Calcium stimulated calcitonin measurement: a procedural proposal.

Human calcitonin (hCT) is a tumor marker essential to the diagnosis and follow-up of medullary thyroid cancer (MTC). Current consensus recommends hCT measurement when initially evaluating thyroid nodules; if slightly elevated, a confirmatory stimulated calcitonin test is commonly performed, usually using pentagastrin. In recent years the supply of pentagastrin was not guaranteed with long periods of unavailability; the outlook for future availability is unknown. Therefore it is desirable for many institutions to establish a procedure for calcitonin stimulation using a stimulant with a secure supply; stimulation of calcitonin using calcium represents the easiest alternative.Several schemes and dosages have been used in the past for calcium stimulated calcitonin measurement. In this paper we propose a procedure for calcium stimulated calcitonin measurement based on our experiences. Furthermore we will briefly point out the limitations of this method with regard to available data in literature.

Is medullary thyroid cancer predictable? A prospective study of 86 patients with abnormal pentagastrin tests.

BACKGROUND: The aim of this prospective study was to distinguish biochemically between C-cell hyperplasia (CCH) and medullary thyroid cancer (MTC) before surgery. METHODS: Eighty-six consecutive patients with an abnormal stimulated calcitonin level (> 100 pg/mL) underwent thyroidectomy and lymph node dissection. In sporadic MTC, histopathologic findings and postoperative biochemical outcomes were documented prospectively and correlated with preoperative basal and stimulated calcitonin levels. RESULTS: Analysis of variance revealed a highly significant difference in basal/stimulated calcitonin levels (P < .0001), with a comparison of CCH (n = 39 patients) and sporadic MTC (n = 38 patients). With a comparison of sporadic MTC N0 M0 (n = 25 patients) and N1 M0/1 (n = 12 patients), the basal calcitonin level was significantly different (P < .05). There was a close correlation between the n-log of basal/stimulated calcitonin level and the n-log of the tumor volume; there were also different distributions of the n-log of basal/stimulated calcitonin level among CCH, MTC N0, and MTC N1. Assuming that a basal calcitonin level of more than 64 pg/mL and/or a stimulated calcitonin level of more than 560 pg/mL implies MTC, 31 of 38 patients with sporadic MTC were detected before surgery. Three patients were predicted false positive (neoplastic CCH). Patients with stimulated calcitonin levels of less than 129 pg/mL had CCH only. Patients with basal calcitonin levels of less than 22 pg/mL and sporadic MTC (7/38 patients) were node negative. CONCLUSIONS: All patients with abnormal pentagastrin tests showed C-cell pathologic evidence. Sporadic MTC was predicted in 81% of the patients; CCH or N0 was predicted in 36% of the patients. Central neck dissection is recommended to avoid difficult reoperations. Lateral neck dissection is possible "on demand."

Development and validation of transient isotachophoretic capillary zone electrophoresis for determination of peptides.

Although capillary zone electrophoresis (CZE) is known for its high resolution power and low mass detection limits, the concentration detection limits are rather poor when ultraviolet absorbance detection is used. To overcome this limitation, several on-column transient isotachophoresis (tITP) protocols have been developed and validated for the determination of both cationic and anionic model peptides, separately. Using this preconcentration method, up to 72% of the capillary can be filled with sample solution, without any loss in resolution. Thus, without any modification of the hardware set-up, the sensitivity is increased about two orders of magnitude. For the model cationic peptides (gonadorelin, angiotensin II) good linearity and reproducibility is observed in the 20 to 100 ng/mL concentration range. For the anionic peptides (N-t-Boc-Pentagastrin and two related peptides), a tITP method was developed using a dynamically coated capillary. The coating was prepared by adding Fluorad FC-135 to the leading electrolyte buffer. In this way a positively charged bilayer was formed on the inside of the capillary, producing an electroosmotic flow towards the outlet using reversed polarity conditions. In this way, acceptable analysis times were achieved. Using the developed tITP method, up to 72% of the capillary can be filled with sample solution as well. The anionic peptides are separated even better than when using CZE conditions. Linearity and reproducibility in the 20-100 ng/mL range proved to be excellent.

Secretory, endoscopic and histophatologic changes and prevalence of Helicobacter pylori in the gastroduodenal mucosa in patients with chronic alcoholic pancreatitis

Com o intuito de determinar, em nosso meio, a prevalência de ulcera péptica em pancreatopatas crônicos de etiologia alcoólica, e sua eventual relaçäo com alteraçöes histopatológicas, endoscópicas e da produçäo ácida, bem como a ocorrência de colonizaçäo pelo Helibacter pylori na mucosa gastroduodenal desses pacientes, foram investigados prospectivamente 30 pancreatopatas crônicos (Grupo I) e dez controles (Grupo II). Todos os pacientes foram submetidos a avaliaçäo clinica, teste de secreçäo ácida, basal e estimulada por pentagastrina, dosagem de gastrinemia basal, esofagogastroduodenoscopia com biopsia de fundo, corpo e antro gastricos e de bulbo duodenal, para identificaçäo e gradaçäo da inflamaçäo e ocorrência do Helicobacter pylori

Immunocytochemical evidence for the colocalization of neurotensin/xenopsin- and gastrin/caerulein-immunoreactive substances in Xenopus laevis gastrointestinal tract.

Distribution and association of neurotensin (NT)- and xenopsin (XP)-like peptides were investigated using immunocytochemical techniques in the amphibian gut. Antisera against both groups of peptides showed an identical distribution pattern of NT- and XP-positive cells in Xenopus laevis gastrointestinal tract. Immunolabeling of consecutive semithin sections revealed the coexistence of NT- and XP-like substances within cells of the stomach and small intestine. Recent reports of the colocalization of XP-like material with gastrin in mammalian G cells led us to study the association of NT/XP-like peptides with members of the gastrin/cholecystokinin (CCK)/caerulein (G/C) family in amphibians. The data obtained from immunolabeling serial sections with NT/XP-specific and G/C-specific antisera show that in some intestine NT/XP- and G/C-like peptides do exist in the same cells. In the stomach, however, G/C-like material is confined to endocrine cells of the antral region, while NT/XP-like substances occur in distinct cells accumulating in cardial glands but absent in the pyloric glands. Our findings thus indicate that in amphibian gastrointestinal tract there is some association between the regulatory peptide families NT/XP and G/C, similar to mammals. The regional distribution of both hormone families, however, is different from that in mammals.

[An improved synthesis of pentagastrin (Acignost)]. / Eine verbesserte Synthese von Pentagastrin (Acignost).

The large-scale synthesis of the pentapeptide Boc-beta-Ala Trp-Met-Asp-Phe-NH2 is described and a convenient procedure for purification of the crude peptide will be reported.

Simulated meal test. A new method for estimation of parietal and non-parietal secretion in response to food.

In ten healthy volunteers gastric secretion was stimulated by a simulated meal, in which the cephalic phase was activated by modified sham feeding and the gastric phase by repeated instillations and withdrawals of a meat soup. The gastric aspirates were analyzed for acid and pepsin and the outputs quantitated by the recovery of an unabsorbable marker (polyethylene glycol). Instillation of liquid meal without sham feeding produced 58% and 65% of pentagastrin-stimulated secretion of acid and pepsin, respectively. Concomitant sham feeding increased the stimulation further, so that the outputs evoked by the combined stimulus (simulated meal test) were similar to that achieved by the pentagastrin test. The coefficient of variation of duplicate tests was 4.5% for acid and 5.4% for pepsin output. The technique is suitable for measuring both parietal and non-parietal secretion in response to food.