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Biomedical subjects

A Fokin

Publications and source records attributed to A Fokin.

12 recordsLinked to original sources
PubMed2004

Changes in sternal blood flow after different methods of internal thoracic artery harvesting.

OBJECTIVE: The study was designed to assess the early changes in sternal perfusion after midline sternotomy and different (skeletonized versus semiskeletonized) techniques of internal thoracic artery (ITA) harvesting. METHODS: The experiments were performed in the swine model. After midline sternotomy, ITA harvesting (skeletonized technique) was performed unilaterally in Group I (6 animals). The ITA and the internal thoracic vein (ITV) were harvested (semiskeletonized technique) in Group II (5 animals). The contralateral sternal half served as a control. Using a thermographic camera with a 0.06 degrees C sensitivity, sternal perfusion was assessed 2 and 5 hours after surgery. RESULTS: Midline sternotomy alone did not affect sternal blood flow. A statistically significant ( p < 0.05) reduction in perfusion of the involved sternal half in comparison to the control side was detected at 2 and 5 hours after surgery. The degree of perfusion deficit was not related to the harvesting technique. CONCLUSIONS: Skeletonized and semiskeletonized ITA harvesting techniques caused a similar acute reduction in sternal perfusion during the early postoperative period and this effect lasted for at least 5 hours.

Animals↗
PubMed2003

Structure and properties of confined sodium nitrite.

The temperature evolution of the structure of NaNO(2) nanocomposite ferroelectric material in a porous glass with 7 nm pores was studied by neutron diffraction in temperature region from room temperature up to the melting, i.e. in the ferro- and paraelectric phases. It is demonstrated that in the ferroelectric phase the structure is consistent with the structure of the bulk, but above the ferroelectric phase transition (and up to approximately 513 K) a volume premelted state is formed, manifesting itself in a growth of amplitudes of ion thermal vibrations, a steep increase of elementary cell volume and "softening" of lattice. For the first time the temperature dependence of order parameter eta for confined sodium nitrite is determined. eta (T) follows a power law with T(C)=425.6+/- 2.1 K and beta= 0.31+/- 0.04, which is essentially different from that for bulk NaNO(2). Our obtained data are in a good agreement with the results of earlier dielectric and neutron diffraction measurements.

Journal Article↗
PubMed2000

Apoptosis is initiated by myocardial ischemia and executed during reperfusion.

Ischemia/reperfusion leading to myocyte cell death has been reported as either necrotic or apoptotic or a combination of both. The importance of necrosis is well established but the role of apoptosis and the time of initiation are still unknown. Normothermic global ischemia of either 45 or 90 min duration followed by 6 h of reperfusion were induced in isolated canine hearts. After 45 min of ischemia, left ventricular function and adenine nucleotide (AN) content had recovered during reperfusion indicating reversible injury. DNA fragmentation determined by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) was absent as was the 85 kDa fragment of poly-(ADP-ribose) polymerase (PARP). After 90 min of ischemia, electron microscopy indicated necrotic cell death in 90% of myocytes. Recovery of function and AN content during reperfusion was minimal. At the end of ischemia, caspase-3 was activated in 30% of all myocytes and PARP 85 kDa fragments were present by Western blot, indicating initiation of the apoptotic cascade. Lamin-B(1)labeling was significantly reduced from 90% in myocytes in control and ischemia to 30% in early reperfusion. Completion of apoptosis seen by TUNEL was evident in late reperfusion (7.6% of myocytes and 8.3% of non-myocytes). Experiments with 6 h ischemia without reperfusion showed absence of DNA fragmentation. We conclude that apoptotic cell death is initiated by ischemia but that reperfusion is needed for completion of the apoptotic cascade. Furthermore, it is concluded that cell death in acute global ischemia followed by reperfusion occurs predominantly by necrosis and that apoptosis is of minor importance in this pathophysiological situation.

Adenine Nucleotides↗
PubMed2000

Sternal instability after midline sternotomy.

The purpose of this paper is to discuss sternal instability a problem occasionally associated with midline sternotomy, including the etiology, predisposing conditions, diagnosis and management. Among the methods of repair, sternal weaving and pectoralis muscle advancement are thought to be especially effective.

Bone Wires↗
PubMed1999

Transport of colloidal particles in lymphatics and vasculature after subcutaneous injection.

