Biomedical subjects

G Pearson

Publications and source records attributed to G Pearson.

At least 19 recordsLinked to original sources

PubMed2002

The effect of Nd:YAG radiation at nanosecond pulse duration on dentine crater depth.

The effect of laser parameters on laser-dentine interaction is little known. The aim of this in vitro study was to determine the effect on dentine crater depth of Nd:YAG laser radiation in relation to pulse repetition rate, total delivered energy, dentine site and the presence or absence of a dye. One hundred and forty-four sound third molars were extracted and sectioned transversely to provide 288 upper and lower cut surfaces. The upper surfaces were painted with a layer of dye (IR5) suitable for absorption at 1064 nm. The specimens were divided into 12 sub-groups each containing 12 upper and 12 lower specimens. These were exposed to a Nd:YAG laser with a 30 nanosecond (ns) pulse duration. This laser operated in a non-contact mode (spot diameter 165 microm) with pulse repetition rates of 2.5, 5.4 and 10.5 Hz. Four total energies were delivered at each repetition rate; 2.3, 3.63, 3.96, 4.29 joule (J) at 2.5 Hz repetition rate; 2.3, 2.64, 3.63, 4.29 J at 5.4 and 10.5 Hz repetition rates. Five outer and three inner sites were irradiated on each specimen. Each dentine crater depth was measured five times using a Reflex Microscope and a three-dimensional centre of gravity derived. An upper and lower specimen were taken from each sub-group and viewed under a scanning electron microscope (SEM). ANOVA was applied: total delivered energy and dyed/undyed were found to have a statistically significant effect on crater depth (p<0.0001). In general increasing energy and the presence of dye produced deeper craters. Inner/outer dentine location and repetition rate were not found to be statistically significant. All craters were carbonised.

Dentin↗

PubMed2002

Rationale and cost-efficiency compared for urine or saliva testing and behavioural inquiry among UK offender populations: injectors, arrestees and prisoners.

BACKGROUND: Costs, methodology and efficiency at obtaining behavioural information and biological sample to be tested for blood-borne viruses or illegal drugs are compared for UK surveys of offender populations: injectors in the community or attending drug agencies, arrestees and prisoners. METHODS: Arrestee surveys use extensive behavioural interview + urine sample and measure a key performance indicator in UK's Drugs Strategy. They have low efficiency (urine sample for drugs testing available from under 60% of eligible arrestees) at high cost (pound sterling 110-190 or 350 per urine sample and at least pound sterling 500-800 per injector). Random mandatory drugs testing of prisoners has the highest efficiency (because refusals are punishable), but the cost is high (pound sterling 110-120 per urine sample and pound sterling 300-500 per injector) and behavioural data are lacking. Prisoner surveys use self-completion questionnaire + saliva sample. They guarantee demonstrable anonymity in estimating the prevalence of blood-borne viruses and prisoners' associated risk behaviours, have high efficiency (saliva sample from over 80% of inmates) at low cost (pound sterling 30 per saliva and pound sterling 70-110 per injector), but behavioural data are limited to risk factors for blood-borne viruses. Low cost also characterises comprehensive interview + saliva sample from injectors in the community (pound sterling 90 per saliva sample, all from injectors) but efficiency cannot be assessed because the sampling frame of eligible injectors is not known. Voluntary unlinked anonymous surveys of injectors at drug agencies use self-completion questionnaire + saliva sample to be tested for blood-borne viruses. They are the least costly at pound sterling 43 per injector and moderately efficient with two-thirds volunteer rate by eligible injectors. DISCUSSION: For scientific added-value, we recommend co-location of survey types geographically and temporally; a common core set of behavioural questions; saliva sample as well as (and, eventually, instead of) the less acceptable urine sample. Survey methodologies for measuring key performance indicators should stand up to scrutiny in terms of openness, design credentials, statistical power, and costs. We examine how participation bias or inadequate survey size can compromise the effective monitoring of a key performance indicator.

Cost-Benefit Analysis↗

PubMed2001

A reduction in interstitial cells of Cajal in horses with equine dysautonomia (grass sickness).

