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Biomedical subjects

C Rosati

Publications and source records attributed to C Rosati.

At least 55 records · Page 3Linked to original sources
PubMed1988

[Na+, K+, Cl-]-cotransport function and dysfunction in different forms of primary hypertension.

We investigated the effect of an increase in cell Na+ content on outward and inward unidirectional fluxes catalyzed by the [Na+, K+, Cl-]-cotransport system in human erythrocytes (incubated in Li-Rb media). Erythrocytes with low Na+ content exhibited an uncoupled K+ efflux. The increase in cell Na+ content resulted in a more marked stimulation of outward Na+, K+ than of inward Li+, Rb+ cotransport fluxes (with stoichiometries not very different from one-to-one). These results suggest that in human erythrocytes and in nonepithelial cells with small but outwardly directed electrochemical Cl- gradients, the [Na+, K+, Cl-]-cotransport system may behave as a "second pump" by using the extra energy supplied by an additional net [K+, Cl-] efflux. The [Na+, K+, Cl-]-cotransport system (of vascular cells and/or noradrenergic endings) may play two different roles in primary hypertension: (a) "defective second pump" in some essential hypertensive patients with decreased cotransport affinity for internal Na+ and (b) "compensatory second pump" in other forms of primary hypertension where abnormalities in the Na+, K+ pump or in other ion transport systems may predispose the cell to a defective extrusion of excess cell Na+ content.

Biological Transport↗
PubMed1988

Sodium transport kinetics in erythrocytes from spontaneously hypertensive rats.

Rat erythrocytes with five different amounts of Na+ content have been prepared by using a new, nondetrimental Na+-loading method (net NaHPO4-influx through the anion carrier). This method allowed the determination of 1) maximal translocation rates and apparent dissociation constants for internal Na+ of the Na+-K+ pump, outward Na+-K+ cotransport, and Na+-Li+ countertransport and 2) rate constants of Na+ leak in erythrocytes from spontaneously hypertensive rats of the Okamoto strain and Wistar-Kyoto normotensive controls aged 2 to 26 weeks. Two major abnormalities were found in erythrocytes from spontaneously hypertensive rats: 1) a decreased cotransport affinity for internal Na+, which was constantly observed from 2 to 26 weeks of age (mean intracellular Na+ content for half-maximal stimulation of outward Na+-K+ cotransport = 33.1 +/- 7.0 [SD] mmol/L cells in spontaneously hypertensive rats vs 16.7 +/- 4.7 mmol/L cells in Wistar-Kyoto rats; p less than 0.001), and 2) a decreased maximal pump rate in adult (15- to 26-week-old) spontaneously hypertensive as compared with that for age-matched Wistar-Kyoto rats (9-37 vs 34-70 mmol/L cells/hr). Therefore, the low cotransport affinity for internal Na+ appears to be a stable, possibly genetic defect of spontaneously hypertensive rats. Conversely, the decreased maximal pump rate may be a secondary event, possibly reflecting the appearance of endogenous pump inhibitors in the plasma of adult spontaneously hypertensive rats.

Age Factors↗
PubMed1987

Microsurgical selective posterior rhizotomy in the dorsal root entry zone for treatment of limb spasticity.

SPR in the DREZ, which was introduced in 1972 by the senior author on the bases of anatomical studies in humans, selectively interrupts the (lateral) nociceptive and the (central) myotatic fibers, while sparing the (medial) lemniscal fibers. In addition it enhances the inhibitory mechanisms of the Lissauer's tract and dorsal horn. The procedure was effective--with a follow-up ranging from 1 to 14 years--in 93% of the paraplegic patients with flexion-adduction postures (50 cases) or severe hyperextension (3 cases) and in 89% of the hemiplegic patients with irreducible flexion of the upper extremity (23 cases) or lower limb (5 cases).

Extremities↗
PubMed1987

[Selective posterior rhizotomy at the posterior radiculomedullary junction in the treatment of hyperspasticity and pain in the lower limbs].

