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Biomedical subjects

P Roche

Publications and source records attributed to P Roche.

At least 19 recordsLinked to original sources
PubMed2006

A novel luminescent lifetime-based optrode for the detection of gaseous and dissolved oxygen utilising a mixed ormosil matrix containing ruthenium (4,7-diphenyl-1,10-phenanthroline)3Cl2 (Ru.dpp).

A novel luminescent lifetime optrode is presented for the detection of gaseous and dissolved oxygen. The optrode utilises ruthenium (4,7-diphenyl-1,10-phenanthroline)(3)Cl(2) as the sensing fluorophore immobilised in a hydrophobic ormosil matrix. The ormosil matrix is synthesised at room temperature from octyltriethoxysilane and methyltriethoxysilane precursors. Investigations of different ormosils were conducted and the most effective one was selected for optrode production. Optrodes were tested for responses to gaseous and dissolved oxygen. Their responses were modelled using traditional two-site or two-exponential methods and feed-forward artificial neural networks. Comparison of the two modelling methodologies is presented and further improvements in modelling and ormosil design are suggested.

Chlorides↗
PubMed2006

[MR spectroscopy of brain tumors].

MR spectroscopy (MRS) can complement MRI in the evaluation of intracranial tumors. Before treatment, MRS can contribute to the differential diagnosis between tumor and non tumoral lesion (especially intracranial abscesses), to assess the aggressiveness of a glial tumor or to determine its extension to better delineate the surgical removal or the target volume of radiotherapy. During treatment follow-up, MRS helps differentiate recurrent tumor from radionecrosis or physiological post-surgical contrast enhancement. The current studies are trying to determine if the indications of MRS, alone or in association with other MR sequences can further be extended in the study of brain tumors, in particular the follow-up of lesions undergoing chemo or radiotherapy.

Brain Neoplasms↗
PubMed2005

The importance of histology in the evaluation of pulmonary transplantation: carcinomatous lymphangitis.

Pulmonary carcinomatous lymphangitis is a form of neoplastic metastatic spread to the lungs, which represents a poor prognosis for the patient. The physician may be confronted by a differential diagnosis with diffuse pulmonary interstitial affections requiring specific treatment, including lung transplantation. We present the case of a patient, diagnosed with pulmonary interstitial disease with rapidly progressive worsening of lung function, who was considered for lung transplantation. Videothoracoscopic lung biopsy demonstrated the existence of carcinomatous lymphangitis, which completely changed the therapeutic direction.

Contraindications↗
PubMed2004

Fano factor reduction on the 0.7 conductance structure of a ballistic one-dimensional wire.

We have measured the nonequilibrium current noise in a ballistic one-dimensional wire which exhibits an additional conductance plateau at 0.7x2e(2)/h. The Fano factor shows a clear reduction on the 0.7 structure, and eventually vanishes upon applying a strong parallel magnetic field. These results provide experimental evidence that the 0.7 structure is associated with two conduction channels that have different transmission probabilities.

Journal Article↗
PubMed2004

Hanbury Brown-Twiss correlations to probe the population statistics of GHz photons emitted by conductors.

We present the first study of the statistics of GHz photons in quantum circuits, using Hanbury Brown and Twiss correlations. The super-Poissonian and Poissonian photon statistics of thermal and coherent sources, respectively, made of a resistor and a radio frequency generator, are measured down to the quantum regime at milli-Kelvin temperatures. As photon correlations are linked to the second and fourth moments of current fluctuations, this experiment, which is based on current cryogenic electronics, may become a standard for probing electron/photon statistics in quantum conductors.

Journal Article↗
PubMed2003

Cognitive performance and MR markers of cerebral injury in cognitively impaired MS patients.

OBJECTIVE: To relate neuropsychological performance to measures of cerebral injury in persons with MS selected for cognitive impairment. METHODS: Participants were 37 individuals with relapsing-remitting (59.5%) and secondary progressive (40.5%) MS. They were tested at baseline as part of a clinical trial to enhance cognition with an acetylcholinesterase inhibitor. Eligibility criteria included at least mild cognitive impairment on a verbal learning and memory task. A modified Brief Repeatable Battery of Neuropsychological Tests formed the core of the behavioral protocol. Neuroimaging measures were central (ventricular) cerebral atrophy, lesion volume, and ratios of N-acetyl aspartate (NAA) to both creatine and choline. RESULTS: A clear, consistent relation was found between cognitive and MR measures. Among neuroimaging measures, central atrophy displayed the highest correlations with cognition, accounting for approximately half the variance in overall cognitive performance. NAA ratios in right hemisphere sites displayed larger correlations than those on the left. Multiple regression models combining the MR measures accounted for well over half the variance in overall cognitive performance. The Symbol Digit Modalities Test was the neuropsychological task most strongly associated with the neuroimaging variables. CONCLUSIONS: If a strong and stable association can be firmly established between cognitive and MR variables in appropriate subsets of MS patients, it might aid in the investigation of interventions to enhance cognition and modify the course of the disease.