Equine dysautonomia (grass sickness) is a common, frequently fatal disease of horses characterised by dysfunction of the gastrointestinal tract. Interstitial cells of Cajal are the c-Kit-immunoreactive cells responsible for the generation of pacemaker activity in gastrointestinal smooth muscle. Impairment of this pacemaker action has been implicated in several motility disorders in humans and laboratory mammals. The aim of this study was to test the hypothesis that changes in interstitial cells of Cajal may be involved in the pathophysiology of the intestinal dysfunction observed in equine grass sickness. Interstitial cells of Cajal were identified using immunohistochemical labelling with an anti-c-Kit antibody and their density was assessed using a semi-quantitative grading system. Segments of ileum were examined from 24 horses free from gastrointestinal disease and compared to tissues from 28 horses with grass sickness. Segments of the pelvic flexure region of the large colon were examined from 13 horses free from gastrointestinal disease and compared to tissues from 10 horses with grass sickness. In horses with grass sickness, interstitial cells of Cajal were significantly decreased in both the myenteric plexus and circular muscle regions of both ileum and pelvic flexure compared to normal animals. Therefore, it is possible that the decline in interstitial cells of Cajal may be an important factor in the development of intestinal dysmotility observed in grass sickness.

Acute Disease↗

PubMed2001

Activated MEK5 induces serial assembly of sarcomeres and eccentric cardiac hypertrophy.

Mitogen-activated protein kinase (MAPK) pathways couple intrinsic and extrinsic signals to hypertrophic growth of cardiomyocytes. The MAPK kinase MEK5 activates the MAPK ERK5. To investigate the potential involvement of MEK5-ERK5 in cardiac hypertrophy, we expressed constitutively active and dominant-negative forms of MEK5 in cardiomyocytes in vitro. MEK5 induced a form of hypertrophy in which cardiomyocytes acquired an elongated morphology and sarcomeres were assembled in a serial manner. The cytokine leukemia inhibitory factor (LIF), which stimulates MEK5 activity, evoked a similar response. Moreover, a dominant-negative MEK5 mutant specifically blocked LIF-induced elongation of cardiomyocytes and reduced expression of fetal cardiac genes without blocking other aspects of LIF-induced hypertrophy. Consistent with the ability of MEK5 to induce serial assembly of sarcomeres in vitro, cardiac-specific expression of activated MEK5 in transgenic mice resulted in eccentric cardiac hypertrophy that progressed to dilated cardiomyopathy and sudden death. These findings reveal a specific role for MEK5-ERK5 in the induction of eccentric cardiac hypertrophy and in transduction of cytokine signals that regulate serial sarcomere assembly.

Animals↗

PubMed2001

Changes in the profile of paediatric intensive care associated with centralisation.

OBJECTIVES: To compare intensive care admissions from a defined population of children in 1991 and 1999, during a period of organisational change and centralisation of paediatric intensive care. DESIGN: Two 12-month population-based audits were compared. Data were collected from hospitals in Birmingham and the surrounding districts. Denominator data were obtained from the Office for National Statistics. The place and rate of intensive care admission, the use of mechanical ventilation at admission, mortality and length of stay were compared. SETTING: Hospitals in the West Midlands. PARTICIPANTS: All children (<15 yrs) living in Birmingham who received intensive care during the study periods. MEASUREMENTS AND RESULTS: The number of Birmingham resident children admitted for intensive care increased from 277 to 510 (p<0.0001) i.e. from 1.3 to 2.3 admissions per 1,000 children per year. The proportion of admissions to the principal paediatric intensive care unit increased from 60% to 90% (p<0.0001) in association with its expansion from 6 to 18 beds. Length of ICU stay decreased from 103 to 74 h (difference 29 h, 95%CI, 4.78-54.2 h, p=0.0117). Child mortality fell over this period by 34 deaths per 100,000 children (95%CI 16-51, p<0.0001). The proportion of children requiring mechanical ventilation at admission to intensive care was unchanged. CONCLUSIONS: Centralisation by expansion of the lead centre was associated with a large increase in the numbers of children receiving intensive care consistent with an unmet need for paediatric intensive care in 1991, which may still exist. Centralisation of paediatric intensive care may have contributed to the fall in child mortality over this time period.

Bed Occupancy↗

PubMed2001

The effect of Nd:YAG pulse duration on dentine crater depth.

