PubMed Health⌕ Search

Biomedical subjects

A Amato

Publications and source records attributed to A Amato.

At least 91 records · Page 5Linked to original sources
PubMed1994

Intracellular pH changes produced by glutamate uptake in rat hippocampal slices.

1. The mean intracellular pH in area CA1 of rat hippocampal slices was monitored fluorescently after loading the cells with the dye BCECF-AM. 2. Including L-glutamate in the solution superfusing the slice led to the intracellular pH becoming more acid. This acidification had a roughly Michaelis-Menten dependence on the superfused glutamate concentration with a half-maximal dose around 200 microM: this value must overestimate the glutamate concentration at most of the cells, which will be reduced by uptake. 3. The glutamate-evoked acidification was not significantly reduced by blockers of glutamate-gated ion channels [6-cyano-7-nitroquinoxaline-2,3- dione (CNQX) and D-aminophosphonovalerate (APV)] nor by blockers of gamma-aminobutyric acid (GABA)- and glycine-gated channels (picrotoxin and strychnine), and so was not produced by H+ entry through alpha-amino-3-hydroxy-5-methyl-4- isoxazolepropionic acid (AMPA) or N-methyl-D-aspartate (NMDA) receptor channels nor by HCO3- exit through the chloride channels controlled by GABA or glycine. 4. The glutamate-evoked acidification was not reduced by tetrodotoxin (TTX), ruling out the possibility of it being generated by action potentials. It was also unaffected by saturation of presynaptic L-amino-4-phosphonobutanoate (AP4) receptors with AP4. 5. In the presence of blockers of glutamate-, GABA-, and glycine-gated channels, the acidification showed the pharmacology of glutamate uptake and was reduced by a glutamate uptake blocker. 6. The glutamate-evoked acidification showed an ion dependence similar to that of glutamate uptake. It was abolished by removal of extracellular sodium and was reduced by raising the extracellular potassium concentration. It was unaffected by blockers of Na+/H+ exchange (amiloride) and Na+/HCO3- cotransport [4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS)] and so was not produced by the Na+ influx accompanying glutamate uptake changing the activity of these carriers. 7. These data show that the glutamate uptake carrier acidifies hippocampal cells, possibly because it transports a pH-changing anion out of the cell as in salamander glial cells. Glutamate uptake may thus contribute to activity-induced pH changes in the nervous system.

Acid-Base Equilibrium↗
PubMed1994

Immunohistochemical study of placental endothelium in physiologic and gestosis-complicated pregnancies.

In this study we examined the placentae of gestosic patients and controls, with immunoistochemical method and HLA-DR monoclonal antibody, in order to show the role of placental endothelium in gestosic pathology onset. Our results show a marked expression of class II histocompatibility antigens in gestosic placentae with respect to controls. We suppose, in gestosic patients, a role for a particular, genetically determined HLA haplotype which increases disease receptivity.

Endothelium↗
PubMed1993

Long term prognosis of asymptomatic carotid artery occlusion.

Twenty six asymptomatic patients with internal carotid artery occlusion had ultrasound follow-up for a mean period of 34.3 months. During follow-up 3 patients (11.5%) reported transitory ischemic attacks (TIAs), one of these (3.8%) occurred in the vascular territory ipsilateral to the occlusion. There were not strokes. Annual TIA rate was 4% for all vascular territories, and 1.3% for the territory ipsilateral to the occlusion. Annual mortality was 9.4%. Our data on stroke risk in patients with asymptomatic carotid artery occlusion show a good prognosis in the long-term.

Adult↗
PubMed1993

[Color-Doppler and angioplasty in renovascular hypertension].

Renovascular hypertension is defined as a kind of hypertension secondary to altered renal perfusion with the activation of the renin-angiotensin system. Since a large number of these patients benefits from treatment--be it medical, surgical or angioplastic--a non-invasive low-cost method allowing accurate screening was looked for. Color-Doppler was employed by many authors to evaluate renovascular hypertension, for both the early diagnosis of the condition and the evaluation of treatment results in renal artery stenoses. However, the authors agree that color-Doppler cannot play a major role in the screening of renovascular hypertension due to the various qualitative and quantitative variables not being adequately codified, to the lack of a single color-Doppler method and to the difficult comparison of the results from the different units. Nevertheless, improved results are promised by technological evolution, together with the possibility to codify color-Doppler variables more easily repeatable. B-mode units with 3.5 and 5 MHz probes were employed in the thinnest subjects. In 5-25% of cases accessory renal arteries were observed. After identifying the vessel to be studied with several spatial scans, the smallest possible sample volume (usually 3-5 mm) was positioned. The normal flowmetric range was 0.07-0.1 s: it must not exceed 0.16 s, with persistence of high diastolic flow. Some authors' criteria were followed to define either stenosis or renal artery obstruction; moreover, pulsatile flow index was considered, together with the resistive index, pulsatility index and stenosis index.

Angioplasty↗
PubMed1992

The glial cell glutamate uptake carrier countertransports pH-changing anions.

