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Biomedical subjects

A Amato

Publications and source records attributed to A Amato.

At least 73 records · Page 4Linked to original sources
PubMed1996

Spatial organization of calcium dynamics in growth cones of sensory neurones.

The concentration of calcium ions in the cytosol ([Ca2+]i) has a dominant influence on neuronal development. A [Ca2+]i rise can, depending on the amplitude and location, promote outgrowth or dramatically inhibit it. We have used the fluorescent calcium indicators Fura-2 and Fura-2 dextran to measure [Ca2+]i dynamics in sensory neurones from the adult rat. [Ca2+]i was low and uniform in advancing growth cones, even during specific behaviours such as protrusion, filling and consolidation. A brief train of action potentials caused [Ca2+]i to rise at the extreme leading edge of the growth cone. [Ca2+]i changes in more proximal regions of the growth cone were much smaller. This spatially organized [Ca2+]i change, which may result from a concentration of calcium channels at the growth cone leading edge, is likely to function in spontaneously active regenerating axons in vivo to specifically activate calcium-dependent processes at the growth cone tip.

Animals↗
PubMed1996

Clinical, manometric and sonographic assessment of the anal sphincters. A comparative prospective study.

One hundred patients with various anorectal disorders but intact anal sphincters were evaluated prospectively by three independent observers to determine the specificity, sensibility and accuracy of digital exploration and anal ultrasound compared to anal manometry, in assessing internal and sphincter hypertonicity (IH) and the relaxation of sphincters on straining (SR). Accuracy of the digital examination in evaluating IH was 80 vs 74%, while the SR was detected by the three observers in 82, 71 and 65% of cases. The thickness of internal sphincter increased with age (r = 0.37, P = 0.01), whereas the resting tone decreased with age (r = 0.27, P = 0.06). There was an inverse correlation between the sonographic thickness of the internal sphincter and the manometric resting tone (r = 0.29, P = 0.004). The internal sphincter thickness was 1.97 +/- 0.41 mm in constipated patients, 2.06 +/- 0.39 in the others (P = 0.03). In conclusion, IH and SR may be assessed by digital exploration with a good accuracy and the thickness of internal sphincter at ultrasound may change according to its functional state.

Adult↗
PubMed1996

Differentiated thyroid cancer: surgical treatments of 190 patients.

Between 1968 and 1991, 190 patients (51 men, 139 women) with a mean age of 46.3 years underwent surgery for differentiated thyroid cancer (148 papillary and 42 follicular carcinomas). In 29.5% of the cases a concomitant goitre was histologically demonstrated. These patients were significantly older (mean: 54.7 years) (P<0.01). The patients who had previously received cervical radiotherapy were significantly younger (mean: 29.7 years) (P<0.01). The analysis of historical and clinical findings failed to identify predictive factors of biological aggressiveness. Hyperthyroidism occurred in 5.7% of patients: this subgroup did not show any difference in clinical behaviour. Occult carcinoma (14.7%) and multifocality (9.4%) were found more frequently in the glands with a pre-existent goitre (P<0.05), but the clinical significance of these aspects is uncertain. The surgical treatment of choice was total thyroidectomy (135 patients); more conservative procedures were performed only in younger patients with small lesions, without a difference in survival. Post-operatively a permanent recurrent laryngeal nerve injury occurred in four patients (2.1%) and nine patients (4.7%) required a permanent calcium supplementation. Among patients in follow-up (91.6%), those who underwent a total thyroidectomy were studied using a total body scinti scan. A poor prognosis was associated with age (>40 years), pT, stage, pM and symptomatic metastases.

Adenocarcinoma, Follicular↗
PubMed1996

Changes in energy metabolism of calf muscle in patients with intermittent claudication assessed by 31P magnetic resonance spectroscopy: a phase II open study.

Energy status and metabolism in skeletal muscle of nine patients with peripheral arterial disease and suffering from intermittent claudication were evaluated using 31phosphorus magnetic resonance spectroscopy (MRS) before and after treatment for 3 months with propionyl-L-carnitine (PLC; 2 g/day p.o.). Maximum walking distance (MWD) was assessed on a standard treadmill (4 km/h, zero incline). For the group as a whole 31P MRS results did not change significantly with PLC. Although MWD increased by a mean of 36%, this change did not reach significance. However, when these variables were assessed with respect to the change in MWD, there were significant differences between those who increased MWD by > 30% (responders, R; n = 5) and those who did not (nonresponders, NR; n = 4). Compared with pretreatment values, during exercise the decrease in muscle pH in R relative to the decrease in phosphocreatine was less after PLC (p = 0.04). After exercise there was a significant inverse correlation between the changes in recovery half-time (t1/2) for phosphocreatine and in MWD (r = -0.91, p = 0.01). With PLC, Vmax increased in R (p = 0.04), but not in NR. For the patient group as a whole, the changes in Vmax and MWD correlated positively (r = 0.90, p = 0.01). This study helps to identify the changes in muscle metabolism that correlate with changes in exercise performance, and may accompany treatment with PLC.