Adult↗
PubMed2003

Quantum partition noise of photon-created electron-hole pairs.

We show experimentally that even when no bias voltage is applied to a quantum conductor, the electronic quantum partition noise can be investigated with GHz radio frequency excitation. Using a quantum point contact configuration as the ballistic conductor we are able to make an accurate determination of the partition noise Fano factor resulting from the photon-assisted shot noise. Applying both voltage bias and rf irradiation we are able to make a definitive quantitative test of the scattering theory of photon-assisted shot noise.

Journal Article↗
PubMed2003

Impaired nitric oxide function in the basilar artery of the obese Zucker rat.

The effect of insulin-resistance syndrome on vascular function has been examined in isolated basilar arteries using the obese Zucker rat (OZR) and age-matched lean littermate controls (lean Zucker rat; LZR) at 36 weeks of age. The OZR showed significantly reduced oral glucose tolerance and increased body weight, blood pressure, proteinuria, plasma levels of triglycerides, cholesterol, and insulin compared with the LZR. The contractile response to serotonin was significantly increased in the OZR. Furthermore, contractions to serotonin in LZR but not OZR were enhanced in the presence of the nitric oxide synthase inhibitor Nomega-nitro-L-arginine methyl ester (NAME). Relaxations to acetylcholine (ACh), histamine, and A23187 were significantly reduced in precontracted arteries from the OZR. In the presence of NAME, histamine responses were significantly reduced whereas ACh and A23187 responses were almost abolished. Relaxations to free-radical nitric oxide (NO) and papaverine were not different in arteries from the OZR, even though responses to sodium nitroprusside were reduced in the OZR. Western blot and immunofluorescent quantitative analyses of eNOS content in cerebral microvessel fractions and basilar artery preparations, respectively, were not significantly different between OZR and LZR. The results suggest impairment in endothelial function resulting in reduced NO function in the basilar artery from the OZR.

Acetylcholine↗
PubMed2002

Adoptive T cell therapy using antigen-specific CD8+ T cell clones for the treatment of patients with metastatic melanoma: in vivo persistence, migration, and antitumor effect of transferred T cells.

Adoptive T cell therapy, involving the ex vivo selection and expansion of antigen-specific T cell clones, provides a means of augmenting antigen-specific immunity without the in vivo constraints that can accompany vaccine-based strategies. A phase I study was performed to evaluate the safety, in vivo persistence, and efficacy of adoptively transferred CD8+ T cell clones targeting the tumor-associated antigens, MART1MelanA and gp100 for the treatment of patients with metastatic melanoma. Four infusions of autologous T cell clones were administered, the first without IL-2 and subsequent infusions with low-dose IL-2 (at 0.25, 0.50, and 1.0 x 10(6) unitsm(2) twice daily for the second, third, and fourth infusions, respectively). Forty-three infusions of MART1MelanA-specific or gp100-specific CD8+ T cell clones were administered to 10 patients. No serious toxicity was observed. We demonstrate that the adoptively transferred T cell clones persist in vivo in response to low-dose IL-2, preferentially localize to tumor sites and mediate an antigen-specific immune response characterized by the elimination of antigen-positive tumor cells, regression of individual metastases, and minor, mixed or stable responses in 8 of 10 patients with refractory, metastatic disease for up to 21 mo.

Adult↗
PubMed2002

[MRI: an essential examen for the management of sacrococcygeal chondromas].

Chordomas are rare tumors, involving mainly the sacrococcygeal area and the clivus. Although a significant radiological semiology exists (osteolytic, lobulated, calcified tumor), the definite diagnosis is histological. Five cases of sacral and/or coccygeal chordomas were studied by CT scan and MRI. Clinical, radiological (tumoral topography and extension) and histological data were noted in all cases. At CT scan, the tumor was median, osteolytic, often calcified, of intermediate density, sparing iliac bones. MRI showed, in all the cases, a tumoral lobulation making easier the diagnosis of chordoma. Futhermore, as compared to CT scan MRI brought new information for the study of the tumoral extension, revealing a frequent involvement of adjacent muscles and spinal canal. It also showed that the tumor most often spared the rectal wall. These data are fundamental in the management of patients: the therapeutical aim must be, if possible, a complete removal of the tumor. Thus, besides its interest in the diagnosis, MRI appears to be essential in the pre-therapeutical assessment of sacro-coccygeal chordomas.

Aged↗
PubMed2001

Genetic analysis of early- versus late-stage ovarian tumors.

