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Biomedical subjects

R Alfieri

Publications and source records attributed to R Alfieri.

At least 37 records · Page 2Linked to original sources
PubMed1994

The influence of high and low doses of diltiazem on isolated alveolar type II cells during normothermic and hypothermic ischemia: cytoprotection or cytotoxicity?

The alteration of calcium homeostasis is of outstanding importance for the cytotoxic reactions that place after ischemia, for this reason calcium channel blockers have been used with the purpose to protect the lung during transplantation. This work analyses the effect of Diltiazem at two different doses (10 mg/l and 50 mg/l) on Wistar rat alveolar type II cells, incubated for 8 hours at 37 degrees C and at 4 degrees in an electrolytic solution. Total protein content and the rate of protein synthesis derived from 35S Methionine uptake were used to evaluate cells viability. The data showed that Diltiazem did not improve cellular viability after warm and cold metabolic ischemia either using 10 mg/l or 50 mg/l, while at 4 degrees C a significantly cytotoxic effect (p < 0.05) was observed. At this temperature toxicity was independent on the dose used.

Animals↗
PubMed1993

Different HSP70 expression and cell survival during adaptive responses of 3T3 and transformed 3T3 cells to osmotic stress.

Responses both to hyperosmotic stress and to heat shock were compared in 3T3 cells, spontaneously transformed cells (ST3T3) and simian virus 40-transformed cells (SV3T3). Cell adaptation to these stresses was measured in terms of surviving cell viability and plating efficiency, while their induced synthesis of stress proteins was monitored in terms of the presence of mRNA for HSP70, the pattern of polypeptides synthesised and the accumulation of HSP70 detectable by monoclonal antibodies. All three types of cells responded similarly to heat shock in their expression of HSP70 and showed no clear differences in ability to recover. In contrast, both ST3T3 and SV3T3 cells adapted more poorly and much more slowly to hyperosmotic stress (0.5 osM incubation) than did normal 3T3 cells. This different pattern of adaptation to hyperosmotic stress was parallelled by the cells' different expression of a stress protein that could not be distinguished from the heat-induced HSP70 by any of the methods listed above. In view of these findings it seems possible that hyperosmotic treatment might be useful in selectively affecting the survival of tumour cells.

3T3 Cells↗
PubMed1993

[Analysis of type II pneumocyte protection by pneumoplegic solutions. An experimental in vitro study of lung preservation for transplantation].

With the aim of studying the physiopathological mechanism of lung preservation, we have valued the Pneumocytes Type II viability after six hours of incubation at 4 degrees C in extracellular (Ringer Lactate) and intracellular (Collins, Euro-Collins and Belzer) solutions. The cells have been cut off from adult rat's lung using the modified Dobbs' method. Alveolar Type II viability have been valued using two methods: the total protein content in each culture and the metabolic function of the cells using the rate of protein synthesis by means of 35 S methionine uptake assay. The results have demonstrated a significant difference (p < 0.05) using extracellular solution instead of intracellular. Besides, we have observed a better Pneumocytes Type II survival during Belzer's solution incubation comparing with Collins and Euro-Collins (p < 0.05). Pneumocytes type II require for a better preservation a specific solution that must be similar to extracellular fluid and added with substances able to minimize noxious events during preservation.

Albumins↗
PubMed1992

Serum beta 2-microglobulin levels and p24 antigen, lymphocyte depletion and disease progression in human immunodeficiency virus infection.

Abnormally elevated serum beta 2-microglobulin levels have been associated with progression of human immunodeficiency virus disease. In this study we have analyzed the relationship between serum beta 2-microglobulin levels of patients at different stages of the disease and serological and immunological parameters commonly used for monitoring the infection. The investigation was performed on 150 patients and 30 controls during the period from March 1989 to March 1990. At that time, 30 patients had the acquired immunodeficiency syndrome or its related complex and 120 had persistent generalized lymphadenopathy or were asymptomatic. Thirty-nine antibody-negative subjects, belonging to a high-risk group for the acquired immunodeficiency syndrome, were used as controls. All patients had normal renal function. There was a significant relationship between increased serum beta 2-microglobulin levels and the presence of p24 antigen, a decrease in the total number of lymphocytes (less than or equal to 1500/mm3) and a decrease in CD4+ T lymphocytes (less than or equal to 200/mm3). No significant relationship between serum beta 2-microglobulin levels and CD3+ T lymphocytes was found.

Adolescent↗
PubMed1992

Glucagon-independent renal hyperaemia and hyperfiltration after an oral protein load in Child A liver cirrhosis.

The work was designed to study the effects of a meat meal on glomerular filtration rate (GFR), renal plasma flow (RPF), and plasma concentrations of glucagon, insulin, growth hormone, renin, aldosterone, total amino acids, and NH3 in healthy humans (H) as well as in patients with Child A liver cirrhosis (LC). The meat meal produced renal hyperaemia and hyperfiltration without changes in the filtration fraction. Fractional Na excretion in urine increased significantly after the meat meal only in LC. Hyperinsulinaemia and hyperglucagonaemia were seen at baseline in LC and were not affected by the meat meal, whereas in H glucagon concentration increased significantly over baseline within 30 min from the meat meal and insulin within 60 min. Growth hormone concentration was normal at baseline in LC and increased significantly 120-180 min after the meal, whereas it was not affected in H. Renin and aldosterone were stable in both H and LC. Plasma amino acid concentration began to increase 60 min after the meat meal, when hyperfiltration was present. The data indicate that in human Child A cirrhosis of the liver renal haemodynamic response to a meat meal is independent of changes in glucagon.

