• Archives of Pharmacal Research
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• v.10 no.1
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• pp.42-49
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• 1987

This study is to evaluate the potential use of aclarubicin-loaded gelatin microspheres as an intravascular biodegradable drug delivery system for the regional cancer therapy. The diameter of the microspheres prepared by water in oil emulsion polymerization could be controlled by adjusting the stirring rate in the range of 10-50 $\mu$m : D(in $\mu$m) = -73.8 log (rpm) + 262.7. The addition of proteolytic enzyme increased the in vitro aclarubicin release but it did not change the amount of the initial burst release which reached about 45%. Microspheres injected intravenously into the mouse tail vein embolized only to the lung when observed by fluorescence microscopy. From histological examination following injection of gelatin microspheres into mouse femoral muscle, mild inflammation was observed from the appearance of neutrophils after 2 days and rapid repair process was confirmed thereafter. Biodegradation process of gelatin microspheres lodged on the pulmonary capillary bed was followed up by microscopic observation; degradation was taking place by about 36 hrs, followed by severe damage on the spheerical shape and microspheres was no longer found 10 days after injection.

• MALSORI
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• no.56
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• pp.49-73
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• 2005

This study explores the most important temporal cues in the perception of the voiced/voiceless distinction of English plosives in terms of newly defined measures of perception: original signal to response agreement, unit signal to response agreement, and robustness. Seven native speakers of English and three leveled groups of Korean English learners participated in the present study. The results showed that both native speakers of English and Korean groups failed to successfully perceive the voiced/voiceless distinction of English plosives, particularly alveolar plosives, in word-medial trochaic positions. The results also showed that in word-initial and word-medial iambic positions both native speakers of English and Korean groups employ the information in the release burst and aspiration in the perception of the voiced/voiceless distinction, of English plosives, and that in word-final positions native speakers of English employ the information in the preceding vowel, while Korean groups employ the information in the closure interval.

• Journal of Pharmaceutical Investigation
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• v.35 no.3
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• pp.151-155
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• 2005

A drug delivery system(DDS) for practically insoluble meloxicam was developed and evaluated by dissolution study. A novel DDS is two layered system, where the first layer is consisted of gas-forming agent for an immediate release and the second layer is composed of metolose SR(HPMC) for sustained release. This bilayered tablets were manufactured by using manual single punch machine. The results of dissolution study showed an initial burst release followed by sustained release for the experimental period time. From a pharmaceutical point of view, the designed DDS for meloxicam would be informative system in terms of poorly soluble analgesic medicines.

• Biomedical Science Letters
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• v.13 no.3
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• pp.175-182
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• 2007

In vitro ciprofloxacin (CFX)-release study and bioassay using microorganisms were performed to estimate the retention of the antimicrobial activity of the CFX-incorporated central venous catheters (CFX-CVCs). The release experiments were carried out under the optional CFX-release conditions to mimic the in vivo environment. The release of CFX experienced an initial burst followed by a slow and steady matrix-diffusion controlled release. The 1.0CP (polyurethane catheter containing 1.0% (w/w) of CFX) under dynamic condition showed a near zero-order CFX release profile, which is beneficial for the long-tenn antimicrobial activity. The modified Kirby-Bauer method was performed employing S. aureus and E. coli to evaluate the retention of antimicrobial activity of the catheters retrieved from the release experiments. The 1.0CP showed the long-term antimicrobial activity (${\geq}\;21$ days) against both S. aureus and E. coli. These results indicate that 1.0CP is useful as a long-tenn indwelling CVC.

• Macromolecular Research
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• v.14 no.4
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• pp.461-465
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• 2006

Two types of injectable system using thermosensitive chitosan (chitosan-g-NIPAAm), hydrogel and microparticles (MPs)-embedded hydrogel were developed as drug carriers for controlled release and their pharmaceutical potentials were investigated. 5-Fluorouracil (5-FU)-loaded, biodegradable PLGA MPs were prepared by a double emulsion method and then simply mixed with an aqueous solution of thermosensitive chitosan at room temperature. All 5-FU release rates from the hydrogel matrix were faster than bovine serum albumin (BSA), possibly due to the difference in the molecular weight of the drugs. The 5-FU release profile from MPs-embedded hydrogel was shown to reduce the burst effect and exhibit nearly zero-order release behavior from the beginning of each initial stage. Thus, these MPs-embedded hydrogels, as well as thermosensitive chitosan hydrogel, have promising potential as an injectable drug carrier for pharmaceutical applications.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.139-144
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• 2002

