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Biomedical subjects

G Fehér

Publications and source records attributed to G Fehér.

At least 19 recordsLinked to original sources
PubMed1999

[Renal gravel formation inducing renal insufficiency as a side-effect of ceftriaxon].

Ceftriaxon is a third-generation cephalosporin with a wide and powerful spectrum of antimicrobal activity. It is often used in pediatrics. The authors draw the attention to the side-effect of the medicament, which might cause renal gravel-formation. They report a case of a 9-years old boy, who suffered from ceftriaxone-associated cholelithiasis and hephrolithiasis, which induced anuria and uraemia.

Accidents, Traffic↗
PubMed1997

Effects of hypoxia and hypercapnia on capillary flow velocity in the rat cerebral cortex.

The velocity of red blood cells (RBC) in individual capillaries of the rat cerebral cortex was assessed using direct, intravital video microscopy under normal conditions and during systemic hypoxia or hypercapnia. The movement of RBC in capillaries within 50-microm depth of the parietal cortex was visualized with the aid of fluorescent labeling of RBC in a closed cranial window preparation in pentobarbital-anesthetized, artificially ventilated adult rats. Hypoxia was produced by lowering the concentration of oxygen in the inspired gas from 30 to 15% for 5 min. Hypercapnia was achieved by increasing the inspired CO2 concentration (FiCO2) from 0 to 5% and then to 10% for 5 min at each level. The mean arterial pressure was maintained constant during both maneuvers. Under control conditions, fast and heterogeneous RBC flow in multioriented, tortuous capillaries was observed. During hypoxia, RBC velocity increased from 0.61 +/- 0.06 to 0.82 +/- 0.10 mm/sec (35% change). During hypercapnia, RBC velocity increased from 0.73 +/- 0.05 to 1.07 +/- 0. 11 mm/sec (46% change) at 5% CO2 and to 1.19 +/- 0.11 mm/sec (63% change) at 10% CO2. Corresponding changes in regional blood flow as assessed by laser-Doppler flowmetry during hypercapnia were 69 +/- 7 and 128 +/- 21%, respectively. The RBC velocity increased in almost all capillaries during hypoxia and during moderate hypercapnia. However, a substantial number of capillaries showed no change or a small decrease in RBC velocity during severe hypercapnia. A significant negative correlation between the velocity change at 10% CO2 and the normocapnic resting velocity was found in a group of capillaries isolated by cluster analysis. These results suggest that the dominant component of cerebral hyperemic response to hypoxia and to moderate hypercapnia is an increase in capillary RBC flow velocity. A more complex change in the velocity distribution occurs during severe hypercapnia and results in increased homogeneity of RBC perfusion in the cerebrocortical capillary network.

Animals↗
PubMed1996

Postnatal remodeling of the leptomeningeal vascular network as assessed by intravital fluorescence video-microscopy in the rat.

An intriguing characteristic of the ontogenic development of the cerebral vasculature is the rapid differentiation of the neonatal leptomeningeal vascular plexus into the mature, adult network form. The physiological and cellular mechanisms of this cerebrovascular remodeling process are unclear. The objective of this work was to determine and correlate changes in vascular density, network pattern and flow velocity in leptomeningeal microvessels of the rat during postnatal development in vivo. To this end, microvascular diameter, segment length, and vascular density of reconstructed leptomeningeal networks were measured from video-recordings of the microcirculation visualized through a cranial window in 0-15-day-old Sprague-Dawley rats. The velocity of erythrocytes in the microvessels was measured by frame to frame tracking of fluorescently labeled red blood cells. We found that surface vascular density (total vessel length per area), node density and segment density (object per area) decreased significantly by the second week after birth. Anastomosing vascular polygons, characteristic to newborn networks, became less numerous and larger in diameter during the postnatal 2-week period, indicating progressive rarefaction of the networks. Vessel diameter and red cell velocity showed transient increases at 1.5 weeks. The velocity/diameter ratio (V/D), an index of wall shear rate, increased by the age of 1.5 weeks and remained unchanged afterwards. There was a negative correlation between V/D and diameter at 1 week; this relationship was reversed to a positive correlation at 2 weeks. We conclude that postnatal remodeling of the leptomeningeal vascular network is associated with rarefaction and an adaptation of vessel caliber to wall shear rate. These changes may contribute to arterio-venous differentiation and redistribution of blood flow from the superficial to the intracortical vasculature in the developing brain.

