宜婷科展預定工作時程

完成日期	工作項目
12/22	設計實驗方法、報告架構
12/29	完成初步實驗，檢討方法
01/02	第一階段報告製作
01/16	完成實驗內容、分析資料
01/20	第二階段報告製作
01/31	資料討論與結論
02/06	完成報告書並提送

科展進度review

到目前為止,對凝血時間的量測,還是以導電度最簡單.(光學穿透,超音波,磁場等都各有優劣)
開始準備維他命B , K及阿斯匹靈等三種藥之溶液.購買滴管及塑膠瓶等.

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磁場對凝血之作用

1. Aggregation of blood platelets in static magnetic fields
Iwasaka, M.; Takeuchi, M.; Ueno, S.
Magnetics, IEEE Transactions
Volume 36, Issue 5, Sep 2000 Page(s):3721 - 3723
Digital Object Identifier   10.1109/20.908952
Summary:We investigated the effects of intense magnetic fields on the blood platelet aggregation process with and without static magnetic fields of up to 14 T. A rabbit plasma and collagen mixture was used as the model system for a wounded blood vessel. Platelet aggregation was activated by the stimulation of acid soluble collagen. The platelet aggregates in strong magnetic fields were larger than the aggregates in an ambient field. An optical transmission of blood plasma during platelet aggregation also indicated that strong magnetic fields enhanced blood platelet aggregation in plasma.

 

2. Magnetic relaxation in blood and blood clots.

Bryant RG, Marill K, Blackmore C, Francis C.

Department of Biophysics, University of Rochester, School of Medicine and Dentistry, New York 14642.

Magn Reson Med. 1990 Jan;13(1):133-44.

Summary:Nuclear magnetic relaxation rates are measured for whole blood, blood plasma, whole blood clots, and plasma clots in vitro. Relaxation rates are linear in the hematocrit and transverse relaxation rates are significantly greater than longitudinal relaxation rates. Longitudinal relaxation rates measured from 0.01 to 42 MHz for proton Larmor frequencies are found to decline monotonically with increasing magnetic field strength; however, the dispersion curves do not follow a simple Lorentzian behavior, which is anticipated in a suspension of particles in a solution of proteins having a distribution of molecular weights. The transverse relaxation rate is a function of the acquisition parameters, in particular, the choice of TE in either Hahn echo experiments or in echo-train experiments. The origin of this dependence of T2 on TE or the interpulse spacing in an echo train is identified with the exchange of water from inside the red blood cell to the outside and is only an important relaxation mechanism in the case where the blood cell membrane is intact and the cell contains deoxygenated hemoglobin. The dependence of the apparent transverse relaxation rate on the interpulse spacing in a Meiboom-Gill-Carr-Purcell pulse sequence provides the estimate that the mean residence time of water inside the blood cell is about 10 ms. These data provide a sound basis for understanding the dependence of magnetic images on magnetic field strength and the choices of the image acquisition parameters, TE and TR.

 

3. The Mechanics of Blood Clots：How Biophysics can Investigate One Aspect of Hemostasis

Robert Harrand

   When a person is cut, there is an immediate cascade of reactions resulting in the formation of a blood clot. Molecules called fibrinogen are altered, with small sections being snipped off, allowing them to join together in long chains. These chains then line up and form thick, rigid fibres called fibrin. The final clot is made up of a fibrous network which traps platelets (fragments of cells) and red blood cells, stemming the flow of blood from the damaged area. This process of preventing blood loss is known as hemostasis.

Summary:

Disorders in the Blood Clotting System

Throughout the evolution of this highly sophisticated system, genetic faults and diseases have emerged that circumvent the clotting mechanism. Haemophiliacs, for example, lack one type of molecule involved in the clotting reaction, and tricks by other animals can disrupt our clotting ability, such as the hindrance of clot formation by the saliva of both snakes and mosquitos.

Blood Clots Have Different Characteristics

Not all blood clots are the same - some are tight and compact, others are sparse and flexible, and forming the right one in the right circumstances can be a matter of life and death. If a clot is too stiff, the body will have trouble breaking it down when the wound has healed. A clot that is too compliant will not stop the flow of blood from the wound.

