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G Capasso

Publications and source records attributed to G Capasso.

At least 91 records · Page 5Linked to original sources
PubMed1987

Renal bicarbonate reabsorption in the rat. II. Distal tubule load dependence and effect of hypokalemia.

We studied two groups of rats acutely loaded with bicarbonate, control rats on a standard diet and rats kept on a K-free diet for 3 wk. Compared with controls, K-depleted rats had reduced fractional excretion of bicarbonate despite their elevated filtered bicarbonate load. Distal bicarbonate reabsorption increased in K-depleted rats. In the presence of almost identical early distal bicarbonate loads (481 +/- 40 pmol/min in controls and 444 +/- 50 pmol/min in K depletion), distal bicarbonate reabsorption was significantly enhanced in K depletion (247 +/- 17 pmol/min) as compared with controls (179 +/- 18 pmol/min). These values are significantly different from each other, and both are severalfold higher than bicarbonate reabsorption in nonloaded conditions. In conclusion, distal bicarbonate reabsorption is load dependent, and distal bicarbonate reabsorption is stimulated in K depletion.

Animals↗
PubMed1987

A new method for the radiographic evaluation of spondylolisthesis.

The methods of evaluating the degree of spondylolisthesis in present use are based solely on morphological criteria related to the alignment of the profile of the vertebral bodies. The authors maintain that these methods often result in errors due to false positives or false negatives. To remedy this they propose a method of qualitative and quantitative evaluation based on the alignment of the barycentres of the vertebral bodies, with a correction to take account of their different angles of inclination. If this is expressed as a percentage of body width, the degree of slippage can be exactly quantified in any part of the spine and also in the case of retrospondylolisthesis. It eliminates all the inaccuracies inherent in present methods of evaluation.

Cervical Vertebrae↗
PubMed1987

Intraerythrocytic cation metabolism in children with uremia undergoing hemodialysis.

Erythrocytes from children with uremia who are undergoing hemodialysis show normal maximal velocity of NA+-Li+ countertransport and Na+/K+/Cl- cotransport and normal intracellular sodium content. These aspects of intracellular sodium metabolism are not affected by dialysis. The normality of intraerythrocytic cation metabolism in children with uremia is associated with anemia, increased systolic and diastolic blood pressure, reduced body mass index, retention of solutes (urea, creatinine, potassium), a low triiodothyronine and thyroxine syndrome, and high parathormone levels.

Adolescent↗
PubMed1987

Mechanical behaviour of two types of vertebral distractors submitted to compression-flexion tests.

The authors submitted two different types of vertebral distractors to compression-flexion tests in order to assess their biomechanical behaviour. By using special devices it was possible to simulate the load to which these methods are subjected after insertion into a tract of the spinal column. The aim was to determine the mechanical resistance and in particular, the yielding load, namely the amount of load beyond which the distractor is deformed, thus losing its initial characteristics. Our study showed that these methods of distraction possess the qualities of stability, strength and elasticity.

Biomechanical Phenomena↗
PubMed1986

Amphotericin B and amphotericin B methylester: effect on brush border membrane permeability.

In order to explain the nephrotoxicity of polyene antibiotics such as Amphotericin B (AM), an effect on the tubule membrane permeability has been postulated. However, studies on the action of AM have been complicated by the use of sodium deoxycholate (DOC), a membrane dissociating detergent as a solvent. Recently, a derivative, the methylester aspartate salt of Amphotericin B (AME) has been synthesized, which is highly water soluble in the absence of organic solvents. We have tested the action of AM, DOC, and AME on the sodium permeability of brush border (BBM) vesicles isolated from rat kidney cortex. It was found that both AM and AME increased the 22Na uptake as measured by a rapid filtration technique. However, a large fraction of the AM action was due to the effect of DOC on the BBM sodium permeability. We also investigated the time- and dose-dependent action of AME on 22Na and 3H-D-mannitol efflux from BBM vesicles. After 15 sec of exposure, efflux from 22Na-preloaded vesicles was unchanged in the presence of 1 microgram AME/mg protein compared to control vesicles. With 10, 50, and 100 micrograms AME/mg protein, the efflux increased 16, 25, and 35% respectively; 260 micrograms AME/mg protein did not elicit a further increment in the 22Na efflux. In the same membrane vesicles 3H-D-mannitol efflux did not change. After preincubation of the membranes for 60 min with different concentrations of AME, the 15 sec 22Na efflux increased 26% in the presence of 1 microgram/mg protein AME with no change in the 3H-D-mannitol efflux.(ABSTRACT TRUNCATED AT 250 WORDS)

