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C Simpson

Publications and source records attributed to C Simpson.

At least 19 recordsLinked to original sources
PubMed2006

Isolation, purification and characterization of a novel glucose oxidase from Penicillium sp. CBS 120262 optimally active at neutral pH.

A novel glucose oxidase (GOX), a flavoenzyme, from Penicillium sp. was isolated, purified and partially characterised. Maximum activities of 1.08U mg(-1)dry weight intracellular and 6.9U ml(-1) extracellular GOX were obtained. Isoelectric focussing revealed two isoenzymes present in both intra- and extracellular fractions, having pI's of 4.30 and 4.67. GOX from Penicillium sp. was shown to be dimeric with a molecular weight of 148kDa, consisting of two equal subunits with molecular weight of 70k Da. The enzyme displayed a temperature optimum between 25 and 30 degrees C, and an optimum pH range of 6-8 for the oxidation of beta-d-glucose. The enzyme was stable at 25 degrees C for a minimum of 10h, with a half-life of approximately 30 min at 37 degrees C without any prior stabilisation. The lyophilized enzyme was stable at -20 degrees C for a minimum of 6 months. GOX from Penicillium sp. Tt42 displayed the following kinetic characteristics: Vmax, 240.5U mg(-1); Km, 18.4mM; kcat, 741 s(-1) and kcat/Km, 40 s(-1)mM(-1). Stability at room temperature, good shelf-life without stabilisation and the neutral range for the pH optimum of this GOX contribute to its usefulness in current GOX-based biosensor applications.

Enzyme Stability↗
PubMed2006

Tracking the motion of charges in a terahertz light field by femtosecond X-ray diffraction.

In condensed matter, light propagation near resonances is described in terms of polaritons, electro-mechanical excitations in which the time-dependent electric field is coupled to the oscillation of charged masses. This description underpins our understanding of the macroscopic optical properties of solids, liquids and plasmas, as well as of their dispersion with frequency. In ferroelectric materials, terahertz radiation propagates by driving infrared-active lattice vibrations, resulting in phonon-polariton waves. Electro-optic sampling with femtosecond optical pulses can measure the time-dependent electrical polarization, providing a phase-sensitive analogue to optical Raman scattering. Here we use femtosecond time-resolved X-ray diffraction, a phase-sensitive analogue to inelastic X-ray scattering, to measure the corresponding displacements of ions in ferroelectric lithium tantalate, LiTaO(3). Amplitude and phase of all degrees of freedom in a light field are thus directly measured in the time domain. Notably, extension of other X-ray techniques to the femtosecond timescale (for example, magnetic or anomalous scattering) would allow for studies in complex systems, where electric fields couple to multiple degrees of freedom.

Journal Article↗
PubMed2005

Outcome predictors and complications in the management of intradural spinal tumours.

The results of the management of 115 patients with intradural spinal tumours are presented. Data was collected retrospectively from the case notes. Tumours were categorized as intramedullary or extramedullary for statistical analysis. Meningioma, schwannoma and ependymoma accounted for 70% of tumours. Complete macroscopic excision was achieved in 84% of extramedullary and 54% of intramedullary tumours. There were two post-operative deaths, one of which was secondary to methacillin-resistant staphylococcus aureus (MRSA) meningitis. Cerebrospinal fluid leak (10%) and meningitis (7%) were the commonest complications. Ninety-six percent of patients with extramedullary tumours improved or remained unchanged on the Frankel scale. In the intramedullary group, 82% remained unchanged or improved after treatment. Pre-operative functional status was a predictor of good post-operative function for intra- and extramedullary tumours and for intramedullary tumours a good post-operative Frankel score predicted long-term survival.

Adolescent↗
PubMed2004

Animal models for the study of the effect of prolonged stress on lactation in rats.

