Biomedical subjects

T S Lee

Publications and source records attributed to T S Lee.

At least 19 recordsLinked to original sources

PubMed2006

Pectoral stretching program for women undergoing radiotherapy for breast cancer.

Surgery and radiotherapy commonly cause adverse musculoskeletal problems, particularly loss of strength and range of motion, in the upper quadrant of breast cancer patients. Few well-designed studies have investigated whether these impairments can be prevented. Stretching is an effective technique for increasing range of motion, hence the aim of this study was to investigate whether a stretching program reduced acute musculoskeletal impairments in patients undergoing radiotherapy for breast cancer. Sixty-four women were recruited prior to commencement of radiotherapy following breast cancer surgery. Participants were randomised to either a control or stretch group. Participants in both groups were reviewed by the physical therapist on a weekly basis for approximately 6 weeks, and were given general information about skin care and lymphedema. The control group received no advice about exercise. The stretch group received instruction on low-load, prolonged pectoral stretches, which were to be performed daily and were checked at weekly visits. Shoulder range of motion, strength, arm circumference, and quality of life measurements were taken prior to, and at completion of radiotherapy, and at 7 months after radiotherapy. There was no difference in any outcome between groups. Breast symptoms increased for both groups during radiotherapy, without loss of strength or range of movement. The incidence of lymphedema during the study was low for both groups and did not differ between groups. The pectoral stretching program did not influence the outcomes measured because the symptoms reported by patients were not a consequence of contracture.

Breast Neoplasms↗

PubMed2006

A 3D analysis of oxygen transfer in a low-cost micro-bioreactor for animal cell suspension culture.

A 3D numerical model was developed to study the flow field and oxygen transport in a micro-bioreactor with a rotating magnetic bar on the bottom to mix the culture medium. The Reynolds number (Re) was kept in the range of 100-716 to ensure laminar environment for animal cell culture. The volumetric oxygen transfer coefficient (k(L)a) was determined from the oxygen concentration distribution. It was found that the effect of the cell consumption on k(L)a could be negligible. A correlation was proposed to predict the liquid-phase oxygen transfer coefficient (k(Lm)) as a function of Re. The overall oxygen transfer coefficient (k(L)) was obtained by the two-resistance model. Another correlation, within an error of 15%, was proposed to estimate the minimum oxygen concentration to avoid cell hypoxia. By combination of the correlations, the maximum cell density, which the present micro-bioreactor could support, was predicted to be in the order of 10(12) cells m(-3). The results are comparable with typical values reported for animal cell growth in mechanically stirred bioreactors.

Animals↗

PubMed2005

Low-power hybrid wireless network for monitoring infant incubators.

We have created a pilot wireless network for the convenient monitoring of temperature and humidity of infant incubators. This system combines infrared and radio frequency (RF) communication in order to minimize the power consumption of slave devices, and we therefore call it a hybrid wireless network. The slave module installed in the infant incubator receives the calling signal from the host with an infrared receiver, and sends temperature and humidity data to the host with an RF transmitter. The power consumption of the host system is not critical, and hence it uses the maximum power of infrared transmission and continuously operating RF receiver. In our test implementation, we included four slave devices. The PC calls each slave device every second and then waits for 6 s, resulting in a total scan period of 10 s. Slave devices receive the calling signals and transmit three data values (temperature, moisture, and skin temperature); their power demand is 1 mW, and can run for about 1000 h on four AA-size nickel-hydride batteries.

Electric Power Supplies↗

PubMed2005

Assessing clinical performance of gynecology residents: sonographic evaluation of adnexal masses based on morphological scoring systems.

OBJECTIVE: To assess the performance of inexperienced gynecology residents in the evaluation of adnexal masses using sonographic scoring systems. METHODS: From April 2003 to October 2004, transvaginal sonography was performed preoperatively by junior gynecology residents on 1-month shifts on 123 patients suspected of having adnexal masses. A total of 137 adnexal masses were found and evaluated using two different morphological scoring systems (those of DePriest and Lerner). The diagnostic performance of the sonographic scoring systems was assessed using the McNemar test and receiver-operating characteristics (ROC) curve analysis was used for lesion characterization. The diagnostic accuracy when the results of both scoring systems satisfied malignancy cut-off values was also investigated. RESULTS: Histopathological analysis revealed that, of the 137 lesions, 109 were benign, 23 were malignant and five were borderline. Best clinical cut-off levels were > or = 5 on the DePriest and > or = 3 on the Lerner scores. Both systems achieved good performance for characterizing malignancy. No significant difference was found in terms of the accuracy of the two systems as determined by mean areas under the ROC curves (0.816 and 0.783, P = 0.562). The combined approach using both scoring systems resulted in higher specificity (77.1%, P < 0.05) and positive predictive value without a significant decrease in sensitivity (82.1%) compared with either system alone. Of the 43 histologically confirmed false-positive cases, mature cystic teratoma was most common, with 13/22 (59%) cases being misinterpreted as malignancies. CONCLUSION: Junior residents, inexperienced at sonography, performed fairly in terms of evaluating adnexal masses with the help of morphological scoring systems.