Animals↗
PubMed1995

Video microscopy of cerebrocortical capillary flow: response to hypotension and intracranial hypertension.

Although autoregulation of cerebral blood flow is well established, the response of cerebral capillary circulation to reduced cerebral perfusion pressure (CPP) is unclear. The objective of this study was to determine whether red cell flow velocity in individual capillaries of the cerebral cortex is maintained during acute decreases in CPP. Microcirculation of the superficial parietal cerebral cortex of adult barbiturate-anesthetized artificially ventilated rats was visualized using a new design of closed-perfused cranial window and epifluorescent-intensified video microscopy. Fluorescein-isothiocyanate-labeled red blood cells (FRBC) injected intravenously were used as markers of capillary flow. CPP, defined as mean arterial pressure minus intracranial pressure, was reduced by controlled hemorrhage or by stepwise elevation of local intracranial pressure. The movement of FRBC in the parenchymal capillary network was video recorded at each pressure level, and FRBC velocity in each capillary was measured off-line with use of the dual-window digital cross-correlation technique. FRBC flux in the capillaries was measured by automated cell counting. FRBC velocity at normal perfusion pressure was 1.47 +/- 0.58 (SD) mm/s and changed little in the perfusion pressure range of 70-120 mmHg. The autoregulatory index in this pressure range was 0.0049 mm.s-1.mmHg-1. Opening of previously unperfused capillaries was not observed. FRBC flux correlated with FRBC velocity, but the latter was maintained in a narrower range than FRBC flux, suggesting a decrease in capillary diameter or hematocrit with decreasing perfusion pressure. The results suggest that flow autoregulation is associated with the maintenance of capillary flow velocity and that capillary recruitment does not contribute to flow autoregulation in the rat cerebral cortex.

Animals↗
PubMed1994

Erythrocyte flow heterogeneity in the cerebrocortical capillary network.

The heterogeneity of erythrocyte flow velocity and erythrocyte flux and their dependence on decreased cerebral perfusion pressure were studied in the rat cerebral cortex using intravital video microscopy. With decreased perfusion pressure, both mean and range of erythrocyte flow velocity of individual capillaries was reduced. Both cell velocity and cell flux decreased more in high flow capillaries than in low flow capillaries. The results are compatible with the hypothesis that redistribution of capillary flow during hypotension may help to maintain the perfusion of arterio-venous capillary flow pathways. Although the data are preliminary, they represent the first direct measurements of capillary flow path length and transit time in the capillary network of the cerebral cortex.

Animals↗
PubMed1993

Imaging system for three-dimensional mapping of cerebrocortical capillary networks in vivo.

A personal computer-based image analysis system was developed for the three-dimensional mapping of cerebrocortical capillary networks from intravital video recordings. Capillary circulation in the parietal cortex of anesthetized rats was visualized to 70 microns depth using a closed cranial window preparation and epi-fluorescent, intensified video microscopy. The circulation was video recorded during slow (0.1 micron/frame) scanning of the focal plane (depth of field = 10 microns) through regions of interest. Capillary networks were traced from still video images of several microscope fields recorded at different X, Y, and Z stage coordinates. The length of vessel segments from five networks ranged between 10 and 178 microns and was best approximated by the Gamma distribution. Vessel diameter (2.5 to 8.7 microns) was best fitted by the lognormal distribution. A specific capillary network contained 51 segments and five anastomosing loops with circumferences between 575 and 1226 microns. Velocity of fluorescently labeled red blood cells ranged from 0.77 to 2.22 mm/sec within the capillary loops. The study demonstrates the feasibility of reconstructing capillary networks from intravital video recordings as deep as 70 microns within the cerebral cortex and finds an anastomosing pattern and heterogeneous red blood cell velocity in the capillary network.

