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Biomedical subjects

Y S Won

Publications and source records attributed to Y S Won.

14 recordsLinked to original sources
PubMed2006

Development of a new pulsatile extracorporeal life support device incorporating a dual pulsatile blood pump.

A new pulsatile extracorporeal life support device (ECLS) has been developed, designed to sustain pulsatile blood flow during emergency cardiopulmonary resuscitations and cardiopulmonary operations. This device features two identical pulsatile pumps that operate alternately and can therefore provide blood inflow in a more uniform manner than similar systems featuring a single-pump configuration. In order to confirm the presumed benefits of this newly-developed dual pulsatile pump configuration, we have conducted a series of in vitro experiments designed to compare the properties of the new system with a single pump system, specifically with regard to pump delivery rate and active filling efficiency. Our results reveal that the dual pump configuration can, indeed, deliver a higher flow than can the single-pump system, and exhibits an active filling efficiency superior to that of the single-pump configuration. We performed a series of animal experiments to measure the pulsatility of the dual-pump configuration in terms of equivalent energy pressure (EEP). In order to measure EEP, we measured femoral arterial pressure and pump outflow. The results of our animal experiments revealed that the newly-developed pulstile ECLS exhibits sufficient pulsatility in terms of the EEP considerations.

Advanced Cardiac Life Support↗
PubMed2003

Applications of the pulsatile flow versatile ECLS: in vivo studies.

INTRODUCTION: T-PLS (Twin-Pulse Life Support) is the first commercial pulsatile ECLS (Extra Corporeal Life Support) device (1). The dual sac structure of T-PLS can effectively reduce high membrane oxygenator inlet pressure and hemolysis. To verify both the use of T-PLS for ECLS and the advantages of T-PLS, we tested various models. METHOD AND RESULTS: In the partial CPB (cardio pulmonary bypass) model (swine), T-PLS (N = 6), and Biopump (N = 2), a single pulsatile pump (N = 2), were compared. In the case of single pulsatile flow, during pump systole, pressure increased to 700 - 800 mmHg at the inlet port of the membrane oxygenator. fHb, a hemolysis measurement value, was about 80 mg/dL at 3 hours. On the contrary, because of T-PLS's dual sac system, the pressure of T-PLS had a maximum value of about 250 mmHg and fHb was similar to that of the commercial centrifugal pumps. In the total CPB model (bovine, N = 6), the heart was stopped via cardioplegia (Kcl). T-PLS flow was maintained at 3.0-4.5 L/min. T-PLS functioned like a natural heart, having a pulse pressure of 26-43 mmHg and a pulse rate of 40-60 bpm (beats per minute). In the emergency case model (canine, N = 6), T-PLS was started 10 minutes after cardiac arrest from electronic shock. In spite of cardiac arrest for a period of 40 minutes, the heart was recovered after defibrillation. In the ARDS (Acute Respiratory Distress Syndrome) model (canine, N = 6), minimal ventilator parameters were set: tidal volume 130 ml, respiration rate = bpm, FiO2 = 10%. Three hours after starting T-PLS, PO2 of the carotid artery blood (after 2 hours: 195 +/- 89.4; after 3 hours: 258 +/- 99.3 mmHg) was above half the value of the femoral artery but was within normal range. CONCLUSION: It is suggested that a portable pulsatile ECLS like T-PLS may be used as a CPB device and as an alternative CPR (cardiopulmonary resuscitation) device in the case of cardiac arrest. Due to the pulsatile flow, oxygenated blood is delivered to the patient without overloading the ARDS patients heart.

Animals↗
PubMed2001

C57Bl/6 and BALB/c mice have similar neutrophil response to acute Streptococcus pneumoniae sinus infections.

