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Biomedical subjects

S C Davies

Publications and source records attributed to S C Davies.

At least 19 recordsLinked to original sources
PubMed2007

Effect of myeloablative bone marrow transplantation on growth in children with sickle cell anaemia: results of the multicenter study of haematopoietic cell transplantation for sickle cell anaemia.

Although haematopoietic cell transplantation (HCT) is curative for sickle cell anaemia (SCA), concerns about its short- and long-term toxicities limit its application. A potential toxicity is an adverse effect on growth. To identify an HCT growth effect, serial height and weight measurements from 53 children and adolescents with SCA after receiving a transplant were compared to historical controls. Hierarchical Linear Models for longitudinal data were used for analysis. In general growth was not impaired by HCT for SCA in young children; however, diminished growth may occur if HCT is carried out near or during the adolescent growth spurt.

Age Factors↗
PubMed2006

A nontransfusional perioperative management regimen for patients with sickle cell disease undergoing laparoscopic cholecystectomy.

BACKGROUND: Patients with sickle cell disease (SCD) are at increased risk for cholelithiasis. Laparoscopic cholecystectomy is the most frequent general surgical operation performed for this group of patients. Acute chest syndrome (ACS) is the most common cause of postoperative death among SCD patients. This study aimed to evaluate the impact of a novel perioperative management regimen involving prophylactic continuous positive airways pressure (CPAP) ventilation and avoidance of preoperative blood transfusion on postoperative SCD-related complications after laparoscopic cholecystectomy. METHODS: A retrospective study included all SCD patients who underwent laparoscopic cholecystectomy since 1997 at our institution. Medical notes were analyzed to assess the rates of postoperative complications in relation to the severity of SCD. RESULTS: A total of 13 patients were identified. There were no recorded episodes of acute painful crises and only one patient experienced an episode of ACS requiring protracted CPAP. CONCLUSION: Laparoscopic cholecystectomy can be safely performed for SCD patients without prior blood transfusion. A defined perioperative regimen including the use of routine postoperative prophylactic CPAP for these patients helps to reduce SCD-related postoperative complications such as ACS and painful vaso-occlusive crises.

Adolescent↗
PubMed2005

Implications of increased haemoglobin A2 values in HIV positive women in the antenatal clinic.

Universal antenatal haemoglobinopathy screening in this hospital has identified several women with increased haemoglobin A(2) values, but without hypochromic microcytic red cell indices. This report describes two cases where there is evidence that the raised haemoglobin A(2) value is not caused by heterozygous beta thalassaemia, but rather results from these patients being human immunodeficiency virus (HIV) positive and on antiretroviral therapy. This will have important implications as universal antenatal haemoglobinopathy screening becomes more widespread, and as the number of HIV positive women of childbearing age increases.

Adult↗
PubMed2005

The uptake of HIV post-exposure prophylaxis within a sexual assault setting in Sydney, Australia.

Our aim was to compare the assault characteristics of victims presenting to a sexual assault service who were prescribed HIV post-exposure prophylaxis (HIV PEP) with those not prescribed HIV PEP. A retrospective review was carried out of the medical records of victims who were seen over a 12-month period in 1999/2000.HIV PEP may have been potentially appropriate for 117 victims, of whom nine (7.7%) were prescribed PEP (eight women, one man). There was a trend for prescription of PEP to depend on the type of assault, with those suffering anal penetration most likely to be prescribed PEP, followed by those with vaginal, and then oral penetration (P = 0.08). Those who gave a history of oral or vaginal mucosal contact with ejaculate were more likely to receive PEP compared with those in whom ejaculation occurred at a non-mucosal site (P = 0.03). Most prescribed PEP regimens involved three antiretroviral drugs. In this study, HIV PEP, when prescribed, was in accord with existing guidelines. Future studies should aim to better document HIV seroconversions in victims of sexual assault and HIV seroprevalence in assailants.

Adolescent↗
PubMed2001

Mass spectral analysis of asymmetric hemoglobin hybrids: demonstration of Hb FS (alpha2gammabetaS) in sickle cell disease.

