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Biomedical subjects

S Khan

Publications and source records attributed to S Khan.

At least 19 recordsLinked to original sources
PubMed2006

Characteristics and treatments of patients with peripheral arterial disease referred to UK vascular clinics: results of a prospective registry.

BACKGROUND: Peripheral arterial disease (PAD) is often associated with risk factors including cigarette smoking, hypertension and hypercholesterolaemia, and patients have a high risk of future vascular events. Good medical management results in improved outcomes and quality of life, but previous studies have documented sub-optimal treatment of risk factors. We assessed the management of cardiovascular risk factors in patients with PAD referred to specialist vascular clinics. METHODS: This was a prospective, protocol driven registry carried out in UK vascular clinics. Patients who were first-time referrals for evaluation of PAD were eligible if they had claudication plus ankle-brachial pressure index (ABPI) < or = 0.9. Statistical associations between key demographic and treatment variables were explored using a chi-squared test. RESULTS: We enrolled 473 patients from 23 sites. Mean age was 68 years (SD 10) and 66% were male. Mean estimated claudication distance was 100 m, and ABPI was 0.74. Mean systolic blood pressure (SBP) was 155 mmHg, and 42% had a SBP >160 mmHg. Forty percent were current smokers and half had tried to give up in the prior 6 months, but there was no evidence of a systematic method of smoking cessation. Mean total cholesterol was 5.4 (SD1.2) mmol/l and 30% had levels >6 mmol/l. Antiplatelet therapy had been given to 70% and statins to 44%. Prior CHD was present in 29% and these patients had significantly higher use of antiplatelet therapy, statins and ACE-inhibitors. CONCLUSIONS: In spite of attempts to raise awareness about PAD as an important marker of cardiovascular risk, patients are still poorly treated prior to referral to a vascular clinic. In particular, the use of evidence-based treatments is sub-optimal, while hypertension and cigarette smoking are poorly managed. More work needs to be done to educate health professionals about the detection and optimal medical management of PAD.

Adult↗
PubMed2006

Earthquakes and crush syndrome casualties: lessons learned from the Kashmir disaster.

Major earthquakes may provoke a substantial number of crush casualties complicated by acute kidney injury (AKI). After the 1988 Armenian earthquake, the International Society of Nephrology (ISN) established the Renal Disaster Relief Task Force (RDRTF) to organize renal care in large disasters; this approach proved to be useful in several recent disasters. This paper depicts the organizational aspects of the rescue intervention during the Kashmir earthquake, in 2005. Specific problems were fierce geographic circumstances, lack of pre-registered local keymen, transportation problems, and inexperience of local teams to cope with problems related to mass disasters. Once treatment was installed, global outcomes were favorable. It is concluded that well-organized international help in renal disasters can be effective in saving many lives, but still necessitates conceptual adaptations owing to specific local circumstances.

Acute Disease↗
PubMed2006

Portosystemic shunts versus endoscopic therapy for variceal rebleeding in patients with cirrhosis.

BACKGROUND: Randomised clinical trials have compared portosystemic shunting procedures with endoscopic therapy for variceal haemorrhage, but there is no consensus as to which approach is preferable. OBJECTIVES: To compare the effects of shunts (total surgical shunt (TS); distal spleno-renal shunts (DSRS) or transjugular intrahepatic porto-systemic shunts (TIPS) with endoscopic therapy (ET, sclerotherapy and/or banding) for prevention of variceal rebleeding in patients with cirrhosis. SEARCH STRATEGY: The Cochrane Hepato-Biliary Group Controlled Trials Register, The Cochrane Library, MEDLINE, EMBASE, conference proceedings, and the references of identified trials were searched (last search February 2004). Researchers in the field and in industry were contacted. SELECTION CRITERIA: Randomised clinical trials comparing TS, DSRS or TIPS with ET in patients who had recovered from a variceal haemorrhage and were known to be cirrhotic. DATA COLLECTION AND ANALYSIS: Data were collected to allow intention-to-treat analysis where possible. For each outcome, a pooled estimate of treatment effect (log hazard ratio for time to outcome, Peto odds ratio for binary outcomes, and differences in means for continuous outcomes) across trials was calculated. MAIN RESULTS: Twenty-two trials evaluating 1409 patients were included. All trials had problems of method. Shunt therapy compared with ET demonstrated significantly less rebleeding (OR 0.24, 95% CI 0.18 to 0.30) at the cost of significantly increased acute hepatic encephalopathy (OR 2.07, 95% CI 1.59 to 2.69) and chronic encephalopathy (OR 2.09, 95% CI 1.20 to 3.62). There were no significant differences regarding mortality (hazard ratio 1.00, 95% CI 0.82 to 1.21) and duration of in-patient stay (weighed mean difference 0.78 day, 95% CI -1.48 to 3.05). The proportion of patients with shunt occlusion or dysfunction was 3.1% (95% CI 0.4 to 10.7%) following TS (two trials), 7.8% (95% CI 3.8 to 13.9%) following DSRS (four trials), and 59% (range 18% to 72%) following TIPS (14 trials). AUTHORS' CONCLUSIONS: All shunts resulted in a significantly lower rebleeding rate at the expense of a higher incidence of encephalopathy. TIPS was complicated by a high incidence of shunt dysfunction. No survival advantage was demonstrated with any shunt.