The suppressive effect of stress on lactation is well acknowledged. Animal models used to study this problem have used primarily acute stressors. As such, they are not adequate for the study of the effect of prolonged stress on lactation. This study aimed at developing a paradigm(s) in rats for the study of the effect on lactation of prolonged exposure to a stressful situation. Two models were examined. The first consisted of a separation paradigm whereby dams had 1, 2, 4, or 6 contacts per day with their pups, but only for a total of 4 h per day. The second model implicated the introduction of a male intruder into the home cage during the 12-h light period. Both protocols were implemented for four consecutive days beginning on Days 10/11 postpartum. Milk release was measured on Day 13/14 postpartum. For both models, milk release was significantly reduced following the preexposure period. During the assessment of milk release, maternal behavior of the experimental and control animals was similar at all times. It is advanced that these two rat models of stress are appropriate for the study of lactation following a prolonged exposure to stress.

Animals↗
PubMed2004

Herpes simplex type 1 shedding is associated with reduced hospital survival in patients receiving assisted ventilation in a tertiary referral intensive care unit.

The impact of shedding of herpes simplex virus type 1 (HSV-1) on hospital survival of patients receiving assisted ventilation in an adult tertiary referral, acute trauma intensive care unit was assessed. The study was designed to address a clinical impression linking HSV-1 recovery with poor survival. Two hundred and forty-one males and 152 females were enrolled into a longitudinal cohort study. Combined throat swabs and tracheal secretions were tested for HSV-1 shedding using a nested nucleic acid amplification protocol; patients were ranked as nonshedders, shedders, and high-level shedders. Nonparametric analysis assessed the impact of shedding on hospital survival and logistic regression measured the confounding influence of sex, age, and the Acute Physiology, Age and Chronic Health Evaluation (APACHE II) score. Linear-by-linear association determined the influence of the level of shedding on hospital survival. The observed mortality rate was 113/393 (28.8%). Patients shedding HSV-1 106/393 (27%) had a significant reduction in hospital survival 66/106 (62%) in HSV-1 shedders compared with 217/287 (75.6%) in nonshedders (P = 0.002). This difference remained significant when adjusted for age and sex (P = 0.026). Respective mortality figures for HSV-1 shedders and nonshedders were 43/106 (40.6%) and 70/287 (24.4%) (P = 0.002). HSV-1 shedding was associated with a significant reduction in hospital survival amongst patients receiving assisted ventilation. Hospital mortality in HSV-1 shedders was increased by 16.2% over nonshedders. The role of HSV-1 in this setting needs to be addressed.

Adolescent↗
PubMed2004

A new autologous keratinocyte dressing treatment for non-healing diabetic neuropathic foot ulcers.

AIMS: To evaluate the use of a new cell-tailored carrier surface (TranCell) for delivery of autologous keratinocytes to promote wound healing in patients with chronic neuropathic foot ulcers. METHODS: TranCell is a sterile medical grade polymer coated with a plasma-polymerized functional surface containing 20% carboxylic acid which enables keratinocytes to attach and proliferate. Six diabetic patients with neuropathic ulcers resistant to conventional therapy were treated with weekly applications of autologous keratinocytes delivered on TranCell. A split-thickness skin biopsy was taken from each patient followed by isolation, expansion and freezing down of keratinocytes. Keratinocytes were thawed and seeded on TranCell 48 h prior to application. This procedure was repeated weekly in addition to conventional therapy until wound healing was achieved. RESULTS: Complete healing was achieved in six out of nine ulcers in six patients, a reduction in ulcer size was achieved in one ulcer and no response was seen in one ulcer. Treatment was discontinued in one patient due to development of Methicillin-Resistant Staphylococcus aureus (MRSA) after only three applications of TranCell. Wound healing took 6-17 applications over 6-20 weeks. There were no recurrences in the healed ulcers after a follow-up of 6 months. CONCLUSIONS: TranCell delivery of autologous cells is a promising treatment for chronic diabetic foot ulcers with no side-effects and no recurrence in the healed ulcers.

Adult↗
PubMed2004

Safe duration of postoperative monitoring for malignant hyperthermia susceptible patients.

