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Ian Davidson

Publications and source records attributed to Ian Davidson.

13 recordsLinked to original sources
PubMed2006

Growth-induced changes in the proteome of Helicobacter pylori.

Helicobacter pylori is a major human pathogen that is responsible for a number of gastrointestinal infections. We have used 2-DE to characterise protein synthesis in bacteria grown either on solid agar-based media or in each of two broth culture media (Brucella and brain heart infusion (BHI) broth). Significant differences were observed in the proteomes of bacteria grown either on agar-based or in broth media. Major changes in protein abundance were identified using principal component analysis (PCA), which delineated the profiles derived for the three key growth conditions (i.e. agar plates, Brucella and BHI broth). Proteins detected across the gel series were identified by peptide mass mapping and Edman sequencing. A number of proteins associated with protein synthesis in general as well as specific amino acid synthesis were depressed in broth-grown bacteria compared to plate-grown bacteria. A similar reduction was also observed in the abundance of proteins involved in detoxification. Two of the most abundant spots, identified as UreB and GroEL, in plate-grown bacteria showed a >140-fold drop in abundance in bacteria grown in Brucella broth compared to bacteria grown on agar plates. Two protein spots induced in bacteria grown in broth culture were both identified as glyceraldehyde 3-phosphate dehydrogenase based on their N-terminal amino acid sequences derived by Edman degradation. The underlying causes of the changes in the proteins abundance were not clear, but it was likely that a significant proportion of the changes were due to the alkaline pH of the broth culture media.

Agar↗
PubMed2005

Proteomic analysis of the entomopathogenic nematode Steinernema feltiae IS-6 IJs under evaporative and osmotic stresses.

In order to improve the storage capability under desiccation of the widely sold biological insecticides based on entomopathogenic nematodes (EPNs), we need to understand how these organisms respond to desiccation stress. As part of our studies to achieve this, we studied survival and protein expression in infective juveniles of the EPN Steinernema feltiae IS-6 when exposed to evaporative (exposure to 97% relative humidity (RH) for 3 days, followed by a 1-day exposure to 85% RH) and osmotic (exposure to 24% glycerol for 8h) stresses. More than 400 protein spots that were detected by proteomic analysis showed reproducible abundance within replications. Of these, 10 spots and 7 spots showed detectable changes in abundance under evaporative and osmotic stress, respectively, compared to fully hydrated nematodes. Three spots exhibited a differential response pattern between evaporative and osmotic desiccation (one was down regulated and two were novel in evaporative desiccation). Peptide mass mapping with MALDI-TOF mass spectrometry (MS) identified 10 desiccation-response proteins, among which several are known to be stress responsive including heat shock protein 60, coenzyme q biosynthesis protein, inositol monophosphatase and fumarate lyase that were found in both stresses. Other identified proteins are known to be involved in the cell cycle regulation, regulation of gene transcription, organization of macromolecular structure and some currently have no known functions. Our results suggest that it is unlikely that improvement of desiccation tolerance in EPNs can be achieved through genetic transformation and addition of single genes and that selective breeding could be the best approach to generate desiccation resistant worms.

Adaptation, Physiological↗
PubMed2005

Effects of a stroke rehabilitation education programme for nurses.

AIMS: This paper reports a study which aimed to explore the effects of education on the practice of nurses working in stroke rehabilitation units. BACKGROUND: It has been suggested that a key component of the success of stroke units in reducing mortality and disability is the contribution made by nurses, but debate continues around their specific role. Literature has concentrated on nurses' perceptions of their role rather than their actual activities with patients. In studying the effects of education on nurses' practice with stroke patients there is a need to identify what nurses actually do, rather than what they say they do. METHODS: A quasi-experimental, non-equivalent control group design was used to study two stroke rehabilitation units. Non-participant observation was conducted during morning care sessions, focusing on styles of physical interaction. Base-line observations were recorded in each unit, after which the staff in the intervention unit received 7 hours' education, specifically focused on therapeutic handling in relation to morning care activities. Following this, postintervention observations were conducted and comparisons of interaction styles made between units. RESULTS: Twenty-six staff and 37 patients took part in the study. Following the education, staff in the intervention unit showed a change in physical interaction style more in line with therapeutic practice, with the proportion of 'doing for' interventions reducing (45.4% vs. 33.2%; P < 0.05). The proportion of facilitatory interventions increased (3.9% vs. 6.1%) however, this difference was not statistically significant (P = 0.098). The change in styles of practice was achieved with no increased demand on nurses' time. CONCLUSION: Education for nurses which aims to change styles of interaction with stroke patients can be effective. However, further research is required to identify the effect of nursing interventions on patient outcomes following stroke.