Amphotericin B↗
PubMed1986

Effects of hypothyroidism and hypoparathyroidism on rat myocardium: mechanical and electrical alterations.

The mechanical and electrical effects of hypoparathyroidism (Px), hypothyroidism (Tx), and hypothyroidism combined with hypoparathyroidism (TPx) were investigated by comparing simultaneously recorded transmembrane action potentials and isometric and isotonic contractions recorded from the myocardium. Left ventricular papillary muscles from male Wistar rats were studied electrically and mechanically in a muscle bath at 30 degree C, stimulated at 0.1 Hz and external calcium = 2.4 mM. No significant difference was found between control (C), Px, Tx, and TPx preparations with regard to resting tension and developed tension. However, time to peak tension, time to one half relaxation and time to peak shortening were significantly increased in preparations from animals that were Px, Tx, and TPx as compared with age-matched controls. Maximum velocities of shortening (Vs) and relengthening (Vr) at all relative loads studied were significantly depressed in Px preparations when compared with those of C muscles. A greater depression was found in the Tx muscle and still greater depression of these indices was noted in TPx muscles. No significant difference was found between C, Px, Tx, and TPx action potential with regard to resting membrane potential (RMP), action potential amplitude (AMP), overshoot (OS), or maximum rate of rise of the upstroke (Vmax).(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1986

Renal bicarbonate reabsorption in the rat. I. Effects of hypokalemia and carbonic anhydrase.

Free-flow micropuncture studies were carried out on superficial rat proximal and distal tubules to assess the participation of different nephron segments in bicarbonate transport. Particular emphasis was placed on the role of the distal tubule, and micro-calorimetric methods used to quantitate bicarbonate reabsorption. Experiments were carried out in control conditions, during dietary potassium withdrawal, and after acute intravenous infusions of carbonic anhydrase. We observed highly significant net bicarbonate reabsorption in normal acid-base conditions as evidenced by the maintenance of significant bicarbonate concentration gradients in the presence of vigorous fluid absorption. Distal bicarbonate reabsorption persisted in hypokalemic alkalosis and even steeper transepithelial concentration gradients of bicarbonate were maintained. Enhancement of net bicarbonate reabsorption followed the acute intravenous administration of carbonic anhydrase but was limited to the nephron segments between the late proximal and early distal tubule. The latter observation is consistent with a disequilibrium pH along the proximal straight tubule (S3 segment), the thick ascending limb of Henle, and/or the early distal tubule.

Absorption↗
PubMed1985

Short term effect of low doses of tri-iodothyronine on proximal tubular membrane Na-K-ATPase and potassium permeability in thyroidectomized rats.

Tri-iodothyronine (T3), even when administered for short time and at low doses, induces a large increase in the isotonic fluid reabsorption (Jv) in proximal tubules of thyroidectomized rats (TX). In order to investigate the role of the Na-K-ATPase in this process, we measured the Na-K-ATPase activity in early proximal convoluted tubules (S1) and proximal straight tubules (S2) microdissected from TX rats and rats treated with low doses of T3 (10 micrograms/kg body wt), either for 3 days (TX + 3T3) or for 7 days (TX + 7T3). In both segments no changes in Na-K-ATPase activity were found in TX + 3T3 rats versus TX rats, while an increase was registered in TX + 7T3 rats. Using micropuncture techniques, Jv measured on the same tubular segments increased by 68% in TX + 3T3 rats versus TX. Thus, no correlation between Jv and Na-K-ATPase activity measured in vitro could be detected after short term treatment of TX rats with T3. Na-K-ATPase activity in vivo is also regulated by the potassium permeability of the membrane, which might be altered by tri-iodothyronine. This hypothesis was tested by perfusing intraluminally and peritubularly proximal tubules of TX rats with the K ionophore, valinomycin (1 microgram/ml). In the dual perfusion experiments valinomycin elicited 40% of the action induced on Jv by 3 days treatment with T3. On the other hand, no further increase in Jv was recorded when valinomycin was applied in TX rats pretreated with T3.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗
PubMed1985

