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Biomedical subjects

J Thomas

Publications and source records attributed to J Thomas.

At least 19 recordsLinked to original sources
PubMed2007

Piezoelectric generators for biomedical and dental applications: effects of cyclic loading.

This paper presents the results of a study of the effect of cyclic loading parameters on the performance of piezo crystals. The output power of the crystals was observed to increase with parameters such as the cyclic frequency and the dynamic load range. However, the output power also decreased with increasing mean load. The efficiency of the crystal was calculated based on the mechanical energy applied to the piezo crystal. The ratio of the electrical output to mechanical energy input was taken as the efficiency of the crystal. This ratio was seen to increase with the cycling frequency, and also with the dynamic load range. However, increasing mean load caused the efficiency to drop significantly. The implications of the results are discussed for possible applications implanted bioMEMS and microelectronics systems.

Biomechanical Phenomena↗
PubMed2006

Chemoimmunotherapy with dacarbazine, cisplatin, interferon-alpha2b and interleukin-2 versus two cycles of dacarbazine followed by chemoimmunotherapy in patients with metastatic melanoma: a randomised phase II study of the European Organization for Research and Treatment of Cancer Melanoma Group.

BACKGROUND: Chemoimmunotherapy for patients with metastatic melanoma is associated with high toxicity, and only a subset of patients will benefit. This randomised phase II study was performed with the primary objective of exploring whether two cycles of dacarbazine monotherapy could select the subset of patients that would benefit most from more intensive chemoimmunotherapy. PATIENTS AND METHODS: Patients with metastatic melanoma were randomised to either receive chemoimmunotherapy with dacarbazine, cisplatin, interferon-alpha and interleukin-2 (arm A) or initial treatment with two cycles of dacarbazine monotherapy followed irrespective of response by the same 4-drug regimen of chemoimmunotherapy (arm B). Chemoimmunotherapy was continued in the absence of disease progression for a maximum of four cycles. Primary end-point was the disease stabilisation rate. RESULTS: A total of 93 patients were randomised, and 89 patients were eligible. Disease stabilisation (complete/partial response or stable disease) was achieved in 19 patients (42.2%) in arm A and 9 patients (20.5%) in arm B. In arm B 32 of the 44 patients continued chemoimmunotherapy after two cycles of dacarbazine. Of 20 patients with progressive disease (PD) after two cycles of dacarbazine in arm B, only 2 patients achieved an objective response. Median overall survival (OS) in arms A and B was 10.5 months and 9.5 months, respectively. CONCLUSIONS: Despite a lower initial stabilisation rate, the strategy of starting with 2 courses of DTIC prior to a 4-drug regimen led to comparable median overall survival. Only few transient responses were achieved with the 4-drug regimen in patients with disease progression on DTIC, suggesting frequent cross resistance. Two cycles of dacarbazine monotherapy cannot be recommended to select patients for more intensive chemoimmunotherapy.

Adult↗
PubMed2006

Induction of melanoma cell apoptosis and inhibition of tumor growth using a cell-permeable Survivin antagonist.

The inhibitor of apoptosis gene family member Survivin is highly expressed in most tumors, and appears to be a promising target for cancer therapy. Although a variety of Survivin antagonists have been shown to induce apoptosis in malignant cells, the potential utility of these agents is limited by inefficient delivery and cell impermeability. We generated recombinant fusion proteins containing the TAT protein transduction domain and either wild-type Survivin (TAT-Surv-WT) or a dominant-negative mutant (TAT-Surv-T34A). The TAT-Surv proteins were purified by sequential affinity and ion-exchange chromatography, and at 30 nM concentration demonstrated rapid entry into cells at 30 min. Whereas TAT-Surv-WT had minimal effect on YUSAC2 or WM793 melanoma cells, TAT-Surv-T34A induced cell detachment, DNA fragmentation, caspase-3 activation and mitochondrial release of apoptosis-inducing factor at low microM concentrations. Intraperitoneal (i.p.) injection of mice bearing subcutaneous YUSAC2 xenografts with TAT-Surv-T34A (10 mg/kg) was associated with rapid tumor accumulation at 1 h, and increased tumor cell apoptosis and aberrant nuclei formation in situ. Repeated i.p. injection of TAT-Surv-T34A resulted in a 40-50% reduction in growth and mass of established tumors, compared to those similarly injected with saline buffer or TAT-Surv-WT. These studies demonstrate the feasibility of systemic tumor treatment using a cell-permeable Survivin antagonist.

