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Biomedical subjects

S Wiseman

Publications and source records attributed to S Wiseman.

At least 19 recordsLinked to original sources
PubMed2001

Evidence that hospital hygiene is important in the control of methicillin-resistant Staphylococcus aureus.

Observational and microbiological data were collected from the patients and environment of a male general surgical ward over a period of 27 months from January 1998. Isolates of methicillin-resistant Staphylococcus aureus (MRSA) from patients and environment were typed by antibiogram, bacteriophage and pulsed field gel electrophoresis of chromosomal DNA. In September 1999, an intervention was put in place which included increasing the domestic cleaning time by 57 hours per week, with emphasis on removal of dust by vacuum cleaning, and allocation of responsibility for the routine cleaning of shared medical equipment. From January 1998 to September 1999, despite standard infection control measures (emphasis on hand hygiene, isolation of affected patients and staggered closure and cleaning of ward bays), 69 patients acquired a strain of E-MRSA16. This strain was also widespread in the ward environment. Typing confirmed that isolates from patients and environment were indistinguishable from one another and that the outbreak was due to a single strain. This strain was responsible for postoperative infection in approximately one third of the patients who acquired it. In the six months following the intervention, only three patients were colonized with the outbreak MRSA and monthly surveys failed to detect this strain in the environment. Thorough and continuous attention to ward hygiene and removal of dust was needed, to terminate a prolonged outbreak of MRSA infection on a general surgical ward, in addition to standard infection control measures. Control of hospital-acquired infection with MRSA requires a combination of measures, none of which are completely effective in isolation.

Cost-Benefit Analysis↗
PubMed2001

Tea flavonoids: bioavailability in vivo and effects on cell signaling pathways in vitro.

The elucidation of the potential health benefits of tea beverage continues to be a focus of research in many laboratories. Beneficial effects of tea have been particularly evident in animal tumorigenesis models, with green and black tea frequently demonstrating similar effectivity. Human data are now emerging to support a beneficial role for tea in cardiovascular disease, but the data with respect to cancer risk at various sites remain inconclusive. The constituent flavonoids of green and black tea beverage are known to be potent antioxidants, and although this may be a major factor in explaining their biological activity, it appears that the gallated flavonoids in particular (e.g., epigallocatechin gallate and the gallated theaflavins) impact on a wide range of molecular targets that influence cell growth and more specifically pathways such as those involving angiogenesis. Data on the pharmacokinetic properties of tea flavonoids, primarily on the catechins and therefore related most closely to green tea, have provided indications of the plasma levels and circulating molecular forms that may be expected in humans following tea consumption. The structural complexity of black tea flavonoids, in particular the thearubigins, has hindered efforts to describe their bioavailability and to perform mechanistic studies. Recent studies on the effects of catechins and theaflavins on growth factor-, nuclear factor-kappaB-, and stress-mediated signal transductions are described in this review, where possible in relation to their bioavailability in vivo. These studies indicate that effects that may be relevant to both cancer and atherosclerosis are often observed at tea flavonoid levels that could realistically be encountered in vivo. However, more studies need to be performed using those molecular forms of tea flavonoids (methylated, sulfated, and glucuronidated conjugates) that are the major circulating species encountered following tea consumption. Such studies, combined with further human epidemiological and interventional data, should ultimately elucidate the full beneficial potential of tea beverage on human health.

Cell Cycle↗
PubMed2001

Dietary tomato paste protects against ultraviolet light-induced erythema in humans.

Carotenoids are efficient antioxidants capable of scavenging reactive oxygen species generated under conditions of photooxidative stress. It has been shown that supplementation with high doses of beta-carotene protects skin against UV-induced erythema. This study was designed to investigate whether intervention with a natural dietary source rich in lycopene protects against UV-induced erythema in humans. Tomato paste (40 g), providing approximately 16 mg/d of lycopene, was ingested with 10 g of olive oil over a period of 10 wk by 9 volunteers. Controls (n = 10) received olive oil only. Erythema was induced by illumination of dorsal skin (scapular region) with a solar simulator at the beginning of the study, after 4 wk and after 10 wk. Intensity of erythema was measured by chromatometry; the a-value was determined directly before and 24 h after irradiation. Serum carotenoid levels were measured by HPLC. At the beginning of the study, carotenoid levels did not differ between the two groups. Serum levels of lycopene increased in supplemented subjects; the other carotenoids did not change significantly, and no change in serum carotenoids was observed in the control group. At wk 10, dorsal erythema formation was 40% lower in the group that consumed tomato paste compared with controls (P = 0.02; Wilcoxon-Mann-Whitney test). No significant difference between groups was found at wk 4 of treatment. The data demonstrate that it is feasible to achieve protection against UV light-induced erythema by ingestion of a commonly consumed dietary source of lycopene.