Adenosine Diphosphate↗
PubMed1995

Modulation of GABAA receptors by tyrosine phosphorylation.

gamma-Aminobutyric acid type-A (GABAA) receptors are the major sites of fast synaptic inhibition in the brain. They are presumed to be pentameric heteroligomers assembled from four classes of subunits with multiple members: alpha (1-6), beta (1-3), gamma (1-3) and delta (1). Here, GABAA receptors consisting of alpha 1, beta 1 and gamma 2L subunits, coexpressed in mammalian cells with the tyrosine kinase vSRC (the transforming gene product of the Rous sarcoma virus), were phosphorylated on tyrosine residues within the gamma 2L and beta 1 subunits. Tyrosine phosphorylation enhanced the whole-cell current induced by GABA. Site-specific mutagenesis of two tyrosine residues within the predicted intracellular domain of the gamma 2L subunit abolished tyrosine phosphorylation of this subunit and eliminated receptor modulation. A similar modulation of GABAA receptor function was observed in primary neuronal cultures. As GABAA receptors are critical in mediating fast synaptic inhibition, such a regulation by tyrosine kinases may therefore have profound effects on the control of neuronal excitation.

Amino Acid Sequence↗
PubMed1995

Lithium transport pathways in human, chicken and eel erythrocytes.

The contribution of four transport pathways to Li+ influx in human, chicken and eel erythrocytes was studied. All pathways were measured simultaneously in each kind of blood sample to avoid possible temporal variations in transport parameters. We found that: 1) Li+ influx via Na(+)-K+ pump increased 2-3 fold in the order human < eel < chicken; 2) by the countertransport exchange system lithium influx increases its variance between 15% and 35% when saline medium is replaced by choline Cl; 3) the anion exchange system (band 3 protein) shows very little interindividual variability on the lithium influx; 4) the lithium leak pathway, for human and eel red blood cells, is the major contribution, whereas it is negligible for chicken erythrocytes. It is concluded that a similar transport system exists in the red cell membranes of the three species which can transport lithium. However, the exchange system does not exhibit identical transport characteristics in the three species and shows a marked inter- and intra-species variability in maximum transport capacity and some differences in susceptibility towards the inhibitors.

Animals↗
PubMed1995

Calf muscle mitochondrial and glycogenolytic ATP synthesis in patients with claudication due to peripheral vascular disease analysed using 31P magnetic resonance spectroscopy.

1. We set out to define abnormalities of oxidative ATP synthesis, cellular proton efflux and the efficiency of ATP usage in gastrocnemius muscle of patients with claudication due to peripheral vascular disease, using data obtained by 31P magnetic resonance spectroscopy during aerobic exercise and recovery. 2. Eleven patients with moderate claudication were studied and results were compared with 25 age-matched control subjects. Changes in pH and phosphocreatine concentration during recovery were used to calculate the maximum rate of oxidative ATP synthesis (Qmax.) and the capacity of net proton efflux. Changes in pH and phosphocreatine concentration were used to estimate rates of non-oxidative and (indirectly) oxidative ATP synthesis throughout exercise, taking account of abnormalities in proton efflux during exercise. 3. In patients with claudication, slow post-exercise phosphocreatine recovery showed a 42 +/- 9% decrease in Qmax., and the slow ADP recovery was consistent with this. pH recovery was slow, showing a 77 +/- 9% decrease in the capacity for proton efflux. Both abnormalities are compatible with a substantial reduction in muscle blood flow. 4. During exercise, increased phosphocreatine depletion and intracellular acidification were a consequence of impaired oxidative ATP synthesis and the consequent increase in non-oxidative ATP synthesis, compounded by reduced proton efflux. The acidification prevented an increase in ADP concentration which could otherwise partially compensate for the oxidative defect. All these abnormalities are compatible with a reduced muscle blood flow. 5. In addition, initial-exercise changes in pH and phosphocreatine concentration implied a 44 +/- 5% reduction in 'effective muscle mass', necessitating an ATP turnover (per litre of muscle water) twice as high for given power output as in control muscle. Some of this is probably due to a localized loss of muscle fibres, but the rest appears to reflect reduced metabolic efficiency of the muscle. This is not a direct consequence of reduced blood flow, and may be related to change in muscle fibre type.