Endoscopy↗
PubMed2006

A computational modelling study of oxygen vacancies at LaCoO3 perovskite surfaces.

Atomistic computational modelling of the surface structure of the catalytically-active perovskite LaCoO(3) has been undertaken in order to develop better models of the processes involved during catalytic oxidation processes. In particular, the energetics of creating oxygen ion vacancies at the surface have been investigated for the three low index faces (100), (110) and (111). Two mechanisms for vacancy creation have been considered involving dopant Sr(2+) cations at the La(3+) site and reduction of Co(3+) to Co(2+). For both mechanisms, there is a general tendency that the smaller the cation defect separation, the lower the energy of the cluster, as would be expected from simple electrostatic considerations. In addition, there are clear indications that oxygen vacancies are more easily created at the surface than in the bulk. The results also confirm that the presence of defects strongly influences crystal morphology and surface chemistry. The importance of individual crystal surfaces in catalysis is discussed in terms of the energetics for the creation of oxygen vacancies.

Binding Sites↗
PubMed2006

Femtosecond undulator radiation from sliced electron bunches.

At the 1.7-GeV electron storage ring BESSY II, a first source of synchrotron radiation with 100 fs pulse duration, variable (linear and circular) polarization, tunable photon energy (300 to 1400 eV), and excellent signal-to-background ratio was constructed and is now in routine operation.

Journal Article↗
PubMed2006

Work design and management in the manufacturing sector: development and validation of the Work Organisation Assessment Questionnaire.

OBJECTIVES: To examine the factor structure, reliability, and validity of a new context-specific questionnaire for the assessment of work and organisational factors. The Work Organisation Assessment Questionnaire (WOAQ) was developed as part of a risk assessment and risk reduction methodology for hazards inherent in the design and management of work in the manufacturing sector. METHOD: Two studies were conducted. Data were collected from 524 white- and blue-collar employees from a range of manufacturing companies. Exploratory factor analysis was carried out on 28 items that described the most commonly reported failures of work design and management in companies in the manufacturing sector. Concurrent validity data were also collected. A reliability study was conducted with a further 156 employees. RESULTS: Principal component analysis, with varimax rotation, revealed a strong 28-item, five factor structure. The factors were named: quality of relationships with management, reward and recognition, workload, quality of relationships with colleagues, and quality of physical environment. Analyses also revealed a more general summative factor. Results indicated that the questionnaire has good internal consistency and test-retest reliability and validity. Being associated with poor employee health and changes in health related behaviour, the WOAQ factors are possible hazards. It is argued that the strength of those associations offers some estimation of risk. Feedback from the organisations involved indicated that the WOAQ was easy to use and meaningful for them as part of their risk assessment procedures. CONCLUSIONS: The studies reported here describe a model of the hazards to employee health and health related behaviour inherent in the design and management of work in the manufacturing sector. It offers an instrument for their assessment. The scales derived which form the WOAQ were shown to be reliable, valid, and meaningful to the user population.

Adolescent↗
PubMed2006

Investigation of polymerisation shrinkage strain, associated cuspal movement and microleakage of MOD cavities restored incrementally with resin-based composite using an LED light curing unit.

