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Biomedical subjects

C L Morgan

Publications and source records attributed to C L Morgan.

At least 19 recordsLinked to original sources
PubMed2000

Cord blood serum does not increase lymphocyte responses in comparison to adult serum.

To date, over 1000 cord blood (CB) transplants have been reported from different centers worldwide and it is generally agreed that CB represents an encouraging alternative to bone marrow (BM) transplantation. There are a variety of reasons for this, however, possibly the two most controversial aspects are (a) whether there is less graft versus host disease (GVHD) with CB compared to BM transplantation, and (b) whether we can use more HLA mismatches with CB transplantation. The major theory regarding the reduced immunological response of CB lymphocytes is that CB T and NK cells are naive and, therefore, not primed for activation. However, the naive phenomena that has been noted in vitro may be bypassed in vivo by unforeseen factors. We show evidence that there are differences in the soluble factors present in CB and adult serum and that these differences play a role in T cell function. Thus, adult serum will enhance both mitogen and IL-2 specific T cell growth whereas CB serum has no effect, suggesting that there is an activation/growth factor present in adult sera, which is absent in CB sera. This work could enable us to identify the molecular mechanisms which are associated with a lower GVHD in CB compared to BM transplanted individuals.

Adult↗
PubMed2000

Relative activity and referral patterns for diabetes and non-diabetes in general practice.

AIMS: To describe and compare general practice (GP) activity for patients with and without diabetes using a survey of general practices representing over 10% of the Welsh population. METHODS: The Welsh GP Morbidity Database Project (GPMDP) collected data including demographic and lifestyle information and consultation data such as diagnosis, referral and surgical procedures. These data were analysed to establish the annual period prevalence of diabetes and compare the relative number of consultations and referrals. RESULTS: A total of 4,182 diabetic patients were recorded (prevalence 1.41%) and accounted for 77,371 (4.4%) consultations. Patients with diabetes were four-times more likely to be referred to community services (relative risk (RR) 4.1, 95% CI 3.7-4.7), in particular district nursing (RR 3.8, 1.9-7.7), optician services (RR 8.9, 5.0-15.7), chiropody (RR 8.2 6.4-10.5) and dietician services (RR 21.2, 17.6-25.5). Patients with diabetes were also more likely to be followed-up in general practice (RR 6.7, 6.2-7.2) both within 1 month (RR 6.7, 6.2-7.2) and 1 month to 1 year (RR 9.7, 8.9-10.7). Emergency admissions were also more likely for patients with diabetes (RR 6.8, 6.2-7.5) as were elective admissions to general medicine (RR 5.6, 4.6-6.7), surgery (RR 1.8, 1.5-2.0) and opthalmology (4.2, 3.4-5.2). CONCLUSION: The increased utilization of health services apparent in secondary care was confirmed in primary care. Further research is required to determine levels of community activity after initial referral.

Adolescent↗
PubMed2000

Estimating the prevalence of diagnosed diabetes in a health district of Wales: the importance of using primary and secondary care sources of ascertainment with adjustment for death and migration.

AIMS: To determine diagnosed diabetic prevalence within our district (population 434398) in 1996 using data from two sources. METHODS: A general practice audit comprising data on patients with diabetes from 61 (82%) of 74 general practices was linked to a record linkage-derived patient index in which data from secondary care and other sources underwent a process of probability matching to identify records relating to the same patient and to flag those with diabetes. By linking this dataset to a mortality dataset, patients known to have died before 1996 could be excluded. Age and sex-stratified emigration rates were applied to those identified by the hospital dataset for each year from 1991 onwards. RESULTS: A total of 386988 residents (89.1%) were listed with a general practitioner participating in the audit, of whom 6050 patients were identified as having diabetes in 1996; a prevalence rate of 1.56%. From the hospital-based source, 7639 patients were identified who were alive in 1996, a period prevalence of 1.76%. By combining the two sources, and extrapolating the general practice audit to the population as a whole, a total of 10 530 patients were identified of whom 8735 were confirmed as still resident within South Glamorgan during 1996. This represented a period prevalence of between 2.01% to 2.42%. By applying age and sex-stratified migration rates to the diabetic population identified by hospital sources, a diagnosed diabetic population of 10,004 was identified, a prevalence of 2.3%. CONCLUSIONS: This study demonstrates that to calculate the true prevalence of diagnosed diabetes from health sources, it is necessary to use both primary and secondary care sources.

Adolescent↗
PubMed2000

The prevalence of multiple diabetes-related complications.

