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Biomedical subjects

P Bálint

Publications and source records attributed to P Bálint.

At least 19 recordsLinked to original sources
PubMed1995

Ultrasound-guided aspiration in suspected sepsis of resection arthroplasty of the hip joint.

The authors described 17 patients who had had resection arthroplasty of the hip and who were suspected of having an infection. The resection arthroplasties had been performed for previous infection. All the patients were studied by ultrasonography to detect effusion in the pseudoarticular space. Thirteen of the 17 patients were found to have an effusion by ultrasonography. Fluid was obtained in 9 of the 13 patients by ultrasonographic-guided aspiration. The mean aspirated volume was 3 ml (range 1-25 ml). Five of the 9 aspirates proved to be septic. The echopattern in all but one of those five with sepsis was nonechofree. Of four other patients in whom it was not possible to aspirate fluid lavage of the pseudoarticular space one yielded a positive culture. The role of ultrasonography in the diagnosis and management of patients who have undergone resection arthroplasty of the hip and who are suspected of having an infected pseudoarticular space is discussed.

Aged↗
PubMed1992

Nocturnal pain correlates with effusions in diseased hips.

Thirty-five of 50 patients with different hip joint disease had sonographic evidence of joint effusion. Arthrocentesis confirmed effusions in 30 of these 35 patients. Thirty-two of the 35 patients had nocturnal pain. Both nocturnal pain and sonographic evidence of effusion decreased after aspiration (15 patients) and aspiration and injection of corticosteroids (15 patients). In a further group of 61 patients who subsequently had Charnley arthroplasties, 35 had positive sonograms before operation. Of these, 25 had effusions confirmed at operation, the remaining 10 having synovitis and capsule thickening. Again a correlation was found with nocturnal pain. The sensitivity of sonography in detecting hip joint effusion was 92% with a specificity of 70%. Nocturnal pain had a lower sensitivity, 85%, but higher specificity, 94%.

Adrenal Cortex Hormones↗
PubMed1985

Effect of imidazole and indomethacin on hemodynamics of the obstructed canine kidney.

In the anesthetized dog renal blood flow (RBF) and its intrarenal distribution were investigated by the radioactive microsphere technique 24 hr after bilateral (BUL) and unilateral (UUL) ureteral ligation. In the control series indomethacin (IM) led to a decrease in RBF with outward shifting of zonal perfusions; imidazole (IA) did not cause significant changes in renal hemodynamics. In the BUL series there was a sharp drop in RBF with a proportional decrease in outer (OC) and inner (IC) cortical perfusion; IM treatment resulted in a further decrease in overall and zonal perfusions. IA, a selective inhibitor of thromboxane synthetase, relieved IC vasoconstriction. In the ligated kidney of the UUL preparations decrease in RBF was due to OC vasoconstriction, while IC perfusion equalled controls. IM led to an overall vasoconstriction in all cortical layers; IA did not influence either total RBF or its distribution. It was concluded that BUL "unmasked" TXA2 production in the IC layers, while IM treatment, by inhibiting the production of PGE2, PGI2, and TXA2, resulted in an overall vasoconstriction both in controls and the BUL and UUL preparations.

Animals↗
PubMed1985

Renal haemodynamics in chronic unilateral ureteral obstruction in the dog.

Renal blood flow and its intrarenal distribution have been investigated after 7 and 14 days of unilateral ureteral ligation (UUL) in both the ligated and the undisturbed kidney by the radioactive microsphere technique without opening the abdomen and the obstructed ureter. It has been found that renal blood flow (RBF) decreased to about 26% after 7 days and to about 10% after 14 days of normal controls in the obstructed kidney. There was a pronounced inward shifting of the much reduced RBF. The slight increase in RBF of the undisturbed kidney was not significant and did not compensate the pronounced decrease of RBF in the obstructed one.

Animals↗
PubMed1981

Reliability of the measurement of intrarenal haemodynamics in the dog, as determined by the radioactive microsphere technique.

In the anaesthetized dog total renal blood flow (RBF) and its intrarenal distribution were investigated by the radioactive microsphere technique under control conditions and after various experimental interventions. (i) In five control series performed within the last four years, there was a small but significant scatter in total RBF, due entirely to changes in inner cortical (IC) perfusion, while outer cortical (OC) perfusion proved to be constant. (ii) Repeated measurements in the same dog, performed after 1 h interval revealed constancy of total RBF with some inward shifting in cortical perfusion. (iii) Surgical intervention or manipulation of the kidney did not alter total RBF but led to an increase in IC, compensated by a decrease in OC perfusion (iv) The possible role of local intrarenal hormones (angiotensin and prostaglandin) in the above changes is discussed.