Animals↗
PubMed2006

Photorefractive polymer device with video-rate response time operating at low voltages.

The high-voltage bias required for video-rate compatible, efficient operation of a photorefractive polymer composite is reduced from 6-8 to 1.3 kV. At this low voltage, the device can hold erasable Bragg holograms with 80% efficiency in addition to having a video-rate response time. The transition of the hologram's state from thick to thin is analyzed in detail.

Journal Article↗
PubMed2006

Hyaluronidase for cervical ripening and induction of labour.

BACKGROUND: Dilatation and effacement of the cervix are not only a result of uterine contractions, but are also dependent upon ripening processes within the cervix. The cervix is a fibrous organ composed principally of hyaluronic acid, collagen and proteoglycan. Hyaluronic acid increases markedly after the onset of labour. An increase in the level of hyaluronic acid is associated with an increase in tissue water content. Cervical ripening during labour is characterised by changes of the cervix and an increased water content. Cervical injection of hyaluronidase was postulated to increase cervical ripening. This is one of a series of reviews of methods of cervical ripening and labour induction using standardised methodology. OBJECTIVES: To determine the effects of hyaluronidase for third trimester cervical ripening or induction of labour in comparison with other methods of induction of labour. SEARCH STRATEGY: We searched the Cochrane Pregnancy and Childbirth Group Trials Register (January 2006) and bibliographies of relevant papers. SELECTION CRITERIA: Clinical trials of hyaluronidase for third trimester cervical ripening or labour induction. DATA COLLECTION AND ANALYSIS: A strategy was developed to deal with the large volume and complexity of trial data relating to labour induction. This involved a two-stage method of data extraction. We assessed trial quality. We contacted study authors for additional information. We collected adverse effects information from the trials. MAIN RESULTS: One trial, with 168 women participating, was included in the review. When compared with placebo for cervical ripening intracervical injections of hyaluronidase resulted in women receiving significantly fewer caesarean sections (18% versus 49%, relative risk (RR) 0.37, 95% confidence interval (CI) 0.22 to 0.61), less need for oxytocin augmentation (10% versus 47%, RR 0.20, 95% CI 0.10 to 0.41), and increased cervical favourability after 24 hours (60% versus 98%, RR 0.62, 95% CI 0.52 to 0.74). No side-effects for mother or baby were reported in this trial. AUTHORS' CONCLUSIONS: Intracervical injections of hyaluronidase for cervical ripening appear beneficial. However, this is not common practice. In addition it is an invasive procedure that women may find unacceptable in the presence of less invasive methods.

Cervical Ripening↗
PubMed2006

Corticosteroids for cervical ripening and induction of labour.

BACKGROUND: The role of corticosteroids in the process of labour is not well understood. Animal studies have shown the importance of cortisol secretion by the fetal adrenal gland in initiating labour in sheep. Infusion of glucocorticosteroids into the fetus has also shown to induce premature labour in sheep. Given these studies it has been postulated that corticosteroids will promote the induction of labour in women. This is one of a series of reviews of methods of cervical ripening and labour induction using standardised methodology. OBJECTIVES: To determine the effects of corticosteroids for third trimester cervical ripening or induction of labour in comparison with other methods of cervical priming or induction of labour. SEARCH STRATEGY: We searched the Cochrane Pregnancy and Childbirth Group Trials Register (December 2005) and bibliographies of relevant papers. SELECTION CRITERIA: Clinical trials of corticosteroids for third trimester cervical ripening or labour induction. DATA COLLECTION AND ANALYSIS: A strategy was developed to deal with the large volume and complexity of trial data relating to labour induction. This involved a two-stage method of data extraction. We assessed trial quality. We contacted study authors for additional information. We collected adverse effects information from the trials. MAIN RESULTS: Only one small trial (66 women) was included. The primary outcome vaginal birth within 24 hours was not reported. No benefit of intramuscular administration of corticosteroids with intravenous oxytocin was found when compared with oxytocin alone. However, given the small size of this trial this result should be interpreted cautiously. AUTHORS' CONCLUSIONS: The effectiveness of corticosteroids for induction of labour is uncertain. This method of induction of labour is not commonly used and so further research in this area is probably unwarranted.

Administration, Topical↗
PubMed2006

Influence of presentation on outcome in abdominal aortic aneurysm repair.