AIMS: To determine the prevalence of the complications of diabetes and the interrelationship between them within a United Kingdom district health authority population. METHODS: Data extracted from a general practice diabetes audit were combined with data for patients with diabetes derived from a patient index constructed using record linkage techniques. RESULTS: A total of 10709 patients were identified as having diabetes (prevalence 2.47%). Coronary heart disease was present in 25.2%, cerebrovascular disease in 9.6%, complications of the 'diabetic foot' in 18.1%, retinopathy in 16.5% and nephropathy in 2.0%. Over a half of the patients (52.1%) had none of the studied complications, 30.2% had one, 12.7% had two, 4.1% had three, 0.8% had four and 0.1% had all five. All complications were related to both age and duration of diabetes but duration was particularly apparent for the microvascular complications (retinopathy and nephropathy). Macrovascular complications in the Type 2 diabetic population appear advanced in onset compared with Type 1. CONCLUSIONS: Multiple complications are apparent in almost one fifth of patients with diabetes. Macrovascular morbidity in Type 2 diabetes of early onset indicates that a targeted approach to treatment may prove most beneficial in both patient and health service terms.

Adolescent↗
PubMed2000

Social deprivation and prevalence of epilepsy and associated health usage.

OBJECTIVES: To examine the relation between social deprivation and the prevalence of epilepsy and associated morbidity using hospital activity data as a proxy. METHODS: The study was conducted in the health district of South Glamorgan, United Kingdom (population 434 000). Routinely available hospital data (inpatient and outpatient), an epilepsy clinic database, and mortality data underwent a process of record linkage to identify records relating to the same patient and to identify patients with epilepsy. Each patient was allocated a Townsend index deprivation score on the basis of their ward of residence. Age standardised correlations were calculated between deprivation score and prevalence of epilepsy, inpatient admissions, and outpatient appointments. Standardised mortality ratios (SMR) were also calculated. All analyses were performed on two cohorts: (1) all patients with epilepsy and (2) those patients with epilepsy without any underlying psychiatric illness or learning disability. RESULTS: The prevalence of epilepsy ranged between 2.0 and 13.4 per 1000 with a median of 6.7. There were positive correlations between social deprivation and prevalence in both populations: (1) r=0.75 (p<0.001) and (2) r=0.70 (p<0.001). After standardising for underlying prevalence there were also correlations for mean inpatient admissions: (1) r=0.62 (p<0.001), (2) r=0.59, (p<0.001) and for outpatient appointments: (1) r=0.53, (p=0.001) and (2) r=0. 51 (p=0.001). The SMR for those deprived was (1) 1.66 (95% confidence interval (95% CI) 1.27-2.05) and (2) 1.80 (95% CI 0.71-1. 67). For the population as a whole (with and without epilepsy) the SMR was 1.25 (95% CI 1.27-2.32). CONCLUSION: This study shows a strong correlation between the prevalence of epilepsy and social deprivation and weaker correlations between social deprivation and mean hospital activity.

Adolescent↗
PubMed2000

Health care provision for people with a learning disability. Record-linkage study of epidemiology and factors contributing to hospital care uptake.

BACKGROUND: We know little about how people with a learning disability access secondary health care. AIMS: To describe the epidemiology of learning disability, the influence of deprivation on prevalence and the pattern of secondary care uptake, including the effect of institutionalisation. METHOD: A record-linkage study of secondary care contacts of 434,000 people between 1991 and 1997. A population with learning disability was identified; their secondary care contact was calculated and compared with the general population's. RESULTS: The distribution of people with a learning disability (n = 1595) correlated significantly with deprivation. The presence of a learning disability hospital significantly affected care uptake. Place of residence also affected acute admission to the learning disability hospital. Former institution residents generated 212 admissions per 1000 patients; community patients generated 18 per 1000. The admission rate with any psychiatric diagnosis to any setting was 26.3 per 1000 people with a learning disability; 16.5% of such patients had a dual diagnosis. CONCLUSIONS: Health provision for people with a learning disability is affected by institutional provision.

Adolescent↗
PubMed2000

Relationship between diabetes and mortality: a population study using record linkage.