OBJECTIVES: The effect of alteration of laser parameters on laser-dentine interaction, in particular the effect of pulse duration, has not been well documented. The aim of this in vitro study was to determine the effect on dentine crater depth of Nd:YAG laser pulse duration, and total delivered energy, dentine site and the presence or absence of dye. METHODS: Ninety-six sound third molars were extracted and sectioned transversely to provide 192 upper and lower cut surfaces. The upper surfaces were painted with a layer of dye (IR5) suitable for absorption at 1064 nm. The specimens were divided into 16 sub-groups and exposed to two Nd:YAG lasers; one of pulse duration 7 ms and the second of pulse duration 35 ps. Both lasers operated in a non-contact mode (spot diameter 165 microm) with repetition rates of 10.5 and 10 Hz, respectively. Four total energies (2.28, 2.64, 3.6, 4.2 J) were delivered to eight dyed and eight undyed sub-groups. Eight outer and five inner sites were irradiated on each specimen. Dentine crater depth was measured five times using a Reflex Microscope and a three-dimensional centre of gravity derived. An upper and lower specimen were taken from each sub-group and viewed under a SEM. RESULTS: ANOVA and multiple regression analysis were applied and the following factors were found to have a statistically significant effect on crater depth (p<0.0001): total delivered energy, pulse duration and inner/outer location. CONCLUSIONS: Increasing energy and pulse duration produced deeper craters. Similarly inner dentine sites produced deeper crater depths. Only craters produced at the ms pulse duration were carbonised. It would appear that laser-dentine interaction has a non-thermal component at picosecond pulse duration.

Analysis of Variance↗

PubMed2001

MAP kinases.

Explore the source record for details and available documents.

Mitogen-Activated Protein Kinases↗

PubMed2001

Normal drug use: ethnographic fieldwork among an adult network of recreational drug users in inner London.

A key debate in late 1990s Britain is the "normalization" of illicit drug use among young people. This qualitative research study explores recreational drug use (mainly cannabis and cocaine) among an adult friendship network in an inner London neighborhood. It finds that the use of these drugs is accepted as a normal and routine aspect of daily life. In addition to patterns of drug consumption and drug dealing, some aspects of risk perception are also described. Adults are neglected in current UK drug policy debates. "Normal" adult recreational drug use poses the need for a new public health policy agenda for the new century.

Adult↗

PubMed2001

Mitogen-activated protein (MAP) kinase pathways: regulation and physiological functions.

Mitogen-activated protein (MAP) kinases comprise a family of ubiquitous proline-directed, protein-serine/threonine kinases, which participate in signal transduction pathways that control intracellular events including acute responses to hormones and major developmental changes in organisms. MAP kinases lie in protein kinase cascades. This review discusses the regulation and functions of mammalian MAP kinases. Nonenzymatic mechanisms that impact MAP kinase functions and findings from gene disruption studies are highlighted. Particular emphasis is on ERK1/2.

Animals↗

PubMed2001

Condom use by adolescents.

The use of condoms as part of the prevention of unintended pregnancies and sexually transmitted diseases (STDs) in adolescents is evaluated in this policy statement. Sexual activity and pregnancies decreased slightly among adolescents in the 1990s, reversing trends that were present in the 1970s and 1980s, while condom use among adolescents increased significantly. These trends likely reflect initial success of primary and secondary prevention messages aimed at adolescents. Rates of acquisition of STDs and human immunodeficiency virus (HIV) among adolescents remain unacceptably high, highlighting the need for continued prevention efforts and reflecting the fact that improved condom use can decrease, but never eliminate, the risk of acquisition of STDs and HIV as well as unintended pregnancies. While many condom education and availability programs have been shown to have modest effects on condom use, there is no evidence that these programs contribute to increased sexual activity among adolescents. These trends highlight the progress that has been made and the large amount that still needs to be accomplished.

Adolescent↗

PubMed2001

Care of the adolescent sexual assault victim.

Sexual assault is a broad-based term that encompasses a wide range of sexual victimizations, including rape. Since the American Academy of Pediatrics published its last policy statement on this topic in 1994, additional information and data have emerged about sexual assault and rape in adolescents, the adolescent's perception of sexual assault, and the treatment and management of the adolescent who has been a victim of sexual assault. This new information mandates an updated knowledge base for pediatricians who care for adolescent patients. This statement provides that update, focusing on sexual assault and rape in the adolescent population.

Adolescent↗

PubMed2000

ERK5 and ERK2 cooperate to regulate NF-kappaB and cell transformation.

We have previously demonstrated an involvement of MEK5 and ERK5 in RafBXB-stimulated focus formation in NIH3T3 cells. We find here that MEK5 and ERK5 cooperate with the RafBXB effectors MEK1/2 and ERK1/2 to induce foci. To further understand MEK5-ERK5-dependent signaling, we examined potential MEK5-ERK5 effectors that might influence focus-forming activity. Consistent with results from our focus-formation assays, constitutively active variants of MEK5 and MEK1 synergize to activate NF-kappaB, and MEK5 and ERK5 are required for activation of NF-kappaB by RafBXB. The MEK5-ERK5 pathway is also sufficient to activate both NF-kappaB and p90 ribosomal S6 kinase. Our results support the hypothesis that NF-kappaB and p90 ribosomal S6 kinase are involved in MEK5-ERK5-dependent focus formation and may serve as integration points for ERK5 and ERK1/2 signaling.