OBJECTIVES: In the absence of formal screening abdominal aortic aneurysms (AAA) are detected in an opportunistic manner. Many remain asymptomatic and undetected until they rupture. Incidentally discovered small AAAs are entered into a surveillance programme until they reach a suitable size for repair. The aim of this study was to examine trends in the management of AAA and whether the method of presentation had an effect on subsequent mortality. DESIGN: Observational study in UK district general hospital. MATERIALS/METHODS: This study reports a single surgeon case series identified using a prospectively maintained database. Data on mode of presentation, management and mortality were retrieved from case notes, PIMS hospital database and the Office of National Statistics. RESULTS: Two hundred and five patients were referred with AAAs between 1992 and 2004, 78% presenting in elective circumstances. The surveillance programme fed 33% of the operated cases. Two aneurysms ruptured whilst under surveillance. Overall elective operative mortality was 11.8% and has progressively decreased over time. Thirty-day operated mortality was significantly lower in patients having a period of surveillance than those having immediate elective repair (2.3 vs. 16.3%, p=0.018). A slight reduction in emergency AAA repairs was noted over the study period (r2=0.6) although registered aneurysm deaths continue to increase (r2=0.83). CONCLUSIONS: Elective mortality following AAA surgery decreased over the study period. Outcome was better in those patients who had surgery for aneurysms that had been under surveillance. Despite opportunistic screening the population adjusted mortality rate of aortic aneurysms showed a progressive increase. A reduction in deaths from aneurysms is unlikely without a formal screening programme.

Aortic Aneurysm, Abdominal↗
PubMed2006

Kimberley Indigenous Cognitive Assessment tool (KICA): development of a cognitive assessment tool for older indigenous Australians.

BACKGROUND: Indigenous Australians have a unique cultural heritage dating back many thousands of years. Unfortunately, there is no validated tool to assess cognition in older indigenous Australians. This study was designed to address this deficiency. The Kimberley Indigenous Cognitive Assessment (KICA) was developed with Indigenous health and aged care organizations, and comprises cognitive, informant and functional sections. The psychometric properties of the cognitive assessment section (KICA-Cog) are described in this paper. METHODS: The KICA-Cog was tested in 70 indigenous subjects, of varying cognitive abilities and diagnoses, over 45 years of age. Subjects were interviewed using the KICA-Cog and then independently assessed by expert clinical raters using DSM-IV and ICD-10 criteria. Interrater and internal reliability were determined. RESULTS: The KICA-Cog score showed no systematic interrater difference; the mean was -0.07 (SD = 1.83). Interrater reliability for 16 individual questions from the cognitive section revealed a kappa-value > or = 0.6 and intraclass correlations for 12 questions. Internal consistency, as assessed by Cronbach's alpha, was 0.88. Three items on the cognitive score (pension week, recall and free recall) effectively discriminated 85-7% of dementia cases. Sensitivity and specificity were 90.6% and 92.6%, respectively, using a cut-off score of 31/32. CONCLUSIONS: The KICA-Cog appears to be a reliable assessment tool for cognitive impairment in an Australian older traditionally living indigenous population.

Adolescent↗
PubMed2006

High interlaboratory reproducibility of DNA sequence-based typing of bacteria in a multicenter study.

Current DNA amplification-based typing methods for bacterial pathogens often lack interlaboratory reproducibility. In this international study, DNA sequence-based typing of the Staphylococcus aureus protein A gene (spa, 110 to 422 bp) showed 100% intra- and interlaboratory reproducibility without extensive harmonization of protocols for 30 blind-coded S. aureus DNA samples sent to 10 laboratories. Specialized software for automated sequence analysis ensured a common typing nomenclature.

Bacterial Typing Techniques↗
PubMed2006

Current and future water issues in the Oldman River Basin of Alberta, Canada.

Long-term trends in alpine and prairie snow pack accumulation and melt are affecting streamflow within the Oldman River Basin in southern Alberta, Canada. Unchecked rural and urban development also has contributed to changes in water quality, including enhanced microbial populations and increased waterborne pathogen occurrence. In this study we look at changing environment within the Oldman River Basin and its impact on water quality and quantity. The cumulative effects include a decline in net water supplies, and declining quality resulting in increased risk of disease. Our data indicates that decreases in the rate of flow of water can result in sedimentation of bacterial contaminants within the water column. Water for ecosystems, urban consumption, recreation and distribution through irrigation is often drawn from waterholding facilities such as dams and weirs, and concern must be expressed over the potential for contaminate build-up and disproportionate potential of these structures to pose a risk to human and animal health. With disruption of natural flow rates for water resulting from environmental change such as global warming and/or human intervention, increased attention needs to be paid to use of best management practices to protect source water supplies.