The authors report a series of 53 bedridden patients having harmful spasticity in one (6) or both (47) lower limb(s) and treated with selective posterior rhizotomy (SPR) in the dorsal root entry zone (DREZ). This severe spasticity was associated with irreducible flexion contracture in 49 cases and hyperextension in 3 others. 37 of these patients also had painful manifestations. The method was introduced in 1972 on the basis of anatomical studies of the DREZ in humans which showed a topographical segregation of the afferent roots according to their anatomico-functional destinations. The technique consists of a 2 mm deep DREZ microsurgical cut directed at a 45 degree angle into the posterior lateral sulcus just ventral to DREZ and Lissauer's tract of the spinal cord. The procedure was carried out at each sensory rootlet considered to be responsible for the harmful spasticity and pain. SPR interrupts selectively the lateral nociceptive and central myotactic afferent fibers curving toward Lissauer's tract and the anterior spinal cord, while sparing most of the medial lemniscal fibers curving toward the dorsal columns, as well as the fibers of the inhibitory circuitry of Lissauer's tract and dorsal horn. The results were evaluated after a 1 to 14 year follow-up. Mild to severe complications occurred in 25 patients (47.1%) and were responsible for death in 5 (9.4%). Both spasticity and spasm were significantly decreased or completely eliminated in 75% and 88.2% respectively; when present, pain was relieved without a total suppression of sensation in 91.6%. These benefits-combined with complementary orthopedic surgery in 23 patients--resulted in either a complete resolution or marked reduction of the abnormal postures and articular limitations (85.2% complete and 96.75 marked reduction). Because of the extreme severity of the pre-operative neurological deficits in almost all the patients in this series, surgery improved voluntary movements with a significant functional benefit in only 5 cases and vesico-sphincter function in none. Thanks to its valuable effects on hyperspasticity and pain, SPR in the DREZ made it possible for these very disable patients to be more comfortable in bed and wheel-chair and it allowed effective nursing and kinesitherapy to be resumed.

Adult↗
PubMed1987

Sodium transport in primary hypertension.

Humans and rats with primary hypertension may exhibit different and stable abnormalities in membrane Na+ transport systems: (i) Pump (-) = decreased apparent affinity of the pump for internal Na+, (ii) Co (-) = decreased apparent affinity of the Na+, K+ cotransport system for internal Na+ (iii) Leak (+) = increased passive Na+ permeability and (iv) = Counter (+) abnormality (increased maximal rate of Na+-Li+ and perhaps Na+-H+ exchange). Excess Na+ intake tends to be compensated by the transient secretion of endogenous "digitalis-like" and other natriuretic factors. The presence of Co(-) or Leak(+) abnormalities may amplify transitory cell Na+ rises induced by endogenous digitalis-like factors at the vascular wall. The Counter(+) abnormality may increase renal Na+ reabsorption and induce permanent hypersecretion of endogenous digitalis-like factors.

Animals↗
PubMed1986

Stimulation of beta-adrenoceptors inhibits calcium-dependent potassium-channels in mouse macrophages.

K+ efflux in mouse macrophages exhibited a rate constant (kK) of 0.67 +/- 0.04 (h)-1 (mean +/- SEM of 16 experiments). This was strongly stimulated by increasing concentrations of the Ca2+ ionophore A23187 up to a maximal value of 4.01 +/- 0.25 (h)-1 with an IC50 of 7.6 +/- 1.9 microM (mean +/- SEM of 6 experiments). Similar results were obtained with the Ca2+ ionophore ionomycin. Binding experiments with 3H-dihydroalprenolol revealed a high density of beta-adrenergic receptors (97.5 +/- 5.2 fmol/mg protein) with apparent dissociation constant of 2.03 +/- 0.06 nM. Isoproterenol at a concentration of 10(-6)-10(-5) M induced a two- to threefold stimulation of endogenous levels of cyclic AMP (cAMP). A23187-stimulated K+ efflux was partially inhibited by stimulation of adenylate cyclase with isoproterenol, forskolin or, PGE1; exogenous cAMP; and inhibition of phosphodiesterase with MIX (1-methyl-3-isobutylxanthine). Maximal inhibition of K+ efflux was obtained by simultaneous addition of isoproterenol and MIX. In dose-response curves, the isoproterenol-sensitive K+ efflux was half-maximally inhibited (IC50) with 2-5 X 10(-10) M of isoproterenol concentration. Propranolol was able to completely block the effect of isoproterenol, with an IC50 of about 1-2 X 10(-7) M. Isoproterenol and MIX were also able to partially inhibit ionomycin-stimulated K+ efflux. Isoproterenol and MIX did not inhibit A23187-stimulated K+ efflux in an incubation medium where NaCl was replaced by sucrose (or choline), suggesting the involvement of an Na+:Ca2+ exchange mechanism. Our results show that stimulation of beta-adrenoceptors in mouse macrophages counterbalances the opening of K+ channels induced by the calcium ionophore A23187. This likely reflects a decrease in cytosolic free calcium content via a cAMP-mediated stimulation of Na+:Ca2+ exchange.

1-Methyl-3-isobutylxanthine↗
PubMed1985

Effects of an intravenous saline load on erythrocyte sodium transport in normal human subjects.

The effects of a 2 litre intravenous infusion of saline (0.9% NaCl solution) over 3 h on erythrocyte transmembrane sodium transport were studied in 12 normal human subjects. After saline infusion a significant (P less than 0.01) reduction of both outward Na+,K+ pump- and Na+,K+ cotransport-mediated Na+ effluxes was observed. The Na+,Li+ countertransport rate and the passive Na+ permeability did not change. The incubation of the subjects' erythrocytes, obtained on a separate occasion, with their own plasma taken after the saline infusion, induced an inhibition of both Na+,K+ pump and Na+,K+ cotransport outward sodium fluxes. The percentage decrease after incubation was closely correlated with the percentage reduction induced by the saline infusion in vivo (r = 0.93 for the pump and r = 0.96 for cotransport; P less than 0.01). These data suggest that extracellular fluid volume expansion affects the release of circulating factors modulating sodium transport by the Na+,K+ pump and by Na+,K+ cotransport.