Regulation of volume reabsorption by thyroid hormones in the proximal tubule of rat: minor role of luminal sodium permeability.

In order to investigate whether changes in luminal membrane sodium permeability can explain the increase in isotonic fluid reabsorption (Jv) found in proximal tubules of thyroidectomized rats (TX) treated with tri-iodothyronine (T3), experiments were carried out on TX rats and TX rats treated for 3 days (TX + T3) with physiological doses (10 micrograms/kg body wt) of T3. Two sets of experiments were performed: 1) in vivo, using the micropuncture technique for the measurements of Jv; 2) in vitro, using isolated brush border membrane vesicles for the direct measurement of Na+ permeability. In micropuncture studies a 65% increase in Jv of TX rats was observed after treatment with T3. Luminal perfusion of proximal tubules of TX rats with Amphotericin B (10 micrograms/ml), to increase luminal sodium permeability, enhanced Jv only by 15%. Brush border membrane vesicles isolated from TX and TX + T3 rats showed the same sodium permeability in uptake or efflux experiments. These results were confirmed by the fact that sodium gradient dependent histidine transport into brush border membrane vesicles did not change after T3 treatment. Finally, measuring the amiloride sensitive sodium uptake, it was also found that Na+-H+ exchange was also only slightly affected by T3. These micropuncture and vesicle data indicate that the large effect of T3 on the trans-cellular sodium transport and volume reabsorption in the proximal tubule, cannot be explained by an action of T3 on the sodium entry step across the brush border membrane.

Absorption↗
PubMed1983

CAPD + hemoperfusion once a week in the management of children with end-stage renal disease.

With hemoperfusion there is a sharp decline in the solute concentration of the blood compartment, but immediately after HP the concentration of these substances rises to the original level (post-Hp rebound). It may be inferred that the result would be better and the rebound phenomenon less marked if hemoperfusion could be combined with a continuous dialysis system such as CAPD. The study was performed in 3 children of our CAPD program. All patients were dialysed with 5 daily exchange each of one liter. The patients underwent at 2-hours hemoperfusion with a charcoal column (Gambro Adsorba 150 c) once a week. The data obtained with this form of treatment are indicative for a: significant increase of weekly clearance for uric acid and creatinine. low urea generation rate far 1-3 days after HP. low post-Hp rebound and reduced platelet count but not platelet activation.

Child↗
PubMed1982

Metabolic aspects of continuous ambulatory peritoneal dialysis with reference to energy-protein input and growth.

Glucose utilization from the dialysate of up to 140 g/day was found during CAPD therapy in 5 children on short and long term studies. The energy input via the dialysate was associated with increased insulin secretion as indicated by the daily insulin response calculated from analyzing the area under the insulin curve during 5 daily exchanges of dialysate. After 6 months glucose tolerance was normal with normal values for early and late insulin response as well as for glucose disappearance rate during an intravenous glucose tolerance test. Nitrogen balance on free diets (energy input 100% RDA and protein input 133% RDA) showed that CAPD is an anabolic technique since the balance was positive when measured during 42 days out of 12 months in each child. Growth was normal in one boy and in addition a girl reached her final height; it was unsatisfactory in the other children. It is concluded that CAPD is an anabolic technique which favourably affects many factors associated with growth retardation in children with end stage renal failure and therefore it represents an interesting tool for defining a more rationale approach for research in this field.

Adolescent↗