Alberta↗
PubMed2006

3.0- Versus 1.5-T MR cholangiography: a pilot study.

OBJECTIVE: The purpose of our study was to evaluate quantitative and qualitative image quality of MR cholangiography at a field strength of 3.0 T compared with the standard field strength of 1.5 T. MATERIALS AND METHODS: A standardized MR cholangiography sequence protocol was used for 15 healthy male volunteers (mean age +/- SD, 32.4 +/- 4.3 years) who underwent both 1.5- and 3.0-T MRI within 2 hr in an alternating fashion. Dedicated circular polarized torso coils (1.5 and 3.0 T) were used. The sequence protocol included breath-hold single-slice rapid acquisition with relaxation enhancement (slice thickness, 50 mm; orientation, coronal and +/- 20 degrees oblique coronal); breath-hold multislice HASTE (slice thickness, 3 mm; coronal only); and a non-breath-hold, respiratory-triggered 3D turbo spin-echo (TSE) T2-weighted sequence (slice thickness, 1 mm; 60 slices per slab; coronal only). Maximum intensity projections were generated from each multislice data set. Bile duct (common bile duct, right posterior segmental branch, and left hepatic duct) to periductal tissue contrast-to-noise ratios were compared at 1.5 and 3.0 T. Qualitative image analysis was performed by three independent reviewers. Qualitative analysis included delineation of the extra- and intrahepatic biliary anatomy, with specific attention given to the presence (or absence) of cystic or intrahepatic ductal variants, using a 4-point confidence scale. Statistical analysis consisted of the paired Student's t test and the signed rank test. RESULTS: Contrast-to-noise ratios between the bile duct and the periductal tissue were higher at 3.0 T in all three locations (common bile duct, right posterior segmental branch, and left hepatic duct). In each magnet class, the 3D TSE sequence offered the best contrast-to-noise ratio and qualitative analysis. Superiority of the 3D TSE sequence was statistically significant in all analyses. Five of the 15 volunteers had intrahepatic biliary variants that were detected with a higher level of confidence (p < 0.01) on the 3.0-T system than on the 1.5-T system. CONCLUSION: Compared with MR cholangiography at 1.5 T, MR cholangiography at 3.0 T offers improved contrast-to-noise ratio and a higher level of confidence for depicting intrahepatic variants.

Adult↗
PubMed2006

Primary bone lymphoma: a retrospective analysis.

The aim of this study was to retrospectively define those patients with unequivocal primary bone lymphoma presenting to the Sheffield Lymphoma Group and document patient and tumour characteristics and management strategies, and correlate these with survival. Thirty-seven patients were documented from a total of 3148 cases of non-Hodgkin's lymphoma seen over 34 years. There were 17 males and 20 females, with a mean age of 55.4 years (range, 27-78). Pain was the most commonly presented symptom (67.5%), and the pelvis was the most frequently presented site (21.3%). Grade 2 and diffuse large B cell lymphoma comprised the majority of histologies (78.7% and 70.3%, respectively). Treatment was most often with radiotherapy alone (41.8%) or combined with CHOP-like chemotherapy (37.9%). The overall response rate was 56.7%, and 5- and 10-year survival rates were 64.5% and 49.6%, respectively. Univariate analysis showed an age of <60 years and complete response to be favourable prognostic factors. There was a trend toward better survival with combined modality therapy involving CHOP-like chemotherapy. Bone lymphoma has a better survival than other extranodal lymphomas. Younger age and complete response are favourable predictive factors. Combined modality treatment is likely to be the treatment of choice but this remains to be confirmed in large prospective multicentre studies.

Adult↗
PubMed2006

[Assessment of occupational exposure to ortho-toluidine using gas chromatography-mass spectrometry].

