Single diastereomeric desaminotyrosylalanyl tetra- and heptapeptides with opioid antagonistic activity.

The N-terminal dipeptide Tyr-d-Ala of a mu-selective agonist, dermorphin tetrapeptide (DT, H-Tyr-D-Ala-Phe-Gly-NH2) and delta-selective agonist deltorphin C (DEL-C, H-Tyr-D-Ala-Phe-Asp-Val-Val- Gly-NH2) was changed into an aminodiacyl moiety. The relevant synthetic step is a nucleophilic substitution of bromine from a chiral 2-bromopropanamide by the amino group of tyrosine, with overall retention of configuration. The resulting pseudo tetra- and heptapeptides I-VI were characterized for mu- and delta-opioid receptor binding properties using [3H]DAGO and [3H]DPDPE, respectively, and in a bioassay using guinea pig ileum (GPI) and mouse vas deferens (MVD). As a result of chemical alteration of N-terminal depeptide moiety, all synthesized analogs showed considerable reduction in opioid receptor affinity compared to mu- and delta-prototypes (500-fold on the mu-site, analog I, and 125-fold on the delta-site, analog IV). Interestingly, analogs I and IV showed moderate antagonist activity, respectively, on GPI and MVD, with pA2 values of 6.05 and 6.82. Analog IV did not exhibit the delta-antagonist potency and delta-selectivity of TIPP peptides.

Is CA242 really a new tumour marker for pancreatic adenocarcinoma?

CA 242, a sialylated carbohydrate epitope situated on the same macromolecule as CA 50 has been proposed as a new tumour marker for pancreatic cancer (PC). The aims of the present study were: (1) to evaluate serum CA 242 versus CA 19-9 in PC patients, and (2) to assess whether these markers can predict tumour spread or patient survival. We studied 59 healthy controls, 27 PC patients, 12 chronic pancreatitis cases, 107 with extra-pancreatic gastrointestinal tumours, 30 with benign jaundice and 24 with benign extra-pancreatic gastrointestinal diseases. Mean CA 242 values were significantly higher in PC than in any other group; CA 19-9 showed a similar pattern. The best diagnostic efficacy (ROC curves analysis) in diagnosing PC was 86% for CA 242 and 84% for CA 19-9, using cut-off values of 60 and 80 U/ml, respectively. In PC, serum levels of both markers were unrelated to tumour spread or size; in PC patients with high levels of CA 242 or CA 19-9 survival was significantly shorter. CA 242 and CA 19-9 were correlated both when considering all the patients together (r = 0.962, p < 0.001) and PC alone (r = 0.880, p < 0.001). Given the very close relationship between CA 242 and CA 19-9, we tested for cross-reactivity between CA 242 antigen and CA 19-9 antibody: CA 242 antigen with CA 19-9 antibody produced a similar curve to CA 242 antigen and its corresponding antibody. In conclusion, CA 242 showed similar diagnostic values to CA 19-9 in assessing PC patients; both seem unrelated to tumour size or spread, but seem to predict survival. Their remarkably similar behaviour is due to cross-reactivity between CA 242 antigen and CA 19-9 antibody, so CA 242 cannot, in our opinion, be considered a new tumour marker for PC.

Diabetes mellitus in pancreatic cancer follow-up.

The aim of this study was to assess the behavior of fasting serum glucose, C-peptide levels and OGTT in pancreatic cancer follow-up. We studied 49 patients with pancreatic cancer (stage I = 8 pts; II = 16 pts; III = 12 pts; IV = 13 pts). At diagnosis 13/49 patients had fasting serum glucose levels of above 140 mg/dL. Of the remaining 36 pts, 22 underwent OGTT, which indicated diabetes mellitus in 9/22 (41%) and impaired glucose tolerance in 7/22 (32%) cases. C-peptide basal values were within the normal range (0.8-2.0 micrograms/L) in 14/49 (28%), above 2.0 micrograms/L in 6/49 (13%) and below 0.8 micrograms/L in 29/49 (59%) of the cases. No significant correlation was found between tumor stage or size and the presence of diabetes or of a reduced glucose tolerance. Twenty-four patients underwent curative resection (group 1) and 16 palliative resection, while the remaining nine did not undergo surgery (group 2). Group 1 and 2 patients had a follow-up of 2 to 40 months (mean = 14 months) and from 1 to 7.5 months (mean = 3.5 months) respectively. In group 1 patients no significant difference was found between pre- and post-operative fasting serum glucose levels. However, in 11/15 (73%) patients who underwent OGTT before and after surgery, an improvement in glucose tolerance was observed after tumor resection. In group 2 patients, a significant increase in fasting serum glucose levels was found during follow-up. In neither of the groups studied were significant variations found in C-peptide levels during the follow-up, although a slight increase was observed in patients who did not undergo surgery. In conclusion, the reduced glucose tolerance or frank diabetes mellitus, which frequently occurs during the onset of pancreatic cancer, does not seem to be related to tumor stage or size. Curative resection ameliorates glucose intolerance, while tumor persistence can enhance serum glucose levels.