3T3 Cells↗

PubMed2000

Uncoupling Raf1 from MEK1/2 impairs only a subset of cellular responses to Raf activation.

The Raf family of serine/threonine protein kinases is intimately involved in the transmission of cell regulatory signals controlling proliferation and differentiation. The best characterized Raf substrates are MEK1 and MEK2. The activation of MEK1/2 by Raf is required to mediate many of the cellular responses to Raf activation, suggesting that MEK1/2 are the dominant Raf effector proteins. However, accumulating evidence suggests that there are additional Raf substrates and that subsets of Raf-induced regulatory events are mediated independently of Raf activation of MEK1/2. To examine the possibility that there is bifurcation at the level of Raf in activation of MEK1/2-dependent and MEK1/2-independent cell regulatory events, we engineered a kinase-active Raf1 variant (RafBXB(T481A)) with an amino acid substitution that disrupts MEK1 binding. We find that disruption of MEK1/2 association uncouples Raf from activation of ERK1/2, induction of serum-response element-dependent gene expression, and induction of growth and morphological transformation. However, activation of NF-kappaB-dependent gene expression and induction of neurite differentiation were unimpaired. In addition, Raf-dependent activation of p90 ribosomal S6 kinase was only slightly impaired. These results support the hypothesis that Raf kinases utilize multiple downstream effectors to regulate distinct cellular activities.

3T3 Cells↗

PubMed2000

An investigation of the diagnostic value of bilateral femoral neck bone mineral density measurements.

This paper describes a study to assess the clinical value of bilateral femoral neck bone mineral density (BMD) measurements. Although a range of factors will determine clinical decisions, the classification of the site with the lowest T-score is likely to have significant bearing on the management of a patient. While it is common practice to measure BMD at the lumbar spine and a single neck of femur, knowledge of the BMD of the second femur may also be of diagnostic value. Using dual-energy X-ray absorptiometry, BMD of the lumbar spine and right and left femoral neck was measured in a group of 2372 white, Caucasian women (mean age +/- SD, 56.6 +/- 13.9 years) routinely referred for bone densitometry. Analysis of the measurements showed a significant (p = 0.02) but small difference between the mean BMD of the right (0.840 +/- 0.152 g/cm2) and left (0.837 +/- 0.150 g/cm2) femoral neck. Further investigation of femur scans revealed 79 (3.3%) patients in whom one side was osteoporotic while the other side and spine were normal or osteopenic using the World Health Organization diagnostic criteria in combination with manufacturer's reference data. Patients in whom the femoral neck BMD measurements differed by less than the precision error of the system were then excluded. This left only 51 (2.2%) patients, that is 29 (1.2%) for right femur and spine scan and 22 (0.9%) for left femur and spine scan, in whom knowledge of both femoral neck BMD measurements could have altered the classification of the lowest site assessed to osteoporotic. These data suggest that there is only a small benefit from performing bilateral femoral neck BMD measurements. Since BMD measurements are only one of a range of factors considered as part of a patient's management, it is suggested that the extra time, cost and radiation dose associated with measurement of the second femur may not be justified.

Absorptiometry, Photon↗

PubMed2000

Use of Raman spectroscopy in the characterisation of the acid-base reaction in glass-ionomer cements.

Raman spectra of various combinations of glass-ionomer cement components have been compared with those of the reactants and the salts of polyacrylic and tartaric acids. The components consisted of a fast-setting acid-degradable dental glass (containing, inter alia, oxides of Si, Al, Ca, Ba and Na), polyacrylic acid (PAA) and/or tartaric acid (TA). On the addition of water to the glass and tartaric acid, Raman spectroscopy indicated loss of acid and production of tartrate salts within seconds of mixing. Mixtures containing the glass, PAA and water in mass ratios 2:1:(0.1-4) reacted to form polyacrylate salts. The maximum fraction of unreacted PAA was found to decrease linearly with initial water/PAA mass ratio to a minimum of approximately 20% when this ratio exceeds 1.5. The data are consistent with 5.6 moles of water being required when each mole of acidic groups is neutralised. In newly prepared cements containing glass, water, polyacrylic and tartaric acids, polyacrylic acid and its salts, in both ionised and solid state form, can be detected. After about 1 h, however, Raman peaks associated with ionised species disappear.