Animals↗
PubMed1980

Prostaglandin-dependent changes in renal haemodynamics and excretory patterns before and after release of 24 hours bilateral ureteral ligation.

In the anesthetized dog during and 1 hr after release of 24 h bilateral ureteral ligation (BUL) renal blood flow (RBF) decreased to 44 and 51%, respectively, as compared with normal controls. After release there was a marked increase in sodium and water excretion, so-called postobstructive diuresis (POD), in spite of a considerably reduced glomerular filtration rate (GFR). Radioactive microspheres revealed a proportionate decrease of perfusion in all cortical layers before, and inward shifting after release of the ligature. Inhibition of intrarenal prostaglandin (PF) synthesis by indomethacin (IM) before release of BUL led to a further pronounced decrease in RBF both in the pre- and postrelease phases, characterized by a proportionate decrease of perfusion in all cortical layers. Fractional excretion of sodium and water remained moderately increased in spite of a very pronounced hypofiltration. It is assumed that, in contrast to PG-dependent changes in renal haemodynamics due to BUL, enhanced sodium and water excretion (POD) are due to a PG-independent mechanism, most probably to some natriuretic substance produced and/or accumulated during 24 h complete retention.

Animals↗
PubMed1979

Intrarenal haemodynamics in postobstructive diuresis in the dog.

Intrarenal haemodynamics were investigated in the dog prior to and after relief of 24 hr bilateral ureteral ligation (BUL), by the radioactive microsphere technique. Prior to release of 24 hr BUL there was an about 50% reduction in total blood flow (RBR), with a nearly proprotional decrease in the perfusion of the four cortical layers. Following release of the obstruction, total renal and outer cortical (zones 1 and 2) blood flow remained diminished, while perfusion of the inner (juxtamedullary) layers (zones 3 and 4) increased as compared to its prerelease values and equalled controls. Glomerular filtration rate (GFR) amounted to about 27% of controls in the postrelease phase. A marked increase in absolute and fractional sodium water excretion was observed after release of 24 hr BUL, as contrasted to normal controls and dogs after 24 hr unilateral ureteral ligation (UUL). This state, designated as postopstructive diuresis, might be explained by redistribution of intrarenal blood flow towards the juxtamedullary zones, and by a powerful natriuretic substance accumulated during complete obstruction.

Animals↗
PubMed1979

Intrarenal haemodynamics in uranyl nitrate-induced acute renal failure.

Intrarenal haemodynamics were investigated in the dog at various intervals after the iv. injection of 10 mg/kg uranyl nitrate (UN). Renal blood flow (RBF), as determined by measuring the renal venous effluent and by radioactive microspheres, decreased by about 23% at 6 hr after UN administration, as compared to normal controls, then rose and reached controls at 24 to 48 hr; subsequently, RBF increased and surpassed controls by about 36% at 96 hr. Thus, the early phase (6 hr) and the late phase (96 hr) of uranyl nitrate-induced acute renal failure (UNARF) were characterized by an increase and by a decrease, respectively, in overall renal vascular resistance. Glomerular filtration rate (GFR) diminished to about 37% of controls at 6 hr, with no change in urinary output (V). In the following hours, however, GFR and V fell quickly and reached practically zero at 12 to 24 hr. Approximate calculations revealed a predominantly preglomerular vasoconstriction in the early phase and post-glomerular vasodilatation in the late phase. Radioactive microspheres showed a nearly proportionate decrease in perfusion of all cortical layers in the early phase (6 hr); in the late phase (96 hr), however, blood flow to the outermost layer remained unaltered, while perfusion of the inner cortical and juxtamedullary layers increased significantly.

Acute Kidney Injury↗
PubMed1978

Functional changes in compensatory hypertrophy of the canine kidney after uninephrectomy.

