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Biomedical subjects

E Kan

Publications and source records attributed to E Kan.

11 recordsLinked to original sources
PubMed2007

Transport of living cells with magnetically assembled nanowires.

We present a technique of transporting and positioning living cells internalized by nickel (Ni) nanowires guided by magnetic field. Nanoscale magnetic nanowires are internalized by the Rat Neuroblastoma (ATCC number CRL-2754) and the cells are transported and positioned by magnetic fields from the magnetic material-coated electrodes. This technique may enable the interfacing between neurons and electronic devices to empower investigations pertaining to non-invasive neuron probing as well as nanofabricated neural pharmacological technologies.

Animals↗
PubMed2006

Normal developmental changes in inferior frontal gray matter are associated with improvement in phonological processing: a longitudinal MRI analysis.

This study asked whether previously identified developmental changes in the gray matter of the left inferior frontal gyrus are associated with maturation of a linguistic skill. To test this hypothesis, we examined whether thickening of this region was correlated with developmental improvements in phonological processing but not hand motor skills in a unique longitudinal data set of 45 normally developing children (between ages 5 and 11 years) studied over a 2-year interval. We analyzed structural magnetic resonance imaging data using cortical pattern matching methods and correlated within-individual changes in cortical thickness with 2 neurocognitive scores. As predicted, gray matter thickening in the left inferior frontal cortex was associated with improving phonological processing scores but not with improving hand motor skills. By contrast, motor skill improvement was associated with thinning in the hand region of the left motor cortex, and cortical change in this region was not associated with phonological processing. This study illustrates a specific correspondence between regional gray matter thickness change and language skill change in normally developing children.

Aging↗
PubMed2006

Scale-up and cost evaluation of a foamed emulsion bioreactor.

In the present paper, the potential of the foamed emulsion bioreactor (FEBR), a novel biological reactor for air pollution control was evaluated. Experimental data obtained on a laboratory-scale prototype were used to scale-up the process for a hypothetical case consisting of a contaminated air flow rate of 10,000 m(3) h(-1), a toluene inlet concentration of 1 g m(-3) and minimum required treatment efficiency of 92%. Reactor design and operating issues for the full-scale FEBR were identified. They included the requirement for stable foam generation with appropriate air distributors, and recycling of the auxiliary organic phase, surfactants and cells from the discharge of the reactor. The capital and operating costs for the concept full-scale FEBR were evaluated and compared to those of competing technologies, namely biofiltration, biotrickling filtration and catalytic and thermal oxidation. All three biological techniques had significantly lower capital and operating costs. Among the biological techniques, the FEBR had the lowest estimated capital cost since its greater effectiveness allowed a smaller reactor to meet the treatment objectives. The operating costs for the FEBR were higher than those of biofilters and biotrickling filters because of the requirements for nutrients and auxiliary chemicals. Overall, the results highlight that biotreatment is much more cost effective than thermal and catalytic oxidation. They further suggest that the FEBR may an interesting alternative to biofilters and biotrickling filters where the available space for air pollution control equipment is limited.

Air Pollution↗
PubMed2001

Activation of purified cardiac ryanodine receptors by dihydropyridine agonists.

Prior observations have raised the possibility that dihydropyridine (DHP) agonists directly affect the sarcoplasmic reticulum (SR) cardiac Ca(2+) release channel [i.e., ryanodine receptor (RyR)]. In single-channel recordings of purified canine cardiac RyR, both DHP agonists (-)-BAY K 8644 and (+)-SDZ202-791 increased the open probability of the RyR when added to the cytoplasmic face of the channel. Importantly, the DHP antagonists nifedipine and (-)-SDZ202-791 had no competitive blocking effects either alone or after channel activation with agonist. Thus there is a stereospecific effect of SDZ202-791, such that the agonist activates the channel, whereas the antagonist has little effect on channel activity. Further experiments showed that DHP agonists changed RyR activation by suppressing Ca(2+)-induced inactivation of the channel. We concluded that DHP agonists can also influence RyR single-channel activity directly at a unique allosteric site located on the cytoplasmic face of the channel. Similar results were obtained in human purified cardiac RyR. An implication of these data is that RyR activation by DHP agonists is likely to cause a loss of Ca(2+) from the SR and to contribute to the negative inotropic effects of these agents reported by other investigators. Our results support this notion that the negative inotropic effects of DHP agonists result in part from direct alteration in the activity of RyRs.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed2000

Structure-activity relationships in platelet-activating factor (PAF). 10. From PAF antagonism to inhibition of HIV-1 replication.