Mechanical Measurements of Clots Using Magnets

How is the stiffness of a blood clot measured? What can test whether or not a patient can form a healthy clot, or if a certain type of treatment can help to turn a poor clotting response into something healthier? This is where a simple trick with magnets steps in to lend a hand.

A magnet can be moved, from a distance, by inducing an external magnetic field. Sliding a magnet across a desk using a second magnet held underneath is a classic example.

Now imagine the first magnet stuck in the middle of a sponge, which bends and distorts when a second magnet is moved around. Picture the sponge as a blood clot, around ten thousand times smaller than an actual sponge.

Forming and Testing Blood Clots

In the experimental procedure, fibrinogen molecules extracted from blood samples are mixed with a second type of molecule that initiates the clotting reaction. In addition, small magnetic particles (acting like tiny magnets) are added, and nature left to run its course. The clot forms and traps the magnetic particles. Next, the clot is placed under a microscope, one of the magnetic particles is located, and a nearby, much larger electromagnet is activated.

The result is that the tiny magnets inside the clot move towards the larger one, and this distorts the fibrin network. By knowing how strong the magnets are, and how far they move, the mechanical properties of the clot can be worked out. If this is repeated with different samples, from, say, one patient with diabetes and one without, the differences in the various types of clot can be measured.

The Merging of Scientific Disciplines

Today, at the edges of the traditional scientific disciplines, there is a merging of ideas and techniques. Physics on the scale of between millionths and billionths of a metre is precisely where biology happens, whether it be a living cell, a single molecule of DNA, or a blood clot. And in this case, it took no more than the principle behind a classroom trick to further increase our understanding of nature.

References:

Ramzi Ajjan, Bernard C. B. Lim, Kristina F. Standeven, Robert Harrand, Sarah Dolling, Fladia Phoenix, Richard Greaves, Radwa H. Abou-Saleh, Simon Connell, D. Alastair M. Smith, John W. Weisel, Peter J. Grant, and Robert A. S. Ariëns. Common variation in the C-terminal region of the fibrinogen β-chain: effects on fibrin structure, fibrinolysis and clot rigidity. Blood, Jan 2008; 111: 643 - 650

 

血液凝固機制

在出血15~20秒左右，即會開始血液凝固(blood coagulation)的反應。這是一個複雜的過程，可分為3階段。其中第1階段凝血因子來源不同，可分為外在途徑及內在途徑；第2及第3階段則為共同途徑。
1.外在途徑(extrinsic pathway)：由受傷組織釋出組織凝血質(tissue thromboplastin)而啟動。因啟動反應的凝血因子來自血管以外之周圍組織，故名之為外在途徑，其過程較內在途徑短。最終生成凝 血酶原致活素(thromboplastin)。
2.內在途徑(intrinsic pathway)：所有之凝血因子皆來自血管之內故稱為內在途徑。由血中血小板接觸受傷管壁上之膠原纖維啟動活化第XII因子，再加入Ca² ，I、Ⅸ、Ⅷ及Ⅶ因子，最終形成血小板凝血質(platelet thromboplastin)，其過程較複雜。
凝血反應中生成之纖維蛋白絲與血小板栓子，形成更穩定之網狀構造，再加上血液中的血球黏附其上，形成更堅固之止血栓子。

Conductivity of Blood During Coagulation

References for Sciences Fair

1.S. Gelfan, J. P. Quigley : Am. J. Physiol 94: 531-534, 1930;
2.R. T. Frank：Am. J. Physiol 14: 466-468, 1905;
3.J. A. Connelly and M. J. Buckler：Med. and Biol. Engineering and Computing V. 13, No. 4 / 1975
4.V. F. Rusyaev：Biomedical Engineering ：No. 3, pp. 36–40, 1983.
5.F. G. HIRSCH, E. C. TEXTER, L. A. WOOD, W. C. BALLARD, F. E. HORAN, I. S. WRIGHT, C. FREY, and D. STARR：J. Am. Soc. Hematology Blood, 1950, Vol. 5, No. 11, pp. 1017-1035.