Adult↗
PubMed1985

Acute effects of hemodialysis on erythrocyte sodium fluxes in uremic patients.

The acute effects of both acetate and bicarbonate hemodialysis on erythrocyte transmembrane sodium fluxes were investigated in 15 patients with chronic uremia. We observed a significance (p less than 0.01) stimulation of the Na+,K+ pump in both procedures, with a significant correlation to the amount of fluid removed during hemodialysis (r = 0.56, p less than 0.03). Outward Na+ cotransport fluxes significantly rose (p less than 0.05) after acetate hemodialysis and decreased (p less than 0.05) after bicarbonate hemodialysis. Minor and not significant pre- and posthemodialysis bidirectional changes were observed as regards the intraerythrocyte Na+ and K+ concentration, passive Na+ and K+ permeability, and Na+,Li+ countertransport. Hemodialysis may acutely affect the erythrocyte sodium pump and cotransport fluxes, possibly through the modulation of hormonal factors triggered by the extracellular volume changes.

Acetates↗
PubMedDate not supplied

Peritoneal dialysis compared with hemodialysis in the treatment of end-stage renal disease.

Whether to use peritoneal dialysis (PD) or hemodialysis (HD) is a major decision in terms of clinical outcome and management implications; the final choice is difficult because of the conflicting results of comparisons reported in the literature. A review of studies comparing survival shows either superiority of HD, or superiority of PD, or equivalence of the two techniques, but an analysis of the comparisons as a whole brings to light two clear phases in the survival curves. In the first, residual renal function (RRF) gives PD an advantage, or at least puts it on the same level as HD. In the second phase, the reduction in Kt/V as RRF declines gives PD a potential risk. After a few years of PD treatment a sharp watch is therefore necessary to detect signs of under-dialysis promptly and to shift the patient to HD. In patients without RRF it is more difficult to control hypertension with PD and they are more prone to hyperhydration. Despite a widespread belief in the Eighties that PD was the treatment modality of election for diabetics, HD is in fact preferable in these patients, except younger ones. High-turnover and low-turnover bone lesions are more frequent respectively in HD and PD patients. Anemia is better controlled with PD. Blood lipids and nutritional indices are less well controlled with PD. Despite poor technical survival, the "pool" of patients treated with PD frequently reaches 20-30% because it is indicated as first treatment in a large proportion. PD preserves renal function better than HD and is useful while awaiting renal transplantation, with faster postoperative restoration of diuresis. The quality of life with PD as home treatment is usually better than with HD. In conclusion, dialytic centers should establish an integrated PD/HD programme as the two methods are not competitive but are different tools for the treatment and rehabilitation of uremic patients.

Australia↗
PubMedDate not supplied

[Dialysis in the elderly].

Assuming >/= 75 years old as the age limit to define dialysis in the elderly, the incidence in this group of patients is progressively increasing in most dialysis units, with an annual growth of 8 to 16%, and represents 20 to 33% of the overall population being affected. The prevalence of the elderly dialysis group is also high, 14 to 20%, in the main literature casistics. Vascular nephropathies, 13 to 50%, represent the major cause of end-stage renal disease, followed by diabetes, 11 to 37%. First year survival rate is an acceptable 52 to 82%, whereas the fifth year value is on average 20 %, also due to the high baseline mortality in these patients. The death causes are mainly cardiac related and represent 45% of the overall mortality. The main prognostic factors are frequency and severity of comorbid factors, in addition to nutritional indexes that are particularly important in this age group. Dialysis dose and treatment time are not related to mortality. Haemodialysis and peritoneal dialysis complement each other to allow the best results. The survival rate, however, is usually better with haemodialysis, especially in old diabetic patients and after some years of treatment. Vascular access, intradialytic hypotension, cardiopathy, intestinal bleeding and amyloidotic arthropathy represent the more critical aspects of dialysis in the elderly, while the quality of life is sometimes unexpectedly good.

Age Factors↗
PubMedDate not supplied

[Neonatal hyperthyroidism. A clinical contribution].

A case of female child who had transient signs of hyperthyroidism after the birth is presented. Authors describe the clinical course and discuss the possible pathogenetic mechanisms. The importance of a timely diagnosis, a correct therapy and follow-up is emphasized.

Female↗
PubMedDate not supplied

[Condylomata acuminata in childhood: description of a case].

Recent advances in understanding human papillomavirus imply that HPV infections are increasing in both men and women. HPV may cause subclinical disease and play a role in genital tumors. In prepuberal children the problem remains uncommon and can offer a difficult task of management and epidemiologic evaluation.

Anus Neoplasms↗