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Biomedical subjects

A Amato

Publications and source records attributed to A Amato.

At least 127 records · Page 7Linked to original sources
PubMed1986

Substrate preferences of human placental DNA methyltransferase investigated with synthetic polydeoxynucleotides.

A DNA methyltransferase partly purified from human placenta has been tested on a variety of synthetic polydeoxynucleotides. The results showed that: the enzyme is most active as a 'maintenance' or 'hemi-' methylase but also has some de novo methylating activity; the presence or absence of A or T in the substrate strand has little influence on maintenance or de novo activity, while polymers containing C but not G in the same strand are poor de novo substrates and bind poorly to the enzyme; single-stranded polymers are about as good substrates as double-stranded ones, and the effects of nucleotide composition (particularly G and mC content) on enzyme activity with single strands are similar to those with double-stranded polymers; strands in which all the cytosines are methylated bind the enzyme well. A mechanism is suggested involving two different sites on the enzyme that recognize CG and mCG, and which rationalizes the activity of eukaryotic DNA methyltransferases towards single-stranded DNA.

DNA↗
PubMed1986

Inosine pranobex-BAN increases the resistance to the challenge with cells or cell-free fluid from Yoshida ascites tumor.

Inosine pranobex-BAN injected intraperitoneally at a daily dose of 500 mg/kg for 15 days into young Sprague-Dawley rats, beginning 24 hours after the implantation of Yoshida ascites tumor cells and the injection of cell-free ascites fluid from the same neoplasia, increased the resistance to the tumor in both cases. This antitumor activity of the drug was mediated by its action on cellular immunity of the host. In our model we considered the role of macrophages.

Animals↗
PubMed1984

Relation between serum cathodic trypsinogen levels and exocrine pancreatic function.

To assess the relation between circulating cathodic trypsinogen (CT) levels and exocrine pancreatic function, and to compare the radioimmunological with the enzymatic measurement of duodenal trypsin, we evaluated exocrine pancreatic function in 34 controls and in 32 patients with proven chronic pancreatitis (CP). There was no relation between CT and the volume rate of pancreatic secretion, nor did serum CT levels correlate with the concentration output of duodenal bicarbonate in controls. However, in CP patients, there was a low value of the correlation coefficient. A good relationship between serum CT levels and duodenal trypsin secretion was detected when the trypsin content was expressed as the mean value of both concentration and output. The enzymatic estimation of duodenal trypsin was related closely to its radioimmunological measurement, but there was better correlation of serum CT to duodenal immunoreactive than to enzymatic trypsin. In patients with CP, low levels were observed in 29% of cases with serum CT estimation, in 75% with duodenal bicarbonate, and in 63% and 79% with enzymatic and immunoreactive trypsin outputs, respectively. We conclude that serum CT levels may reflect the functioning mass of pancreatic acinar cells and that in assessing pancreatic secretory capacity, the immunoreactive measurement of trypsin excretion is more sensitive than the enzymatic measurement and as accurate as bicarbonate output.

Bicarbonates↗
PubMed1983

Dose-related effect of bombesin on serum cationic trypsinogen levels.

The present study has been addressed to study the serum cationic trypsinogen (CT) response after the ingestion of a mixed meal and following the infusion of caerulein and bombesin. On the first day of study a mixed meal was administered to 12 normal volunteers. On the following day 6 of these subjects received bombesin infusion in stepwise increasing doses (18.7, 37.5, 75 and 150 pM/kg/h) every 30 min, while the remaining 6 subjects received caerulein infusion (18, 37, 75 and 150 ng/kg/h). The time course of the serum CT response to bombesin (150 pM/kg/h) was also studied in 6 patients with distal gastrectomy. Serum CT levels did not vary after the ingestion of the meal or the infusion of caerulein. Bombesin infusion was followed by a dose-related increase on serum CT levels, but it had no effect on serum amylase and isoamylases. The CT concentrations peaked 30 min after starting the infusion and remained unchanged as long as bombesin was administered. It is suggested that the bombesin action on the pancreatic acinar cells may be direct and not mediated through cholecystokinin or gastrin release.

Bombesin↗
PubMed1983

Serum immunoreactive cationic trypsinogen response to secretin in normal subjects.

Serum immunoreactive cationic trypsinogen (ICT) response to bolus injection of secretin (1 Clinical Units/kg of body weight) has been evaluated in 123 normal controls and related to sex, age, smoking habit, and alcohol and coffee consumption. A 100% increase of serum immunoreactive cationic trypsinogen levels after secretin has been considered as a positive response (R+). When the population was considered as a whole, 55% of subjects proved to be R+ and the remaining were R-. In the R+ group the serum immunoreactive cationic trypsinogen response was appreciated as early as 5 min after secretin and even after 2 min in the few cases in which it was evaluated. It is suggested that this direct leakage of the proenzyme from the pancreas may be due to an increased sensitivity of the pancreas to secretin. Coffee consumption and age of subjects did not affect the test. Male sex, smoking habit, and alcohol intake were associated with a significantly higher percentage of R+. Therefore, we suggest that alcohol and smoking might result in the development of biochemical abnormalities in pancreatic function before the appearance of clinical evidence of pancreatic disease.

Adult↗