Uptake into glial cells helps to terminate glutamate's neurotransmitter action and to keep its extracellular concentration, [Glu]o, below neurotoxic levels. The accumulative power of the uptake carrier stems from its transport of inorganic ions such as sodium (into the cell) and potassium (out of the cell). There is controversy over whether the carrier also transports a proton (or pH-changing anion). Here we show that the carrier generates an alkalinization outside and an acidification inside glial cells, and transports anions out of the cells, suggesting that there is a carrier cycle in which two Na+ accompany each glutamate anion into the cell, while one K+ and one OH- (or HCO3-) are transported out. This stoichiometry predicts a minimum [Glu]o of 0.6 microM normally (tonically activating presynaptic autoreceptors and post-synaptic NMDA receptors), and 370 microM during brain anoxia (high enough to kill neurons). Transport of OH-/HCO3- on the uptake carrier generates significant pH changes, and may provide a mechanism for neuron-glial interaction.

Acetazolamide↗
PubMed1992

Estimation of parameters of allometric equations.

Accurate parameter estimation of allometric equations is a question of considerable interest. Various techniques that address this problem exist. In this paper it is assumed that the measured values are normally distributed and a maximum likelihood estimation approach is used. The computations involved in this procedure are reducible to relatively simple forms, and an efficient numerical algorithm is used. A listing of the computer program is included as an appendix.

Algorithms↗
PubMed1992

[Renal artery stenosis. Doppler color study before and after angioplasty].

Doppler flowmetry can be successfully employed to assess arterial patency after percutaneous transluminal angioplasty (PTA). The aim of this study was to assess color Doppler sensitivity in detecting renal artery stenosis prior to percutaneous angioplasty (PTRA) and vessel patency after it. Eleven patients (7 males and 4 females) affected with renal artery stenosis, unilateral in 9 cases and bilaterally in 2, underwent color-Doppler evaluation 1 day before and 7 days after PTRA. The operator was unaware of dilatation results. A total of 13 stenoses were treated. The qualitative and quantitative parameters we employed were: a) broadening of the spectrum, b) peak systolic frequency > 4000 Hz, c) stenosis index > 50%. Before PTRA, mean systolic peak at the stenosis was 7978 (range 4050-12500 Hz), while stenosis index was 71.9% (range 48-89%). After PTRA complete recovery was observed in 5 cases, no improvement in 1 and incomplete recovery in 7. Doppler results were in agreement with those of angiography in 6/13 while partial agreement only was seen in 7/13. Our results, although obtained in a small and highly selected group of patients, would seem to support the value of color-Doppler for the follow-up of patients after PTRA.

Adult↗
PubMed1991

[Diagnosis of thyroid metastasis of uveal melanoma by fine needle aspiration biopsy].

The Authors report the case of intra-thyroid metastasis from uveal malignant melanoma, diagnosed by fine needle aspiration biopsy, 15 years after surgical treatment of the primary tumour. The site is very unusual as illustrated by a review of the literature, and confirms the extreme heterogeneity that sometimes the natural history of this pathology shows. The critical analysis of diagnostic reliability of the cytological techniques, proves their usefulness in the differential diagnosis of every suspicious mass.

Biopsy, Needle↗
PubMed1991

Local recurrence following abdominoperineal excision and anterior resection for rectal carcinoma.

The aim of this retrospective study is to compare the outcome of abdominoperineal excision (APE) and anterior resection (AR) for rectal cancer in terms of local tumor recurrence. A further comparison has been carried out between hand-sewn and stapled anastomosis; 147 patients have been followed for at least 2 years: 69 after APE and 78 after AR, 40 being stapled. The following variables potentially related to the risk of recurrence were evaluated: age, grading, staging, and site of the tumor. An overall 2-year local recurrence rate of 11 percent after APE and 12 percent after AR was observed, whereas it was 13 and 11 percent following stapled and hand-sewn sutures, respectively. Both differences were not statistically significant. A similar local recurrence rate was noted after APE and AR when the patients were matched for Dukes' stage and grading of the lesion. A trend toward an increased risk of recurrence following AR (P = 0.07) was shown when comparing the two procedures if mid and upper rectal cancers were grouped together. In the patients with anastomotic leaks after AR, no increase of local recurrence was observed. In conclusion, AR is unlikely to be followed by an increased risk of local recurrence and, therefore, when oncologically indicated, may be considered the operation of choice in the treatment of rectal cancer, although the possible risk of its overuse should be taken into account.

Abdomen↗
PubMed1991

Lack of gastric adverse effects of erdosteine in rats and men.