Kidney weight and renal functional parameters were investigated in dogs 7 to 68 days after uninephrectomy. Average enlargement of the remaining kidney amounted to 35.1%. Renal blood flow (RBF) and glomerular filtration rate (GFR) calculated per 100 g actual kidney weight were identical in the non-hypertrophied controls and in the hypertrophied kidneys, i.e. structural and functional changes were strictly proportional. Calculation of mean nephron parameters (MNRBF and MNGFR) revealed an increase of about 43% in the hypertrophied kidneys, with an appropriate decrease in nephronal vascular resistance. The hypertrophied kidney showed an enhanced responsiveness to mannitol; increased MNRBF under stop flow conditions was due to a pronounced dilatation of the postglomerular vessels. There was no difference between control and hypertrophied kidneys in cortical zonal blood flow, as investigated by the labelled microsphere technique. Increase in parallel-connected cortical resistances towards the inner (juxtamedullary) zones was pronounced.

Adaptation, Physiological↗
PubMed1978

Renal haemodynamics prior to and after release of 24 hr unilateral ureteral ligation in the dog.

Renal functional parameters were investigated prior to and following release of 24 hr unilateral ureteral ligation (UUL). In the obstructd kidney renal blood flow (RBF) and glomerular filtration rate (GFR) decreased to about 50% and 14%, respectively, as compared to normal controls. Relief of the obstruction did not cause any change in renal haemodynamic parameters in the ligated kidney. Urine flow rate and urine osmolality in the previously obstructed kidney were decreased, the excreted fraction of filtered sodium increased as compared to the undisturbed kidney. The excretory lesion of the obstructed kidney is due to arteriolar, presumably preglomerular, vasoconstriction. Radioactive microspheres revealed that the decrease of RBF in the obstructed kidney was caused by diminished perfusion of the outer cortical zones, while blood flow to the inner cortical zones was unaltered. Fractional flow to the outer cortex was decreased, that to the inner cortex increased as compared with normal controls. In the undisturbed kidney there was a shifting of flow from the outer towards the inner cortex, while total blood flow remained unaltered.

Animals↗
PubMed1978

Pathomechanism of postischaemic renal failure in the dog induced by temporary occlusion of the renal artery.

Intrarenal haemodynamics were investigated in previously uninephrectomized dogs, immediately after release and on the third day following two hours clamping of the renal artery. Postischaemic renal failure (PIRF) was considered moderate or severe, if three days after clamping plasma NPN values were under or over 150 mg/dl, respectively. Renal blood flow (RBF) as determined by measuring the renal venous effluent and by radioactive microspheres did not differ significantly from controls either immediately after release, or three days following arterial occlusion. Glomerular filtration rate (GFR) was, however, severely depressed in all postischaemic kidneys. An increase in preglomerular and a decrease in postglomerular resistance was assumed, resulting in unaltered total vascular resistance and a sharp drop in glomerular capillary pressure. Radioactive microspheres revealed a shifting of intrarenal blood flow from the superficial cortex towards the deeper (juxtamedullary) cortical layers. Fractional flow to the outer cortex was decreased, that to the inner cortex increased, as compared with uninephrectomized controls.

Acute Kidney Injury↗
PubMed1976

Renal haemodynamics in mercuric chloride-poisoned dogs.

Intrarenal haemodynamics and glomerular dynamics have been investigated in dogs with mercuric chloride-induced acute renal failure. The early phase (12 and 24 hr after the intravenous injection of 2 mg/kg HgCl2) is characterized by some decrease in renal bloodflow, due to afferent (preglomerular) vasoconstriction, while in the later phase (48 and 72 hr after poisoning a pronounced increase in RBF due to efferent (postglomerular) vasodilatation supervenes. Urinary volumes amounts to normal in the early phase, followed by oligo-anuria in the 48 and 72 hr groups. Extraction ratio of inulin, i.e. the filtration fraction and, consequently, glomerular filtration rate show a progessive decline and trend towards zero in the 72 hr group. The pronounced decrease in glomerular capillary pressure is due to both absolute and relative increase and decrease in afferent and efferent resistances, repectively. The progressive fall in effective filtration pressure is brought about by the decrease of glomerular capillary pressure, combined with increased colloid osmotic pressure due to haemoconcentration. Total and segmental intrarenal vascular resistances are reduced by hyperosmotic mannitol infusions resulting in renal hyperaemia. Glomerular filtration rate is, however, not influenced by mannitol and effective filtration pressure remains unaltered. Osmotic diuresis ensues in the early phase but urinary output is not restored in the late, i.e. oligo-anuric, phase.

Acute Kidney Injury↗
PubMed1975

Renal function following branch-artery ligation in the canine kidney.

