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Biomedical subjects

F Robicsek

Publications and source records attributed to F Robicsek.

At least 55 records · Page 3Linked to original sources
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

The influence of sizing on the dynamic function of the free-hand implanted porcine aortic homograft: an in vitro study.

BACKGROUND AND AIMS OF THE STUDY: The influence of sizing on the function of a porcine aortic valve after its implantation using the free-hand technique in the subcoronary position was investigated. METHODS: Dynamic function and leaflet configuration of the valve (n = 16) were first analyzed in its natural aortic root in a left heart simulator at 120/80 mmHg pressure and 4 l/min cardiac output. The valve was then implanted in the recipient porcine aortic root and re-studied. Three groups were investigated: group I (n = 4) comprised of 1-2 mm smaller donor aortic valve than the recipient; group II (n = 8) 3-4 mm smaller; and group III (n = 4) 5-7 mm smaller. Orifice area (OA), systolic and diastolic configurations of the leaflets, pattern and timing of leaflet opening and closure, commissural movement, pressure gradient and valvular regurgitation were analyzed. RESULTS: In the intact donor aortic root, average expansion of the aorta at the commissures, for a pressure change from 0 to 80 mmHg, was about 42%. This was reduced significantly in all assemblies. Group I showed a 34% reduction in OA, and excessive leaflet bending; there was no aortic insufficiency (AI) or pressure gradient across the valve. In group III there was a lesser reduction in OA and reduced leaflet bending, but two of four valves had AI. In group II, the reduction in OA was only 13%, there was less leaflet bending, and no AI. CONCLUSIONS: The donor valve 3-4 mm smaller than the recipient seems an optimal match. The current practice of using the same size donor as recipient may be responsible for excessive leaflet bending and may be implicated in early deterioration of the homograft.

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

Cardiomyocyte apoptosis in acute and chronic conditions.

Myocytes can die by necrosis or by apoptosis and the characteristics of both kinds of cell death are so typical that a differentiation can be made by histological and molecular-biological methods using electron microscopy, dUTP labeling with fluorescence or peroxidase staining (TUNEL) and the DNA laddering method. However, the problem of quantification of apoptotic cells has not been completely solved because of lack of standardization as well as uncritical use and interpretation of the TUNEL method. Equally, quantification of apoptotic cells is not optimal until now because of three reasons: methodological (overinterpretation of results, no differentiation between myocytes and non-myocytes), experimental (global or regional acute ischemia, chronic conditions such as heart failure or hibernating myocardium), and interpretation (unknown time period for the completion of apoptosis). This problem is reflected in the large differences in incidence of apoptosis reported. Our own data show that in dog myocardium made globally ischemic for 90 min, 8% of the myocytes showed a positive staining for apoptosis (TUNEL method) after 6 h of reperfusion. Despite these results the question of reperfusion injury and the influence of apoptosis still remains open, because it can not be excluded until now that the apoptotic process is initiated during the ischemic period. Studies in hibernating myocardium and chronic heart failure show a similar situation, because of a wide variation of numbers of apoptotic cells and the limited possibility to investigate human tissue. There is no doubt that apoptosis plays an important role in chronic pathophysiological situations such as heart failure and hibernating myocardium but the importance of apoptosis in the acute situation of ischemia/reperfusion still has to be clarified.

Animals↗
PubMed1998

Application of cyanoacrylate adhesive (Krazy Glue) in critical cardiac injuries.

BACKGROUND AND AIMS OF THE STUDY: Although small lacerations of the myocardium may be repaired easily using conventional methods, larger tears or ruptures, especially if they occur in infarcted myocardial tissue, may create formidable technical challenges. Described is a method for applying sutureless pericardial patches for control of hemorrhage. METHODS: A sutureless pericardial patch was glued to the myocardium with commercially available household cyanoacrylate (Krazy Glue) in seven patients. RESULTS: No patient in this series developed any evidence of mediastinal infection as a result of this technique. Six patients were discharged home without any long-term sequelae noted. One patient developed reinfarction and died of arrhythmia two weeks following surgery. Autopsy revealed that the laceration had healed and that the patch was closely adherent. Bacteriology studies revealed that different brands of cyanoacrylate are not only bacterium-free but also exhibit a bactericidal effect. CONCLUSIONS: Sutureless pericardial patches fastened to the myocardium with cyanoacrylate glue to control hemorrhage under critical situations were easy to apply, safe and effective in this series of patients.

Adhesives↗
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↗
PubMed1997

"Above-under" exposure of the first rib: a modified approach for the treatment of thoracic outlet syndrome.

To provide both adequate exposure of the structures of the thoracic inlet and make removal of the antero-medial portion of the first rib easier, the authors recommend that the customarily used anterior supraclavicular approach for the treatment of thoracic outlet syndromes should be modified by performing through the same incision an additional transmuscular exposure of the first rib below the clavicle to facilitate its removal.

Humans↗
PubMed1997

Transected thoracic aorta: age-specific differences in incidence and possible reasons.

The objective of this study was to determine the incidence of aortic transaction in relation to age, and to examine possible reasons for the observed differences. Data from the North Carolina Medical Database over a 7-year period were examined for the total number of motor vehicle accident victims and for the subset with aortic rupture, based on age at presentation. Data were then divided into 10-year intervals and the differences analyzed using chi-square analysis. Differences among various age groups were statistically significant (P = 0.0001). The highest rate was in the 21-30-year-old age group and average incidence for all ages was 0.7%. High incidence of aortic transaction in the 21-30-year-old group may be due to an increase in high-risk behaviors in such persons, to an improved survival compared with other age ranges, or to an inherent susceptibility of the aorta at this stage of life. These data have important implications for the diagnosis and treatment of aortic transaction and should be taken into account when developing practice guidelines for its management.

Accidents, Traffic↗
PubMed1997

Prevention of secondary hemorrhage in Hanuman syndrome (open mediastinal drainage).

The author describes three common mechanisms of hemorrhage which may occur following "open management" of sterno-mediastinitis after cardiac surgery. Recommendations for prevention and treatment are presented including the suggestion that whenever sterno-mediastinitis is treated by the open method in the initial stage of management, the patient should be paralyzed and maintained on artificial respiration.

Cardiac Surgical Procedures↗