Activities of Daily Living↗
PubMed2005

A study to assess the effect of nursing interventions at the weekend for people with stroke.

OBJECTIVE: To examine whether additional therapy provided by nurses at the weekend improved the physical outcome for people with stroke on a stroke rehabilitation unit. DESIGN: A single blind randomized controlled trial. SETTING: A 16-bed stroke rehabilitation unit in the north of England. SUBJECTS: Forty-one people with stroke were randomized by means of minimization to intervention and control groups. INTERVENTIONS: The intervention group received additional exercise at the weekend provided by the nursing staff and the control group received their usual care. Both groups received usual care during weekdays. MAIN OUTCOME MEASURES: The Motor Assessment Scale (MAS), the Barthel Index (BI) and length of stay in hospital. RESULTS: No significant differences were found between the groups in terms of MAS and BI at discharge but there was a borderline significant difference between the groups on unconditional testing in terms of length of stay in hospital and on the stroke unit (p = 0.05 and p = 0.07 respectively). However, these findings were in favour of the control group. On conditional testing (adjusting for BI on admission and age) these differences disappeared (p = 0.14 and p = 0.15) for length of stay in hospital and on the stroke unit respectively. CONCLUSIONS: The present study indicates that an increase in one-to-one input by nurses for people with stroke did not lead to a measurable difference in outcome in this small study.

Adult↗
PubMed2004

Charging for NHSPlus: an inferential study based on the internal provision of occupational health services within the National Health Service.

BACKGROUND: 'NHSPlus' was conceived as a national agency that would provide occupational health services to organizations, for a fee, without imposing any financial burden on the taxpayer. This self-funding requirement brings into focus the resource implications for such a service and the determination of the charges to be made to external clients. AIM: The existing provision of occupational health services to >100000 National Health Service (NHS) staff by 13 NHS occupational health services of various sizes was analysed, with the objective of determining an appropriate charge-out rate to third parties. METHOD: Two focus groups were questioned on their work external to the NHS. Data collected on the allocation of doctors and nurses to occupational health services in relation to the number of NHS clients serviced were used to investigate the nature of the resourcing relationship using regression analysis. RESULTS: The relationship was found to be stable enough to provide a good estimate of staff requirements (the key resource requirement). Combining this with costing information allowed inferences to be drawn concerning the economic cost and hence the break-even rate of charge for the service. This was then compared with the employer charge rates in the NHSPlus published case studies. CONCLUSIONS: The results suggest that the per capita charges to external clients are lower than the per capita cost of internal occupational health provision within the NHS, raising questions about the viability of the service.

Fees and Charges↗
PubMed2004

Regulation of catabolic enzymes during long-term exposure of Delftia acidovorans MC1 to chlorophenoxy herbicides.

Delftia acidovorans MC1 is able to grow on chlorophenoxy herbicides such as 2,4-dichlorophenoxypropionic acid (2,4-DCPP) and 2,4-dichlorophenoxyacetic acid as sole sources of carbon and energy. High concentrations of the potentially toxic organics inhibit the productive degradation and poison the organism. To discover the target of chlorophenoxy herbicides in D. acidovorans MC1 and to recognize adaptation mechanisms, the response to chlorophenoxy acids at the level of proteins was analysed. The comparison of protein patterns after chemostatic growth on pyruvate and 2,4-DCPP facilitated the discovery of several proteins induced and repressed due to the substrate shifts. Many of the induced enzymes, for example two chlorocatechol 1,2-dioxygenases, are involved in the metabolism of 2,4-DCPP. A stronger induction of some catabolic enzymes (chlorocatechol 1,2-dioxygenase TfdC(II), chloromuconate cycloisomerase TfdD) caused by an instant increase in the concentration of 2,4-DCPP resulted in increased rates of productive detoxification and finally in resistance of the cells. Nevertheless, the decrease of the (S)-2,4-DCPP-specific 2-oxoglutarate-dependent dioxygenase in 2D gels reveals a potential bottleneck in 2,4-DCPP degradation. Well-known heat-shock proteins and oxidative-stress proteins play a minor role in adaptation, because apart from DnaK only a weak or no induction of the proteins GroEL, AhpC and SodA was observed. Moreover, the modification of elongation factor Tu (TufA), a strong decrease of asparaginase and the induction of the hypothetical periplasmic protein YceI point to additional resistance mechanisms against chlorophenoxy herbicides.

