to assess whether patients with recurrent transient ischaemic episodes have a particular propensity to gradual deterioration in left ventricular ejection fraction in the absence of infarction. METHODS AND RESULTS: One hundred and forty eight patients (127 males; mean age 59 years), part of a natural history cohort of 172 patients who had undergone exercise testing, 48 h ambulatory ST monitoring, and resting radionuclide ventriculography at baseline, and who had not suffered any intervening cardiac event, underwent repeat radionuclide ventriculography at 1 year follow-up on identical or very similar medications. Furthermore, 56 patients (50 males; mean age 65 years) of this cohort, who had ischaemia both on exercise testing and ambulatory monitoring at baseline (n=33), or no ischaemia on either test at baseline (n=23), and who had suffered no intervening event, underwent repeat exercise testing, ambulatory monitoring and radionuclide ventriculography at a mean of 61.8 months follow-up. In 38 of these 56 cases, long-term testing mirrored baseline testing in terms of presence or absence of ischaemia (both tests +, n=25; both tests -, n=13). At one year there was no change in left ventricular ejection fraction, either for the whole group (n=148; left ventricular ejection fraction 47=11.6% - 47.13+11.07%, P=ns) or for subgroups with (n=62; left ventricular ejection fraction 48+12.1%-48.5+10.5%, P=ns) and without (n=86; left ventricular ejection fraction 46.2+10.4%-46.2+11.3%, P=ns) evidence of transient ischaemia at baseline. At 61 months, there was a small fall in mean left ventricular ejection fraction for the total study group (n=56; left ventricular ejection fraction 45.8+9.3%-42.1+8.8%, P<0.05); however, this fall was not significant for those patients with both baseline and 5 year evidence of transient ischaemia (n=25; left ventricular ejection fraction 44.9+8.7%-41.3+7.5%, P=0.056). CONCLUSION: In medically treated stable coronary patients who do not suffer any intervening cardiac event, recurrent transient (silent) ischaemic episodes do not, in themselves, lead to gradual deterioration in left ventricular systolic function over a 1-5 year period.

Adult↗
PubMed1998

Matrix metalloproteinase expression during experimental autoimmune neuritis.

Experimental autoimmune neuritis (EAN) is an animal model of Guillain-Barré syndrome. We have shown recently that BB-1101, a broad-spectrum matrix metalloproteinase (MMP) inhibitor, prevents development of EAN when given from the day of immunization and, more important clinically, reduces disease severity when given from symptom onset. This suggests the involvement of MMP activity in the pathogenesis of EAN. However, the exact function and expression patterns of MMPs in acute inflammation of the PNS have not been investigated. MMP-like enzymes are also involved in the processing of tumour necrosis factor-alpha (TNF-alpha), which has been implicated previously in the pathology associated with EAN. In the present study we investigated the profile of MMP and TNF-alpha expression and their localization in sciatic nerve tissue during EAN, using a semiquantitative competitive reverse transcriptase-coupled polymerase chain reaction and immunohistochemistry. In the normal rat PNS, four of the 10 MMPs studied were constitutively expressed and four MMPs were differentially regulated during EAN. Expression of TNF-alpha was elevated at peak disease severity and localized to Schwann cells, macrophages and endoneurial blood vessels. Expression levels of 92 kDa gelatinase and stromelysin-1 were significantly increased early in the development of EAN and continued to rise, peaking at day 15 coincident with maximum disease severity. Schwann cells and endothelial cells were the main cellular source of these enzymes. Prominent infiltration of inflammatory cells into the sciatic nerve was concordant with a significant increase in the expression levels of matrilysin and macrophage metalloelastase. Both matrilysin and macrophage metalloelastase were detected in invading macrophages, T lymphocytes and resident Schwann cells. The selective upregulation of specific MMPs during EAN and their varied cellular localization suggests that MMPs play a multifactorial role in the aetiology of EAN. Activity of MMPs could participate in the disruption of the blood-nerve barrier, breakdown of the myelin sheath, the release of TNF-alpha, and facilitate leukocyte invasion into the PNS. These observations highlight MMPs as potential targets for therapeutic intervention in acute peripheral neuropathies, such as Guillain-Barré syndrome.

Animals↗
PubMed1998

Parent-victim agreement in adolescent suicide research.

OBJECTIVE: The necessary absence of the victim's report in psychological autopsy studies is likely to introduce a systematic reporting bias. The authors investigated the nature and extent of this bias by examining agreement between accounts of symptomatology given by adolescents who made a serious suicide attempt and their parents. METHOD: Fifty-two attempters younger than age 20 were matched individually on age, sex, and ethnicity to a sample of suicide completers in two previous investigations. A semistructured interview was used to assess symptoms for DSM-III disorders. Diagnoses were assigned using two distinct computer algorithms, based respectively on youth and parent informant reports. Kappa values were estimated for each diagnostic category and related symptoms. RESULTS: Highest rates of parent-youth agreement were found for substance abuse and disruptive disorders. Rates of conduct disorder (nonaggressive) and major depression were reported less frequently by parents relative to their children. At the symptom level, parents less frequently reported Gets drunk and Frequency of drinking. CONCLUSIONS: Psychological autopsy studies of adolescent suicide are likely to underestimate the prevalence of psychiatric disorders in general and major depression and alcohol abuse in particular. These risk factors may be more predictive than previously thought.