Viable kidney mass has been reduced in dogs by branch-artery ligation combined with uninephrectomy. 1. When viable kidney remnants amount to about 1/4 of the original kidney mass dogs survive in apparent good health with moderate azotaemia; with 1/8 to 1/10 kidney remnants azotaemia is progressive and uraemic death supervenes within some days. 2. Reduction of renal blood flow and of glomerular filtration rate to about one-fourth of their respective control values seems to be compatible with survival; with further reduction death ensues. An inverse and linear relationship between NPN and GFR on a log-log basis has been found. 3. Mean nephron blood flow is equally enhanced in both the more and the less severely infarcted kidneys. On the other hand, mean nephron glomerular filtration is increased when about one half of the kidney is viable, but decreased with more extensive infarction. 4. Mean nephron vascular resistance is diminished; considering the pronounced decrease in Ein, i.e. filtration fraction, predominance of postglomerular vasodilatation is assumed. The formation of non-filtering, actively perfused nephrons is taken into consideration.

Animals↗
PubMed1975

Quantitative aspects of autoregulation in the canine kidney.

Autoregulatory changes in series connected vascular resistances were studied in the normal canine kidney. Two sets of observations were made: a) ureter pressure was increased by ureteral obstruction and b) arterial pressure was decreased by aortic clamping. It was assumed that in both experimental panels the decrement in intrarenal resistance is solely due to dilatation of the preglomerular vessels. Proximal tubular pressure is thought to equal deep venous (wedged) pressure under free flow and ureteral pressure under stop flow conditions. Calculation of the glomerular filtration coefficient yielded the same value in both sets of observations: k similar to 2 ml/min/100 g per 1 mm Hg effective filtration pressure. Glomerular capillary pressure rises steeply and roughly parallels arterial pressue below the autoregulatory range (about 40-80 mm Hg), whereas in the autoregulatory range (about 90-150 mm Hg) its value is stabilized at 74 plus or minus 1 (S.E.)mm Hg. Afferent resistance is negligible in the hypotensive range and increases progressively in the normotensive range. Changes in efferent and venular resistance are insignificant in the whole pressure range considered, i.e. 40 to 150 mm Hg.

Animals↗
PubMed1975

Autoregulation of renal circulation in mannitol-loaded dogs.

Renal haemodynamics and autoregulatory behaviour of the renal vessels have been investigated in mannitol-loaded dogs both for free-flow and for stop-flow conditions. Arterial pressure has been decreased by aortic clamping. For free-flow conditions: (i) relative constancy of RBF and GFR are well preserved in the entire autoregulatory pressure range, i.e., over 80 mm Hg arterial pressure; (ii) decreased GFR is due to enchanced intratubular pressure; (iii) autoregulation is connected with a sharp rise in afferent resistance, accompained by a passive decrease in efferent resistance. For stop-flow conditions: (i) enchancement of total vascular resistance is due to an increase in the passive resistance of the postglomerular vessels; (ii) afferent resistance drops to minimal values as casused by the relaxation of the corresponding arterioles; (iii) autoregualation is abolished: pressure-flow relations are linear over the entire arterial pressure range examined.

Animals↗
PubMed1975

Renal haemodynamics in dogs with dehydration azotaemia.

Intrarenal pressure gradients and glomerular dynamics have been investigated in dogs with severe dehydration elicited by pyloric ligation. 1. Because of the proportionate decrease in arterial pressure and renal blood flow, calculated total renal vascular resistance was found unaltered as compared with normohydrated controls. The slight changes in series connected intrarenal resistances were not significant. 2. Net hydrostatic pressure across the glomerular membrane, i.e. glomerular capillary minus proximal tubular pressure was slightly diminished. The pronounced fall in effective filtration pressure was due to the considerable increase in colloid osmotic pressure of the plasma proteins. 3. Reduced arterial pressure due to clamping of the aorta did not diminish vascular resistance. Thus, the autoregulatory capacity of renal circulation seems to be lost in dehydrated animals. 4. No correlation was found between plasma NPN values on the one hand and RBF and GFR on the other. Azotaemia seemed to be due to retention and enhanced rediffusion of urea and increased katabolism of tissue proteins. 5. Reduced urine flow caused by dehydration was restored by isosmotic saline or hyperosmotic mannitol infusions. Both agents act by decreasing intrarenal vascular resistance and by diminishing the increased colloid osmotic pressure.

Animals↗