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C Christodoulou

Publications and source records attributed to C Christodoulou.

90 records · Page 5Linked to original sources
PubMedDate not supplied

Near Poisson-type firing produced by concurrent excitation and inhibition.

The effect of inhibition on the firing variability is examined in this paper using the biologically-inspired temporal noisy-leaky integrator (TNLI) neuron model. The TNLI incorporates hyperpolarising inhibition with negative current pulses of controlled shapes and it also separates dendritic from somatic integration. The firing variability is observed by looking at the coefficient of variation (C(V)) (standard deviation/mean interspike interval) as a function of the mean interspike interval of firing (delta tM) and by comparing the results with the theoretical curve for random spike trains, as well as looking at the interspike interval (ISI) histogram distributions. The results show that with 80% inhibition, firing at high rates (up to 200 Hz) is nearly consistent with a Poisson-type variability, which complies with the analysis of cortical neuron firing recordings by Softky and Koch [1993, J. Neurosci. 13(1) 334-530]. We also demonstrate that the mechanism by which inhibition increases the C(V) values is by introducing more short intervals in the firing pattern as indicated by a small initial hump at the beginning of the ISI histogram distribution. The use of stochastic inputs and the separation of the dendritic and somatic integration which we model in TNLI, also affect the high firing, near Poisson-type (explained in the paper) variability produced. We have also found that partial dendritic reset increases slightly the firing variability especially at short ISIs.

Neurons↗
PubMedDate not supplied

Genetic stability of poliovirus insertion mutants with a foreign oligopeptide on the capsid surface.

The genetic stability of poliovirus mutants which carry a foreign oligopeptide on the surface of their capsid was studied (1) upon mutant isolation, (2) after serially diluted passages in cell cultures, and (3) in persistently infected cultures which have been recently developed. Viruses having a 3-codon insertion within the VP1 capsid protein-encoding region appeared to be extremely stable, except in the specific case of persistent infection. Viruses having a 6-codon insertion were slightly less stable. Point mutations and one recombination event were observed as soon as viruses were recovered and studied following plasmid transfection. Additional point mutations appeared within the insertion after 12 serially diluted passages in monkey kidney cells. Under all test conditions, the foreign insertion was never deleted from the virus genome.

Animals↗
PubMedDate not supplied

Evidence-based medicine in physiatry: the experience of one department's faculty and trainees.

Evidence-based medicine is regarded by many as the new paradigm in medical practice. Sixty-seven medical school faculty and trainees in a physical medicine and rehabilitation department were surveyed with regard to training and competence in the use of evidence-based medicine techniques. The majority of subjects in the present study supported the use of evidence-based medicine techniques, although a number of the respondents indicated that they lacked adequate training or competence in their use. It is suggested that medical schools and physiatry residency programs provide a greater emphasis on training in evidence-based medicine. Recommendations are provided that individuals can use to develop a systematic strategy to keep up with the rapidly expanding medical literature.

Adult↗
PubMedDate not supplied

Prolonged administration of weekly paclitaxel and trastuzumab in patients with advanced breast cancer.

PURPOSE: To evaluate the efficacy and safety of weekly paclitaxel and trastuzumab in patients with HER2-positive metastatic breast cancer, with trastuzumab administered beyond disease progression. PATIENTS AND METHODS: Twenty-six women with metastatic breast cancer, that was HER2-positive as determined by immunohistochemistry, were treated with weekly paclitaxel 70 or 90 mg/m2 and trastuzumab (4 mg/kg initial dose followed by 2 mg/kg weekly). RESULTS: The median duration of treatment was 28 (8-72) weeks for paclitaxel and 59 (14-150) weeks for trastuzumab. Two (8%) patients experienced complete and 14 (54%) partial responses, for an overall response rate of 62%. The median time to disease progression was 11 (2.89-36) months and median survival 34+ months. Grade 3/4 adverse events were alopecia (46%), neurotoxicity (15%), leukopenia (12%) and neutropenia (12%). Infusion-related reactions were mild to moderate. No symptomatic cardiac toxicity was observed. No patient discontinued trastuzumab due to toxicity. CONCLUSION: Prolonged administration of weekly paclitaxel and trastuzumab is effective and well-tolerated in women with HER2-positive metastatic breast cancer.

Adult↗
PubMedDate not supplied

Exploitation of a 650 bp probe for quantification of Pneumocystis carinii.

Signals obtained from serial dilutions of rat-derived Pneumocystis carinii DNA were used to assess the sensitivity of a 650-bp DNA probe which recognises both cystic and non-cystic forms. Enhanced chemiluminescence was selected as a non-radioactive detection method and signals could be semi-quantitated by scanning densitometry. This technique was used to examine the inhibitory effect of pentamidine in vitro indicating that DNA probes might be useful tools in the search for a novel therapeutic agent.

Animals↗