In the United States, ovarian cancer is the fourth most common cause of cancer-related deaths among women. The most important prognostic factor for this cancer is tumor stage, or extent of disease at diagnosis. Although women with low-stage tumors have a relatively good prognosis, most women diagnosed with late-stage disease eventually succumb to their cancer. In an attempt to understand early events in ovarian carcinogenesis, and to explore steps in its progression, we have applied multiple molecular genetic techniques to the analysis of 21 early-stage (stage I/II) and 17 advanced-stage (stage III/IV) ovarian tumors. These techniques included expression profiling with cDNA microarrays containing approximately 18,000 expressed sequences, and comparative genomic hybridization to address the chromosomal locations of copy number gains as well as losses. Results from the analysis indicate that early-stage ovarian cancers exhibit profound alterations in gene expression, many of which are similar to those identified in late-stage tumors. However, differences observed at the genomic level suggest differences between the early- and late-stage tumors and provide support for a progression model for ovarian cancer development.

Disease Progression↗
PubMed2001

In vivo 1H magnetic resonance spectroscopic measurement of brain glycine levels in nonketotic hyperglycinemia.

Nonketotic hyperglycinemia (NKH) is an autosomal recessive disorder of glycine metabolism. Defective glycine cleavage causes elevated concentrations of glycine in plasma, urine, and cerebrospinal fluid. A longitudinal study using magnetic resonance imaging (MRI) and single-voxel 1H magnetic resonance spectroscopy (MRS) was performed on an infant with the typical clinical picture of NKH. He was examined twice during the course of treatment with sodium benzoate and dextromethorphan. At the age of 10 months, MRI showed normal brain structure, while MRS detected a prominent glycine peak in the brain. Repeat MRS at the age of 13 months showed a small increase in glycine peak and a prominent glutamate/glutamine peak not previously detected. The MRS measurements were consistent with the slight increase in blood glycine level and the elevation in glutamine level, indicating that 1HMRS can be a valuable tool in the diagnosis and monitoring of treatment effects in patients with NKH.

Aspartic Acid↗
PubMed2001

Annual report of the National Influenza Surveillance Scheme, 2000.

Surveillance of influenza in Australia in 2000 was based on data from national and state-based sentinel general practice consultations for influenza-like illness, laboratory isolations of influenza virus and absenteeism rates from a national employer. The peak in influenza cases was in mid-September. Influenza A was the dominant strain, with the highest proportion being influenza A (H3N2), but with a significant proportion of isolates of influenza A (H1N1) (16%) for the first time since 1995. The influenza A (H3N2) isolates were predominantly related to A/Moscow/10/99 and vaccine strain A/Panama/2007/99. Influenza A (H1N1) was predominantly A/New Caledonia/20/99. The proportion of Influenza B viruses isolated also increased in keeping with a three-yearly cycle of influenza B epidemics in Australia. influenza B isolates showed a progressive drift away from the B/Beijing/184/93 strain with the majority closely related to the B/Sichuan/379/99 strain. In 2000, influenza vaccination levels reached 74 per cent in persons aged over 65 years.

Australia↗
PubMed2001

Australia's notifiable diseases status, 1999: annual report of the National Notifiable Diseases Surveillance System.

In 1999 there were 88,229 [corrected] notifications of communicable diseases in Australia reported to the National Notifiable Diseases Surveillance System (NNDSS). The number of notifications in 1999 was an increase of 3 per cent on notifications in 1998 (85,227) and the second largest reporting year since the NNDSS commenced in 1991. Notifications in 1999 consisted of 29,977 bloodborne infections (34% of total), 22,255 gastrointestinal infections (25%), 21,704 sexually transmitted infections (25%), 5,986 vector borne infections (7%),5,228 vaccine preventable infections (6%), 1,967 (2%) other bacterial infections (legionella, meningococcal, leprosy and tuberculosis), 1,012 zoonotic infections (1%) and 3 quarantinable infections (0.003%). Notifications of bloodborne viral diseases particularly hepatitis B and hepatitis C and some sexually transmitted infections such as gonorrhoea and chlamydia continue to increase in Australia. Steep declines in vaccine preventable diseases such as Haemophilus influenzae type b, measles, mumps and rubella continued in 1999. This report also summarises data on communicable diseases from other surveillance systems including the Laboratory Virology and Serology Surveillance Scheme (LabVISE) and sentinel general practitioner schemes. In addition this report comments on other important developments in communicable disease control in Australia in 1999.

Australia↗
PubMed2001

Tuberculosis notifications in Australia, 1999.

Australia has one of the lowest incidence of tuberculosis in the world. The crude annual notification rate for tuberculosis (TB) has remained stable at between 5 and 6 per 100,000 population since 1991. In 1999, there were a total of 1,159 TB notifications in Australia of which 1,117 were new TB cases, and 42 were relapsed cases. The corresponding annual notification rate for new and relapsed TB was 5.9 and 0.2 per 100,000 population respectively. People born overseas accounted for 83 per cent of the notified cases. TB notification rates remain highest among overseas-born residents from high prevalence countries, and indigenous Australians. The lowest rates of disease are in the non-indigenous, Australian born population and data from the last 7 years indicate that the rate of tuberculosis in this population is continuing to fall.

Age Distribution↗