Amino Acid Sequence↗
PubMed2003

Percutaneous biliary metal wall stenting in malignant obstructive jaundice.

BACKGROUND: Most patients with advanced stage malignant obstructive jaundice will be suitable for palliation only. Metallic stents are safe, effective and minimally invasive. DESIGN: A review of case notes of patients who had Wallstents inserted percutaneously from January 1996 to December 2000. RESULTS: Eighty-nine patients with a median age of 72 years underwent percutaneous insertion of biliary metal stents. The diagnoses were cholangiocarcinoma (41.5%), pancreatic carcinoma (40.5%), nodal metastases at the porta hepatis (14.6%) and gall bladder cancer (3.4%). Ninety-six per cent of patients improved their hyperbilirubinaemia to normal levels by 1 month. The median post-procedure hospital stay was 16 days. Early overall complications (within 30 days of stenting) occurred in 30% of patients (70% of these were disease related). The 30 day mortality rate was 20% (n = 18). Fifty (70%) patients were readmitted to hospital, most commonly because of carcinomatosis (16) or stent obstruction (12). The symptom-free period ranged from 2 weeks to 13 months. Median survival for all patients was 3.5 months. Survival correlated inversely with serum bilirubin at presentation (r = -0.34, P = 0.001), but not with other liver function tests. DISCUSSION: Metal wall stenting for malignant obstructive jaundice provides good palliation with low, procedure-related morbidity and mortality, but poor overall survival from disease-related morbidity. Survival significantly correlates with pre-stenting serum bilirubin levels. There is a need to identify the subgroup of patients in whom stenting has no beneficial effect.

Aged↗
PubMed2002

Diagnosis of lower-limb deep venous thrombosis: a prospective blinded study of magnetic resonance direct thrombus imaging.

BACKGROUND: Current magnetic resonance techniques generate high signal from venous blood and show thrombi as filling defects. Magnetic resonance direct thrombus imaging (MRDTI) directly visualizes acute thrombus. OBJECTIVE: To determine the accuracy of MRDTI for diagnosis of acute symptomatic deep venous thrombosis (DVT) below and above the knee. DESIGN: Prospective, blinded study. SETTING: A 1355-bed university hospital. PATIENTS: 101 patients with suspected DVT who had had routine venography. Participants were recruited from a cohort of patients with suspected DVT. All patients with a positive venogram and one quarter of patients with a negative venogram were selected by using a random sequence. INTERVENTION: MRDTI was performed within 48 hours of venography and was interpreted by two reviewers. MEASUREMENTS: Diagnosis of DVT overall; isolated calf, femoropopliteal, and ileofemoral DVT; and thrombus in the calf, femoropopliteal, and iliac segments. RESULTS: The reports from two readers had sensitivities of 96% and 94% and specificities of 90% and 92% for diagnosis of DVT. Sensitivities were 92% and 83% for isolated calf DVT, 97% and 97% for femoropopliteal DVT, and 100% and 100% for ileofemoral DVT. Specificities were 94% and 96% for isolated calf DVT and 100% and 100% for both femoropopliteal and ileofemoral DVT. Similarly, sensitivity and specificity within each of the venous segments ranged from 91% to 100%. Interobserver variability measured by using a weighted kappa statistic ranged from 0.89 to 0.98 for these measures. CONCLUSION: Magnetic resonance direct thrombus imaging is an accurate noninvasive test for diagnosis of DVT, and its accuracy is maintained below the knee. Comparison of individual venous segments showed that results of MRDTI agreed strongly with findings on venography. Scanning was well tolerated, and interpretation was highly reproducible.

Adult↗
PubMed2002

Stent-graft migration after endovascular repair of abdominal aortic aneurysm.