OBJECTIVES: To investigate the polymerisation shrinkage strain, associated cuspal movement, degree of conversion (DC) and cervical gingival microleakage of mesio-occlusal-distal (MOD) cavities restored with four resin-based composite (RBC) filling materials placed incrementally using a light emitting diode (LED) light curing unit (LCU). METHODS: Standardised extensive MOD cavity preparations on extracted teeth were performed on 40 sound upper premolar teeth. Restoration of the teeth involved the placement of RBCs in eight increments with the appropriate bonding system before irradiation using an LED LCU. Buccal and palatal cusp deflections at each stage of polymerisation were recorded using a twin channel deflection measuring gauge. Following restoration, the teeth were thermocycled, immersed in a 0.2% basic fuchsin dye for 24 h, sagittally sectioned and examined for cervical microleakage. The DC was determined using a Fourier transform infra-red (FT-IR) spectrometer. RESULTS: No significantly difference (P=0.677) in cuspal movement was recorded for Z100 (13.1+/-3.2 microm) compared with Filtek Z250 (8.4+/-3.5 microm), P60 (7.3+/-3.8 microm) and Admira (6.7+/-2.7 microm). The LED LCU deflections were compared with a halogen LCU used in a conventional (Fleming GJP, Hall D, Shorthall ACC, Burke FJT. Cuspal movement and microleakage in premolar teeth restored with posterior filling materials of varying reported volumetric shrinkage values. Journal of Dentistry, 2005;33:139-146) and soft-start mode (Fleming GJP, Cara RR, Palin WM, Burke FJT. Cuspal movement and microleakage in premolar teeth restored with posterior filling materials cured using 'soft-start' polymerization. Dental Materials, 2006, , in press) and a significant reduction in cuspal movement was identified for curing type and material type (P<0.001 and P=0.002, respectively). No significant differences were noted between the four RBC materials investigated when the DC or microleakage scores were examined for the LED LCU. SIGNIFICANCE: It would appear that irradiation of RBCs using the LED LCU offered a significant reduction in associated cuspal movement in large MOD cavities. However, the microleakage scores following polymerisation were significantly increased with dye penetration into the pulp chamber from the axial wall evident in teeth restored with the LED LCU.

Bicuspid↗
PubMed2006

Nora's lesion, a distinct radiological entity?

OBJECTIVE: To describe the radiological findings of "Bizarre parosteal osteochondromatous proliferation"(BPOP)-otherwise known as Nora's lesion, to describe the natural evolution of BPOP and to assess radiologically if BPOP is indeed part of a spectrum of reactive lesions including florid reactive periostitis and turret exostosis. DESIGN: Four experienced musculoskeletal radiologists studied plain radiographs and other imaging documents of histologically-proven Nora's lesions, looking for soft-tissue changes, periosteal reaction/calcification and calcified/ossified pseudotumours, and compared those findings with findings on pathology reviewed by a peer group of pathologists. PATIENTS: Twenty-four Nora's lesions originating from a series of 200 consecutive, histologically-verified bone (pseudo)tumours of the hand, seen by the "Netherlands Committee on Bone Tumours" for review and second opinion. RESULTS: Nora's lesions have a recognised presentation on radiographs without specific MR characteristics. Natural evolution could be assessed retrospectively in four cases. Recurrent lesions were seen in seven cases and are difficult to differentiate from primary lesions. CONCLUSIONS: Nora's lesion, defined as a "well-marginated mass of heterotopic mineralization arising from the periosteal aspect of an intact cortex, without medullary changes" has a distinct radiological presentation and is part of a spectrum of reactive lesions which includes florid reactive periostitis and turret exostosis. As it has a distinct radiological appearance, differential diagnosis of malignant lesions such as osteosarcoma and chondrosarcoma should be clear. It does not require immediate biopsy unless the natural evolution is unspecific.

Adolescent↗
PubMed2006

An audit of fusion CT-PET in the management of colorectal liver metastases.