Erdosteine is a thiol derivative endowed with mucolytic, mucomodulator and free radical scavenging properties. Studies were performed in rats and men with the aim to assess its safety on gastric mucous barrier. Two experiments were performed in rats by comparing the effects of erdosteine, homocysteine thiolactone (HTL), carbocysteine, tiopronin and placebo on a) macroscopic appearance of G. I. ulcer, total HCl, pH and volume of gastric juice 4 and 6 hours after, respectively, pylorus ligation in Shay rats and drug oral treatment, and on b) macroscopic appearance of G. I. ulcer in fasting rats for 50 hours, during which the animals received 4 oral doses of each compound. In both conditions erdosteine was completely inactive in the dose-range of 500-1000 mg/kg p.o. while HTL, carbocysteine and tiopronin were ulcerogenic already at the dose of 500 mg/kg p.o. Accordingly, 15 human beings, undergoing gastroscopy, well tolerated erdosteine at the oral dose of 300 mg TID for 9-13 days. In this open study the patients neither revealed worsening of their pre-existing gastric complains, nor indicated new subjective symptoms, nor manifested macroscopic and histological alterations concerning the parietal tonus, the status of epithelial mucosa and of gastric content (including: volume, total acidity and total, bound and free sialic acid).

Administration, Oral↗
PubMed1991

[Duplex and Doppler color echocardiography for the study of renovascular hypertension. Comparison with arteriography].

Doppler US was employed to examine 46 patients with suspected renovascular hypertension (RVI) to detect stenosis/occlusion of the renal artery. In 25 cases duplex-Doppler technique was used, in 19 color-Doppler US, and 2 patients were examined with both methods. Doppler US was always performed before angiography which was considered as the reference gold standard. Using duplex-Doppler US, the diagnosis of renal artery stenosis was based on qualitative (spectral analysis of the waveform and absence of flow signal in cases of renal artery occlusion), and semiquantitative parameters (resistive index). Diagnostic accuracy of duplex US--which was compared with that of angiography--was 83%, its sensitivity was 91.6%, and specificity was 85%. With color-Doppler, two additional quantitative parameters were used (peak systolic frequency shift at the stenosis and stenosis index). In this group of patients sensitivity was 70%, specificity was 100%, and accuracy 85%. The good diagnostic yield of the method is counter-balanced by some limitations--e.g., operator dependence and long examination time (30-40 minutes, especially with duplex US). In the authors' opinion, Doppler technique can be used in the diagnosis of RVI, even though further study is necessary to exactly define diagnostic parameters, and to verify reproducibility and both inter- and intra-observer repeatibility. Technological progress may in the future reduce both difficulty and time of the examination.

Adult↗
PubMed1990

Detection of bovine leukaemia virus (BLV) infection by DNA probe technology.

Classical serological methods and Southern blot hybridization for the diagnosis of bovine leukaemia virus (BLV) infection have been compared during the first nine months of life of offspring from BLV serum-negative and serum-positive dams belonging to a Friesian dairy herd in Italy. At birth, 9/13 calves analysed showed serum positivity for anti-gp60 BLV antibodies by agar immunodiffusion and/or by ELISA. However, only two calves were positive for BLV integrated proviruses in their lymphocyte DNA. At six months of age, anti-gp60 BLV antibodies and proviral DNA positivities were simultaneously shown only by the two cattle identified as DNA-positive at birth. This pattern remained constant up to nine months of age. Furthermore, analysis of the molecular characteristics of BLV integrated proviruses, carried out by using, as probes, the almost complete proviral genome (Belgian isolate) or a subclone of the env gene radioactively labelled or chemically modified, revealed that the calves under study were infected by a different isolate (Japanese isolate) and that, in one of the cattle, the majority of integrated proviruses was characterized by deletions probably located in the 5' half of the proviral genome.

Animals↗
PubMed1990

[Gastroduodenal surgery using mechanical staplers: our experience].

Results of 71 operations of the gastroduodenal tract performed with stapling devices are reported (51 for malignant diseases and 20 for benign diseases). 20 total gastrectomies, 21 Billroth II gastrectomies, 17 Roux en-Y-gastrojejunoplasty, 6 Billroth II to Roux-ex-Y-conversion and 7 palliative gastroenteroanastomosis were performed, using TA, GIA and EEA stapling instruments. The analysis of the reported data brought us to some considerations regarding the safety and versatility of mechanical viscerosynthesis, also in relation to some technical aspects.

Anastomosis, Roux-en-Y↗
PubMed1989

[A modified Hill's procedure in the surgical treatment of hiatal hernia].

After an introduction on the problems regarding indications and surgical management of gastro-oesophageal reflux disease, the Authors describe the technique they use, which is a modification of Hill's posterior gastropexy, involving the placement of suture through the median arcuate ligament, without exposing the celiac axis. The preliminary results of a prospective randomized clinical trial, conducted at the Surgical Clinic Department of Catholic University, Rome, are described. The trial evaluated early and late results of Hill's modified technique versus a control group, in which a Dor technique has been used. Intraoperative oesophageal manometry has been performed in both groups, to set the cardioplasty more properly. Ninety-one patients out of 132 have been studied; 65 had a good response to medical therapy and 26 have been operated upon. In 9 cases (6 Dor and 3 Hill) intraoperative manometry was performed. All patients have been studied pre-operatively with upper g.i. series, endoscopy with biopsies, oesophageal manometry and 24-h pH monitoring; this protocol has been repeated after 3 to 6 months postoperatively, to evaluate the results more accurately. The preliminary data, although statistically non significant because of the small study group, seem to favour the Hill modified technique, both for complication and reflux control. Further data are needed to confirm them.

Adult↗