Postoperative management of malignant hyperthermia (MH) susceptible patients has changed substantially over the last 20 years, with many patients now managed as day cases. Our previous policy was to monitor known MH susceptible patients (and relatives of known MH susceptible individuals not yet investigated by muscle biopsy) for four hours in the Post Anaesthetic Care Unit. However, anaesthetic literature reports suggest that MH reactions usually commence within one hour of anaesthesia. For this reason we conducted a retrospective review of Post Anaesthetic Care Unit data in 254 MH susceptible/related patients treated between 1991 and late 2000. On the basis of this review we instituted a policy change and reduced our monitoring time to one hour in the Post Anaesthetic Care Unit with a further 1.5h in a step-down unit if indicated. A prospective study in a further 68 MH susceptible/related patients showed that no MH reactions were missed due to the shorter monitoring period.

Adolescent↗
PubMed2003

Assessment of the biological properties of human split skin allografts disinfected with peracetic acid and preserved in glycerol.

Skin allografts derived from cadaveric human donors are widely used in the treatment of serious burn injuries and other conditions, such as ulcers. In order to render these allografts safe for clinical use, and to enable them to be preserved and banked for long periods, effective methods of decontamination and preservation are required. These methods must not adversely affect graft properties essential for clinical performance. We have investigated the application of a peracetic acid (PAA) disinfection protocol, coupled with preservation in either glycerol or propylene glycol to achieve these goals. An effective decontamination procedure, comprising of a 3h exposure to 0.1% (v/v) PAA in phosphate buffered saline (PBS) at pH 7.0, was developed and had no significant detrimental effects on the structure of skin. Cadaveric skin allografts were then treated with this disinfection protocol and subsequently preserved in either 85% (v/v) glycerol or propylene glycol in PBS, and the biological properties of the allografts thought to be essential to successful clinical performance were assessed. The cytotoxicity of the grafts was assessed using both extract and contact assays; damage to the skin collagen was assessed using a collagenase susceptibility assay and the capacity of the grafts to elicit an inflammatory response in vitro was assessed by quantifying the production of the pro-inflammatory cytokine TNF-alpha by human peripheral blood mononuclear phagocytes. Neither the disinfection protocol nor either of the preservation techniques rendered the grafts cytotoxic or pro-inflammatory. The PAA disinfection and glycerol preservation protocol had no effects on collagenase susceptibility, whereas the disinfection protocol in combination with propylene glycol rendered some of the test samples significantly more susceptible to collagenase digestion. Therefore, this study has demonstrated that PAA disinfection combined with glycerol preservation is suitable for skin allografts. The use of propylene glycol as a preservation agent for skin requires further development.

Bacillus subtilis↗
PubMed2001

Exclusion of linkage to the CDL1 gene region on chromosome 3q26.3 in some familial cases of Cornelia de Lange syndrome.

Cornelia de Lange Syndrome (CdLS) is a complex developmental disorder consisting of characteristic facial features, limb abnormalities, hirsutism, ophthalmologic involvement, gastroesophageal dysfunction, hearing loss, as well as growth and neurodevelopmental retardation. Most cases of CdLS appear to be sporadic. Familial cases are rare and indicate autosomal dominant inheritance. Several individuals with CdLS have been reported with chromosomal abnormalities, suggesting candidate genomic regions within which the causative gene(s) may lie. A CdLS gene location (CDL1) has been assigned to 3q26.3 based on phenotypic overlap with the duplication 3q syndrome (critical region 3q26.2-q27) and the report of a CdLS individual with a balanced de novo t(3;17)(q26.3;q23.1). It has been postulated that a gene within the dup3q critical region results in the CdLS when deleted or mutated. We have performed a linkage analysis to the minimal critical region for the dup3q syndrome (that encompasses the translocation breakpoint) on chromosome 3q in 10 rare familial cases of CdLS. Nineteen markers spanning a region of approximately 40 Mb (37 cM) were used. Results of a multipoint linkage analysis demonstrated total lod-scores that were negative across the chromosome 3q26-q27 region. In 4/10 families, lod-scores were less than -2 in the 2 cM region encompassing the translocation, while in the remaining 6/10 families, lod-scores could not exclude linkage to this region. These studies indicate that in some multicase families, the disease gene does not map to the CDL1 region at 3q26.3.