OBJECTIVE: To determine patterns and causes of mortality for patients with diabetes in a district health authority RESEARCH DESIGN AND METHODS: The study used cross-sectional record linkage, combining an electronic death register with a diabetic patient register constructed from a variety of routine health data sources collected from 1991 to 1997. The study was conducted in Cardiff and the Vale of Glamorgan, Wales, U.K., and included all diabetic deaths between 1993 and 1996. RESULTS: Of 1,694 deaths in patients with known diabetes, only 674 (39.8%) had diabetes recorded as an immediate or antecedent cause of death. Mortality rates were 41.8 per 1,000 for the diabetic population and 10.1 per 1,000 for the nondiabetic population. The standard mean ratio for the diabetic population was 1.24 (95% CI 1.12-1.35), with the risk of mortality relative to the nondiabetic population decreasing with age. Males with diabetes lost an average of 7.0 years from the year of diagnosis, and females with diabetes lost an average of 7.5 years. The most common cause of death was cardiovascular disease, which accounted for 49.1% of deaths in the diabetic population. CONCLUSIONS: Diabetes is recorded as a cause of death on a minority of death certificates for patients with diabetes. Using death certificates in isolation, therefore, is a poor method of estimating diabetic mortality, but results can be improved with the use of record linkage techniques. Patients with diabetes have an excess risk of mortality compared with the nondiabetic population. Life-years lost for patients with diabetes is strongly related to age at diagnosis and is a means of expressing mortality without relying on accurate prevalence data.

Adult↗
PubMed1999

Identification of three HLA-A*0201-restricted cytotoxic T cell epitopes in the cytomegalovirus protein pp65 that are conserved between eight strains of the virus.

The Ag specificity of the CTL response against CMV is directed almost entirely to a single CMV tegument protein, the phosphoprotein pp65. We report the identification of three peptides derived from the protein pp65 that displayed a high or intermediate binding to HLA-A*0201 molecules, which were also able to induce an in vitro CTL response in peripheral blood lymphocytes from CMV seropositive individuals. The peptide-specific CTLs generated were capable of recognizing the naturally processed pp65 either presented by CMV-infected cells or by cells infected with an adenovirus construct expressing pp65 in an HLA-A*0201-restricted manner. Thus, we were able to demonstrate responses to subdominant CTL epitopes in CMV-pp65 that were not detected in polyclonal cultures obtained by conventional stimulations. We also found that the amino acid sequences of the three peptides identified as HLA-A*0201-restricted CTL epitopes were conserved among different wild-type strains of CMV obtained from renal transplant patients, an AIDS patient, and a congenitally infected infant, as well as three laboratory strains of the virus (AD169, Towne and Davis). These observations suggest that these pp65 CTL peptide epitopes could potentially be used as synthetic peptide vaccines or for other therapeutic strategies aimed at HLA-A*0201-positive individuals, who represent approximately 40% of the European Caucasoid population. However, strain variation must be taken in consideration when the search for CTL epitopes is extended to other HLA class I alleles, because these mutations may span potential CTL epitopes for other HLA molecules, as it is described in this study.

Antigen Presentation↗
PubMed1999

Soluble CD8 stabilizes the HLA class I molecule by promoting beta2M exchange: analysis in real-time.

Human soluble CD8 (sCD8) is secreted by activated CD8+/- cytotoxic T lymphocytes (CTLs). The immunological role of sCD8 is poorly defined, however. We have studied the influence of sCD8 on HLA class I interactions by real-time analysis. Using an optical biosensor we demonstrated that the binding of sCD8 to HLA-A2 promotes exchange of beta2-microglobulin (beta2m) in order to stabilize the complex. Kinetic analysis showed that sCD8 significantly increased the affinity (K(A)) of HLA-A2 for immobilized human beta2m; from 1.14 +/- 0.04 x 10(9) M(-1) in its absence, to 2.18 +/- 0.21 x 10(9) M(-1) following preincubation with sCD8. This suggests that the sCD8:HLA class I complex is unlikely to be degraded at the cell surface. Even in the presence of exogenous peptide (HLA-A2 specific or nonspecific), sCD8 has a stabilizing influence on the HLA class I molecule. These findings point to an immunosuppressive role for sCD8, because the binding of sCD8 to HLA class I would block the binding site for CTL-bound CD8 and, therefore, interfere with T cell activation and proliferation. This may have particular significance in pathological situations where elevated levels of sCD8 are found in extracellular fluids, and sCD8 may provide an alternative approach for immunosuppressive therapy.

CD8 Antigens↗
PubMed1998

Real-time analysis of cell surface HLA class I interactions.