BACKGROUND: Previous investigations have shown that mice with a tendency toward a T(H)1 or T(H)2 lymphocyte response manifest different reactions to inoculation with the parasite Leishmania major. BALB/c mice (with a tendency for a T(H)2 response) showed evidence of systemic infection, whereas C57Bl/6 mice (with a tendency for a T(H)1 response) showed only a local reaction. OBJECTIVE: To investigate whether BALB/c and C57Bl/6 mice respond differently to acute bacterial infection of the sinuses. METHODS: We inoculated the nasal cavities of C57Bl/6 and BALB/c mice with Streptococcus pneumoniae (type ATCC59), or with broth as a control. The mice were humanely killed 2, 5, 10, and 14 days after inoculation. Their heads were fixed, decalcified, and embedded in paraffin blocks. Sections were stained with hematoxylin and eosin, and the degree of inflammation was quantified by the number of neutrophils per square millimeter of the sinus mucosa and the percentage of the sinus cavity occupied by neutrophil clusters. RESULTS: Both groups of mice showed evidence of inflammation that was significantly greater than controls (P =.01), with no difference between groups. There was a correlation between the number of neutrophils per square millimeter in the sinus mucosa and the percentage of neutrophil clusters (C57Bl/6 mice, r = 0.37, P<.001; BALB/c mice, r = 0.20, P<.001). In the infected mice, the number of infiltrating neutrophils was significantly greater (P<.001) in anatomically lower (dependent) areas of the sinuses compared with the upper areas. CONCLUSION: Unlike leishmaniasis, acute bacterial sinusitis is not affected by the tendency of the host to favor either a T(H)1 or T(H)2 response.

Acute Disease↗
PubMed2001

Malignant solitary fibrous tumor of the pleura causing recurrent hypoglycemia; immunohistochemical stain of insulin-like growth factor i receptor in three cases.

We present three cases of malignant solitary fibrous tumors of the pleura (SFTP) that produced recurrent hypoglycemia. Removal of the tumors produced normoglycemia. The tumors were well circumscribed and lobulated, and consisted of firm masses weighing 1,150 g to 1,450 g with the greatest diameter of 15 to 20 cm. The tumors were composed of spindle cells in fascicles or in a haphazard arrangement and were highly cellular and mitotically active (3-8 mitoses/10 high-power fields), showing histologically malignant features. Ultrastructurally, fibroblastic features of the tumor cells were present. Insulin-like growth factors (IGF) have been implicated in the presentation of hypoglycemia. The serum insulin and C-peptide levels were not elevated. Serum IGF-I levels were also low with values of 97.4, 157.1 and 51.9 ng/mL (ref. 125-317 ng/mL), respectively. However, tumor cells were strongly positive for IGF-I receptor on immunohistochemical analysis. It is tempting to speculate that IGF-I contributes to the hypoglycemia, even though the circulating levels were low.

Aged↗
PubMed2001

Chemical characteristics and leachability of organically contaminated heavy metal sludge solidified by silica fume and cement.

This paper discusses the development of mixtures with silica fume as a stabilization/solidification agent and binder for industrial wastewater residue containing organic and heavy metal contaminants. The UCS (Unconfined Compressive Strength) gradually increased to 66.7% as the silica fume content increased to 15%. The leaching of TOC and chromium decreased as more OPC was substituted with silica fume. When the mix had 5% silica fume, it retained about 85% TOC, and chromium leached out 0.76 mg-Cr/g-Cr in acidic solution. Also, microstructural studies on the solidified wastes through the scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) and X-ray diffraction analysis showed that the silica fume caused an inhibition to the ettringite formation which did not contribute to setting, but coated the cement particles and retarded the setting reactions. The results indicated that the incorporation of silica fume into the cement matrix minimized the detrimental effects of organic materials on the cement hydration reaction and contaminant leachability.

Adsorption↗
PubMed2000

Long-term use of preservatives on rat nasal respiratory mucosa: effects of benzalkonium chloride and potassium sorbate.

OBJECTIVES: The preservatives benzalkonium chloride (BZC) and potassium sorbate (PS) are widely used, not only for nasal drops, but also for eyedrops and cosmetics. However, there have been many case reports that consider lesions such as dermatitis or conjunctivitis to be the results of irritation induced by BZC or PS. METHODS: We evaluated the histological changes after the long-term administration of BZC or PS on rat nasal respiratory mucosa. Forty rats were used for the BZC group and 40 rats for PS group. Animals in each group were divided into four subgroups The first subgroup received a low-concentration preservative solution that was commonly used for nasal sprays. The second subgroup received a high-concentration preservative solution that was reported to induce dermatitis in humans. The third and fourth subgroups received a steroid mixed preservative solution of low and high concentrations, respectively. The control group was administrated normal saline. After each group received 1, 2, and 4 weeks of topical administration, the symptomatic and histological changes on H&E stain were observed. RESULTS: Sneezing and nasal rubbing with forelegs were observed in almost all subgroups by the seventh day of treatment. The preservatives induced nasal lesions, including intraepithelial glandular formation, inflammatory cell infiltration, vascular hyperplasia, and edematous change. The symptomatic and histological changes were pronounced with the prolonged duration of administration. Similar results were observed in the steroid mixed-solution groups. In the PS steroid mixed-solution group, however, symptoms and nasal lesions were reduced with the prolonged duration of administration. CONCLUSION: It is our finding that even a low-concentration solution of preservative can lead to nasal lesion. Hence there is a strong need to develop both a preservative that can be safely and widely used and a nasal spray without preservatives.