AIM: To assess the use of positron emission tomography combined with computerized tomography (CT-PET) with fluoro-18-2-deoxy-d-glucose ((18)F-FDG) to identify hyper-metabolic tumours, especially colorectal metastases (CRM). METHODS: Patient particulars, diagnoses and clinical outcome for each patient were studied. Twenty-three patients underwent CT-PET, 10 males and 13 females, median age 59 (range 34-72). Fourteen patients presented with primary liver CRM and nine had undergone previous liver resections. Indications for CT-PET included; suspected extrahepatic disease in 13/23 patients, possible hepatic recurrence 5/23 and clinical suspicion in 8/23 patients. RESULTS: Seven patients had a major impact on their management. Unexpected (not seen on CT) findings in the CRM group included, 7/23 (30%) patients with extrahepatic disease, 3/23 with hepatic metastases, 8/23 suspected of having liver or distant metastases on CT had a negative study. A clinical decision, based on the CT-PET report, could be undertaken in 21/23 patients. CONCLUSION: CT-PET is useful in patients with CRM where conventional imaging presents dilemmas such as: assessment of suspected extrahepatic disease, recurrence in liver, patients with advanced or perforated initial tumours.

Adrenal Gland Neoplasms↗
PubMed2006

Rapid plant regeneration and analysis of genetic fidelity of in vitro derived plants of Chlorophytum arundinaceum Baker--an endangered medicinal herb.

An efficient in vitro multiplication system via multiple shoot bud induction and regeneration has been developed in Chlorophytum arundinaceum using shoot crown explants. Optimum regeneration frequency (87%) and desirable organogenetic response in the form of de novo organized multiple shoot buds without an intervening callus phase was obtained on Murashige and Skoog's (MS) minimal organics medium containing 3% sucrose (w/v) supplemented with 4 x 10(-6) M Kn and 2 x 10(-6) MIBA. Axenic secondary explants with multiple shoot buds on subculturing elicited best response with 1 x 10(-5) M Kinetin (Kn) and 5 x 10(-6) M indole-3-butyric acid (IBA) giving rise to an average of 18.74 shoots per culture with mean shoot length of 7.6 cm +/- 1.73. Varying molar ratios of either Kn/IBA or Kn/NAA revealed statistically significant differences in the regeneration frequencies among the phytohormone treatments. It was observed that the shoot bud differentiation and regeneration was influenced by the molar ratios of cytokinins/auxin rather than their relative concentrations. Healthy regenerated shoots were rooted in half strength MS basal medium containing 3% sucrose (w/v) supplemented with 5 x 10(-6) M IBA. Following simple hardening procedures, rooted plantlets, were transferred to soil-sand (1:1; v/v) with more than 90% success. Genetic fidelity was assessed using random amplified polymorphic DNA (RAPD), karyotype analysis and meiotic behaviour of in vitro and in vivo plants. Five arbitrary decamers displayed same banding profile within all the micropropagated plants and in vivo explant donor. The cytological and molecular analysis complemented and compared well and showed no genomic alterations in the plants regenerated through shoot bud differentiation. High multiplication frequency, molecular, cytological and phenotypic stability ensures the efficacy of the protocol developed for the production and conservation of this important endangered medicinal herb.

Asparagaceae↗
PubMed2006

Femtosecond terahertz radiation from femtoslicing at BESSY.

Femtosecond far-infrared radiation pulses in the THz spectral range were observed as a consequence of the energy modulation of 1.7 GeV electrons by femtosecond laser pulses in the BESSY storage ring in order to generate femtosecond x-ray pulses ("femtoslicing"). In addition to being crucial for diagnostics of the laser-electron interaction, the THz radiation itself is useful for experiments where intense ultrashort THz pulses of well-defined temporal and spectral characteristics are required.

Journal Article↗
PubMed2006

Depletion of alloreactive T cells via CD69: implications on antiviral, antileukemic and immunoregulatory T lymphocytes.