Adnexal Diseases↗

PubMed2004

Organic and detergent degradation in combined O3/UF for domestic laundry wastewater reclamation.

This paper focuses on the evaluation of organic and detergent degradation in a combined Ozone/UF system for domestic laundry wastewater reclamation. Formation of by-product was investigated by GC/MS for the reclaimed water. Ozone was injected into the raw wastewater in a 10 L contact tank and the wastewater was circulated through the membrane module for inner pressurized cross-flow filtration. The concentrate was returned back to the contact tank. The membrane used in this experiment was hollow fiber polysulfone UF membrane with MWCO 10,000. It has an effective filtration area of 0.06 m2. The experiment was carried out with intermittent ozone injection, 5 min injection and 10 min idling. Ozone was dosed at the concentration of 1.5 mg/L. The flux of the UF could be maintained at 0.24 m/d under filtration pressure 40-45 kPa and water temperature, 20-22 degrees C. The organic removal efficiency by the system was 90% in terms of COD. Ozone was considerably effective to degrade organics in the wastewater. Molecular weight of organics in the raw waste was mostly greater than 10,000 (72% of 950 mgCOD/L). However 86% of effluent COD (94-100 mg/L) was composed of organics smaller than MWCO 500 by ozone injection. No harmful by-products by ozone contact were detected from the analysis of treated water using GC/MS. It was identified that residual organics in the treated water were 1,1'-Oxybisbenzene, Octadecanoic acid, Squalene and Benzenmethanol, etc., which were additives contained originally in the detergent. Consequently the reclaimed water quality could be estimated safe enough to recycle for the rinsing cycle in a washing machine.

Biodegradation, Environmental↗

PubMed2003

Web-based remote monitoring of infant incubators in the ICU.

A web-based real-time operating, management, and monitoring system for checking temperature and humidity within infant incubators using the Intranet has been developed and installed in the infant Intensive Care Unit (ICU). We have created a pilot system which has a temperature and humidity sensor and a measuring module in each incubator, which is connected to a web-server board via an RS485 port. The system transmits signals using standard web-based TCP/IP so that users can access the system from any Internet-connected personal computer in the hospital. Using this method, the system gathers temperature and humidity data transmitted from the measuring modules via the RS485 port on the web-server board and creates a web document containing these data. The system manager can maintain centralized supervisory monitoring of the situations in all incubators while sitting within the infant ICU at a work space equipped with a personal computer. The system can be set to monitor unusual circumstances and to emit an alarm signal expressed as a sound or a light on a measuring module connected to the related incubator. If the system is configured with a large number of incubators connected to a centralized supervisory monitoring station, it will improve convenience and assure meaningful improvement in response to incidents that require intervention.

Computer Communication Networks↗

PubMed2003

NO/cyclic GMP pathway mediates the relaxation of feline lower oesophageal sphincter.

1. We examined the role of the NO/cyclic GMP (cyclic GMP) pathway in nitric oxide (NO)- and vasoactive intestinal peptide (VIP)-induced relaxation of feline lower oesophageal sphincter (LES). Furthermore, it was studied whether methylene blue, LY83583 and ODQ, which are soluble guanylate cyclase (sGC) inhibitors, could inhibit NO-induced relaxation. 2. The nitric oxide synthase (NOS) inhibitor, N omega-nitro-L-arginine (L-NNA) had no effect in sodium nitropruside (SNP)-induced relaxation, but 3-morpholinosydnonimine-N-ethylcarbamide (SIN-1)-induced relaxation was decreased by the pretreatment of L-NNA, which showed that SIN-1, not SNP, could activate NOS to cause relaxation. Methylene blue and LY83583 did not inhibit the relaxation by SNP and SIN-1. However, the more specific sGC inhibitor ODQ blocked the relaxation induced by NO donors. 3. To identify the relationship of NOS, sGC and adenylate cyclase in VIP-induced relaxation, tissue were pretreated with L-NNA and ODQ and SQ22536. These inhibitors produced significant inhibition of this response to VIP. The adenylyl cyclase inhibitor SQ 22536 also inhibited relaxation by VIP. 4. In conclusion, our data showed that SNP- and SIN-1-induced relaxation was mediated by sGC. Of sGC inhibitors, methylene blue and LY83583 were not adequate for the examination of NO donor-induced feline LES smooth muscle relaxation. VIP also caused relaxation by the pathway involving NO and cGMP and cAMP.