Beta-cell function in pancreatic adenocarcinoma.

To evaluate beta-cell function in patients with pancreatic cancer, the glucagon stimulation test was performed in seven patients with pancreatic adenocarcinoma, seven patients with type I diabetes mellitus, seven patients with type II diabetes mellitus, and in seven healthy controls. C-peptide serum levels were determined before and after a 1-mg i.v. glucagon injection. Basal C-peptide values were normal or slightly increased in pancreatic cancer and type II diabetic patients and low in type I diabetic patients. Following glucagon stimulation, no significant increase was observed in C-peptide values of type I diabetics and pancreatic cancer patients, whereas significant increases occurred in controls and type II diabetics. It is concluded that the altered beta-cell function found in pancreatic cancer patients may lead to hyperglycemia, which is frequently associated with this tumor type.

C-peptide pattern in patients with pancreatic cancer.

The pathogenetic mechanism underlying glucose intolerance in pancreatic cancer is still unclear. We studied the pattern of three glucose regulating hormones (C-peptide, glucagon and GH) in pancreatic cancer patients with (N = 34) and without (N = 8) hyperglycemia, and compared the findings made with those from subjects with other hyperglycemic conditions of well-known origin [type I diabetes mellitus (8 cases) and diabetes mellitus secondary to chronic pancreatitis (13 cases) or liver cirrhosis (4 cases)]. In hyperglycemic pancreatic cancer patients, C-peptide was absent in 26% of the cases, reduced in 24%, elevated in 29% and within the normal range in the remaining 21%. In normoglycemic pancreatic cancer this hormone was reduced in two cases (25%) and within the normal range in all the others. GH was within the normal range in all cases: glucagon was below the normal range in some hyperglycemic pancreatic cancer patients (41%) or within the normal range in all the remaining patients. No correlations were found between the three hormones when findings from subjects were considered all together. However, in pancreatic cancer C-peptide and glucagon presented consensual variations. C-peptide, glucagon and GH levels were not related to tumor volume; glucagon was found to be associated with liver metastases. C-peptide was correlated with serum ALT and ALP. We may conclude that hyperglycemia associated with pancreatic cancer may be caused by different mechanisms. In some cases a reduced secretion of both insulin and glucagon was observed, as occurs in chronic pancreatitis. In the majority of patients, beta cell function appears normal, and the hyperglycemic state may depend on an altered peripheral sensitivity to insulin due to the pancreatic pathology itself or to consensual liver involvement.

Structure-activity relationship in the mutagenic effect of chiral or racemic 2-bromo-propanamides on Salmonella typhimurium.

Some 2-bromo-propanamides were prepared and tested for direct mutagenicity in Salmonella typhimurium TA 100. Results confirm the mutagenic activity of 2-bromo-N-benzyl-propanamide and indicate that it is independent of enantiomeric configuration. A variation in the chemical structure, namely, the addition of a methyl group at the benzylic carbon, causes the four resulting diastereomers to be devoid of any activity. Conversely, some racemic ring-substituted methoxy and/or hydroxy derivatives of the parent compound displayed mutagenic properties, causing an increase in the number of his+ revertants up to 524 per milligram per plate.

Selective mutagenic activity of 2-bromo-propanamides on Salmonella typhimurium. A structure-activity study.

Nineteen 2-halogeno-acetamides, -propanamides, and -iso-butyramides and four related epoxyamides were tested as mutagens for Salmonella typhimurium TA100. Mutagenic activity was observed in strictly selected 2-halogenoamides and in all epoxyamides. The effectiveness of 2-halogenoamides depends upon: the character of the carbon carrying the halogen (1 degree, 2 degrees, 3 degrees); the nature of the halogen (Br, Cl); the substitution at nitrogen. Some considerations concerning the selectivity observed are presented.