Adult↗
PubMed2000

Gangliosides as modulators of dendritogenesis in normal and storage disease-affected pyramidal neurons.

Pyramidal cells initiate the formation of dendritic arbors in a prolific burst of neurite outgrowth during early cortical development. Although morphologically mature pyramidal neurons do not normally sprout additional primary dendrites, the discovery of ectopic dendritogenesis in neuronal storage diseases has revealed that these cells do retain this ability under appropriate stimulation. The capacity for renewal of dendritogenesis has been found to exhibit a species gradient with human > cat, dog, sheep > mouse. A consistent metabolic feature of ectopic dendrite-bearing pyramidal neurons is a heightened intracellular expression of GM2 ganglioside. Elevated expression of this same glycosphingolipid has also been found to correlate with normal dendritogenesis. Immature neurons in developing cat and ferret cortex exhibit high levels of GM2 ganglioside immunoreactivity coincident with normal dendritic sprouting and a similar relationship has now been shown for human cortical development. Ultrastructural studies of all three species revealed GM2 localized to vesicles in a manner consistent with Golgi synthesis and exocytic trafficking to the somatic-dendritic plasmalemma. We propose that GM2 ganglioside functions in glycosphingolipid-enriched microdomains (lipid rafts) in the plasmalemma to promote dendritic initiation through modulation of specific membrane proteins and/or their associated second messenger cascades.

Animals↗
PubMed1995

Total antioxidant activity of low density lipoproteins and the relationship with alpha-tocopherol status.

A rapid method is described for measuring the antioxidant activity of low density lipoproteins. Studies were undertaken on individuals attending a hyperlipidaemia clinic, an unsupplemented group and a group after supplementation with 300 mg dl-alpha-tocopherol acetate for nine weeks. The results show a positive correlation between the antioxidant activity and alpha-tocopherol content of LDL in the supplemented group.

Antioxidants↗
PubMed1990

The influence of smoking and plasma factors on prosthetic graft patency.

The effects of smoking and plasma risk factors on the patency of prosthetic femoro-popliteal bypass grafts were investigated in 93 patients entered into a multicentre trial of prosthetic graft materials (70 patients had patent grafts and 23 patients had occluded grafts 2 years after surgery). The smoking markers thiocyanate and fibrinogen were significantly higher in patients with occluded grafts, whereas LDL-cholesterol was significantly higher in patients with patent grafts 2 years after bypass. Based on smoking markers, graft patency in smokers was 57% at 2 years by life table, compared to 78% in non-smokers. P less than 0.05. Fibrinogen was an important variable, predicting graft occlusion with graft patency in patients with below median fibrinogen levels, being 84% at 2 years by life table compared to 51% in those with above median fibrinogen levels, P less than 0.025. Although increased levels of LDL-cholesterol have been associated with accelerated atherosclerosis, patients with above median levels of LDL-cholesterol had improved graft patency (83%) at 2 years compared to patency in patients with below median LDL-cholesterol (60%), P less than 0.05. The plasma risk factors associated with the failure of prosthetic grafts are similar to those associated with the failure of saphenous vein grafts, indicating that higher fibrinogen levels and smoking may contribute to an hypercoagulable state. Greater efforts are needed to stop patients smoking after vascular reconstruction.

Aged↗
PubMed1989

Influence of smoking and plasma factors on patency of femoropopliteal vein grafts.