Adenosine Triphosphate↗
PubMed1995

Surgical management of substernal goiter: analysis of 237 patients.

Between 1968 and 1991, 237 patients underwent thyroidectomy for substernal goiter. Sixteen of them presented malignancies (6.8%). Mean age of the 159 women and 78 men was 57.7 years. Twenty-five patients had undergone previous thyroid surgery. The initial symptoms were cervical mass (72%), compression (16.2%), hyperthyroidism (13.1%), hypothyroidism (1.3%), and 5.5 per cent were asymptomatic. Most patients had long-standing goiter (mean duration: 12.9 yrs). All but eight operations were performed through a cervical incision. There were two postoperative deaths (0.8%), both in patients with advanced neoplasms. Early postoperative complications were hemorrhage (0.8%), dysphonia (4.6%), and transient hypocalcemia (2.9%). Five patients (2.1%) required tracheotomy. Complications were more frequent after total thyroidectomy than partial resection (P < 0.05), after surgery for malignancy than for benign disease (P < 0.05), and in complex than in simple forms (P < 0.05). One hundred ninety-four patients were followed after surgery; dyspnea was found in two patients (1.0%), dysphonia in seven (3.6%), and hypoparathyroidism in one. Analysis of our data indicates that 1) substernal goiter arose in elderly patients more than a decade later than cervical goiter; 2) goiters with a "complex" endothoracic development had an increased rate of short and long term complications; 3) cancer occurred in a significant number of patients, without any specific symptoms of malignancy; 4) the group of patients with hyperthyroidism was characterized by a significantly longer clinical history than euthyroid patients; 5) nearly all substernal goiters could be approached through a cervical collar incision; 6) the morbidity and mortality were low also after sternotomy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Primary lymphoplasmacytic lymphoma of the liver associated with a serum monoclonal peak of IgG kappa.

We report a case of primary lymphoma of the liver successfully treated by major liver resection. The tumor exhibited the immunohistological features of a B-cell low-grade lymphoma of the lymphoplasmacytic type. Tumoral plasmacytic cells showed cytoplasmic-positive staining for IgG and kappa light chains. In addition, we detected a serum monoclonal peak of IgG kappa, a finding that has not been reported previously. Clinical, pathological, and immunohistochemical data from the literature are reviewed.

Adult↗
PubMed1994

Counter-transport of potassium by the glutamate uptake carrier in glial cells isolated from the tiger salamander retina.

1. To investigate the transport of potassium on the glutamate uptake carrier, the glutamate uptake current in isolated retinal Müller cells was monitored by whole-cell clamping, while measuring changes of potassium concentration outside the cells ([K+]o) with an ion-sensitive microelectrode. 2. Activating glutamate uptake led to an accumulation of potassium outside the cells, consistent with the hypothesis, based on less direct evidence, that the glutamate uptake carrier transports potassium out of the cell. 3. The glutamate-evoked rise of [K+]o showed the pharmacology and sodium dependence of glutamate uptake. 4. The rise in [K+]o was proportional to the uptake current flowing between 0 and -80 mV, implying that the ratio of K+ transported to charge transported by the uptake carrier is constant over this voltage range. The K+ to charge transport ratio was the same for uptake of D-aspartate and L-glutamate. 5. By clamping cells with pipettes containing solutions of different [K+], the dependence of the glutamate and aspartate uptake currents on intracellular [K+] was determined. L- and D-aspartate transport showed a smaller maximum uptake current (Imax), and a smaller apparent Michaelis constant (Km) for activation by intracellular K+, than did L-glutamate transport. The ratio of Imax to Km was the same for these three analogues, a result which can be predicted from simple models of the carrier's operation. 6. Fully activating glutamate uptake in Müller cells in the intact retina would produce a K+ load into the extracellular space of about 0.6 mM s-1. Suppression of glutamate release from photoreceptors by light will reduce K+ efflux from Müller cells in the outer retina; this may contribute to the light-evoked fall of [K+]o observed in the outer retina, and thus contribute to shaping the electroretinogram.

Amino Acid Transport System X-AG↗