Excessive levels of PAF and cells of macrophage lineage appear to play an important role in neuronal cell injury, inflammatory syndrome, and HIV replication in CNS resulting in AIDS dementia complex (ADC). The beneficial effects of PAF receptor antagonists are evident and give rise to expected therapeutic strategies for neurotrauma. Piperazine derivatives bearing a "cache-oreilles" (ear-muff) electronic distribution are able to inhibit in vitro PAF effects and, thus, could be used in pathologies where this mediator is involved. Therefore, their potential anti-HIV activity was investigated, and we find that (i) these PAF antagonists are effectively active in HIV-infected monocyte-derived macrophages (MDM) but there is no correlation between both anti-HIV and anti-PAF activities; (ii) the presence of a carbamate function (compounds 1a-d) is favorable to the antiviral activity; (iii) the lipophilicity of the substituent on the piperazinic cycle seems to be less important for the anti-PAF activity than for the antiviral one. Our leading compound, PMS 601 (compound 1a), presents a dual activity with IC(50) of 8 and 11 microM for anti-PAF and anti-HIV activity, respectively, without cytotoxic events at 1000 microM in MDM. Although its mode of action is not clearly defined, these data suggest that PMS 601, which displays no effect on acellular reverse transcriptase or protease tests, deserves further investigation in the treatment of HIV-1-associated dementia.

Anti-HIV Agents↗
PubMed1997

An action research study into the development of nurses as reflective practitioners.

This study adopted an action research approach in addressing the question: How could nurses be prepared to be reflective practitioners? The study took place among a group of registered nurses who enrolled in the first year of their degree studies at the Hong Kong Polytechnic University. The methods of data collection included observation, interview, students' written material, and teacher reflection. The experience of this study suggested that teachers and students should be partners in the promotion of reflective learning among students. As teachers reflected on their teaching arrangement and the progress of student learning, students could accordingly be offered appropriate guidance. Throughout the span of their studies, students learned to gradually develop different perspectives in viewing professional nursing practice. The reconceptualization of nursing practice helped students challenge taken-for-granted views and eventually reconstruct their conception of nursing.

Curriculum↗
PubMed1993

Multicenter study with recombinant human erythropoietin.

A multicenter study with recombinant human erythropoietin (rh-EPO) was carried out. Of 172 hemodialysis patients with anemia selected for the study from 20 hospitals and clinics, 77 were males and 95 females (mean age 53.9 years). A starting dose of 1,500 U of rh-EPO (Epoetin beta) was administered intravenously at the end of every dialysis session. If the efficacy was not acceptable, the dose was increased to 3,000 U. When the target hematocrit was achieved (30%), the total dose was decreased. The results of the study were excellent relative to those of other multicenter studies with regard to efficacy, safety, and changes in laboratory data. The incidence of hypertension was lower in our study compared with other reports because we used a low initial dose. The efficacy of rh-EPO therapy was determined earlier and more reliably by reticulocytes than by hematocrit or hemoglobin. Prompt iron supplement therapy is recommended with careful observation of serum iron and ferritin.

Anemia↗
PubMed1993

EPO test in hemodialysis patients.

It is well known that red blood cell (RBC) and reticulocyte counts increase when anemic hemodialysis patients receive repeated administrations of recombinant human erythropoietin(rh-EPO). However, the early response of reticulocyte has not been reported precisely. In this study, reticulocyte counts and its fractions were observed in 8 maintenance hemodialysis patients after a single intravenous administration of 60 u/Kg of rh-EPO. The peripheral blood cells taken from the patients were stained with auramine 0, which bound to RNA and caused fluorescence. R-1000 (Sysmex, Kobe, Japan) analyzed the reticulocytes and classified the stained cells into three groups by the intensity of fluorescence. The number of highly fluorescent reticulocyte, which was young and large, increased and reached its highest level on day 4 after a single administration of rh-EPO. The reticulocyte counts paralleled these changes, but RBC counts did not change after administrations of rh-EPO. These data suggest that the observation of reticulocytes and its fractions in hemodialysis patients after a single administration of rh-EPO could tell us whether reticulocytes are responsive to rh-EPO or not, and this could be called as EPO test.

Adult↗
PubMed1991

[Case report: a foreign body (gauze) in the bladder].

A case of bladder tamponade caused by a foreign body (gauze) in the bladder of a 24-year-old man is reported. He had been treated with the Lambotte wire and screw to repair his pubic bone fracture caused by a traffic accident. About one year later, the wire and screw were removed from the patient. However, he suffered from gross hematuria and bladder tamponade on the 11th day after the 2nd operation, and he was transferred to our outpatient department on emergency. Further urological examinations were done for this case. The patient was diagnosed as having bladder tamponade caused by a foreign body, a gauze, in the bladder. Among these examinations NMR-CT gave us the most interesting and useful findings. NMR-CT showed that the gauze penetrated the bladder wall.

Adult↗