Chromosomes, Human, Pair 3↗
PubMed2001

Nurse practitioner peer review: process and evaluation.

PURPOSE: To describe the initiation and evaluation of a nurse practitioner (NP) peer review program for a group of 15 NPs practicing at a Veteran's Affairs Medical Center. DATA SOURCES: Using a standardized review form, 15 NPs performed a peer review on a total of 163 medical records; each review was re-reviewed by 2 researchers who were also NPs. To determine the congruency of the reviews among the 15 NPs, the data were analyzed with Intraclass correlations (ICC) and ANOVA. CONCLUSIONS: A relatively low ICC (r = 0.37) was found for the 15 NPs. The ANOVA indicated that there were significant differences among the NPs (F = 11.92, p < .0001). IMPLICATIONS FOR PRACTICE: The outcome of a peer review process depends upon the motivation and values of the NPs, practice sites, and standardization of the format, as well as the degree of collective participation. Peer review can reveal charting deficiencies as well as identify topics for continuing education and risk management programs.

Adult↗
PubMed2000

Posttransplant bone disease: evidence for a high bone resorption state.

Loss of bone is a significant problem after renal transplant. Although bone loss in the first post transplant year has been well documented, conflicting data exist concerning bone loss after this time. It is equally unclear whether bone loss in long-term renal transplant recipients correlates with bone turnover as it does in postmenapausal osteoporosis. To examine these issues, we conducted a cross-sectional study to define the prevalence of osteoporosis in long-term (> 1 year) renal transplant recipients with preserved renal function (mean creatinine clearance 73 +/- 23 ml/min). Bone mineral density (BMD) was measured at the hip, spine and wrist by DEXA in 69 patients. Markers for bone formation (serum osteocalcin) and bone resorption [urinary levels of pyridinoline (PYD) and deoxypyridinoline (DPD)] were also measured as well as parameters of calcium metabolism. Correlations were made between these parameters and BMD at the various sites. The mean age of the patients was 45 +/- 11 years. Eighty eight percent of patients were on cyclosporine (12% on tacrolimus) and all but 2 were on prednisone [mean dose 9 +/- 2 mg/day)]. Osteoporosis (BMD more than 2.5 SD below peak adult BMD) at the spine or hip was diagnosed in 44% of patients and osteopenia was present in an additional 44%. Elevated levels of intact parathyroid hormone (i PTH) were observed in 81% of patients. Elevated urinary levels of PYD or DPD were present in 73% of patients and 38% had elevated serum levels of osteocalcin. Levels of calcium, and of 25(OH) and 1,25(OH)2 vitamin D were normal. In a stepwise multiple regression model that included osteocalcin, PYD, DPD, intact PTH, age, years posttransplant, duration of dialysis, cumulative prednisone dose, smoking, and diabetes: urinary PYD was the strongest predictor of bone mass. These results demonstrate that osteoporosis is common in long-term renal transplant recipients. The data also suggest that elevated rates of bone resorption contribute importantly to this process.

Adult↗
PubMed2000

Nud1p links astral microtubule organization and the control of exit from mitosis.

The budding yeast spindle pole body (SPB) not only organizes the astral and nuclear microtubules but is also associated with a number of cell-cycle regulators that control mitotic exit. Here, we describe that the core SPB component Nud1p is a key protein that functions in both processes. The astral microtubule organizing function of Nud1p is mediated by its interaction with the gamma-tubulin complex binding protein Spc72p. This function of Nud1p is distinct from its role in cell-cycle control: Nud1p binds the spindle checkpoint control proteins Bfa1p and Bub2p to the SPB, and is part of the mitotic exit network (MEN) in which it functions upstream of CDC15 but downstream of LTE1. In conditional lethal nud1-2 cells, the MEN component Tem1p, a GTPase, is mislocalized, whereas the kinase Cdc15p is still associated with the SPB. Thus, in nud1-2 cells the failure of Tem1p to interact with Cdc15p at the SPB probably prevents mitotic exit.