Acrylic Resins↗

PubMed2000

Ibuprofen versus other non-steroidal anti-inflammatory drugs: use in general practice and patient perception.

OBJECTIVE: To investigate whether ibuprofen was as well-regarded by patients as other non-steroidal anti-inflammatory drugs (NSAIDs). DESIGN: Questionnaire sent to 1137 consecutive recipients of an NSAID prescription from 21 doctors in six general practices with computerized records. Patient responses were subsequently linked to data held on the practice records. SETTING: General practices in and around Nottingham, selected to reflect local variations in number of partners, list size, geographical location, deprivation, prescribing burden and prescribing rate. SUBJECTS: Unselected patients receiving NSAIDs prescribed for all indications for use. MAIN OUTCOME MEASURES: Effectiveness of ibuprofen and other NSAIDs, possible drug related adverse events, patients' overall satisfaction with ibuprofen and other NSAIDs, factors associated with choice of ibuprofen, drug costs of ibuprofen and other NSAIDs. RESULTS: The main NSAIDs used were ibuprofen, diclofenac and naproxen. Ibuprofen use ranged from 1.0% of prescriptions in one practice to 69.1% in another. Although ibuprofen was generally prescribed in low doses, it was perceived by patients as being as effective as the other NSAIDs used, even after allowing for severity of the pre-treatment condition. Overall, 50.5% of patients rated their NSAID the best treatment they had received for their condition with no differences between individual drugs. CONCLUSIONS: Ibuprofen is as highly regarded as other NSAIDs when used in similar circumstances. Switching patients to ibuprofen may be a realistic way of reducing financial and medical costs associated with NSAIDs.

Adolescent↗

PubMed2000

Structured interview and uniform assessment improves diagnostic reliability.

OBJECTIVE: To compare a Childhood Uniform Assessment Package (CUAP), including a computerized structured diagnosis, with routine assessment and treatment in public mental health settings. DATA SOURCES/STUDY SETTINGS: Data was collected prospectively on 250 children and adolescents in both public mental health inpatient and outpatient settings in a large metropolitan area and a rural area. STUDY DESIGN: Subjects were randomized to either routine assessment and treatment as usual (ATU) or ATU plus an additional "gold standard" assessment battery Childhood Uniform Assessment Package (CUAP). Outcome measures were taken at admission (baseline), discharge, and again 6 months later. METHODS: The study was conducted at a State Hospital (CUAP, n = 75; ATU, n = 75) and a Community Mental Health center (CUAP, n = 50; ATU, n = 50). The "gold standard" diagnostic process was established at the Children's Medical Center-Dallas. Research focused on a comparison of the CUAP diagnostic process to the existing diagnostic process (ATU) and the service delivery system of an inpatient and outpatient public sector clinical treatment setting. PRINCIPAL FINDINGS: A bachelor's level individual can be trained to administer a highly reliable diagnostic battery to meet a "gold standard," suggesting a possible cost-effective way to assist in diagnostic evaluations. Higher reliability was found between this standardized assessment package (CUAP) and inpatient physicians than for outpatient physicians. The highest interrater reliabilities were found for attention deficit and substance abuse disorders, less so for the other behavior disorders. The use of CUAP results in more reliable diagnoses in public settings than those provided by typical clinical staff by identifying mood and anxiety disorders (disorders with the lowest reliability) with better reliability. The addition of "gold standard" diagnostic assessments (CUAP) did not appear to affect length of stay, number of medication changes, use of seclusion or restraints, and other behavioral interventions in the inpatient setting. Outpatient follow-up services did not differ for CUAP versus ATU either. CONCLUSIONS: A standard uniform assessment package that includes a structured diagnostic instrument can improve overall diagnostic reliability but may not have a significant overall impact in clinical treatment strategies or outcomes without additional intervention to assure proper use of the information. A well-trained bachelor's level assistant can administer such a battery.

Adolescent↗

PubMed2000

Implementing and maintaining school-based mental health services in a large, urban school district.

The Dallas (Texas) Public Schools established the first school-based health center in the United States in 1969. In 1993 a partnership between two school principals, a school mental health professional, and the medical director of the county mental health center was the impetus for the first comprehensive school-based mental health center in Texas. In 1995 the programs joined together as Youth and Family Centers (YFCs) to provide physical health, mental health, and other support services to students and their families. The 10 strategically located school-based centers are directed by licensed mental health professionals employed by the district who lead a multidisciplinary team of physical health and mental health providers. Students served by the YFCs have fewer discipline problems, course failures, and school absences.

Adolescent↗