Characterisation of the kinetics of assembly and dissociation of the HLA class I heterotrimeric complex provides valuable insights into the relative contributions of each element to complex stability. However, to date there has been no real-time binding analysis on whole cells. Here we have developed an optical biosensor model to investigate the binding of class I HLA complexes on whole cells to human beta 2-microglobulin (beta 2m) and the effects of different HLA-specific peptides on this binding. We immobilised beta 2m on an IAsys biosensor surface and established conditions to analyse the binding of this to HLA-A2 expressing cells (T2 cells). Using 721.221 cells as an HLA negative control we showed that HLA-A2 binding was optimal using a) a carboxymethylated dextran surface and b) no growth factors or supplements in the culture medium at the binding event. Using these conditions we verified specificity of binding by inhibition of the reaction with free beta 2m and determined the dissociation rate constant for T2 cell binding to beta 2m (0.03 s-1). In addition, we demonstrated the ability of different HLA specific peptides to modulate cellular HLA-A2 binding to beta 2m. This is the first time that interactions of cell surface HLA class I molecules has been investigated using real-time analysis. Furthermore, our peptide analysis has shown that this model can be used to characterise peptide specific HLA-binding responses on the whole cell surface in real-time.

Cell Line↗
PubMed1998

The matrix effects on kinetic rate constants of antibody-antigen interactions reflect solvent viscosity.

This study describes the influence of different matrices on two model antibody-antigen interactions; that between beta2microglobulin and anti beta2microglobulin, and that of rabbit anti mouse Fc fragment (RAMFc) with mouse IgG. The matrices investigated were; phosphate-buffered saline pH 7.4 containing 0.05% Tween 20 detergent, horse serum, a 50:50 mixture of phosphate-buffered saline/Tween 20 and horse serum, and four glycerol solutions of differing concentrations. A recently developed optical biosensor, the IAsys, was used to monitor the interactions in real-time and provide precise determinations of k(ass), k(diss) and KA values. The results show that the rates of association and dissociation for the two different antibody:antigen models are significantly affected by the surrounding matrix. Glycerol of known viscosity was used as a matrix in both models to show that this effect is attributable to the viscosity as opposed to proteins present in the matrix. The viscosity of the matrix has also been shown to have an apparent influence upon the overall equilibrium/affinity constant for the interaction, with measurements of KA tending to increase with viscosity. The significant effects of matrix on kinetic rate constants for antibody-antigen interactions shown here have important implications in the use of immunoassays where non-equilibrium measurements are made in serum matrices.

Animals↗
PubMed1998

The influence of exogenous peptide on beta2-microglobulin exchange in the HLA complex: analysis in real-time.

We used an optical biosensor to determine the relative binding affinity of peptides to purified HLA class I molecules. In this assay we monitor beta2-microglobulin (beta2m) exchange within the HLA-A2 molecule, whereby native beta2m in the complex is replaced by beta2m immobilized at the surface of the biosensor. Quantitative kinetic measurements permit us to obtain association rate (kass), dissociation rate (kdiss) and affinity constants (KA) for the beta2m exchange reaction, alone, (control) and in the presence of exogenous peptide. We tested a panel of six peptides which had been designed and synthesized with an HLA-A2 binding motif, and had also been tested by the T2-cell binding assay, along with control peptides. The biosensor results demonstrate that exogenous peptide influences the dynamics of beta2m exchange in a sequence-specific manner. Five of six peptides increased the association rate, decreased the dissociation rate, and significantly increased the affinity (KA=1. 55-1.88x10(9) M-1) of HLA-A2 for immobilized beta2m compared with the control (KA =1.14+/-0.04x10(9)M-1), demonstrating stabilization of the complex. One peptide was unable to stabilize the complex, as also shown in the T2 binding assay. However, analysis of peptide sequences demonstrated that the HLA-A2 secondary motif as well as primary motif residues are required for HLA-A2 stabilization. Further experiments demonstrated that beta2m exchange alone cannot stabilize the HLA class I complex at the cell surface until a peptide of sufficient binding affinity is bound. Hence kinetics equal to or below the control values in our biosensor assay probably represent an unstable complex in vivo. Unlike other methods described for the analysis of peptide stabilization, this approach is significantly faster, provides full kinetic analysis, and is simpler, since it requires no labeling of peptides. Furthermore, this may have important implications in the assessment of peptide vaccines.

Biosensing Techniques↗
PubMed1998

Evaluating CPR performance in basic life support: the VIDRAP protocol.

This paper presents the second part of the validated Cardiff test for one rescuer basic life support skills, based on observation of video recording combined with the Recording Resusci Anne printout (VIDRAP). The authors believe that this is a robust evaluation tool which is capable of assessing the potential value to a casualty of a simulated resuscitation. The adoption of a widely accepted test methodology would facilitate comparison of research in different centres, which is not possible at present.

Adult↗
PubMed1998

The demand for hospital services for patients with epilepsy.