Aminoquinolines↗

PubMed2003

Acid-activated spent bleaching earth as a sorbent for chromium (VI) in aqueous solution.

Spent bleaching earth, an industrial waste produced after the bleaching of crude palm oil, was investigated for its potential in removing Cr(VI) from aqueous solution. The earth was treated with different amounts of sulfuric acid and under different activation temperatures. Results show that the optimum treatment process involved 10% sulfuric acid at 350 degrees C. The effects of contact time, pH, initial concentration, sorbent dosage, temperature, sorption isotherms and the presence of other anions on its sorption capacity were studied. Isotherm data could be fitted into a modified Langmuir isotherm model implying monolayer coverage of Cr(VI) on acid activated spent bleaching earth. The maximum sorption capacity derived from the Langmuir isotherm was 21.2 mg g(-1). This value was compared with those of some other low cost sorbents. Studies of anion effect on the uptake of Cr(VI) on acid activated spent bleaching earth provided the following order of suppression: EDTA >PO4(3-)>SO4(2-)>NO3(-)>Cl(-).

Adsorption↗

PubMed2003

Effects of salt concentration on floc characteristics and pollutants removal efficiencies in treatment of seafood wastewater by SBR.

Most seafood wastewater has been treated by the activated sludge process. Due to changes in salt concentration, pollutant loadings and raw materials, the process is not operated satisfactorily to meet effluent regulation. Most problems faced at present are solid liquid separation. In this study, effects of salt concentration on floc characteristics and pollutants removal efficiencies were investigated in treatment of seafood wastewater by SBR. For analyzing fractal dimension of flocs, the small angle laser light scattering (SALLS) method was applied using a Diffraction Particle Sizer (Malvern Instruments). Organic removal efficiencies (in terms of COD(Mn)) decreased with increasing salt concentration, but eventually reached a steady state. Fractal dimension and floc size also showed similar trends with changing salt concentration. The main reasons to reduced pollutant removal efficiencies were deteriorated biological activity and settling properties. The biological activity was affected faster than the floc characteristics by increasing salt concentration. The deteriorated settling properties were explained by decreased size and fractal dimension of floc due to increasing salt concentration. The settling properties of floc such as sludge volume index (SVI) and zone settling velocity (ZSV) were related to size and fractal dimension of floc. The fractal dimension of floc was better related to the settling properties than the size of floc.

Bioreactors↗

PubMed2003

Non-woven fabric filter separation activated sludge reactor for domestic wastewater reclamation.

A non-woven fabric filter was experimentally evaluated for solid-liquid separation in an activated sludge reactor as an alternative membrane. A polypropylene fabric filter (70, 50 and 35 g/m2) was used for the experiment. The pilot system was operated in A/O (Anaerobic/Oxic) type in which the filter module was submerged into the oxic compartment. The filtration module consists of 10 plate type rectangular filter elements with effective filtration area, 2 m2. Gravity filtration was carried out for solid-liquid separation by changing the water head 0.05-0.5 m without backwashing during the system operation. Initial permeate flux was set at 0.4 m/d. C/N ratio of raw wastewater was controlled at 4.5 in terms of BOD/T-N. The fabric filter system showed a good performance enough for domestic wastewater treatment. Effluent solid concentration was 3.2 mg/L (93.5% removal). COD removal efficiency was 91.6% producing an effluent concentration around 13 mg/L. 66% of total nitrogen removal could be obtained at the adjusted C/N ratio of influent wastewater. However phosphorus removal was very low at 23%. It was found that the initial flux of 0.4 m/d should be maintained for stable performance of the system.

Conservation of Natural Resources↗

PubMed2003

Bipolar clavicular injury.