Richard Cheng
ADA Corp.
0988258115
tdirichard@army.com

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Science Fair Report -- Abstract

科展報告

 

壹、研究動機:

      家族中的成員病史有非常高的心血管系統疾病的發病率。在祖父那一代成員共有四位男性，全部都有出血性腦中風，也都有心臟疾病。到了父親這一代，不但有肥胖、高血壓、糖尿病，更在四十出頭就作了冠狀動脈繞道手術。這些令人膽戰心驚的病史使我燃起了面對它並解決它的鬥志。而這一切都與血液的凝結功能有關，我決定要了解血液凝結的控制因素，血液凝結時間如何量測？那些藥物會影響血液凝結？血型與血液凝結的關係？血糖值與血液凝結的關係？酸鹼值與血液凝結的關係？運動與血液凝結的關係？藉由這些觀察來發現究竟是遺傳的原罪或是生活飲食習慣引起的！

貳、研究目的:

1. 了解血液凝結的的成因及對凝結時間的量測方法,並且發展在週邊有限的資源裡實用簡便的量測方法。   

2. 了解影響血液凝結的控制變因與對血液凝結時間的影響程度，並且用簡單的實驗觀察輔助了解科學研究實事求是之精神。

3. 了解各種控制變因對血液凝結的機制，並且思考可能的防治對策。

4. 學習團隊合作、分析問題與蒐集資料，並找出解決之道。

參、研究器材:

數位型三用電錶一個，電子式血糖機一個，載玻片，蓋玻片，電腦。   

肆、研究過程與結果:

4.1 分配工作與討論研究方向

   我們經過討論後決定從十月初開始針對題目查資料並自十二月十六日起開始紀錄實驗結果，預計在十二月底完成紀錄。並在兩週內完成分析與討論工作。我們將針對血液凝結時間如何量測？那些藥物會影響血液凝結？血型、血糖值與血液凝結的關係？運動與血液凝結的關係？等四大方向去查資料。

4.2 血液凝結時間如何量測

      國際血液學標準化委員會（ICSH）、國際血栓與止血委員會（ICTH）或美國的國家臨床實驗室標準委員會（NCCLS）對凝血酶原時間（ Prothrombin Time ） 與活化部分凝血活酶時間（ Activated  Partial  Thromboplastin Time）及纖維蛋白原測定（Fibrinogen  Estimation）均有明確的規定。

凝血酶原（prothrombin）是血漿中重要的凝固因子之一，需要Vitamin K 合成於肝臟。所以，各種肝病和Vitamin K 缺乏時均可能引起prothrombin 減少，甚至異常出血。傳統Prothrombin Time 的測定是將thromboplastin 和鈣離子加在檸檬酸鈉為抗凝劑的新鮮血漿時，會立刻引起外因性路徑與共同路徑的活化，而產生纖維蛋白凝固，以進行凝血測定，包括：第七因子（Ⅶ）、第十因子（Ⅹ）、第五因子（Ⅴ）、第二因子（Ⅱ）、fibrinogen 等因子是否正常。

Prothrombin Time 的測定方法為1935 年A.J.Quick 提出的一段式凝血酶原時間（one stage prothrombin time），稱Quick 氏試驗。歷經七十餘年來，至今仍是檢查外因性路徑凝血因子與相關抑制物的重要試驗。

近年來凝血測定儀因市面上廠牌眾多，自動化程度也不一樣，測定的原理大體上可分為偵測凝固黏稠度增加，或利用光學變化等為終點判定，包括比濁法及散射光偵測法等。我們想到如果能用血液凝結過程電阻值的變化來作為血液凝結完成的指標，就可以建立一種測定凝血時間的標準，方便我們後續的研究。

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遇到瓶頸

血液的電阻頗大,用三用電表量很不準,不知有否更好的量法否? Impedance or resistence?需要立刻找到解決方式!

血液導電度(電阻值)變化與凝結時間

偶而想到不知有無電阻與Clotting Time之關係? 值得一試!