PURPOSE: To report the incidence of graft migration in patients after endovascular repair of abdominal aortic aneurysms (AAA) and assess the significance of neck diameter changes in patients with and without suprarenal stent implantation. METHODS: The medical records and imaging studies of 176 consecutive patients (175 men; median age 71 years, range 48-88) who had endovascular AAA repair with the Nottingham aortomonoiliac system were reviewed. The following parameters were recorded: preoperative neck diameter and length, presence of intraoperative and late graft migrations, time to onset of late migration, length of late migration, and neck diameter changes in patients with documented late graft migration. The patients were divided into 2 groups based on the placement of an endograft with or without suprarenal bare stent fixation. Median follow-up was 15 months (range 1-48). RESULTS: There were 15 (8.5%) graft migrations (6 intraoperative and 9 late). Of those, 14 (10.9%) were in the 128-patient infrarenal fixation group and 1 (2.1%) in the 48-patient suprarenal stent group. Median neck diameters on preoperative and postoperative computed tomography scans in patients with late migration were 22.2 mm and 23.0 mm, respectively (p>0.05). The median time to graft migration was 14 months after the original operation (range 6-36). CONCLUSIONS: Distal device migration occurred frequently with the Nottingham system. Late graft migration was not associated with neck enlargement. Endografts with a suprarenal stent may have a decreased incidence of graft migration.

Aged↗
PubMed2002

Protein turnover, amino acid profile and amino acid flux in juvenile shrimp Litopenaeus vannamei: effects of dietary protein source.

The effect of dietary protein on protein synthesis and growth of juvenile shrimps Litopenaeus vannamei was investigated using three different diets with equivalent protein content. Protein synthesis was investigated by a flooding dose of tritiated phenylalanine. Survival, specific growth and protein synthesis rates were higher, and protein degradation was lower, in shrimps fed a fish/squid/shrimp meal diet, or a 50% laboratory diet/50% soybean meal variant diet, than in those fed a casein-based diet. The efficiency of retention of synthesized protein as growth was 94% for shrimps fed the fish meal diet, suggesting a very low protein turnover rate; by contrast, the retention of synthesized protein was only 80% for shrimps fed the casein diet. The amino acid profile of the casein diet was poorly correlated with that of the shrimps. 4 h after a single meal the protein synthesis rates increased following an increase in RNA activity. A model was developed for amino acid flux, suggesting that high growth rates involve a reduction in the turnover of proteins, while amino acid loss appears to be high.

Amino Acids↗
PubMedDate not supplied

Color duplex ultrasonography of the superior mesenteric artery after placement of endografts with suprarenal stents.

After endovascular repair of abdominal aortic aneurysm with endografts with suprarenal stents, the proximal uncovered stent may cross the origin of the superior mesenteric artery. Effects on splanchnic circulation are unknown and may include development of stenosis at the vicinity of the stent. The criteria of high-grade superior mesenteric artery stenosis using color duplex ultrasonography have been previously reported. The purpose of this study is to examine the incidence of high-grade superior mesenteric artery stenosis in patients with endografts with suprarenal stents using color duplex ultrasonography. Candidates for the study were patients who had placement of an aortic endograft with a suprarenal stent and were able to undergo ultrasonography of the superior mesenteric artery. After reviewing computed tomography scans, patients who had the origin of the superior mesenteric artery crossed by the suprarenal stent underwent color duplex ultrasonography of this vessel. Presence of turbulence or narrowing of the superior mesenteric artery, or a peak systolic velocity greater than 2.75 m/sec, or an end-diastolic velocity greater than 0.45 m/sec were considered significant for the presence of high-grade superior mesenteric artery stenosis. There were 24 patients (21 males, three females), median age 71 years (range, 59-83). The suprarenal stent was crossing the superior mesenteric artery in 17 of 24 patients (71%). Color duplex ultrasound was technically successful in 13 of 17 (76%). The test was performed after a median follow-up of 9 months (range, 3 days to 34 months). No patient had evidence of turbulence or narrowing of the superior mesenteric artery during ultrasonography. The median peak systolic velocity was 0.92 m/sec (range, 0.53-1.21 m/sec). No patient had peak systolic velocity greater than 2.75 m/sec. The median end-diastolic velocity was 0.10 m/sec (range, 0.09-0.14 m/sec). No patient had end-diastolic velocity greater than 0.45 m/sec. Color duplex ultrasonography did not demonstrate the presence of high-grade superior mesenteric artery stenosis during early follow-up of patients with endografts with suprarenal stents. Longer follow-up of larger series of patients is needed to determine the long-term effects of suprarenal stents on splanchnic circulation.

Aged↗