Animals↗
PubMed2000

Bactrim reduces the inflammatory response in a murine model of acute rhinosinusitis.

OBJECTIVE: To determine whether treatment with an antibiotic (trimethoprim-sulfamethoxazole) reduced the inflammatory response in a murine form of Streptococcus pneumoniae-induced rhinosinusitis. DESIGN: We randomized 18 C57BL/6 mice to either treatment with intraperitoneal trimethoprim-sulfamethoxazole (Bactrim, 30 mg/kg) or no treatment (control). After 2 days, we inoculated all C57BL/6 mice intranasally with a Bactrim-susceptible strain of Streptococcus pneumoniae, ATCC 49619, suspended in Trypticase soy broth. At day 5 after bacterial inoculation, we sacrificed the mice and prepared histopathologic sections of their sinuses after culturing their nasal cavities by lavage. SETTING: Animal care facility at a tertiary, academic institution. METHODS: The histopathologic sections of the sinuses were examined in a blind manner for the percent of sinus cavity area occupied by neutrophil clusters, and for the number of neutrophils per square millimeter of sinus mucosa. RESULTS: The Bactrim group had a significantly smaller sinus area occupied by neutrophil clusters (1.58% +/- 1.13 vs 4.38% +/- 3.41; P < 0.05), significantly fewer neutrophils infiltrating the mucosa (58.81 +/- 29.63/mm2 vs 105.85 +/- 48.49/mm2; P < 0.05), and significantly less growth of Streptococcus pneumoniae colonies in the intranasal cultures (8 few and 1 moderate vs 3 few, 3 moderate, and 1 many; P = 0.05) compared to the control group. CONCLUSION: In our murine model of acute rhinosinusitis, Bactrim decreased the number of neutrophil clusters in the sinus cavities, the number of neutrophils infiltrating the sinus mucosa, and the growth of Streptococcus pneumoniae. We propose that our murine model can be used for the study of the pathophysiology and treatment of acute rhinosinusitis.

Animals↗
PubMed1999

Size assessment of adenoid and nasopharyngeal airway by acoustic rhinometry in children.

Adenoid hypertrophy is known as the most common cause of nasal obstruction in children; thus, adenoidectomy with, or without, tonsillectomy is one of the most commonly performed surgical procedures in the paediatric population. Although many methods have been suggested, few studies have reported on how to assess adenoid size, pre-operatively. Acoustic rhinometry is an objective technique as well as a non-invasive method, which can be easily used in young children. This study confirmed that acoustic rhinometry is a non-invasive and objective technique for assessing the geometry of the nasal cavity and nasopharynx. Forty children were evaluated using symptomology, two different radiological measurements and acoustic rhinometry; the results were compared with endoscopic findings. Clinical symptoms and A/N ratio measured with Fujioka's method significantly correlated with the endoscopic assessment findings (r = 0.769 and 0.604 respectively). Significant increases in the cross-sectional area and volume of the nasopharynx were observed at the adenoid notch after adenoidectomy (p < 0.005 and p < 0.005, respectively). Acoustic rhinometry showed a high degree of correlation of which adenoid occupied the nasopharyngeal airway under endoscopic examination (r = 0.771). Thus, the study concluded that acoustic rhinometry can be as good an objective method for measuring adenoid sizes as endoscopy and can be used as one of the pre-operative examination tools for adenoidectomy.

Adenoids↗
PubMed1999

Simple, efficient and successful vitrification of bovine blastocysts using electron microscope grids.

This study demonstrates that higher survival of vitrified-thawed bovine blastocysts can be obtained using electron microscope (EM) grids as embryo containers at freezing, rather than plastic straws. In-vitro produced day 7 bovine blastocysts after in-vitro fertilization (IVF) were vitrified on grids or in straws with EFS40 freezing solution and their survival after thawing was compared. Embryo survival was assessed as re-expanded and hatched rates at 24 and 48 h after thawing respectively. When the effects of exposure to vitrification solution and chilling injury from the freezing procedure were examined, embryo survival in the exposure group (24 h: 100, 48 h: 73.3%) was not different compared with that in the control group (100, 84.4%). After vitrification, the hatched rate of the EM grid group 48 h after thawing (67.8%) was significantly higher than that of the straw group (53.3%) (P < 0.05). Fast developing embryos (expanded blastocyst and early hatching blastocyst stage) showed better resistance to freezing than delayed ones (early blastocyst stage), irrespective of embryo containers (early: 24 h, 57.1 and 48 h, 24.4%; expanded: 84.7 and 60.6%; early hatching: 91.7 and 80.0%) (P < 0.001). When using expanded and early hatching blastocysts, embryo survival rates in the vitrification-EM grid group (67.8, 95.0% respectively) were significantly higher than that of the vitrification-straw group (53.0, 65.0%) at 48 h.