Anastomosis, Surgical↗
PubMed1991

[Idiopathic priapism in childhood].

The authors described the operation technique of the spongiocavernosum shunt in connection with a successfully operated patient. In their case the Quackels procedure was applied with minor modifications, since the conservative one wasn't successful. Their patient is perfectly healthy functionally too. The etiologic factors could not be clarified.

Child↗
PubMed1990

The comparative morphology of the muscle tissues and changes in constituents in the pig types.

The authors have revealed the main value characteristics of pork production by testing in five different types of pig the volume of contractile and collagen proteins, that of proteoglycans, the constituents of blood and the enzymes of the blood plasma. The contractile proteins of the muscle tissues basically determine the quality of pork. The same applies to the water retention capacity, colloidal characteristics and glycogen content of meat. The amount of contractile proteins has decreased in the best meat producing types of pig. Parallel with the decrease of white meat, and with the increase in the volume of ham, chop and chuck the contractile protein content of muscles decreased. The scientific fact according to which there is a certain correlation among the changes in the volume of contractile proteins, blood sugar level, blood serum CPK and the intensity of activity of the LDH enzymes promotes the qualifying of live animals and the work of the geneticists aiming at the increasing of the contractile protein content of the muscle tissues of pigs by selection. According to tests carried out by us the primary cause of PSE changes is a decreased volume of contractile proteins. Increased stress sensitivity and all the other factors have but a secondary importance and are all consequential. The decrease in the quantity of contractile proteins or--it is better to put it this way--the lack of the proper amount of such proteins characterizing a fully developed pig's organism is caused by the nowadays usual breeding technologies and can be well explained by those selection activities which aim at a one-sided kind of pork production.

Animals↗
PubMed1989

[Surgical treatment of acute epididymitis].

Epididymotomy was performed besides drug therapy in 61 patients suffering from acute epididymitis. Surgical intervention was indicated if the conservative therapy was not successful or the wall of the scrotum became fixed. Epididymotomy is carried out by longitudinal or multiple incision of the inflamed epididymis and by the drainage of the operative region. Significant advantage of the operation is the rapid recovery and the fact that the development of a not infrequently seen chronic epididymitis can be prevented by it. This not yet widely used method in Hungary is recommended for the treatment of the disease, on the basis of the favourable results of the postexaminations.

Abscess↗
PubMed1988

A new concept in the molecular process of muscle contraction: functional role of phosphorylated amino acids in myosin.

In this report a summary is given of our experiments concerning the in vivo endogenous phosphate (P) content of myosin. It was found that besides the ester type phosphates of myosin there was a considerable amount of N-P type energy-rich phosphoryl groups bond to the basic amino acids of peptide chains. The endogenous P concentration of myosin depends on the source of the preparation. The concentration of P is much higher in myosin preparations of well-trained animals and human subjects compared to those found in the control muscles. As the P binding sites of fresh purified myosin are only partially saturated, the preparations can incorporate P up to a definite saturation only. The phosphorylating ability of myosins disappears after prolonged storage as a consequence of an alteration in structure of the myosin molecule. The P groups are moving inside the myosin molecule. It is supposed that the inorganic P release promoted by actin is connected with the thin filament movements towards the centre of the sarcomere, furthermore P replenishment, P linking and movement involve N3-trimethyl-lysine, 3-methylhistidine, P-Arg and two conformers of P-His. The two net negative charges of P group form electric monopoles of a minor battery (myosin head). They help to force generation at head rotation (90 degrees-45 degrees angle) and produce free energy changes that can be calculated from the number of N-P bonds.

Amino Acids↗