Two types of alginate gel beads capable of floating in the gastric cavity were prepared. The first, alginate gell bead containing olive oil(Al-Oil), is a hydrogel bead and its buoyancy is attributable to olive oil held in the alginate gel matrix. The model drug, metronidazole(MZ), contained in Al-Oil was released gradually into artificial gastric fluid. The profiles of MZ release from Al-Oil shown initial burst and after 90 min they were about 100%. The second, alginate gel bead containing curdlan microsphere(Al-C), is a gel bead with curdlan-MZ microsphere in the matrix. To sustained release rate of drug, alginate bead were prepared curdlan microsphere containing MZ. Results demonstrated that sustained delivery of MZ over 2h can be easily achieved while the bead remained float. The release properties of prepared alginate beads are applicable not only for sustained release of drugs but also for targeting the gastric mucosa.

• Applied Chemistry for Engineering
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• v.1 no.2
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• pp.147-153
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• 1990

Poly(hydroxypropyl methacrylate) membranes and matrix devices having tertiary amine moiety were prepared by sintering method, and their permeation characteristics were investigated. The water content of this membrane was increased with decreasing the pH of the medium. The permeability of this membrane was increased with decreasing the sintering pressure. Using sintered matrix device 'burst effect' was found at the early stage, and initial insulin release of glucose oxidase immobilized matrix device could be controlled by glucose concentration of the solution.

• Proceedings of the Korean Information Science Society Conference
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• 2000.04a
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• pp.271-273
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• 2000

본 논문에서는 TCP 수신자가 지연 ACK 옵션(Delayed ACK Option)을 사용할 경우에 TCP 송신자에게 발생하는 성능 저하요인들을 분석하고 다음과 같은 해결책을 제시하였다. 먼저, 느린 시작 구간(Slow Start phase) 처음에 생기는 ACK 타임아웃은 큰 초기 윈도우(large initial window)또는 1-bit 마킹 기법을 통해 해결할 수 있다. 그리고, 느린 시작 구간과 혼잡 회피 구간(Congestion Avoidance phase)에서 혼잡 윈도우(cwnd)가 천천히 증가하는 문제는 적절히 바이트 카운팅 기법을 사용함으로써 해결할 수 있다. 마지막으로, 송신자가 버스트(burst)한 데이터를 네트웍에 발생시키는 문제는 트래픽을 평활(pacing)함으로써 해결할 수 있다. 또한 본 연구에서는 분석적 모델링을 통하여 TCP가 보내는 평균 전송률을 구하였으며 이 결과는 TCP에 친화한 전송률 기반 전송방법(TCP Friendly Rate Based Control)에 응용될 수 있을 것이다. 그리고 시뮬레이션을 통해서 제시한 방법의 성능이 향상됨을 확인하였다.

• Macromolecular Research
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• v.17 no.7
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• pp.464-468
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• 2009

Gelatin nanoparticles derived from bovine or porcine have been developed as various types of drug delivery system, and they need to be cross-linked to maintain their physicochemical properties in aqueous environments. Although gelatin is a widely used material in pharmaceutical industries, the safety issue of animal-origin gelatins, such as transmissible mad cow disease and anaphylaxis, remains to be solved. The purpose of this study was to prepare type A gelatin (GA) nanoparticles by modified, two-step, desolvation method and compare the toxicity of the resulting GA nanoparticles with recombinant human gelatin (rHG) nanoparticles. The GA nanoparticles were characterized, and drug loading and release pattern were measured. FITC-BSA, a model protein, was efficiently loaded in the nanoparticles and then released in a biphasic and sustained release pattern without an initial burst. In particular, the cell viability of the GA nanoparticles was less than that of the rHG nanoparticles. This finding suggests that rHG nanoparticles should be considered as an alternative to animal-origin gelatin nanoparticles in order to minimize the safety problems.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.6
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• pp.929-935
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• 1997

The total energy of fish movement and the maximum burst swimming speed were estimated and formulated in accordance with body length and water temperature for several species in fisheries by empirical methods and also by using published results. Under the assumption of swimming energy reserve of a fish at the initial rest state, the swimming endurance of fish with different body lengths, swimming speeds and angular velocity was calculated using the relevant equations under similar conditions in tank experiments as well as natural conditions in field. Relative swimming energy efficiency or the transition swimming speed between red and white muscle for energy consumption was represented as a trigonometric function of swimming speed ratio. Therefore, this model does closely approach the actual swimming abilities and their limits especially in relation to the fishing gear operation and allow for the greater vitality of the wild fish in the fields.