Formation of the asymmetric hemoglobin hybrid FS (alpha2gammabetaS) inhibits hemoglobin S (Hb S) polymerization in vitro and underlies the protective effect of fetal hemoglobin (Hb F) in homozygous sickle cell disease. Conventional methods for separating Hb reveal only symmetric Hb tetramers because of the rapid dissociation of tetramers to dimers relative to the separation time for electrophoresis and chromatography. To gain insight into the quantitative distribution of asymmetric Hb FS and other tetrameric species in sickle cell disease, the noncovalent association of Hb subunits in hemolysates was studied by a novel application of electrospray ionization mass spectrometry (ESI-MS). Mass spectra of both patient and fetal blood revealed predominance of tetrameric species with dimer and monomer subunits in lower abundance. ESI-MS analysis revealed the hybrid Hb AF (alpha2gammabetaA) in hemolysates shown by conventional high-performance liquid chromatography to contain only the symmetric species Hb A (alpha2betaA2) and Hb F (alpha2gamma2). A unique tetramer of average mass 64,558 Da was identified in hemolysates from patients with sickle cell disease in accordance with the calculated mass of the asymmetric Hb hybrid FS. Hybrid Hb species were stable under the ESI-MS conditions employed allowing concurrent determination of the proportions of Hb FS and the symmetrical Hb S (alpha2betaS2). The ratios of Hb FS to Hb S correlated closely (r2 = 0.96) with those predicted under physiological conditions.

Adolescent↗
PubMed2001

1H-Pyrrole-2-carbothioamide.

The reaction of ethoxycarbonylpyrrole-2-thiocarboxamide with sodium hydroxide affords the known title compound, C(5)H(6)N(2)S, whose structure shows a three-dimensional hydrogen-bonded lattice.

Crystallography, X-Ray↗
PubMed2001

Solid state NMR and X-ray diffraction studies of alpha-D-galacturonic acid monohydrate.

Crystalline alpha-D-galacturonic acid monohydrate has been studied by 13C CPMAS NMR and X-ray crystallography. The molecular dynamics were investigated by evaluating 13C spin-lattice relaxation in the rotating frame (T1rho) and chemical-shift-anisotropy properties of each carbon. Only limited molecular motions can be detected in the low frequency (< 10(4) Hz) range by 13C relaxation time measurements (T1rho) and changes of chemical shift anisotropy properties as a function of temperature. X-ray analysis (at both ambient temperature and 150 K) shows that the acid has the usual chair-shaped, pyranose ring conformation, and that the acid and water molecules are linked, through all their O-H groups, in an extensively hydrogen-bonded lattice.

Carbohydrate Conformation↗
PubMed2001

Neonatal screening for haemoglobinopathies: the results of a 10-year programme in an English Health Region.

Neonatal identification of sickle cell disease can significantly reduce mortality and morbidity during the first 5 years of life. During a 10-year period, 414,801 neonates were screened by isoelectric focusing. The most common variants detected were haemoglobins S, C, D and E. Two hundred and fifty of the samples tested were homozygotes or compound heterozygotes, and 6554 samples were heterozygotes for the common variants. The gene frequencies in the population tested were calculated from this data for the most common variants. They were: S, 0.0057; C, 0.0014; D(Punjab(Los Angeles)), 0.0007; E, 0.0005. Additionally, 16 babies had beta thalassaemia major and 405 had rarer variants, of which six had never previously been described. Knowledge of the distribution of these inherited diseases is useful in healthcare planning and appropriate allocation of resources, while counselling targeted at appropriate couples enables informed parental choice and may prevent disease.

Anemia, Sickle Cell↗
PubMed2000

Impact of bone marrow transplantation for symptomatic sickle cell disease: an interim report. Multicenter investigation of bone marrow transplantation for sickle cell disease.

Fifty children who had symptomatic sickle cell disease received matched sibling marrow allografts between September 1991 and March 1999, with Kaplan-Meier probabilities of survival and event-free survival of 94% and 84%, respectively. Twenty-six patients (16 male, 10 female) had at least 2 years of follow-up after transplantation and were evaluated for late effects of transplantation and for its impact on sickle cell-related central nervous system (CNS) and pulmonary disease. Patients ranged between 3.3 and 14.0 (median, 9. 4) years of age and had a median follow-up of 57.9 (range 38-95) months after transplantation. Among 22 of 26 patients who had stable donor engraftment, complications related to sickle cell disease resolved, and none experienced further episodes of pain, stroke, or acute chest syndrome. All 10 engrafted patients with a prior history of stroke had stable or improved cerebral magnetic resonance imaging results. Pulmonary function tests were stable in 22 of the 26 patients, worse in two, and not studied in two. Seven of eight patients transplanted for recurrent acute chest syndrome had stable pulmonary function. Linear growth measured by median height standard deviation score improved from -0.7 before transplantation to -0.2 after transplantation. An adverse effect of busulfan conditioning on ovarian function was demonstrated in five of seven evaluable females who are currently at least 13 years of age. None of the four males tested had elevated serum gonadotropin levels. These data confirm that allogenic bone marrow transplantation establishes normal erythropoiesis and is associated with improved growth and stable CNS imaging and pulmonary function in most patients. (Blood. 2000;95:1918-1924)

Adolescent↗
PubMed2000

Organisation and cost-effectiveness of antenatal haemoglobinopathy screening and follow up in a community-based programme.