This study was designed to determine the transport of subcutaneously injected viral-size colloid particles into the lymph and the vascular system in the hind leg of the dog. Transport of two colloid particles, with average size approximately 1 and 0.41 microm, respectively, and with and without leg rotation, was tested. Leg rotation serves to enhance the lymph flow rates. The right femoral vein, lymph vessel, and left femoral artery were cannulated while the animal was under anesthesia, and samples were collected at regular intervals after subcutaneous injection of the particles at the right knee level. The number of particles in the samples were counted under fluorescence microscopy by using a hemocytometer. With and without leg rotation, both particle sets were rapidly taken up into the venous blood and into the lymph fluid. The number of particles carried away from the injection site within the first 5 min was <5% of the injected pool. Particles were also seen in arterial blood samples; this suggests reflow and a prolonged residence time in the blood. These results show that particles the size of viruses are rapidly taken up into the lymphatics and blood vessels after subcutaneous deposition.

Animals↗
PubMed1999

Pressure traps in femoro-popliteal reversed vein grafts. Are valves culprits?

BACKGROUND: Stenosis is a major cause of vein graft failure in peripheral arterial surgery. Our goal is to determine whether vein valves play a role in this process by creating a "pressure trap". METHODS: Seventeen patients with femoro-popliteal reversed saphenous vein grafts were studied intraoperatively. Flow and pressure in the grafts were measured, while the graft outflow was gradually occluded and released for 2-4 seconds. In 3 patients the graft flow was reduced by compressing calf muscles. RESULTS: Patients heart rates were 54-84 BPM, blood pressures 170/80-110/55 mm Hg, and normal graft flow was 40-180 ml/min. In 12 patients with competent vein valves, at reduced flow (<30 m/min) the valves opened and closed in each cardiac cycle. At each closure the pressure was "trapped" distal to the valve producing diastolic hypertension. Also the flow was stagnant for a considerable portion of the cardiac cycle. Maximum diastolic pressure gradient across the valve ranged from 35 to 60 mm Hg and the level of pressure trapped was inversely proportional to the graft flow. CONCLUSIONS: In patients in whom reversed vein grafts with competent valves are placed in the femoro-popliteal positions a "pressure-trap" develops in the distal segment. This segmental hypertension combined with the flow stagnation could play an important role in the graft thickening and stenosis.

Anastomosis, Surgical↗
PubMed1999

Surgical correction of pectus excavatum and carinatum.

The author presents three decades of experience in the management of anterior chest wall deformities. During this period more than 800 operations were performed on patients with pectus excavatum and carinatum. In this series, there was no death and serious complications were rare. The author believes that the principles on which surgical treatment of pectus excavatum should be based are as follows: (1) bilateral removal of the "culprit" costal cartilages, (2) adequate mobilization of the sternum and correction of the sternal positional deformity by transverse osteotomy, (3) stabilizing the corrected position of the sternum with a substernal "hammock" support. Using this technique the author developed new surgical techniques for the correction of different varieties of chest wall deformities: Pectus excavatum, asymmetric pectus excavatum, pectus carinatum with xiphoid angulation, horizontal pectus excavatum, asymmetric pectus carinatum, chondrosternal prominence with chondrogladiolar depression, and recurrent pectus excavatum. The present method applied for correction of pectus excavatum utilizes the above principles and a substernal Marlex mesh support with bilateral muscle coverage. For carinatum repair, the author routinely uses positional correction of the sternum and sternal shortening. Patients who have significant pectus deformities should undergo surgical repair, preferably between one and eight years of age.

Biocompatible Materials↗
PubMed1998

Direct anastomosis of the saphenous vein to the unclamped aorta.

The authors present an alternative technique for anastomosis of the proximal saphenous vein to the ascending aorta which allows safe and effective performance of the aorto-to-saphenous connection using neither aortic clamping nor circulatory arrest. This technique can be used in situations such as calcification of the aortic wall or presence of unstable atheromatous plaques which make the application of the more commonly applied method very risky or even impossible.

Aorta↗
PubMed1993

[Aneurysm spurium after resection of aortic coarctation].

25 years after reconstruction of an aortic coarctation by prosthetic material, an insufficiency of the anastomosis gave rise to the development of a false aneurysm. The aneurysm was resected and the anastomosis was reconstructed in parallel extracorporal circulation with femoral cannulation in order to prevent ischemic lesions of the spinal cord and the visceral organs. The patient who works as a circus acrobat, made a successful recovery.

Adult↗