While clavicular injuries are fairly common, bipolar clavicular injuries are not. They may involve dislocations at both ends of the clavicle, or a fracture at one end and a dislocation at the other. We present two cases; a patient with a bipolar clavicular dislocation, and another with a fracture in both medial and lateral ends of the clavicle with anterior dislocation of the sternoclavicular joint. Both were treated conservatively, with fairly good range of motion and return to normal activity.

Accidental Falls↗

PubMed2001

An alternative explanation for the catalytic proficiency of orotidine 5'-phosphate decarboxylase.

Orotidine 5'-phosphate decarboxylase (ODCase) is the most proficient enzyme known, enhancing the rate of decarboxylation of orotidine 5'-phosphate (OMP) by a factor of 10(17), which corresponds to a DeltaDeltaG++ of approximately 24 kcal/mol. Ground-state destabilization through local electrostatic stress has been recently proposed as the basis of catalytic rate enhancement for a mechanism that is the same as in solution. We have carried out gas-phase ab initio quantum mechanical calculations combined with a free energy method, a continuum solvent model, and molecular dynamics simulations to assess an alternative mechanism. Although we are not able to reproduce the experimentally observed DeltaDeltaG++ quantitatively, we present evidence that this DeltaDeltaG++ is very large, in the range found experimentally. We thus conclude that the preferred mechanism may well be different from that in solution, involving an equilibrium pre-protonation of OMP C5 by a catalytic lysine residue that greatly reduces the barrier to subsequent decarboxylation.

Catalysis↗

PubMed2001

Adenovirus-mediated heme oxygenase-1 gene transfer inhibits the development of atherosclerosis in apolipoprotein E-deficient mice.

BACKGROUND: Increasing evidence supports the role of heme oxygenase-1 (HO-1) in cytoprotective response and iron homeostasis. The object of this study was to investigate whether adenovirus-mediated gene transfer of HO-1 in arteries reduces iron overload and inhibits lesion formation in apolipoprotein E (apoE)-deficient mice. METHODS AND RESULTS: Infection of rat aortic smooth muscle cells with adenovirus carrying the human HO-1 gene (Adv-HO-1) resulted in a high-level expression of HO-1 protein, which effectively reduced the hemin-induced iron overload in these cells. Adenovirus-mediated gene transfer in arteries in vivo was achieved by direct injection of Adv-HO-1 into the left ventricles of anesthetized animals. Transgene was expressed in the endothelium and aortic lesion of apoE-deficient mice after they had received recombinant adenovirus for 1 week and gradually decayed during the next 5 weeks. When young apoE-deficient mice (14 weeks old) received Adv-HO-1 (2.5 x 10(9) pfu) for 6 weeks, lesions that developed in the aortic root or aortic arch were significantly smaller than those in control littermates receiving empty viral vector. Furthermore, the iron deposition as well as tissue iron content was much less in aortic tissue of Adv-HO-1-treated mice. The inhibitory effect of HO-1 gene transfer on the progression of advanced lesions was also observed in older apoE-deficient mice (20 weeks old) receiving Adv-HO-1 intraventricularly. CONCLUSIONS: Overexpression of HO-1 in vascular cells facilitates iron metabolism and attenuates development of atherosclerosis in apoE-deficient mice.

Adenoviridae↗

PubMed2001

Dynamics of subjective contour formation in the early visual cortex.

To elucidate the roles of visual areas V1 and V2 and their interaction in early perceptual processing, we studied the responses of V1 and V2 neurons to statically displayed Kanizsa figures. We found evidence that V1 neurons respond to illusory contours of the Kanizsa figures. The illusory contour signals in V1 are weaker than in V2, but are significant, particularly in the superficial layers. The population averaged response to illusory contours emerged 100 msec after stimulus onset in the superficial layers of V1, and around 120--190 msec in the deep layers. The illusory contour response in V2 began earlier, occurring at 70 msec in the superficial layers and at 95 msec in the deep layers. The temporal sequence of the events suggests that the computation of illusory contours involves intercortical interaction, and that early perceptual organization is likely to be an interactive process.

Animals↗

PubMed2001

4-Hydroxy-6-oxo-6,7-dihydro-thieno[2,3-b] pyrimidine derivatives: synthesis and their biological evaluation for the glycine site acting on the N-methyl-D-aspartate (NMDA) receptor.

Bioisostere approach has been shown to be useful to augment potency or to modify certain physiological properties of a lead compound. Based upon well documented bioisosterism, an isosteric replacement of benzene ring of 4-hydroxy-2-quinolone compound (L-695902) with a thiophene moiety was carried out to prepare the title compounds, 4-hydroxy-6-oxo-6,7-dihydro-thieno[2,3-b] pyrimidines 15. The resulting bioisosteric compounds 15 were evaluated for their antagonistic activity (binding assay) for NMDA receptor glycine site.