Ortho-toluidine is a carcinogen aromatic amine. It is in part eliminated as unchanged form and its urine determination allows biologic monitoriing of occupational exposure. We propose a new method simple and fast in gas chromatography mass spectrometry. In the Nord-Pas-de-Calais region, a company initiated destruction and depollution of an old industrialsite.The GS-MS method permits exposition evaluation of workers employed in demolition of a liquid SO2 plant polluted with ortho-toluidine. This plant has been stopped twenty years ago. These results are compared with results of workers without any exposure in the same company. A 5 mL urine sample spiked with internal standard (ortho-toluidine D9) is extracted with hexane. Derivatisation is achieved with anhydrous pentafluoropropionic acid during 30 min at 60 degrees C. Chromatographic separation is performed on a BPX5MS column (25 m x 0.25 mm, 0.25 microm; SGE). Initial column temperature (60 degrees C) is hold 3 min then is raised to 300 degrees C at 25 degrees C/min. Detection is performed with mass spectrometry with negative chemical ionisation with methane. Acquisition is performed in single ion monitoring. Identification ions are 233 ion (m/z) and 213 ion (m/z) with 233 (m/z) used for quantification. Linearity of the method is verified between 0.1 and 100 microg/L. The limit of detection is 0.02 micro/L. Repeatability and intermediate fidelity are satisfactory (CV < 9%). For unexposed workers, urinary concentrations of ortho-toluidine ranged between 0.17 microg/L and 2.46 microg/g creatinine. Urinary concentrations for exposed workers ranged between 26.14 and 462.00 microg/g creatinine and after new action of protection between 2.35 et 20.11 microg/g creatinine. This new GC-MS method is specific and sensitive and allows for urinary determination of ortho-toluidine. Results showed that this method is adapted for biomonitoring as much for unexposed workers to this aromatic amine as for exposed workers.

Gas Chromatography-Mass Spectrometry↗
PubMed2006

Four decades of conjoined twins at Red Cross Children's Hospital--lessons learned.

Conjoined twins represent a rare but fascinating congenital condition, the aetiology of which remains obscure. Over the past four decades, the paediatric surgeons at Red Cross Children's Hospital have been involved in the management of 46 pairs of conjoined twins, of which 33 have been symmetrical and 12 asymmetrical. Seventeen symmetrical twins have undergone separation with 22 children (65%) surviving; all of the live asymmetrical twins survived separation. We describe the important features of this unique cohort, outline our approach to management and present the results of this approach. We consider some of the ethical and moral dilemmas we have confronted, and discuss the prenatal diagnosis, obstetric implications and postnatal care of these children, including the relevant investigations and anaesthetic and surgical management. Specific aspects related to the cardiovascular system, hepatobiliary and gastrointestinal tracts, urogenital tract, central nervous system and musculoskeletal system are highlighted.

Adolescent↗
PubMed2005

Minimally invasive esophagectomy: short- and long-term outcomes.

BACKGROUND: We aimed to assess the outcomes including the effect on quality of life (QoL) of a group of patients having a minimally invasive esophagectomy (MIE). METHODS: Patients with esophageal cancer were offered MIE over a 22-month period. Data on outcomes were collected prospectively, including formal quality-of-assessments. RESULTS: There were 25 patients offered MIE. Two patients were converted to a laparotomy to improve the lymphadenectomy. There were no deaths. Respiratory problems (pneumonia, 28%) were the most common in the 64% of patients who had a complication. The median blood loss was 300 ml, time of surgery 330 min, and time to discharge 11 days. There was a decrease in the measured QoL both in general and specifically for the esophageal patients, taking 18-24 months to return to baseline. CONCLUSIONS: MIE was performed with morbidity similar to other approaches. There were no clear benefits shown in this group of patients with respect to postoperative recovery or short- to medium-term QoL.

Adenocarcinoma↗
PubMed2005

First results of the search for neutrinoless double-beta decay with the NEMO 3 detector.

The NEMO 3 detector, which has been operating in the Fréjus underground laboratory since February 2003, is devoted to the search for neutrinoless double-beta decay (beta beta 0v). The half-lives of the two neutrino double-beta decay (beta beta 2v) have been measured for 100Mo and 82Se. After 389 effective days of data collection from February 2003 until September 2004 (phase I), no evidence for neutrinoless double-beta decay was found from approximately 7 kg of 100Mo and approximately 1 kg of 82Se. The corresponding limits are T1/2(beta beta0v) > 4.6 x 10(23) yr for 100Mo and T1/2(beta beta 0v) > 1.0 x 10(23) yr for 82Se (90% C.L.). Depending on the nuclear matrix element calculation, the limits for the effective Majorana neutrino mass are < 0.7-2.8 e/v for 100Mo and < 1.7-4.9 eV for 82Se.

Journal Article↗