PURPOSE: To describe the patterns of inpatient and outpatient hospital care for patients with epilepsy in our health district. METHODS: Routine hospital data for the health district of South Glamorgan (population 408,000) underwent record linkage to identify those records relating to the same patients and to flag those records for patients with epilepsy. This data was analyzed to determine inpatient and outpatient activity by specialty and compared with the nonepileptic population. RESULTS: We identified 2.267 patients representing a prevalence of 0.56%. The average age was 46 years in both male and female patients. This group, which constituted 1.5% of the hospital population, was responsible for 2.8% of all admissions but, because of increased length of stay, utilized 7.3% of all bed days. The total cost of care for this group lies between these two extreme values and is dependent on case severity. The patterns of associated diagnoses differed considerably in three arbitrary age groups (0-18, 19-55, >55 years). CONCLUSIONS: This study quantifies for the first time the level of demand that this subpopulation places on the service as a whole, and begins to illustrate that there may be evidence for cost containment by, for example, a reduction in multiple admissions. The demand for inpatient services is greater than we would have predicted.

Adolescent↗
PubMed1998

The epidemiology and cost of inpatient care for peripheral vascular disease, infection, neuropathy, and ulceration in diabetes.

OBJECTIVE: To describe the epidemiology and costs of the acute care of peripheral vascular disease, infection, neuropathy, and ulceration in a U.K. population with special consideration of those patients with diabetes. RESEARCH DESIGN AND METHODS: Routine data describing inpatient care for a 4-year period were analyzed (financial years 1991/1992 to 1994/1995). These data had undergone record-linkage to draw together records from the same patients, and records of patients with diabetes were flagged. Cost estimates were determined by attributing a diagnosis-related group cost-weight to each record. RESULTS: A total of 4,245 admissions (1.2% of all admissions) had a primary diagnosis of peripheral vascular disease, infection, neuropathy, or ulceration, and 7,379 (2.1%) admissions had these categories recorded in any one of six diagnostic fields. These figures were generated by 3,159 and 4,751 patients, respectively. This represented a range of crude annual incidence of admission of between 1.9 and 2.9 per 1,000 people. Patients with diabetes accounted for 625 (15.4%) of primary admissions, a crude annual incidence of admission of 18.8 per 1,000. The age-standardized relative risk of admission for patients with diabetes to the nondiabetic population was 7.61 for men and 6.85 for women. The length of stay for patients with diabetes was almost twice that of the nondiabetic population (15.5 vs. 8.7 days). The relative risk of hospital mortality (diabetes vs. non-diabetes) was 2.83. Surgical procedures were carried out on 857 patients, 272 (31.2%) with diabetes. This represented an age-standardized relative risk of 31.19. The estimated cost of admissions for primary diagnoses in these categories over 4 years was 6,128,211 pounds ($9,743,855). Patients with diabetes accounted for 1,236,623 pounds ($1,966,230), an excess of 87% attributable to the diabetic state. CONCLUSIONS: Diabetes is confirmed as a significant risk factor for peripheral vascular disease, infection, neuropathy, and ulceration. The severity of these disorders in terms of increased risk of hospital mortality, length of stay, and risk of surgical procedure is also demonstrated for those patients with diabetes.

Communicable Diseases↗
PubMed1998

Reinforcement frequency, but not gender, determines sensitivity to discriminative stimulus effects of morphine.

We demonstrated previously that several parameters of a morphine discrimination were significantly different in female versus male rats, using a fixed ratio (FR)-10 schedule of food reinforcement; however, this schedule produced a significant bias in reinforcement frequency between saline and morphine sessions in males but not in females. To determine whether this schedule-drug-sex interaction caused the sex difference in discriminability of morphine, female and male rats were trained to discriminate 3.0 mg/kg morphine from saline using a variable interval (VI) 15-s/VI 15-s (Phase I), a VI 7.5-s/VI 15-s (Phase II), and a VI 15-s/VI 15-s (Phase III) schedule of food reinforcement on morphine/saline levers, respectively. After a minimum of 40 training sessions in each phase, mean reinforcement rates in morphine sessions were highest, and the ED50 values for morphine discrimination were lowest, in Phase II. Thus, as predicted, the morphine dose-effect curves shifted to the left from Phase I to Phase II, and back to the right from Phase II to III, presumably due to the bias in reinforcement rate between saline and morphine sessions that was induced by manipulating the VI schedule on the morphine lever. However, there were no sex differences in the morphine versus saline reinforcement rate or in discrimination ED50 in any phase, suggesting that the sex difference observed in our initial study was probably due to the bias in reinforcement frequency (towards the saline condition) that occurred only in males under the FR-10 schedule. This study demonstrates the importance of considering group differences in schedule-drug interactions when comparing discriminative stimulus properties of drugs between groups.

Analysis of Variance↗