Adolescent↗
PubMed1998

Adverse life events and resilience.

OBJECTIVE: Adverse life events are well-documented risk factors of psychopathology and psychological dysfunction in children and adolescents. Youth with good adjustment despite high levels of adverse life events are considered resilient. This study identifies factors that characterize resilience. METHOD: Household probability samples of youth aged 9 through 17 years at four sites were used. Main and interaction effects of 11 factors were examined to assess their impact on youth adjustment. RESULTS: Children at risk because of higher levels of adverse life events exhibited a greater degree of resilience when they had a higher IQ, better family functioning, closer parental monitoring, more adults in the household, and higher educational aspiration. The interaction between maternal psychopathology and adversity was significant, and the interaction between IQ and adversity approached significance. CONCLUSION: Resilient youth received more guidance and supervision by their parents and lived in higher-functioning families. Other adults in the family probably complemented the parents in providing guidance and support to the youth and in enhancing youth adjustment. Higher educational aspirations might have provided high-risk youth with a sense of direction and hope. Although IQ had no impact in youth at low risk, youth at high risk who had a higher IQ might have coped better.

Adaptation, Psychological↗
PubMed1998

Fetal transplants rescue axial muscle representations in M1 cortex of neonatally transected rats that develop weight support.

Fetal transplants rescue axial muscle representations in M1 cortex of neonatally transected rats that develop weight support. J. Neurophysiol. 80: 3021-3030, 1998. Intraspinal transplants of fetal spinal tissue partly alleviate motor deficits caused by spinal cord injury. How transplants modify body representation and muscle recruitment by motor cortex is currently largely unknown. We compared electromyographic responses from motor cortex stimulation in normal adult rats, adult rats that received complete spinal cord transection at the T8-T10 segmental level as neonates (TX rats), and similarly transected rats receiving transplants of embryonic spinal cord (TP rats). Rats were also compared among treatments for level of weight support and motor performance. Sixty percent of TP rats showed unassisted weight-supported locomotion as adults, whereas approximately 30% of TX rats with no intervention showed unassisted weight-supported locomotion. In the weight-supporting animals we found that the transplants enabled motor responses to be evoked by microstimulation of areas of motor cortex that normally represent the lumbar axial muscles in rats. These same regions were silent in all TX rats with transections but no transplants, even those exhibiting locomotion with weight support. In weight-supporting TX rats low axial muscles could be recruited from the rostral cortical axial representation, which normally represents the neck and upper trunk. No operated animal, even those with well-integrated transplants and good weight-supported locomotion, had a hindlimb motor representation in cortex. The data demonstrate that spinal transplants allow the development of some functional interactions between areas of motor cortex and spinal cord that are not available to the rat lacking the intervention. The data also suggest that operated rats that achieve weight support may primarily use the axial muscles to steer the pelvis and hindlimbs indirectly rather than use explicit hindlimb control during weight-supported locomotion.

Animals↗
PubMed1998

Relation between depression and circulating immune products in patients with advanced colorectal cancer.

We have previously suggested that colorectal liver metastases might produce 'toxins' that reduce both quality of life (QoL) and survival. In this study we assessed whether QoL in patients with such metastases was related to immune activation, as determined by increased serum levels of interleukin 6 (IL6), soluble tumour necrosis factor receptor 1 (sTNFr1), soluble interleukin 2 receptor alpha (sIL2r alpha) or the interferon-gamma marker neopterin. Serum IL6, sTNFr1, sIL2r alpha, neopterin, alkaline phosphatase and carcinoembryonic antigen levels, liver metastasis volume, and QoL (Hospital Anxiety and Depression [HAD] scale, Rotterdam Symptom Checklist [RSC], and Sickness Impact Profile [SIP]) were measured in 43 patients. There were significant positive correlations between serum sIL2r alpha and HAD depression score (r = 0.66, P = 0.0001), RSC physical symptom score (r = 0.46, P < 0.01), and SIP score (r = 0.47, P = 0.009). Multiple regression analysis suggested that serum sIL2r alpha level was a significant independent predictor of HAD depression score. Although survival was shorter (logrank test P < 0.05) where sIL2r alpha, sTNFr1 and IL6 levels were higher, the ability of sIL2r alpha to predict HAD depression score was independent of survival.

Aged↗
PubMed1998

Cough and sleep in inner-city children.