Selective depletion of alloreactive T cells from stem-cell allografts should abrogate graft-versus-host disease while preserving beneficial T cell specificities to facilitate engraftment and immune reconstitution. We therefore explored a refined immunomagnetic separation strategy to effectively deplete alloreactive donor lymphocytes expressing the activation antigen CD69 upon stimulation, and examined the retainment of antiviral, antileukemic, and immunoregulatory T cells. In addition to the CD69high T cell fraction, our studies retrieved two T cell subsets based on residual CD69 expression. Whereas, truly CD69(neg) cells were devoid of detectable alloresponses to original stimulators, CD69-low (CD69low)-expressing T cells elicited significant residual alloreactivity upon restimulation. In interferon-gamma enzyme linked immunospot assays, anti-cytomegalovirus and anti-Epstein-Barr virus responses were preserved at significant numbers among CD69neg T lymphocytes. Accordingly, T cells recognizing the leukemia-associated Wilm's tumor-1 antigen were still detectable in the CD69neg subset. However, antiviral and antileukemic specificities were also consistently found within CD69low T cells, suggesting that memory-type donor T cells were partially captured due to residual CD69 expression. Finally, CD4+CD25+ Foxp3+ immunoregulatory T cells did not upregulate CD69 upon allogeneic stimulation. Our data suggest that CD69-mediated removal of alloreactivity can result in efficient allodepletion, but may partially affect the persistence of antiviral and antileukemic donor memory specificities captured among CD69low-expressing lymphocytes.

Antigens, CD↗
PubMed2006

Early indicators of immunodeficiency in adults and children: protocols for screening for primary immunological defects.

Early recognition of primary immunodeficiency is essential to reduce morbidity and mortality, and yet failure to recognize these conditions is still a major problem for clinicians around the world. The problem is that general practitioners, physicians and paediatricians lack familiarity with these rare disorders, and lack guidance regarding the appropriate use of immunological investigations. A working party from the European Society for Immunodeficiencies (ESID) has published screening protocols for these rare disorders, which aim to help select which tests should be done in which patients. The success of these proposals will depend on all immunologists disseminating this information in a format that is suitable for the busy generalist, who may not be familiar with these immunological tests and concepts. Laboratories should expect increasing requests for these screening investigations, and should make themselves familiar with these protocols so that appropriate second-line investigations can be arranged in a timely fashion. Speedy and effective communication between the laboratory and clinician is essential, and clinically interpreted reports are mandatory. Although these protocols are part of a screening process, their effectiveness in practice remains to be established, and further refinement will be required over time. The early involvement of the clinical immunologist in cases of suspected immunodeficiency is key.

Adult↗
PubMed2006

Robotic assisted retroperitoneoscopic nephroureterectomy -- first experience and the hybrid port technique.

Robot-assisted renal surgery is usually performed transperitoneally due to more available space for excursion of the robotic arms. To our knowledge, we report the first experience with robotic retroperitoneoscopic nephroureterectomy using the Da Vinci Surgical System (Intuitive Surgical, Sunnyvale, CA, USA) and a hybrid port technique. Robotic retroperitoneal nephroureterectomy was performed on two male patients. One 37-year-old patient had a painful non-functioning hydronephrotic left kidney and megaureter; the other aged 76 had a muscle invasive lower left ureteric tumour. Both the procedures were successfully completed with the robot without conversion. Mean operative time was 182.5 min and estimated blood loss 75 ml. Histological examination confirmed the preoperative diagnoses; margins were clear in the patient with tumour. Postoperative recovery was uneventful. We report the technical feasibility of robotic retroperitoneoscopic nephroureterectomy. However, as with all new technology, the benefits need to be further evaluated and proven before this technique can be widely accepted.

Adult↗
PubMed2006

Use of amino terminal type III procollagen peptide (P3NP) assay in methotrexate therapy for psoriasis.

Hepatic fibrosis continues to be a risk in patients receiving methotrexate for psoriasis. Measurement of amino terminal levels of type III procollagen (P3NP) has been advocated as an effective non-invasive test for ongoing hepatic fibrogenesis that could avoid liver biopsies. An audit was conducted to assess the practice of P3NP monitoring using guidelines produced by Manchester and whether the agreed levels correlate with histological severity. Sixty five patients with 174 P3NP assays and 30 liver biopsies were reviewed between the years 1999 and 2003. Total number of patient-methotrexate years was 278.9 and the mean cumulative dose of methotrexate received was 2000 (SD 1838) mg. A higher cumulative dose of methotrexate correlated significantly with high mean and maximum P3NP levels. Of the 30 liver biopsies, 26 (86.6%) showed normal histology or mild to moderate steatosis, three had focal fibrosis, and one had early cirrhosis. A median P3NP value of 5.8 mug/l or higher had a stronger correlation with histological severity. It is concluded that P3NP assay is a valuable adjunct to the clinical management of patients receiving long term methotrexate that can avoid or reduce unnecessary liver biopsies.

Adult↗