Animals↗

PubMed2001

Interaction of calmodulin- and PKC-dependent contractile pathways in cat lower esophageal sphincter (LES).

We have previously shown that, in circular muscle cells of the lower esophageal sphincter (LES) isolated by enzymatic digestion, contraction in response to maximally effective doses of acetylcholine (ACh) or Inositol Triphosphate (IP3) depends on the release of Ca2+ from intracellular stores and activation of a Ca2+-calmodulin (CaM)-dependent pathway. On the contrary, maintenance of LES tone, and response to low doses of ACh or IP3 depend on a protein kinase C (PKC) mediated pathway. In the present investigation, we have examined requirements for Ca2+ regulation of the interaction between CaM- and PKC-dependent pathways in LES contraction. Thapsigargin (TG) treatment for 30 min dose dependently reduced ACh-induced contraction of permeable LES cells in free Ca2+ medium. ACh-induced contraction following the low level of reduction of Ca2+ stores by a low dose of TG (10(-9) M) was blocked by the CaM antagonist, CGS9343B but not by the PKC antagonists chelerythrine or H7, indicating that the contraction is CaM-dependent. After maximal reduction in intracellular Ca2+ from Ca2+ stores by TG (10(-6) M), ACh-induced contraction was blocked by chelerythrine or H7, but not by CGS9343B, indicating that it is PKC-dependent. In normal Ca2+ medium, the contraction by ACh after TG (10(-9) M) treatment was also CaM-dependent, whereas the contraction by ACh after TG (10(-9) M) treatment was PKC-dependent. We examined whether PKC activation was inhibited by activated CaM. CGS 9343B inhibited the CaM-induced contraction, but did not inhibit the DAG-induced contraction. CaM inhibited the DAG-induced contraction in the presence of CGS 9343B. This inhibition by CaM was Ca2+ dependent. These data are consistent with the view that the switch from a PKC-dependent pathway to a CaM dependent pathway can occur and can be regulated by cytosolic Ca2+ in the LES.

Acetylcholine↗

PubMed2001

NMDA receptor and NO mediate ET-1-induced behavioral and cardiovascular effects in periaqueductal gray matter of rats.

Endothelin-1 (ET-1), a novel and potent vasoconstrictor in blood vessel, is known to have some functions in the rat central nervous system (CNS). In order to investigate the central functions of ET-1, ET-1 was administered to the periaqueductal gray area (PAG) of anesthetized rats to induce barrel rolling and increase the arterial blood pressure (ABP). ET-1 had a modulatory effect on central cardiovascular and behavioral control. The selective N-methyl-D-aspartate (NMDA) receptor antagonist MK-801 (3 micromol/kg, i.p.) blocked the ET-1 induced responses, and both the nitric oxide synthase (NOS) inhibitor L-NAME (N-nitro-L-arginine methylester 1 mmol/rat) and the nitric oxide (NO) scavenger hemoglobin (15 nmol/rat) had similar effects in reducing the ET-1 (10 pmol/rat)-induced behavioral changes and ABP elevation. However, NO donor sodium nitroprusside (SNP 10 microg, 1 microg/rat) decreased the ET-1 induced ABP elevation, and recovered the ET-1-induced barrel rolling effect that was reduced by MK-801. These results suggest that ET-1 might have neuromodulatory functions such as ABP elevation and barrel rolling induction in the PAG of the rats via the NMDA receptor and NO.

Animals↗

PubMed2001

Peripheral tears of triangular fibrocartilage complex: results of primary repair.

In 16 patients with ulnar wrist pain, we performed primary arthroscopic or open repair of the peripheral rim tears of the triangular fibrocartilage complex (TFCC) (14 ulnar, 4 volar, and 3 radial tears). The wrist function was assessed before and 1 year after the repair using the Mayo-modified wrist score. The average pain score improved from 9.1+/-8.0 to 21.2+/-6.5, the average functional score from 5.0+/-8.1 to 20.6+/-6.3, the average motion score from 4.7+/-2.8 to 15.6+/-7.3, and the average grip point from 4.4+/-3.5 to 15.6+/-7.7, all with significant differences (P<0.01). Ten of the 17 cases had instability of the distal radioulnar joint and five had recurrent instability after repair.

Adult↗