This study aimed to determine whether cough at night keeps children awake, to describe the relationship between children's cough and sleep and to report parents' perceptions of their children's cough and sleep. Thirty-nine children with reported persistent cough at night (>3 weeks) were recruited and studied for 6 nights by video-recording. Coughs were counted and sleep state was coded for awake, restless sleep and quiet sleep. The relationships between cough and sleep state between subjects and within subjects were examined by correlation and regression. After night 2 the parents were asked whether their child had coughed or had disturbed sleep and after night 6 they were asked whether there had been any change. There was a weak relationship between log percentage of the night awake and log number of coughs (r=0.13, SE 0.036), and log (percentage of the night awake plus restless sleep) and log number of coughs (r=0.016, SE 0.0071). If the relationship between cough and sleep state is causal, halving the number of coughs will reduce the percentage of the night awake by 9% (95% confidence interval (CI) 4-15%) and percentage awake and restless by 1% (95% CI 0-2%). All but one parent correctly identified coughing and 82% detected change. Most could not comment on their child's sleep. Improvement in cough would result in little reduction in either the percentage of the night awake or awake and restless in the average child in the population studied. Parents could detect whether their children were coughing but not whether their sleep was disturbed.

Asthma↗
PubMed1998

Adults with Williams syndrome. Preliminary study of social, emotional and behavioural difficulties.

BACKGROUND: In recent years there has been an upsurge of interest in the study of distinctive patterns of behavioural and psychological characteristics associated with specific, biologically determined, intellectually disabling conditions. This study investigates whether such a profile can be identified in adults with Williams syndrome. METHOD: Parents and other care-givers were interviewed about the social, emotional and behavioural characteristics of 70 adults with Williams syndrome, aged 19 years to 39 years 9 months. RESULTS: The adults were reported to have high rates of behavioural and emotional difficulties, particularly in terms of poor social relationships, over-friendliness and social disinhibition, preoccupations and obsessions, and high levels of anxiety and distractibility. CONCLUSIONS: The findings provide preliminary support for the existence of a specific pattern of behavioural and personality characteristics and associated difficulties in adults with Williams syndrome, which persist from childhood and often require intervention from mental health professionals. Implications for clinical practice are considered.

Adolescent↗
PubMed1998

Unique 24-hydroxylated metabolites represent a significant pathway of metabolism of vitamin D2 in humans: 24-hydroxyvitamin D2 and 1,24-dihydroxyvitamin D2 detectable in human serum.

We have produced evidence for a new metabolic pathway for vitamin D2 in humans involving the production of 24-hydroxyvitamin D2 (24OHD2) and 1,24-dihydroxyvitamin D2 [1,24-(OH)2D2]. These metabolites were produced after either a single large dose (10(6) IU) of vitamin D2 or repeated daily doses between 10(3) and 5 x 10(4) IU. We developed assay systems for the metabolites in human serum and showed that in some chronically treated patients, the concentration of 1,24-(OH)2D2 equalled that of 1,25-(OH)2D2 at about 100 pmol/L. The metabolites were identified by high performance liquid chromatography with diode array spectrophotometry for 24OHD2 and by high resolution gas chromatography-mass spectrometry for 1,24-(OH)2D2. We show that 1,24-(OH)2D2 synthesis can be stimulated by PTH, indicating a renal origin for this metabolite and postulate that it is formed from 24OHD2, which may be synthesized in liver. We conclude from this study that vitamin D2 gives rise to two biologically active products, 1,24-(OH)2D2 and 1,25-(OH)2D2, and that 1,24-(OH)2D2 could be an attractive naturally occurring analog of 1,25-(OH)2D3 for clinical use.

Chromatography, High Pressure Liquid↗
PubMed1998

Scaling of intrinsic contractile properties and myofibrillar protein composition of fast muscle in the fish myoxocephalus scorpius L

Contractile properties were determined for fast muscle fibres from short-horn sculpin (Myoxocephalus scorpius L.) ranging from 5 to 35 cm total body length (L) and from 2.0 to 758 g body mass. Maximum unloaded shortening velocity (V0) decreased with increasing body size, scaling as 19.5L-0.34, and isometric twitch activation and tetanus relaxation times became longer, scaling as 12.0L0.31 and 19. 5L0.42 respectively. Myofibrillar Mg2+/Ca2+-ATPase activity scaled as 2.51L-0.28. In order to investigate the mechanisms underlying the scaling of contractile properties, myofibrillar protein composition and I filament lengths were determined. One-dimensional SDS-PAGE and two-dimensional isoelectric focusing/non-equilibrium isoelectric focusing-PAGE revealed no differences in the myofibrillar protein isoforms of myosin light chains, actin, tropomyosin, troponin-T and troponin-C in fish of differing body size. Peptide maps of purified myosin heavy chains digested with eight different proteolytic enzymes were also similar in all fish examined. Three isoforms of troponin-I were present in fish less than 20 cm in total length with relative molecular masses of 17 (TnIf3), 22 (TnIf2) and 23 (TnIf1). The ratio of TnI isoforms varied with body length, and only TnIf3 was present in fish greater than 28 cm total length. The length of I filaments was independent of body length. Thus, although the expression of TnI isoforms changes during growth, the underlying mechanism responsible for increased shortening velocity with decreased body size remains unknown.

Journal Article↗