Animals↗
PubMed1997

Moving actuator type total artificial heart with reverse position of the aortic and pulmonary conduits.

Adequate intrathoracic anatomical compatibility is one of the most important considerations in designing a fully implantable total artificial heart (TAH). We have recently developed an innovative concept of reverse positioning of the aortic and pulmonary conduits to facilitate anatomical compatibility of the moving actuator type TAH. The pulmonary conduit of this TAH is designed to be located posterior to the aortic conduit, which results in a substantial reduction in the anteroposterior diameter of this heart, as well as the virtual elimination of the compression of the low pressure pulmonary conduit. In ovine orthotopic implantation experiments with this model of the TAH, we consecutively achieved 3 day survival in 1 sheep and 2 day survival in another. To the best of our knowledge, these were the first significant short-term survival cases in the orthotopic implantation of electric TAHs in sheep.

Animals↗
PubMed1996

Transaxillary minithoracotomy versus video-assisted thoracic surgery for spontaneous pneumothorax.

BACKGROUND: Although management of spontaneous pneumothorax by video-assisted thoracic surgery (VATS) has generally shown superior clinical results to thoracotomy, management of spontaneous pneumothorax by transaxillary minithoracotomy (TAMT) has also shown good clinical results. The objective of this study was to compare the clinical results of VATS and TAMT in treating spontaneous pneumothorax. METHODS: Sixty-six patients, aged 13 to 81 years, with recurrent, persistent or contralateral spontaneous pneumothorax were involved in this study. Thirty-six patients were treated by VATS and 30 by TAMT. The operating time, the amount of analgesics used on the first postoperative day, the duration of the indwelling chest tube, and the number of recurrences after operation were compared. The follow-up periods of both procedures were from 6 to 24 months. RESULTS: Of the 66 patients, 64 were male and 2 were female. The duration of operation, from start of skin incision to insertion of chest tube, was 91.2 +/- 36.8 minutes in VATS and 86.3 +/- 40.9 minutes in TAMT (p = 0.6061). The amount of analgesics (keptoprofen) used was 1.9 +/- 2.3 ampules in VATS and 2.1 +/- 2.9 ampules in TAMT (p = 0.0883). The duration of indwelling chest tube was 5.0 +/- 4.0 days in VATS and 4.3 +/- 2.1 days in TAMT (p = 0.3707). The number of recurrences after operation was 4 in VATS and none in TAMT. CONCLUSIONS: There were no advantages of VATS over TAMT for management of recurrent, persistent, or contralateral spontaneous pneumothorax in regard to the operating time, the amount of analgesics used on the first postoperative day, the duration of the indwelling chest tube, and the number of postoperative recurrences in patients with apical bullae.

Adolescent↗
PubMedDate not supplied

In vivo experiment leading to clinical application of an electrohydraulic ventricular assist device with magnetic coupling.

We developed an electrohydraulic ventricular assist device with magnetic coupling. The integrated system consists of a blood pump, a water conduit for pressure transmission, a bellows type pumping sac, an actuator for transforming the circular motion of a motor to the linear motion of a pusher plate attached to the pumping sac with magnetic coupling, and a controller. The purpose of the coupling was to prevent excessive sucking against the atrial wall. Number 21 Medtronic Hall (Irvine, CA) mechanical valves were used in the inflow and outflow ports of the blood pump. Maximum dynamic stroke volume was 48 ml, and against a mean afterload of 100 mm Hg, maximum pump output was 7 L/min. Chronic in vivo experiments were performed in three sheep, and during these evaluations the system showed no noticeable problems related to mechanical or electronic devices. When left atrial pressure decreased below 0 mm Hg, the magnetic coupling system decoupled the pumping sac and pusher plate with satisfactory reliability. The device was clinically applied in a postoperative patient with chronic dilating cardiomyopathy, and no significant device related problems ensued. These results prove that the electrohydraulic ventricular assist system with magnetic coupling is a suitable ventricular assist device.

Animals↗