OBJECTIVE: To consider the organisation cost and effectiveness, of universal, community-based antenatal screening for the haemoglobinopathies, and to estimate the cost-effectiveness of programmes at different levels of prevalence and mix of haemoglobinopathy traits. DESIGN: Retrospective review of laboratory and Sickle Cell and Thalassaemia Centre worksheets with costing of capital equipment, consumables, salaries and overheads, and estimation of costs in a range of circumstances. SETTING: A haematology department, including a Sickle Cell and Thalassaemia Centre, providing antenatal and neonatal screening programmes in Inner London. PARTICIPANTS: Two thousand one hundred and one women booking at the antenatal clinic whose samples were referred for screening during 1994. MAIN OUTCOME MEASURES AND RESULTS: In addition to assessing the cost-effectiveness of antenatal haemoglobinopathy screening in a number of settings, the following specific financial information was assembled for the service in Brent: 1. cost of identifying abnormal haemoglobin in mother (ł209); 2. cost of identifying at-risk fetus before confirmation by prenatal diagnosis (ł2,455); 3. cost of providing genetic information and counselling to mother with abnormal haemoglobin (ł109); 4. programme savings from cases averted (ł61,000). Conclusions Antenatal screening with follow up counselling can be self-financing at most prevalences of haemoglobinopathy traits, with greater savings where a high proportion of the traits are beta thalassaemia. There is a net financial cost (ł1,350) only at prevalences below 2.5% of traits if these are mainly for sickle cell disease. Since there are other benefits is it likely that antenatal screening will be considered cost-effective even at quite low levels of trait prevalence.

Algorithms↗
PubMed2000

The predictive value of white cell count in assessing clinical severity of sickle cell anaemia in Afro-Caribbeans patients.

The relationship between each of haemoglobin concentration (Hb), red cell count (RCC), white cell count (WBC), platelet count (PLT), mean corpuscular volume (MCV), red cell width difference (RWD), and average number of acute admissions per year (AVEADM), were determined in a cross-sectional study of 128 Afro-Caribbean sickle cell anaemia patients attending the Sickle Cell Disease Clinic of Central Middlesex Hospital in London for a mean of 7.6 patient-years. The diagnosis of sickle cell anaemia was made by both haematological and DNA analyses. The haematological parameters were determined using Coulter S automated counter during the steady state periods while the AVEADM was computed from all admissions for painful crisis, acute anaemia and acute chest syndrome, priapism, and acute stroke. Haemoglobin F level was determined by HPLC. Analysis was done in the paediatric and adult patients separately. There were no significant correlations between any of the parameters and AVEADM in the paediatric group. In adult patients, there was significant positive correlation (P < 0.05) between WBC and AVEADM. WBC has a negative correlation with Hb concentration and HbF level. WBC 10 x 10(9)/L and above is associated with Hb and HbF level below the mean for the group. WBC is lower but not significantly, in patients with single alpha-gene deletion than in those without deletion (P = 0.06). This study suggests that higher WBC count may suggest possible increased hospital admission, lower Hb concentration, and lower HbF level, in adult patients, and that, as a single parameter it can be of value in the assessment of patients with sickle cell anaemia. Possible mechanisms for these findings are also suggested.

Adolescent↗
PubMed1999

Proteomic definition of normal human luminal and myoepithelial breast cells purified from reduction mammoplasties.

Normal human luminal and myoepithelial breast cells separately purified from a set of 10 reduction mammoplasties by using a double antibody magnetic affinity cell sorting and Dynabead immunomagnetic technique were used in two-dimensional gel proteome studies. A total of 43,302 proteins were detected across the 20 samples, and a master image for each cell type comprising a total of 1,738 unique proteins was derived. Differential analysis identified 170 proteins that were elevated 2-fold or more between the two breast cell types, and 51 of these were annotated by tandem mass spectrometry. Muscle-specific enzyme isoforms and contractile intermediate filaments including tropomyosin and smooth muscle (SM22) alpha protein were detected in the myoepithelial cells, and a large number of cytokeratin subclasses and isoforms characteristic of luminal cells were detected in this cell type. A further 134 nondifferentially regulated proteins were also annotated from the two breast cell types, making this the most extensive study to date of the protein expression map of the normal human breast and the basis for future studies of purified breast cancer cells.

Adult↗