[Lipids in enteral nutrition: does an optimal ratio between omega-6 and omega-3 exist?]. / I lipidi in nutrizione enterale: esiste un rapporto ottimale omega-6/omega-3?

The ratio between PUFA omega-6 and omega-3 is 3:1 in the unweaned, 5:1 in the young man, 5-10:1 in the adult. The PUFA omega-6 prevail over omega-3 because of elongation and desaturation processes. Linoleic acid is the beginning of the omega-6 series, a-linolenic acid of the omega-3 series. Both acids give rise to PUFA which must be introduced with diet because the human race is not able to synthetize. They represent the 2-6% of total daily caloric intake and correspond about to 10 g every day according to LARN 1986-1987. During some diseases (after surgery, trauma, sepsis, etc.) their need increases until 25-50 g every day, so it is necessary a proper enteral nutrition (EN). For this reason the bromatological composition of diets for EN must respect the physiological ratio between omega-6 and omega-3 PUFA. The composition of 37 diets for EN was examined and it was found that 7 (18%) have a proper ratio between the two series of PUFA. Twenty-three (62%) do not signal any ratio, two have 6:1, two 4.5:1, in three the ratio is in favour of omega-3. Then the concentration of linoleic and alfa-linolenic acid was examined and it was found that 24 (64%) diets signal the concentration of linoleic acid, 10 (27%) of both acids, two have no data about and only one diet reports the concentration of alfa-linolenic acid. A more exact formulation of PUFA into the composition of EN diets is suggested because PUFA are now recognized to play an important role in the fields of inflammation and immunity.

Serum immunoreactive elastase: is it useful for the diagnosis of pancreatic cancer?

We have measured serum immunoreactive pancreatic elastase 1 concentrations in 90 patients with pancreatic cancer in order to determine its usefulness in the diagnosis of this tumor. Abnormal elastase 1 concentrations were found in only 58 (64.4%) of the 90 patients. Fifty (55.5%) had abnormally high values, and eight (8.9%) had abnormally low values. No significant differences in elastase 1 levels were observed between patients with resectable cancer (n = 15) and those with unresectable cancer (n = 75). Moreover, no significant differences were found between elastase 1 concentrations of patients with pancreatic cancer and those of 71 patients with chronic pancreatitis. We conclude that serum elastase 1 measurement does not represent a significant advance in the diagnosis, whether early or late, of pancreatic cancer.

A new faecal chymotrypsin method for evaluating the exocrine pancreatic function in patients with different pancreatic diseases.

Using a new colorimetric method we measured the faecal chymotrypsin in 407 subjects, divided as follows: 252 adult subjects with a normal exocrine pancreatic function as shown by duodenal intubation, 24 adult patients with a mild to moderate pancreatic insufficiency, and 26 adult patients with severe pancreatic insufficiency. In addition, 40 healthy children, 50 children with chronic diarrhoea, and 15 with cystic fibrosis were studied before and after substituting enzyme therapy. Faecal chymotrypsin was found to be useful in evaluating the degree of exocrine functional insufficiency in subjects with diseases of the pancreas that had already been clinically ascertained. The same cannot be said for its ability to provide an early diagnosis of subjects with a slight-moderate insufficiency in exocrine pancreatic function.

Serum elastase 1 in clinical practice.

Using radioimmunoassay, we tested serum elastase 1 (E1), an enzyme secreted only from the pancreas, in 200 subjects as follows: 39 healthy subjects as controls, 56 patients with diseases of the digestive tract, 66 patients with hepatobiliary diseases, and 39 patients with pancreatic diseases. The serum E1 showed high specificity and proved very useful in the diagnosis of acute pancreatitis. However it was not useful in diagnosis of clinically silent chronic pancreatitis, nor in its functional evaluation. On the other hand, it was found to be a valuable guide in revealing a concomitant pancreatic pathology during hepatobiliary diseases. Further investigation is needed of the behavior of E1 in patients who have undergone a total pancreatectomy, where the enzyme remains measurable, and in those with an ileocolic disease in an acute phase where E1 is increased in many patients.

Different responses of serum cationic trypsinogen to secretin and bombesin in normal subjects and patients with chronic alcoholic pancreatitis.

We evaluated the behavior of serum cationic trypsinogen (SCT), an enzyme of solely pancreatic origin, in 30 patients with chronic pancreatitis and 25 healthy subjects as a control, after secretin and bombesin stimulation. After both the stimulations, serum cationic trypsinogen is unable to distinguish between the healthy control subjects and the patients with chronic pancreatitis. On the other hand, after secretin, the enzyme is able to separate chronic pancreatitis patients with different levels of exocrine function insufficiency. It does so with a greater statistical significance than that obtained by the rapid injection of bombesin and equal to that of trypsin into the duodenal juice during duodenal intubation. For these reasons, as well as the absence of any side-effects, secretin is preferred to bombesin stimulation in the evaluation of the exocrine pancreatic function in patients with chronic pancreatitis.

Effect of secretin upon the levels of pancreatic enzymes in blood serum.

We have evaluated the serum changes of trypsin, pancreatic isoamylase and lipase, after rapid infusion of secretin, in 45 patients with chronic pancreatitis compared with 35 healthy control subjects. On the basis of duodenal intubation results, chronic pancreatitis patients were divided into two subgroups at different levels of functional impairment. Using the peak activities of the enzymes we have been able to separate the two chronic pancreatitis subgroups by statistical difference; only trypsin distinguishes healthy control subjects from mild to moderate chronic pancreatitis. Therefore, we propose to put into clinical practice this serum provocative test to evaluate the functional damage of an established chronic pancreatitis.

Clinical significance of serum pancreatic enzymes in the quiescent phase of chronic pancreatitis.

The most commonly used serum enzymes in pancreatic diseases are total amylase, pancreatic isoamylase, lipase and trypsin. To determine which of these enzymes is the most useful in the diagnosis of clinically quiescent chronic pancreatitis and which enzyme best reflects exocrine functional reserve, we studied 22 healthy control subjects, 44 patients with gastrointestinal, liver and biliary tract diseases, and 25 patients with chronic pancreatitis. On the basis of duodenal intubation, the latter were divided into two subgroups: one group of 13 patients with slight to moderate secretion deficiency and another of 12 patients with severe exocrine insufficiency. Of the enzymes studied, lipase, trypsin and pancreatic isoamylase are equally suitable for the evaluation of function in severe chronic pancreatitis, but not for the early diagnosis of the disease. Results for total amylase are not reliable so that its use in the study of chronic pancreatitis is not advisable.