OBJECTIVE: To determine the effects of smoking, plasma lipids, lipoproteins, apolipoproteins, and fibrinogen on the patency of saphenous vein femoropopliteal bypass grafts at one year. DESIGN: Prospective study of patients with saphenous vein femoropopliteal bypass grafts entered into a multicentre trial. SETTING: Surgical wards, outpatient clinics, and home visits coordinated by two tertiary referral centres in London and Birmingham. PATIENTS: 157 Patients (mean age 66.6 (SD 8.2) years), 113 with patent grafts and 44 with occluded grafts one year after bypass. MAIN OUTCOME MEASURE: Cumulative percentage patency at one year. RESULTS: Markers for smoking (blood carboxyhaemoglobin concentration (p less than 0.05) and plasma thiocyanate concentration (p less than 0.01) and plasma concentrations of fibrinogen (p less than 0.001) and apolipoproteins AI (p less than 0.04) and (a) (p less than 0.05) were significantly higher in patients with occluded grafts. Serum cholesterol concentrations were significantly higher in patients with grafts that remained patent one year after bypass (p less than 0.005). Analysis of the smoking markers indicated that a quarter of patients (40) were untruthful in their claims to have stopped smoking. Based on smoking markers, patency of grafts in smokers was significantly lower at one year by life table analysis than in non-smokers (63% v 84%, p less than 0.02). Patency was significantly higher by life table analysis in patients with a plasma fibrinogen concentration below the median than in those with a concentration above (90% v 57%, p less than 0.0002). Surprisingly, increased plasma low density lipoprotein cholesterol concentration was significantly associated with improved patency at one year (85%) at values above the median compared with patency (only 68%) at values in the lower half of the range (p less than 0.02). CONCLUSIONS: Plasma fibrinogen concentration was the most important variable predicting graft occlusion, followed by smoking markers. A more forceful approach is needed to stop patients smoking; therapeutic measures to improve patency of vein grafts should focus on decreasing plasma fibrinogen concentration rather than serum cholesterol concentration.

Aged↗
PubMed1988

Pilot study of a screening test for peripheral arterial disease in middle aged men: fibrinogen as a possible risk factor.

A simple one minute exercise test was used as a screening test for asymptomatic peripheral arterial disease in a sample of 100 men in their sixth decade with no previous referrals for cardiovascular disease. Other investigations included resting ECG, non-invasive carotid artery assessment, and plasma biochemical analysis. Of these 100 men (mean age 56), 10 had evidence of peripheral disease on exercise testing, four had ischaemic changes on resting ECG, and one showed evidence of carotid artery stenosis. A total therefore of 15 out of 100 (15%) had asymptomatic arterial disease. These 15 men had increased concentrations of plasma fibrinogen (4.3(0.7) g.litre-1) compared with men with no evidence of arterial disease (3.5(0.7) g.litre-1; p less than 0.01). The one minute exercise test is a useful screening test for peripheral arterial disease, and this pilot study suggests that raised plasma fibrinogen concentrations may be an important risk factor.

Arterial Occlusive Diseases↗
PubMed1985

Picture recognition improves with subsequent verbal information.

In three experiments, subjects studied photographs presented alone or followed by a descriptive sentence. The sentence provided additional information not available in the picture. Subsequent yes-no recognition tests for the pictures demonstrated better memory for those pictures that had been followed by descriptive sentences. Experiment 1 showed that described pictures were remembered better regardless of whether comparison was to undescribed pictures presented in immediate succession or to undescribed pictures followed by a blank period equal in duration to the descriptive sentence. Experiment 2 demonstrated that although both unrelated and related sentences aided picture recognition, related sentences were significantly more helpful. Experiment 3 revealed that increasing the amount of related information (low, medium, and high) had no differential effect on picture recognition. Three explanations of these results are considered: integration of the sentence with the picture, formation of a semantic representation in addition to the pictorial one, and elaboration of the pictorial representation initiated by the sentence. Taken together, the findings seem most consistent with the elaboration account--A post-picture sentence improves attention to and perhaps rehearsal of the representation of the picture following its display.

Adolescent↗
PubMed1970

Transformation of fibroblasts by allogeneic and xenogeneic transplants of demineralized tooth and bone.

Xenogeneic transplants of powdered, dehydrated, demineralized matrix of bone and tooth were well tolerated in three species of rodents. Differences between the species were found in competence of fibroblasts to be transformed into cartilage and bone in vivo by these preparations. Rat fibroblasts were most susceptible to transformation of this sort; they were transformed by demineralized dentin of guinea pig, mouse, and rat, and to a limited extent, by a specimen of decalcified human bone.

Alkaline Phosphatase↗