Dietary Proteins↗
PubMed1991

Lithium clearance in patients with chronic renal failure.

Lithium clearance (CLi) was studied in the healthy subjects (H) and in patients with chronic renal failure (CRF) with a mean GFR of 36.08 +/- 3.8 ml/min x 1.73 m2 in order to evaluate (1) the variability of CLi measurements; (2) the changes of CLi during the hyperfiltration response to a meat meal (2 g/kg b.w. of protein), and (3) the effects on CLi of different protein intakes. CLi correlated with GFR and with urinary sodium, FeLi correlated with FeNa in H and CRF. The intraindividual standard deviation (IISD) of GRF, CLi and FeLi assessed in triplicate studies in the course of a single experiment averaged 4.70, 7.15 and 10.69% in CRF and 1.77, 4.09 and 4.61% in H. When IISD for GFR, CLi, and FeLi was assessed in triplicate measurements in the course of 3 studies performed at 1-week intervals (day 1, day 8, day 15), it averaged 7.36, 9.21 and 15.72% in CRF and 1.83, 5.08 and 5% in H. During the hyperfiltration response to a meat meal, CLi and FeLi did not change in CRF and increased significantly in H. In 10 patients with CRF who were switched for 3 weeks from a protein intake of 0.85 g/kg to a protein intake of 0.60 g/kg, GFR was significantly (p less than 0.001) reduced by 29%, while CLi was stable. The data indicate that because of its variability, CLi is of little use in experiments designed to study subtle changes in renal Na transport.

Adult↗
PubMed1991

Renal hemodynamics, plasma amino acids and hormones after a meat meal in progressive nephron loss.

Ten patients with chronic renal failure (GFR 29-97 ml/min), on free diets providing 1 g/kg B.W. of proteins, ingested an oral protein load (meat meal, 2 g/kg B.W.). GFR and RPF increased significantly over baseline with no change in filtration fraction. Within 30 min of the meal and for the next 3 h a statistically significant increase was observed in the plasma concentrations of the following amino acid groups: essential, non-essential, total, branched-chain, ketogenic, glycogenic, glycogenic and ketogenic, basic, acid, polar and non-polar. At 30 min the smallest increase was seen in acid and polar amino acids (6.7% and 7.6%, respectively). At 180 min the largest increase (78.8%) was seen for glycogenic and ketogenic amino acids and total plasma amino acids were 1.58 times baseline. After the meat meal plasma glucagon and insulin rose significantly, while growth hormone, plasma renin activity and aldosterone did not vary.

Adult↗
PubMed1987

The design of transverse filters and their use in visual electrograms.

The subject under study is a digital filtering method which combines the advantages of both theoretical precision and great flexibility of use. This method has enabled us to develop transverse filters which respect the principle of causality and offer a fast and simple solution in the filtering of electrophysiological potentials. Here we present both the design of transverse filters and their application to visual electrophysiological signals.

Electroretinography↗
PubMed1987

Protein balance during very-low-calorie diets for the treatment of severe obesity.

Very-low-calorie diets (less than 500 kcal/day; VLCD) are widely used for the treatment of severe obesity. We report the effects of such diets, consisting of proteins only or proteins and carbohydrates (CH), on nitrogen balance and protein nutritional status of morbidly obese patients. Cumulative nitrogen loss, serum albumin, transferrin, prealbumin (PA) and retinol-binding protein (RBP) concentrations, and plasma amino acid profile were determined in two groups of obese patients: 5 subjects (3 women, 2 men: BMI 55.3 +/- 2.2 kg/m2) subjected for 4 weeks to a protein VLCD (40 g protein + 2 g fat) and 7 others (4 women, 3 men: BMI 45.6 +/- 2.8 kg/m2) received for the same length of time a protein + CH VLCD (34 g protein + 26 g CH). Nitrogen balance was determined weekly whilst plasma and serum variables were measured on days 0, 3, 5, 10, 20 and 28 of treatment. Nitrogen balance did not significantly differ between the two groups of patients throughout the treatment. Serum PA and RBP concentrations decreased from day 5 and day 10, respectively, in both groups. Plasma amino acids showed a similar pattern in the protein and protein + CH groups. Alanine gradually decreased below baseline values; after a peak value on day 5, branched-chain amino acids (valine, leucine, isoleucine) returned to baseline values in both groups. In conclusion, in severely obese patients subjected to VLCD, nitrogen balance, labile protein concentrations and plasma amino acid profile are not significantly affected by adding CH to proteins.

Adult↗
PubMed1984

Diffusion of the retinal layers of the living human eye.

We measured the modulation depth of an interference pattern after double passage through the eye with different entry positions of the linearly polarized incident beam in the pupil plane. This shifting of the incident beam greatly modifies the mean irradiance and the modulation depth of the aerial image, whatever the direction of the polarizer. These measurements give a better understanding of the respective contributions of the retinal layers to the formation of the aerial image. Consequently, the modulation transfer function of the optics of the eye deduced from measurements with the aerial image must be considered cautiously.

Adult↗