Animals↗
PubMed2000

Novel three-dimensional capillary electrophoresis system for complex and trace analysis.

A novel triple column capillary electrophoresis system is described. Design specifications facilitate method development and analyses by providing on-line, selective, pre-concentration and clean-up of both high (ml) and low (microl) volumes of specific analytes in two dimensions and separation via an additional third dimension. The system described additionally provides four distinct detection capabilities via both contactless conductivity and UV. The addition of a third dimension to the previously reported "coupled-column" systems, and further modifications made, has allowed for optimal identification, separation, and quantitation of micro-components in complex mixtures. The ability to perform both capillary zone electrophoretic and isotachophoretic separations on-line and in any combination enhances the scope for rapid analytical method development and analysis of complex or trace sample components.

Conductometry↗
PubMed2000

Recruitment experience in the first phase of the African American Hereditary Prostate Cancer (AAHPC) study.

The African American Hereditary Prostate Cancer (AAHPC) Study is an ongoing multicenter genetic linkage study organized by Howard University and the National Human Genome Research Institute (NHGRI), with support from the Office for Research on Minority Health and the National Cancer Institute. The goals of the study are to: (i) look for evidence of involvement of chromosome 1q24-25 (HPC1) in African American men with hereditary prostate cancer (HPC) and (ii) conduct a genome-wide search for other loci associated with HPC in African American men. To accomplish these goals, a network has been established including Howard University, the NHGRI, and six Collaborative Recruitment Centers (CRCs). The CRCs are responsible for the identification and enrollment of 100 African American families. To date, 43 families have been enrolled. Recruitment strategies have included mass media campaigns, physician referrals, community health-fairs/prostate cancer screenings, support groups, tumor registries, as well as visits to churches, barber shops, and universities. By far, the most productive recruitment mechanisms have been physician referrals and tumor registries, yielding a total of 35 (81%) families. Approximately 41% (n = 3400) of probands initially contacted by phone or mail expressed interest in participating; the families of 2% of these met the eligibility criteria, and 75% of those families have been enrolled in the study, indicating a 0.5% recruitment yield (ratio of participants to contacts). As the first large-scale genetic linkage study of African Americans, on a common disease, the challenges and successes of the recruitment process for the AAHPC Study should serve to inform future efforts to involve this population in similar studies.

Black or African American↗
PubMed2000

Memory function in patients with stable, moderate to severe cardiac failure.

BACKGROUND: Psychologic dysfunction is common in patients with heart disease. Patients with end-stage cardiac failure have cognitive dysfunction that can affect their ability to comply with complex treatment regimes. The prevalence of cognitive dysfunction in patients with stable, moderately severe cardiac failure is not known. The purpose of this study was to evaluate the prevalence of memory dysfunction in that population. METHODS: Twenty patients with previous myocardial infarction (MI), New York Heart Association class III or IV cardiac failure symptoms, and left ventricular ejection fraction (LVEF) <40% were studied. Twenty patients with previous MI, no heart failure symptoms, and LVEF >50% were studied as a control group. Memory function was assessed with the Rivermead Behavioural Memory Test and digit span test. Results were controlled for affective state and estimated premorbid intellectual function with the National Adult Reading Test. RESULTS: Patients with cardiac failure performed as well as controls in the memory test (mean [95% confidence intervals] score 18.2 [16.5-19.9] versus 19.7 [18.1-21.4] points, P =.20) and digit span test (10.1 [9.2-11.0] versus 11.0 [9.9-12.2] points). Affective symptoms were more prevalent among patients with cardiac failure. Estimated premorbid intellectual function appeared poorer in patients with cardiac failure (reading test score 24 [7-36] versus 32 [11-46] points). Memory test outcomes were not significantly affected after adjustment for these variables. CONCLUSIONS: Patients with prior MI and stable, moderately severe cardiac failure do not have significantly memory impairment. Memory dysfunction is not likely to interfere with rehabilitation or compliance with treatment regimes. Anxiety and depression, however, are relatively common in this group.

Aged↗